Abstract
Acute myocardial infarction (AMI) complicated by cardiogenic shock has high mortality and remains challenging even in the revascularization era. We conducted this study to understand patients’ outcomes. We retrospectively analyzed electronic medical records data from 1175 patients with AMI complicated by cardiogenic shock that developed within 3 days of admission to a multicenter medical care system between January 1, 2000, and July 31, 2018. Patients with AMI were classified into the ST-segment elevation MI (STEMI) group or the non-ST-segment elevation MI (NSTEMI) group. The short-term and 1-year mortality and adverse events after index admission were analyzed via logistic regression and a Cox proportional hazards model. When compared with NSTEMI, patients with STEMI tended to be younger (65.68 ± 14.05 years vs 70.70 ± 12.99 years, P < .001), men (73.29% vs 60.87%, P < .001), and have fewer underlying chronic diseases. Short-term mortality at index hospitalization was 14.83% in the STEMI group and 21.30% in the NSTEMI group; long-term mortality was 17.06% for the STEMI group and 24.13% for the NSTEMI group. No difference was observed between the 2 groups for patients who developed a cerebral vascular accident during the admission period. However, the major and gastrointestinal bleeding rates were higher in the STEMI group (2.66% vs 0.22%, P = .014; 3.36% vs 0.22%, P = .007, respectively). Age and respiratory failure were the most significant risk factors for short-term mortality. Revascularization may be beneficial for the short-term outcome but did not reach significance in multivariable analysis. In patients with AMI with cardiogenic shock, NSTEMI was associated with a significantly higher mortality rate in short-term results.
Keywords: acute myocardial infarction, cardiogenic shock, critical care
1. Introduction
Cardiogenic shock after acute myocardial infarction (AMI) was fatal before revascularization treatment was available, with mortality rates as higher as 50% without revascularization.[1] Although new medical treatment and interventional procedures continued to improved outcomes, their impact on survival in patients with AMI and cardiogenic shock remained marginal.[2]
Patient outcomes with AMI vary according to the clinical setting. Patients with ST-segment elevation MI (STEMI) and non-STEMI (NSTEMI) have different characteristics and disease specificities, explaining their different short-term and long-term survival and prognoses. A study using the OPERA registry reported that compared to patients with STEMI, patients with NSTEMI had a similar in-hospital mortality rate (4.6% vs 4.3%) but a significantly lower 1-year death rate (9.0% vs 11.6%, log-rank P = .009).[3]
Among survivors of AMI complicated by cardiogenic shock who were discharged from the hospital, approximately 20% were readmitted within 30 days, mainly because of acute onset of heart failure (HF) and newly developed AMI.[4] Long-term outcome studies of these Killip IV STEMI or NSTEMI patients remained limited, especially with patients in East Asia. We therefore aimed to investigate the prognoses, patient characteristics, and risk factors among patients hospitalized for AMI complicated by cardiogenic shock.
2. Methods
2.1. Data source
This study was conducted using Chang Gung Research Database (CGRD), a de-identified database from the largest healthcare provider in Taiwan, Chang Gung Memorial Hospital health system. CGRD studies as basis for accurate estimates in medical studies have been previously validated.[5] The Chang Gung Memorial Hospital Institutional Review Board approved this study (201700965B0C502) and waived informed consent. Patient information and records were anonymized and de-identified before analyses. The authors are responsible for designing, conducting, drafting, and editing this manuscript and its contents.
2.2. Study group and cohort definition
From CGRD, we retrieved patients admitted for AMI between January 1, 2000, and July 31, 2018. Patients admitted via our emergency department with AMI complicated by documented cardiogenic shock events required inotropic agent, intra-aortic balloon pump (IABP), or extracorporeal membrane oxygenation (ECMO) in the first 3 days of the index date were enrolled in the study.
The index hospitalization was defined as the date the patient admitted for AMI. The follow-up period was defined as the date of the index hospitalization to the date of death or loss to follow-up or until July 31, 2018, whichever occurred first. Patients with AMI were classified into the STEMI or NSTEMI group according to the International Classification of Diseases (ICD), 9th and 10th Revision codes. STEMI was defined based on ICD-9 codes of 410.0x, 410.1x–410.6x, and 410.8x or ICD-10 codes of I21.0*–I21.3*, I22.0, I22.1, I22.8, and I22.9. NSTEMI was defined based on the ICD-9 code of 410.7x or the ICD-10 codes of I21.4* and I22.2. Cardiogenic shock was defined as the use of inotropic agents, including dopamine, dobutamine, norepinephrine, or epinephrine, or implementing an IABP or ECMO to stabilize hemodynamics. Patients were excluded if they were lost to follow-up 90 days after discharge.
2.3. Outcomes and covariate measurements
The primary outcomes were 30-day mortality or mortality at index hospitalization. Secondary outcomes included new-onset hemodialysis, new-onset stroke, major bleeding, gastrointestinal (GI) bleeding, pneumonia, or sepsis within 30 days after the index admission or during the index hospitalization. We also analyzed 1-year outcomes, including recurrent myocardial infarction, coronary revascularization, death, stroke, or bleeding events. Coronary revascularization was defined as percutaneous coronary revascularization or coronary artery bypass surgery. Stroke included ischemic, hemorrhagic, or unspecified stroke. Death was identified according to the registry data of CGRD, including death or critical discharge. Secondary outcomes, such as HF admission and major bleeding, were specifically evaluated. Major bleeding was defined as life-threatening or critical bleeding requiring a blood transfusion of 2 or more units. All these outcomes and the covariate’s definition were also defined by ICD-9 and ICD-10 codes. A detailed coding list is provided in the supplement (Supplemental Digital Content, http://links.lww.com/MD/H211).
Subgroup analyses for the short-term prognosis of STEMI or NSTEMI were also conducted. Age, gender, IABP, ECMO, revascularization during the index admission, and comorbidity were listