Abstract
Background: Many studies have attempted to determine the incidence, predictors, and outcomes of cerebrovascular stroke after cardiac surgery, with different, sometimes contradictory, results because of differences in population risk profiles, study design, and surgical details.
Methods: We retrospectively reviewed the records of all adult patients who underwent cardiac surgery between January 2018 and January 2023. Univariate, multivariable, and survival analyses were performed to identify the outcomes and predictors of ischemic and hemorrhagic strokes.
Results: Of the 1334 patients studied, 70 (5.2%) patients had ischemic stroke, 23 (1.7%) had intracranial hemorrhage (ICH), and 9 (0.7%) had combined ischemic and hemorrhagic strokes. The patients who developed strokes had longer cardiopulmonary bypass (CPB) time (165.5 [126, 234] versus 136 [104, 171] min, p < 0.001) and aortic cross-clamping time (112 [79, 163] versus 89 [75, 121.5] min, p < 0.001), with higher rates of intra-aortic balloon pump (IABP) use (13.3% vs. 4.4%, p < 0.001), veno-arterial extracorporeal membrane oxygenation use (24.8% vs. 12.37%, p < 0.001), and mediastinal exploration for bleeding (22.9% vs. 8.9%, p < 0.0011). The patients who developed strokes showed increased hospital mortality (37.1% vs. 5.6%, p < 0.001), new need for dialysis (29.5% vs. 10.7%, p < 0.001), higher rate of tracheostomy (13.3% vs. 1.2%, p < 0.001), and longer intensive care unit (ICU) stay (12 [7, 28] versus 3 [2, 8] days, p < 0.001) and post-ICU stay (16 [7, 39] versus 5 [3, 10] days, p < 0.001). Follow-up for 36.4 (21.67, 50.7) months revealed an insignificant mortality difference, but there was an increased risk of recurrent cerebrovascular strokes. Cox-proportional hazards regression showed an increased risk of hospital mortality after cardiac surgery in patients who developed acute ischemic stroke (HR: 5.075, 95% CI: 3.28–7.851, p < 0.001) and ICH (HR: 12.288, 95% CI: 7.576–19.93, p < 0.001). Logistic multivariable regression showed that increased age, hyperlactatemia, redo cardiotomy, history of old stroke, CPB time, and perioperative IABP use were the predictors of ischemic stroke. Young age, old ICH, hyperlactatemia, and hypoalbuminemia were the predictors of postoperative ICH. Postoperative ICH, ischemic stroke, atrial fibrillation, chronic kidney disease, blood lactate level 24 h after surgery, and increased age were the independent predictors of mortality.
Conclusions: Ischemic and hemorrhagic cerebrovascular strokes are serious complications that increase postoperative mortality and prolong hospitalization after cardiac surgery. Atrial fibrillation was not a significant predictor of postoperative stroke but was a predictor of hospital mortality. Careful attention should be given to maintaining hemodynamic stability and minimizing CPB time, especially in patients with a history of cerebrovascular strokes and redo cardiotomy.
Keywords: atrial fibrillation, cardiac surgery, cerebrovascular stroke, intracranial hemorrhage, ischemic stroke, lactate, mortality
1. Background
Neurological dysfunction is a serious complication of cardiac surgery and includes altered consciousness, seizures, cognitive dysfunction, and focal deficits [1–3]. Cerebrovascular stroke after surgery is defined as an evident ischemic or hemorrhagic brain infarction that occurs during surgery or within the first 30 days postoperatively [4]. Stroke after cardiotomy is a devastating, multifaceted complication linked to increased mortality, prolonged hospitalization, increased costs, and impaired quality of life [1, 2, 5–7]. A thorough understanding of the relation of strokes and cardiac surgery is very important to improve the patients' outcomes and reduce the healthcare burdens and costs of treatment. The improvement of percutaneous cardiac interventions increased the risk profiles of patients subjected to cardiac surgery like advanced age and the presence of advanced diabetes mellitus, renal impairment, aortic calcification, or cerebrovascular diseases. Despite the advancements and new technologies of surgical and anesthesiologic techniques with intraoperative neurological monitoring, the occurrence of ischemic and hemorrhagic strokes is still challenging to diagnose early and effectively manage.
Many studies have attempted to determine the predictors and outcomes of postoperative stroke with different, sometimes contradictory, results, owing to differences in study design, population characteristics, and surgical details [2–9]. Most postoperative strokes occur early after cardiac surgery which confirms the direct relation to surgical details like aortic-clamping, cardiopulmonary bypass (CPB), proximal aortic grafting, which will result in cerebral hypoperfusion ± atheroembolism [7]. Moreover, there is limited data regarding intracranial hemorrhage (ICH) after cardiac surgery [10, 11]. The effects of surgical details and CPB vary according to the patients' risk profiles including underlying cerebrovascular disease, age, and concomitant diseases. We reviewed a cohort of adult patients who underwent cardiac surgery to identify the incidence, outcomes, and potential predictors of ischemic and hemorrhagic strokes after cardiac surgery.
2. Methods
The study enrolled all patients ≥ 18 years of age who underwent cardiotomy. The patients were divided according to occurrence of postoperative brain stroke, based on computed tomography (CT) or magnetic resonance imaging (MRI), into stroke and nonstroke groups. The stroke group was further subdivided into ischemic and hemorrhagic groups. Patients with ischemic stroke complicated with hemorrhagic transformation were included in the ischemic stroke group.
Acute stroke has been defined as neurological dysfunction that persists for 24 h because of brain focal vascular occlusion or rupture [12]. It is subdivided into ischemic and hemorrhagic types according to the vascular injury. The ICH includes four subtypes according to the location of blood accumulation: intracerebral, subarachnoid, extradural, and subdural hemorrhages [13].
All studied variables were collected from the hospital electronic records, and follow-up data were collected from hospital visits or phone calls. The preoperative variables included patient variables such as age, sex, body mass index, risk factors for cardiovascular and cerebrovascular diseases, left ventricular ejection fraction, antiplatelet and anticoagulant drugs, and laboratory workup. Perioperative details included type of surgery, intra-aortic balloon pump (IABP) use, aortic cross-clamping (ACC) time, CPB time, and use of veno-arterial extracorporeal membrane oxygenation (VA-ECMO). The laboratory variables included peak blood lactate and levels 24 h after surgery. The primary outcome was hospital mortality, and secondary outcomes included the length of intensive care unit (ICU) stay and hospitalization, occurrence of acute kidney injury (AKI), and new need for dialysis. Follow-up outcomes included mortality and cerebrovascular stroke recurrence.
2.1. Statistical Analysis
Data were coded and tested for normality. Non-normally distributed data were summarized as medians with interquartile ranges and compared using the Wilcoxon rank-sum test. For categorical variables, data were presented as frequencies with proportions, and comparisons were performed using the chi-squared or Fisher's exact test, as appropriate. Kaplan–Meier analysis was performed to obtain the survival curves of the studied groups, and log-rank tests were performed to determine statistical significance. Cox-proportional hazard regressions were used to get the hazard ratios (HRs) and 95% confidence intervals (95% CI) for postoperative ischemic and hemorrhagic strokes. The variables that were clinically and statistically significant in the univariate analysis were included in the forward multivariable logistic regression models to obtain the odds ratios (with 95% CI) for predicting hospital mortality and cerebrovascular stroke after cardiac surgery. The models were evaluated using the Hosmer–Lemeshow test of goodness and variance inflation test. Statistical analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 28 (IBM Corp., USA), and significance was determined as a two-sided p < 0.05.
3. Results
3.1. Characteristics of the Patients Studied
A total of 1334 patients were studied: 328 (24.4%) patients had postoperative neurological manifestations, 223 (16.7%) had negative brain scans, 70 (5.2%) had ischemic stroke, 23 (1.7%) had ICH, and 9 (0.7%) had combined ischemic and hemorrhagic strokes (Figure 1).
Figure 1.
The chart shows that 328 (24.4%) patients had postoperative neurological manifestations, 223 (16.7%) had negative brain scans, and 105 (7.9%) had focal brain damage. Seventy (5.2%) patients had ischemic stroke, 23 (1.7%) had ICH, and 9 (0.7%) had combined ischemic and hemorrhagic strokes.
Forty-four (3.3%) patients had unilateral ischemic stroke, and 35 (2.6%) patients had bilateral ischemic infarctions. Twenty-one (1.6%) patients had unilateral ICH, and 11 (0.8%) patients had bilateral ICH. Of the 32 patients with ICH, 16 (1.2%) had subdural hematoma (SDH), 14 (1.05%) had intracerebral bleeding, 1 (0.1%) had extradural hemorrhage (EDH), and 1 (0.1%) had both SDH and EDH. The median time from surgery to stroke diagnosis was 3.9 (IQR: 2.1, 9) days (Figures 2, 3, 4).
Figure 2.
A 29-year-old female with rheumatic heart disease and chronic atrial fibrillation developed facial drooping and acute hemiparesis 24 h after redo mitral valve replacement. Computed tomography of the brain and angiography revealed acute large right middle cerebral artery (MCA) territory ischemic insult, large vessel occlusion involving the M1 segment of the right MCA, and impaired perfusion parameters (A1–5). Cerebral angiography showed total occlusion of M1 branch of the right MCA (B1). Image B2 shows the thrombolysis in cerebral infarction Flow III after thrombus aspiration, with areas of narrowing consistent with nonflow limiting vasospasm. The patient was discharged without any residual weakness.
Figure 3.
A 56-year-old man with extensive subarachnoid hemorrhage (A1) and intraventricular hemorrhage observed in the fourth ventricle (A3) associated with resultant active hydrocephalus (A1 and 2) presented with sudden loss of consciousness 36 h after third redo mitral valve replacement and tricuspid valve repair. Right (B1) and left (B2) cerebral angiograms excluded arteriovenous malformations or aneurysmal dilatation and showed severe attenuation of distal branches of the left middle cerebral artery (MCA) and posterior circulation. Image C shows the tip of the right frontal external ventricular drain (blue arrow) in the right ventricle, diffuse bilateral cerebral hemispheric sulci effacement with loss of gray-white matter differentiation, and multiple hypodensities, especially in the right MCA territory infarction (likely related to underlying vasospasm) 5 days after the loss of consciousness. The patient died after 23 days of hospital stay.
Figure 4.
A 57-year-old man who underwent on-pump CABG and mitral valve repair with a cardiopulmonary bypass time of 221 min and aortic cross-clamping time of 191 min. Postoperative nonawakening occurred, computed tomography of the brain did not show brain vascular insult (A1–3), and CT angiography did not show large vessel occlusion. Magnetic resonance imaging of the brain (B1–5) revealed multiple patchy foci of restricted diffusion noted in the external watershed zone of both cerebral hemispheres involving bilateral frontoparietal, temporal, and occipital lobe cortices. Faint high signal areas with mild restricted diffusion are also noted in the left thalamus and both cerebellar hemispheres.
The patients with postoperative stroke had higher preoperative rates of infective endocarditis (14.3% vs. 5.3%, p < 0.001), redo cardiac surgery (42.9% vs. 21.1%, p < 0.001), old ischemic stroke (21% vs. 5%, p < 0.001), and old ICH (3.8% vs. 0.7%, p=0.015), with significant postoperative hyperlactatemia, anemia, thrombocytopenia, and hypoalbuminemia compared with the patients without postoperative stroke (Tables 1, 2).
Table 1.
Clinical characteristics of the study patients.
| Variables | All patients (n = 1334) | Stroke group (n = 105, 7.9%) | Group without stroke (n = 1229, 92.1%) | p value | |
|---|---|---|---|---|---|
| Age (years) | 50.15 (39, 62) | 55 (41, 63) | 50 (39, 61.9) | 0.141 | |
|
| |||||
| Sex, male (n, %) | 797 (59.7) | 64 (61) | 733 (59.6) | 0.79 | |
|
| |||||
| BMI (kg/m2) | 27.7 (23.3, 31.8) | 26.4 (22.1, 30.5) | 27.8 (23.4, 31.8) | 0.021 | |
|
| |||||
| Diabetes mellitus (n, %) | 548 (41.1) | 43 (41) | 505 (41.1) | 0.98 | |
|
| |||||
| Systemic hypertension (n, %) | 783 (58.7) | 54 (51.4) | 729 (59.3) | 0.115 | |
|
| |||||
| Chronic kidney disease (n, %) | 227 (17) | 22 (21) | 205 (16.7) | 0.263 | |
|
| |||||
| ESRD on dialysis (n, %) | 49 (3.7) | 4 (3.8) | 45 (3.7) | 0.79 | |
|
| |||||
| Bronchial asthma/COPD (n, %) | 88 (6.6) | 11 (10.5) | 77 (6.3) | 0.09 | |
|
| |||||
| Prior myocardial infarction (n, %) | 145 (10.9) | 12 (11.4) | 133 (10.8) | 0.84 | |
|
| |||||
| Prior PCI (n, %) | 139 (10.4) | 8 (7.6) | 131 (10.7) | 0.328 | |
|
| |||||
| Prior cardiac surgery (n, %) | 304 (22.8) | 45 (42.9) | 259 (21.1) | < 0.001 | |
|
| |||||
| Infective endocarditis (n, %) | 80 (6) | 15 (14.3) | 65 (5.3) | < 0.001 | |
|
| |||||
| Preoperative LV-EF (n, %) | > 55% | 601 (45.1) | 39 (37.1) | 562 (45.7) | 0.243 |
| 45%–55% | 348 (26.1) | 30 (28.6) | 318 (25.9) | ||
| 35%–45% | 136 (10.2) | 10 (9.5) | 126 (10.3) | ||
| < 35% | 249 (18.7) | 26 (24.8) | 223 (18.1) | ||
|
| |||||
| Left atrium diameter (cm) | 4.44 ± 0.93 | 4.5 ± 0.64 | 4.4 ± 0.37 | 0.103 | |
|
| |||||
| Preoperative IABP (n, %) | 13 (1) | 4 (3.8) | 9 (0.7) | 0.015 | |
|
| |||||
| Preoperative VA-ECMO (n, %) | 18 (1.35) | 4 (3.8) | 19 (1.5) | 0.101 | |
|
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| Preoperative atrial fibrillation (n, %) | 341 (25.6) | 22 (21) | 319 (26) | 0.259 | |
|
| |||||
| Old ischemic stroke (n, %) | 84 (6.3) | 22 (21) | 62 (5) | < 0.001 | |
|
| |||||
| Old ICH (n, %) | 13 (1) | 4 (3.8) | 9 (0.7) | 0.015 | |
|
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| Epilepsy (n, %) | 25 (1.9) | 3 (2.9) | 22 (1.8) | 0.44 | |
|
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| History of TIAs (n, %) | 34 (2.5) | 5 (4.8) | 29 (2.4) | 0.182 | |
|
| |||||
| CAS ≥ 70% (n, %) | 19 (0.014) | 1 (1) | 18 (1.5) | 0.54 | |
|
| |||||
| CAS 50%–69% (n, %) | 15 (0.011) | 2 (1.9) | 13 (1.1) | 0.34 | |
|
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| Hypothyroidism (n, %) | 96 (7.2) | 10 (9.5) | 86 (7) | 0.336 | |
|
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| Autoimmune disease (n, %) | 156 (11.7) | 14 (13.3) | 142 (11.6) | 0.35 | |
|
| |||||
| Peripheral vascular disease (n, %) | 35 (2.6) | 6 (5.7) | 29 (2.4) | 0.051 | |
|
| |||||
| Preoperative drugs (n, %) | Aspirin | 516 (38.7) | 32 (30.5) | 484 (39.4) | 0.072 |
| Clopidogrel | 147 (11) | 5 (4.8) | 142 (11.6) | 0.033 | |
| Ticagrelor | 17 (1.3) | 0 | 17 (1.4) | 0.39 | |
| Warfarin | 360 (27) | 29 (27.6) | 331 (26.9) | 0.879 | |
| Rivaroxaban | 37 (2.8) | 1 (1) | 36 (2.9) | 0.356 | |
| Apixaban | 49 (3.7) | 4 (3.8) | 45 (3.7) | 0.791 | |
Abbreviations: BMI, body mass index; CAS, carotid artery stenosis; COPD, chronic obstructive pulmonary disease; ESRD, end-stage renal disease; IABP, intra-aortic balloon pump; ICH, intracranial hemorrhage; LV-EF, left ventricular ejection fraction; PCI, percutaneous coronary intervention; TIAs, transient ischemic attacks; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.
Table 2.
Laboratory variables of the study patients.
| Variables | All patients (n = 1334) | Stroke group | Group without stroke | p value |
|---|---|---|---|---|
| Preoperative variables | ||||
| Hemoglobin (gm/L) | 119 (104, 137) | 108 (99, 127) | 121 (105,137) | < 0.001 |
| Hematocrit (%) | 38 (33, 42) | 34 (31, 39) | 39 (33, 42) | < 0.001 |
| Platelet count (109/L) | 228.5 (170, 278) | 223 (160, 284) | 229 (171, 278) | 0.513 |
| White blood cells (109/L) | 7.54 (5.68, 10.36) | 8.39 (6.06, 11.7) | 7.48 (5.66, 10.16) | 0.043 |
| INR | 1.2 (1.1, 1.4) | 1.3 (1.1, 1.6) | 1.2 (1.1, 1.4) | 0.043 |
| Fibrinogen (g/L) | 2.95 (2.39, 3.51) | 2.78 (2.22, 3.29) | 2.96 (2.4, 3.56) | 0.132 |
| Serum creatinine (umol/L) | 80 (65, 104) | 85 (67,107) | 80 (65,103) | 0.221 |
| Serum bilirubin (umol/L) | 10.7 (6.4, 19) | 13 (7, 24) | 10.3 (6.3, 19) | 0.025 |
| Blood urea (mmol/L) | 5.9 (4.5, 8.8) | 6.3 (4.9, 9.6) | 5.8 (4.5, 8.8) | 0.182 |
| Serum Na (mmol/L) | 140 (137, 142) | 140 (135, 143) | 140 (138, 142) | 0.619 |
| Albumin (gm/L) | 39.2 (35, 42.6) | 36.3 (31, 39.2) | 39.5 (35.6, 42.8) | < 0.001 |
| Postoperative variables | ||||
| Peak blood lactate (mmol/L) | 6.8 (5.4, 9.4) | 11.4 (8.2, 15.7) | 6.4 (5.3, 8.6) | < 0.001 |
| Lactate at 24 h (mmol/L) | 1.7 (1.3, 2.4) | 3.1 (1.9, 4.7) | 1.6 (1.3, 2.3) | < 0.001 |
| Hemoglobin-D1 (gm/L) | 97 (87, 107) | 93 (84.5, 103) | 97 (87, 107) | 0.015 |
| Hematocrit-D1 (%) | 30 (27, 32) | 28 (26, 31) | 30 (27, 32) | 0.003 |
| Hemoglobin-D2 (gm/L) | 92 (85, 101) | 88 (79, 100) | 92 (85, 101) | < 0.001 |
| Platelet count-D1 (109/L) | 148 (105.5, 197) | 124 (80, 170) | 151 (108, 198) | < 0.001 |
| Platelet count-D2 (109/L) | 134 (97, 171) | 113 (77, 152) | 136 (101, 173) | < 0.001 |
| aPTT-D1 | 38.2 (35.1, 42.9) | 42.55 (36.5, 54) | 38 (35, 41) | < 0.001 |
| aPTT-D2 | 42 (38.2, 52) | 42 (38.6, 47.5) | 42 (38.2, 52.3) | 0.95 |
| Fibrinogen-D1 (g/L) | 3 (2.5, 3.66) | 2.7 (2.23, 3.29) | 3.01 (2.52, 3.69) | 0.001 |
| Fibrinogen-D2 (g/L) | 3.79 (2.88, 4.84) | 3 (2.45, 4.01) | 3.88 (2.93, 4.92) | < 0.001 |
| Serum creatinine-D1 (umol/L) | 83 (67, 114) | 88 (74, 124) | 83 (67, 114) | 0.105 |
| Serum bilirubin-D1 (umol/L) | 18.6 (10.9, 29.7) | 24.25 (13.9, 37.5) | 18 (10.7, 28.5) | < 0.001 |
| Blood urea-D1 (mmol/L) | 6.3 (4.9, 9.4) | 7.2 (5.15, 9.85) | 6.2 (4.8, 9.4) | 0.068 |
| Blood urea-D2 (mmol/L) | 7.6 (5.3, 12) | 8.2 (6.7, 11.8) | 7.5 (5.2, 12) | 0.033 |
| Albumin-D1 (gm/L) | 37 (34.1, 40.6) | 34.45 (30.7, 38) | 37 (34.3, 40.7) | < 0.001 |
| Albumin-D2 (gm/L) | 37.3 (34.5, 40.2) | 35 (31.8, 38) | 37.6 (34.8, 40.4) | < 0.001 |
Note: Data are presented as median with the 25th and 75th quartiles.
Abbreviations: APTT, activated partial thromboplastin time; INR, international normalized ratio.
The patients with postoperative stroke also had longer CPB time (165.5 [126, 234] versus 136 [104, 171] min, p < 0.001) and ACC time (112 [79, 163] versus 89 [75, 121.5] min, p < 0.001) with higher rates of perioperative IABP use (13.3% vs. 4.4%, p < 0.001), perioperative VA-ECMO support (24.8% vs. 12.37%, p < 0.001), and mediastinal exploration for bleeding (22.9% vs. 8.9%, p < 0.001). (Table 3).
Table 3.
Perioperative details of the study patients.
| Variables | All patients (n = 1334) | Stroke group (n = 105, 7.9%) | Group without stroke (n = 1229, 92.1%) | p value | |
|---|---|---|---|---|---|
| Type of surgery (n, %) | Isolated CABG | 364 (27.3) | 19 (18.1) | 345 (28.1) | < 0.001 |
| Valve surgery | 707 (52.9) | 43 (40.9) | 664 (54.02) | ||
| CABG + valve | 71 (5.3) | 12 (11.4) | 59 (4.8) | ||
| Bentall's operation | 32 (2.4) | 9 (8.6) | 23 (1.9) | ||
| Heart transplantation | 68 (5.1) | 7 (6.7) | 61 (5) | ||
| LVAD implantation | 56 (4.2) | 7 (6.7) | 49 (4) | ||
| ACHD | 17 (1.3) | 4 (3.8) | 13 (1.1) | ||
| Pulmonary endarterectomy | 11 (0.82) | 0 | 11 (0.89) | ||
| Resection of cardiac tumor | 8 (0.6) | 0 | 8 (0.7) | ||
|
| |||||
| Valve surgery (n, %) | MVR | 309 (23.16) | 19 (18.1) | 290 (23.6) | 0.08 |
| AVR | 188 (14.1) | 18 (17.1) | 171 (13.9) | ||
| MVR + AVR | 73 (5.47) | 10 (9.5) | 63 (5.1) | ||
| TVR | 19 (1.42) | 0 | 19 (1.5) | ||
| MVR + TV repair | 141 (10.57) | 9 (8.6) | 132 (10.7) | ||
| MVR + AVR + TV repair | 59 (4.42) | 7 (6.7) | 52 (4.2) | ||
| Mitral repair | 21 (1.6) | 5 (4.8) | 16 (1.3) | ||
|
| |||||
| Cardiopulmonary bypass time (min) | 136 (105, 174) | 165.5 (126, 234) | 136 (104, 171) | < 0.001 | |
|
| |||||
| Aortic cross-clamping time (min) | 90 (75, 123) | 112 (79, 163) | 89 (75, 121.5) | < 0.001 | |
|
| |||||
| Circulatory arrest (n, %) | 22 (1.65) | 10 (9.5) | 12 (1) | < 0.001 | |
|
| |||||
| Perioperative IABP (n, %) | 68 (5.1) | 14 (13.3) | 54 (4.4) | < 0.001 | |
|
| |||||
| Perioperative VA-ECMO (n, %) | 178 (13.34) | 26 (24.8) | 152 (12.37) | < 0.001 | |
|
| |||||
| ECMO cannulation (n, %) | Central | 87 (6.52) | 16 (15.2) | 71 (5.78) | 0.003 |
| Peripheral | 81 (6.07) | 7 (6.7) | 74 (6.02) | ||
| Central then peripheral | 6 (0.45) | 2 (1.9) | 4 (0.33) | ||
| Peripheral then central | 4 (0.29) | 1 (0.95) | 3 (0.24) | ||
|
| |||||
| Exploration for thoracic bleeding (n, %) | 133 (10) | 24 (22.9) | 109 (8.9) | < 0.001 | |
|
| |||||
| New-onset POAF (n, %) | 95 (7.1) | 9 (8.6) | 86 (7) | 0.54 | |
|
| |||||
| Atrial fibrillation (preoperative and POAF) | 424 (31.8) | 31 (29.5) | 393 (32) | 0.604 | |
Abbreviations: AVR, aortic valve replacement; CABG, coronary artery bypass grafting; IABP, intra-aortic balloon pump; MVR, mitral valve replacement; POAF, postoperative atrial fibrillation; TV, tricuspid valve; TVR, tricuspid valve replacement; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.
Subgroup analysis showed that patients with ischemic stroke were older with longer CPB and ACC times and higher rates of old ischemic stroke, redo cardiotomy, infective endocarditis, and perioperative IABP and VA-ECMO use than those without ischemic stroke. Patients with postoperative ICH were younger with longer CPB and ACC times and higher frequencies of old ischemic and hemorrhagic strokes, redo cardiotomy, infective endocarditis, and perioperative VA-ECMO use and lower rates of diabetes mellitus and systemic hypertension than those without postoperative ICH (Table 4).
Table 4.
Clinical and laboratory characteristics of the ischemic and hemorrhagic strokes.
| Variables | Ischemic stroke group (n = 79, 5.9) | Nonischemic stroke group (n = 1255, 94.1%) | p value | Hemorrhagic stroke group (n = 32, 2.4%) | Nonhemorrhagic stroke group (n = 1302, 97.6%) | p value |
|---|---|---|---|---|---|---|
| Age (years) | 57 (47.5, 64) | 50 (39, 61.9) | 0.009 | 41.85 (23, 55.5) | 51 (40, 62) | 0.014 |
| Sex, male (n, %) | 52 (65.8) | 745 (59.4) | 0.26 | 14 (43.8) | 783 (60.1) | 0.062 |
| BMI (kg/m2) | 26.6 (22.6, 30.5) | 27.75 (23.3, 31.8) | 0.07 | 26.35 (20.2, 30.75) | 27.7 (23.4, 31.8) | 0.12 |
| Diabetes mellitus (n, %) | 38 (48.1) | 510 (40.6) | 0.19 | 5 (15.6) | 543 (41.7) | 0.003 |
| Systemic hypertension (n, %) | 44 (55.7) | 739 (58.9) | 0.58 | 11 (34.4) | 772 (59.3) | 0.005 |
| CKD (n, %) | 15 (19) | 212 (16.9) | 0.63 | 7 (21.9) | 220 (16.9) | 0.46 |
| ESRD on dialysis (n, %) | 4 (5.1) | 45 (3.6) | 0.53 | 0 | 49 (3.8) | 0.63 |
| Bronchial asthma/COPD (n, %) | 7 (8.9) | 81 (6.5) | 0.4 | 3 (9.4) | 85 (6.5) | 0.47 |
| Autoimmune disease (n, %) | 16 (20.3) | 204 (16.3) | 0.35 | 11 (34.4) | 209 (16.1) | 0.006 |
| Old cerebrovascular stroke (n, %) | 19 (24.1) | 65 (5.2) | < 0.001 | 7 (21.9) | 77 (5.9) | 0.003 |
| Old ICH (n, %) | 2 (2.5) | 11 (0.9) | 0.18 | 3 (9.4) | 10 (0.8) | 0.003 |
| Prior cardiac surgery (n, %) | 33 (41.8) | 271 (21.6) | < 0.001 | 15 (46.9) | 289 (22.2) | 0.001 |
| Infective endocarditis (n, %) | 10 (12.7) | 70 (5.6) | 0.023 | 5 (15.6) | 75 (5.8) | 0.038 |
| Preoperative AF (n, %) | 15 (19) | 326 (26) | 0.17 | 7 (21.9) | 334 (25.7) | 0.63 |
| Perioperative IABP (n, %) | 13 (16.5) | 55 (4.4) | < 0.001 | 4 (12.5) | 64 (4.9) | 0.08 |
| Perioperative VA-ECMO (n, %) | 19 (24.1) | 159 (12.67) | 0.006 | 12 (37.5) | 166 (12.75) | < 0.001 |
| CPB time (min) | 164 (122, 215) | 136 (105, 171) | < 0.001 | 189 (134.5, 282.5) | 136 (105, 172) | < 0.001 |
| ACC time (min) | 102 (78, 163) | 90 (75, 122) | 0.023 | 129 (98.5, 179) | 90 (75, 123) | < 0.001 |
| Circulatory arrest (n, %) | 7 (8.9) | 15 (1.2) | < 0.001 | 3 (9.4) | 19 (1.5) | 0.014 |
| Preoperative hemoglobin (gm/L) | 110 (100, 129) | 120 (105, 137) | 0.014 | 106 (99, 125.5) | 120 (105, 137) | 0.022 |
| Preoperative platelet count (109/L) | 225 (171, 277) | 229 (170, 278) | 0.87 | 213 (104, 311) | 229 (171, 278) | 0.6 |
| Peak lactate (mmol/L) | 11 (7.8, 15.3) | 6.5 (5.3, 8.9) | < 0.001 | 14.5 (10, 16.8) | 6.7 (5.3, 9.2) | < 0.001 |
| Lactate at 24 h (mmol/L) | 2.8 (1.9, 4.5) | 1.7 (1.3, 2.4) | < 0.001 | 3.8 (2.35, 5.8) | 1.7 (1.3, 2.4) | < 0.001 |
| Hemoglobin-D1 (gm/L) | 94 (84, 104) | 97 (87, 107) | 0.054 | 91 (84, 104) | 97 (87, 107) | 0.12 |
| Platelet count-D1 (109/L) | 136 (94, 179) | 150 (106, 197) | 0.023 | 100 (60, 151) | 150 (107, 197) | < 0.001 |
| Platelet count-D2 (109/L) | 121 (84, 153) | 135 (98, 172) | 0.02 | 92 (61, 137.5) | 135 (98, 172) | 0.002 |
| Fibrinogen-D1 (g/L) | 2.57 (2.22, 3.24) | 3.01 (2.52, 3.67) | 0.001 | 2.7 (2.4, 3.12) | 3 (2.5, 3.67) | 0.043 |
| Fibrinogen-D2 (g/L) | 3 (2.45, 4.2) | 3.84 (2.9, 4.9) | 0.001 | 3 (2.55, 3.6) | 3.83 (2.89, 4.89) | 0.001 |
| Albumin-D1 (gm/L) | 34.45 (31, 38.1) | 37 (34.3, 40.7) | < 0.001 | 32.4 (29.4, 36.4) | 37 (34.2, 40.6) | < 0.001 |
| Albumin-D2 (gm/L) | 35 (31.8, 38.5) | 37.55 (34.8, 40.3) | < 0.001 | 35 (31.4, 37.4) | 37.4 (34.6, 40.3) | 0.001 |
Abbreviations: ACC, aortic cross-clamping; AF, atrial fibrillation; BMI, body mass index; CKD, chronic kidney disease; CPB, cardiopulmonary bypass; COPD, chronic obstructive pulmonary disease; ESRD, end-stage renal disease; IABP, intra-aortic balloon pump; ICH, intracranial hemorrhage; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.
3.2. Outcomes and Regression Analysis
The patients who developed cerebrovascular stroke showed increased hospital mortality (37.1% vs. 5.6%, p < 0.001), higher frequencies of AKI (49.5% vs. 21.7%, p < 0.001), new need for dialysis (29.5% vs. 10.7%, p < 0.001), higher rate of tracheostomy (13.3% vs. 1.2%, p < 0.001), and longer ICU stay (12 [7, 28] versus 3 [2, 8] days, p < 0.001) and post-ICU stay (16 [7, 39] versus 5 [3, 10] days, p < 0.001). Follow-up for 36.4 (21.67, 50.7) months showed an insignificant mortality difference, but there was an increased rate of recurrent cerebrovascular strokes (Table 5). In the subgroup analysis, patients with either ischemic or hemorrhagic stroke had increased hospital mortality, AKI, new need for dialysis, and tracheostomy with prolonged hospitalization. However, the patients who developed ICH showed increased recurrence and mortality during follow-up (Table 6).
Table 5.
Outcomes of the study patients.
| Variables | All patients (n = 1334) | Stroke group (n = 105, 7.9%) | Group without stroke (n = 1229, 92.1%) | p value |
|---|---|---|---|---|
| Acute kidney injury (n, %) | 319 (23.9) | 52 (49.5) | 267 (21.7) | < 0.001 |
| New need for dialysis (n, %) | 163 (12.2) | 31 (29.5) | 132 (10.7) | < 0.001 |
| ICU days | 4 (2, 9) | 12 (7, 28) | 3 (2, 8) | < 0.001 |
| ECMO days | 7 (5, 9) | 11 (5, 15) | 6 (5, 8) | 0.012 |
| Post-ICU ward days | 5 (4, 10) | 16 (7, 39) | 5 (3, 10) | < 0.001 |
| Tracheostomy (n, %) | 29 (2.2) | 14 (13.3) | 15 (1.2) | < 0.001 |
| Hospital mortality (n, %) | 108 (8.1) | 39 (37.1) | 69 (5.6) | < 0.001 |
| Mortality during follow-up (n, %) | 9 (0.7) | 2 (1.9) | 7 (0.6) | 0.154 |
| Ischemic stroke during follow-up (n, %) | 14 (1.1) | 5 (4.8) | 9 (0.7) | 0.003 |
| ICH during follow-up (n, %) | 3 (0.2) | 2 (1.9) | 1 (0.1) | 0.017 |
Abbreviations: ECMO, extracorporeal membrane oxygenation; ICH, intracranial hemorrhage; ICU, intensive care unit.
Table 6.
Outcomes of the patients with ischemic and hemorrhagic strokes.
| Variables | Ischemic stroke group (n = 79, 5.9) | Nonischemic stroke group (n = 1255, 94.1%) | p value | Hemorrhagic stroke group (n = 32, 2.4%) | Nonhemorrhagic stroke group (n = 1302, 97.6%) | p value |
|---|---|---|---|---|---|---|
| Acute kidney injury (n, %) | 36 (45.6) | 283 (22.5) | < 0.001 | 20 (62.5) | 299 (23) | < 0.001 |
| New need for dialysis (n, %) | 18 (22.8) | 145 (11.6) | 0.003 | 17 (53.1) | 146 (11.2) | < 0.001 |
| Exploration for thoracic bleeding (n, %) | 18 (22.8) | 115 (9.2) | < 0.001 | 9 (28.1) | 124 (9.5) | 0.003 |
| ICU days | 14 (6, 38) | 3 (2, 8) | < 0.001 | 12 (6, 28.5) | 4 (2, 9) | < 0.001 |
| ECMO days | 11 (8, 15) | 6 (5, 8) | 0.008 | 11 (4, 17) | 7 (5, 8) | 0.57 |
| Post-ICU ward days | 16.5 (7, 36.5) | 5 (3.5, 10) | < 0.001 | 17 (7, 61.5) | 5 (4, 10) | < 0.001 |
| Tracheostomy (n, %) | 12 (15.2) | 17 (1.4) | < 0.001 | 4 (12.5) | 25 (1.9) | 0.004 |
| Hospital mortality (n, %) | 24 (30.4) | 84 (6.7) | < 0.001 | 18 (56.3) | 90 (6.9) | < 0.001 |
| Mortality during follow-up (n, %) | 2 (2.5) | 7 (0.6) | 0.09 | 2 (6.3) | 7 (0.5) | 0.018 |
| Ischemic stroke during follow-up (n, %) | 3 (3.8) | 11 (0.9) | 0.045 | 3 (9.4) | 11 (0.8) | 0.004 |
| ICH during follow-up (n, %) | 0 | 3 (0.2) | 1 | 2 (6.3) | 1 (0.1) | 0.002 |
Abbreviations: ECMO, extracorporeal membrane oxygenation; ICH, intracranial hemorrhage; ICU, intensive care unit.
Cox-proportional hazard regression showed an increased risk of hospital mortality after cardiac surgery in patients who developed acute cerebral stroke (HR: 7.588, 95% CI: 5.186–11.103, p < 0.001), ischemic stroke (HR: 5.075, 95% CI: 3.28–7.851, p < 0.001), or ICH (HR: 12.288, 95% CI: 7.576–19.93, p < 0.001). Kaplan–Meier curves revealed significantly increased mortality with ischemic and hemorrhagic cerebrovascular strokes (log-rank p < 0.001). (Figure 5).
Figure 5.
Kaplan–Meier curves showing significantly decreased survival with postoperative ischemic and hemorrhagic strokes (log-rank p < 0.001).
Logistic multivariable regression for postoperative ischemic stroke showed that increased age (odds ratio [OR]: 1.029, 95% CI: 1.01–1.048, p=0.003), hyperlactatemia (OR: 1.287, 95% CI: 1.183–1.431, p < 0.001), redo cardiotomy (OR: 2.835, 95% CI: 1.574–5.104, p=0.001), history of old stroke (OR: 4.683, 95% CI: 2.364–9.278, p < 0.001), CPB time (OR: 1.016, 95% CI: 1.003–1.34, p=0.042), and perioperative IABP use (OR: 2.431, 95%CI: 1.003–5.892, p=0.043) were the predictors. Infective endocarditis, ACC time, and perioperative VA-ECMO use were not statistically significant in the regression model. Logistic multivariable regression was performed to determine the independent predictors of ICH and revealed that young age (OR: 0.96, 95% CI: 0.94–0.99, p=0.006), old ICH (OR: 6.49, 95% CI: 3.266–9.354, p < 0.001), hyperlactatemia (OR: 1.267, 95% CI: 1.123–1.43, p < 0.001), and hypoalbuminemia (OR: 0.9, 95% CI: 0.832–0.973, p=0.009) were the predictors of postoperative ICH (Table 7).
Table 7.
Multivariable logistic regression analysis of cerebrovascular strokes.
| Variables | Odds ratio (OR) | Confidence interval (CI) | p value |
|---|---|---|---|
| Ischemic stroke | |||
| Age | 1.029 | 1.010–1.048 | 0.003 |
| Old ischemic stroke | 4.683 | 2.364–9.278 | < 0.001 |
| Previous cardiotomy | 2.835 | 1.574–5.104 | 0.001 |
| Infective endocarditis | 1.28 | 0.51–3.17 | 0.29 |
| Lactate peak | 1.287 | 1.183–1.431 | < 0.001 |
| Lactate at 24 h | 1.005 | 0.904–1.117 | 0.928 |
| Perioperative IABP | 2.431 | 1.003–5.892 | 0.043 |
| Perioperative VA-ECMO | 0.732 | 0.322–1.67 | 0.457 |
| CPB time | 1.016 | 1.003–1.34 | 0.042 |
| ACC time | 0.992 | 0.982–1.002 | 0.134 |
| Exploration for bleeding | 0.591 | 0.267–1.307 | 0.19 |
| Serum albumin | 0.966 | 0.918–1.015 | 0.17 |
| Intracerebral bleeding | |||
| Age | 0.963 | 0.938–0.989 | 0.006 |
| Old cerebral bleeding | 6.49 | 3.266–9.354 | < 0.001 |
| Previous cardiotomy | 1.423 | 0.598–3.384 | 0.425 |
| Infective endocarditis | 0.847 | 0.258–2.78 | 0.78 |
| Lactate peak | 1.267 | 1.123–1.43 | < 0.001 |
| Lactate at 24 h | 0.869 | 0.737–1.024 | 0.09 |
| Perioperative VA-ECMO | 0.584 | 0.209–1.629 | 0.304 |
| CPB time | 1.002 | 0.991–1.012 | 0.758 |
| ACC time | 1.002 | 0.987–1.017 | 0.790 |
| Serum albumin | 0.9 | 0.832–0.973 | 0.009 |
| Postoperative platelet count | 0.967 | 0.943–1.005 | 0.435 |
| Postoperative fibrinogen level | 0.98 | 0.844–2.053 | 0.225 |
Abbreviations: ACC, aortic cross-clamping; CPB, cardiopulmonary bypass; IABP, intra-aortic balloon pump; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.
The logistic multivariable regression revealed that postoperative ICH (OR: 6.968, 95% CI: 2.319–20.942, p=0.001), ischemic stroke (OR: 2.43, 95% CI: 1.06–5.57, p=0.036), atrial fibrillation (OR: 3.297, 95% CI: 1.687–6.443, p < 0.001), CKD (OR: 2.96, 95% CI: 1.484–5.896, p=0.002), blood lactate at 24 h after surgery (OR: 3.267, 95% CI: 2.659–4.014, p < 0.001), and increased age (OR: 1.028, 95% CI: 1.002–1.069, p=0.027) were the independent predictors of hospital mortality after cardiac surgery (Table 8).
Table 8.
Multivariable logistic regression analysis of hospital mortality.
| Variables | Odds ratio (OR) | Confidence interval (CI) | p value |
|---|---|---|---|
| Age | 1.028 | 1.002–1.069 | 0.027 |
| CKD | 2.96 | 1.484–5.896 | 0.002 |
| Previous cardiotomy | 1.063 | 0.532–2.125 | 0.86 |
| Infective endocarditis | 0.937 | 0.316–2.779 | 0.907 |
| Old cerebrovascular stroke | 2.096 | 0.793–5.539 | 0.136 |
| Acute ischemic stroke | 2.43 | 1.06–5.57 | 0.036 |
| ICH | 6.968 | 2.319–20.942 | 0.001 |
| Lactate at 24 h | 3.267 | 2.659–4.014 | < 0.001 |
| Atrial fibrillation | 3.297 | 1.687–6.443 | < 0.001 |
| Perioperative VA-ECMO | 3.343 | 0.946–11.811 | 0.061 |
Abbreviations: CKD, chronic kidney disease; ICH, intracranial hemorrhage; VA-ECMO, veno-arterial extracorporeal membrane oxygenation.
4. Discussion
Our analysis of all consecutive adult patients who underwent cardiac surgery revealed that cerebral injury occurred in 24.4% of patients, ischemic stroke in 5.2%, and ICH in 1.7%. The occurrence of stroke was associated with increased mortality and many morbidities, including the length of hospitalization and associated costs of treatment. Cerebral injury has been reported to occur in 15%–66% of patients after surgery and in 40% of patients 5 years later [14, 15]. Neurological manifestations include altered consciousness, behavioral and cognitive changes, and focal deficits. There are large variations in the reported rates of stroke and neurological problems after cardiac surgery owing to differences in patient risk factors, surgical techniques, definitions of the studied variables, study design, and brain imaging protocols [2, 5, 6, 14, 16, 17].
Bucerius et al. [14] studied 16,184 patients and reported a 4.6% incidence of ischemic stroke after cardiac surgery. The incidence varied with subgroup analysis from 1.9% after aortic valve replacement to 9.7% after double or triple valve replacement. Messé et al. [16] reported clinical strokes in 17% patients after valve replacement in patients ≥ 65 years old. Salazar et al. [5] studied 5971 patients and reported ischemic stroke in 214 (3.6%) patients with watershed infarcts in 24% of them. Raffa et al. [2] studied 2121 patients and reported major ischemic stroke in 1.7% of patients based on brain CT or MRI. Mao et al. [17] conducted a systematic review of 14 studies and reported an incidence of ischemic stroke up to 7.5% after coronary artery bypass grafting (CABG).
Because CT of the brain may fail to show focal damage and limitations of cardiac MRI after surgery, strokes may be underreported in the early postoperative stage. Pérez-Vela et al. [3] studied 688 patients and reported the failure of CT to identify significant findings in 70% of patients with ischemic stroke and the beneficial role of MRI when feasible to detect strokes. Floyd et al. [18] described the silent ischemic strokes after cardiac surgery. They performed brain MRI before and after cardiac surgery in 34 patients and reported evidence of ischemic infarctions in 18% of patients, of which 67% were clinically silent without any neurological manifestations.
There are limited data regarding ICH after cardiac surgery and mostly case reports. Yuan and Guo [11] reviewed and described 182 patients with ICH after cardiac surgery from 35 reports, mostly intracerebral bleeding. Kim et al. [10] reported a 2.6% incidence rate of ICH after cardiac CABG during a 6-year follow-up with the highest incidence within the first 30 days after surgery.
Our study revealed an association between ischemic and hemorrhagic strokes and hospital mortality. Ischemic stroke and ICH were associated with an increased risk of death and were independent predictors of mortality (HR: 5.075, 95% CI: 3.28–7.851, p < 0.001; OR: 2.43, 95% CI: 1.06–5.57, p=0.036 and HR: 12.288, 95% CI: 7.576–19.93, p < 0.001; OR: 6.968, 95% CI: 2.319–20.942, p=0.001), respectively. Moreover, there were significantly higher rates of AKI, new need for dialysis, tracheostomies, length of ICU and ward stays, with increased treatment costs in patients who had ischemic and hemorrhagic strokes. Our results are consistent with those of other studies that have reported outcomes after cardiac surgeries [2, 5–7, 10]. Gaudino et al. [7] conducted a large meta-analysis including 36 studies with 174,969 adult patients and reported high mortality in patients who developed stroke, especially early “on-awakening” stroke. Early postoperative stroke that occurs with awakening or after endotracheal extubation is linked to intraoperative events and aortic manipulation, whereas delayed stroke refers to stroke that occurs after a symptom-free period and is usually related to patient risk factors, atrial fibrillation, and cerebrovascular disease [7, 19]. The intraoperative risk factors include cerebral hypoperfusion and atheroembolism with aortic clamping, insertion and removal of cannulas, and proximal aortic grafting.
Our analysis of risk factors revealed the significantly prolonged CPB and ACC times in patients with ischemic and hemorrhagic strokes, and CPB was an independent predictor of postoperative ischemic stroke (OR: 1.016, 95% CI: 1.003–1.34, p = 0.042). However, there are contradictory reports on the association between CPB duration and cerebrovascular insults. Many reports linked early postoperative neurological insults to CPB time and ACC [5–8, 20, 21], whereas other reports did not find this association [2, 22]. A CPB time > 120 min was identified as a risk factor for early stroke [14, 20]. A large meta-analysis of 174,969 patients confirmed an inverse association between off-pump surgery and early strokes [7]. John et al. [21] reported that patients with aortic calcification had a more than threefold risk of early stroke and recommended a safe aortic approach, including avoiding proximal anastomoses, using sequential grafts, femoral cannulation, and off-pump surgeries, if feasible. Gas embolism during CPB remains a risk factor for intraoperative stroke despite de-airing techniques, and results in significant focal or generalized brain injury [23, 24]. Carbon dioxide flooding has been proposed to decrease postoperative neurological dysfunction with conflicting results [25, 26].
A history of ischemic or hemorrhagic stroke was a significant predictor of postoperative stroke in our study. Our findings are consistent with those of previous studies that reported a link between a history of cerebrovascular disease and postoperative delayed stroke [6–8, 14, 21, 22, 27]. Atrial fibrillation was not a significant predictor of postcardiotomy stroke in our multivariable models; however, it was an independent predictor of hospital mortality (OR: 3.297, 95% CI: 1.687–6.443, p < 0.001) in our cohort. Most of our patients with atrial fibrillation already required therapeutic anticoagulation because of valve surgery to decrease the risk of thromboembolism. Hogue et al. [27] found no association of atrial fibrillation with postcardiotomy stroke unless it was associated with low cardiac output. Atrial fibrillation was not a predictor of postcardiotomy stroke in many reports [2, 14, 20] but it was a predictor in few reports [6, 22]. Postoperative atrial fibrillation (POAF) was linked to postoperative stroke and worse outcomes in patients who underwent isolated CABG and did not receive therapeutic anticoagulation [6, 28, 29]. POAF was associated with worse outcomes after cardiac surgery, including increased mortality [30, 31]. Perioperative prophylaxis with beta blockers or amiodarone decreases the risk of POAF. Preoperative screening for the need for ablation, left atrial appendage ligation, and posterior pericardiectomy decreased the risk of POAF that was associated with worse outcomes [32].
Blood lactate levels were used as markers of tissue hypoperfusion and microcirculation dysfunction. Hyperlactatemia was a significant variable in the multivariable analysis of the postoperative stroke models. Moreover, blood lactate level 24 h after surgery, which represents persistent tissue hypoperfusion and delayed clearance, was an independent predictor of mortality in our cohort (OR: 3.267, 95% CI: 2.659–4.014, p < 0.001). Hyperlactatemia and delayed clearance are linked to increased mortality and poor outcomes after cardiac surgery [33–37].
Previous cardiotomy was a significant risk factor for ischemic stroke (OR: 2.835), which is consistent with previous reports [2, 14]. Previous cardiotomy increases the risk of bleeding, hypotension, CPB duration, and aortic manipulation, with an increased risk of embolism. Hypoalbuminemia was a predictor of ICH after cardiac surgery in our cohort analysis, which could be explained by fluid shifts and cerebral volume fluctuations, especially with systemic inflammatory response (SIRS), thrombocytopenia, and anticoagulation. Hypoalbuminemia after cardiac surgery occurs because of many factors, including bleeding, fluid resuscitation, CPB circulation, and tissue injury with SIRS [38, 39]. Blood albumin has been shown to exert neuroprotective effects via anti-inflammatory, anti-apoptotic, and antioxidant effects [40]. Berbel-Franco et al. [39] studied 2818 patients and reported an association between hypoalbuminemia 24 h after surgery and worse outcomes, including mortality, AKI, sepsis, hemorrhagic complications, and ICU stay.
Cerebrovascular stroke after cardiac surgery is a multifaceted complication that affects patient outcomes, diagnosis and management challenges, rehabilitation, increased costs, and healthcare burdens. Therefore, a multidisciplinary approach should be considered before cardiac surgery. Careful assessment of patients before surgery should be performed to identify the risk factors for stroke and to choose the surgical approach with minimal risks, such as minimal aortic handling, use of CPB, or the off-pump approach. Avoiding intraoperative hemodynamic instability, minimal aortic handling, and reducing CPB and ACC times decrease the risk of postoperative stroke [19]. Cerebral oximetry allows the continuous monitoring of brain oxygenation and early detection of brain hypoxemia [41]. Early postoperative neurological examination, including pupillary reflex and any motor deficit, is crucial for the early identification of postoperative stroke and allows immediate care, including thrombectomy of the large cerebral vessels and anticoagulation management. Implementing the stroke code policy in our cardiac center allowed for the early detection of ischemic stroke and thrombectomy, which successfully restored blood flow and neurological recovery in eligible patients. Mechanical thrombectomy was reported to be beneficial after cardiac surgery if stroke was detected early and was associated with large-vessel occlusion [42, 43]. A multidisciplinary approach is crucial after cardiac surgery for patients who develop neurological dysfunction and should involve critical care, neurology, neurosurgery, physiotherapy, speech therapy, swallowing assessment, and rehabilitation teams. The aim of this approach is to deliver comprehensive assessment and immediate individualized patient care that will help minimize damage and improve outcomes and quality of life. A multidisciplinary approach for stroke after cardiac surgery has been reported to significantly increase survival [44].
5. Conclusions
Acute ischemic and hemorrhagic cerebrovascular strokes are serious, multifaceted complications that increase postoperative mortality and prolong hospitalization after cardiac surgery. Atrial fibrillation was not a significant predictor of postoperative stroke but was a predictor of hospital mortality. Careful attention should be given to maintaining hemodynamic stability and minimizing CPB and ACC times, especially in patients with a history of cerebrovascular stroke and redo cardiotomy.
5.1. Limitations
This was a retrospective, single-center study with missing intraoperative details such as cerebral oximetry. There was little data regarding preoperative ascending aorta assessment. Most of the missing data were laboratory variables during the postoperative stay. We used only data during the first 48 h after surgery, and missing data were not replaced but were managed as pairwise missed, not listwise.
Nomenclature
- ACC
Aortic cross-clamping
- AKI
Acute kidney injury
- CABG
Coronary artery bypass grafting
- CKD
Chronic kidney disease
- CPB
Cardiopulmonary bypass
- IABP
Intra-aortic balloon pump
- ICH
Intracranial hemorrhage
- VA-ECMO
Veno-arterial extracorporeal membrane oxygenation
Data Availability Statement
The data are available from the corresponding author.
Ethics Statement
This retrospective study was conducted at the King Faisal Heart Center after obtaining ethical approval in April 2023 (reference number 2231124). Informed consent was waived because of the absence of identifiable patient data and the retrospective nature of the study.
Disclosure
The abstract of this work was presented at the American College of Cardiology (ACC) conference held in Chicago, USA, on 29–31 March 2025.
Conflicts of Interest
The authors declare no conflicts of interest.
Funding
No funding was received for this research.
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Data Availability Statement
The data are available from the corresponding author.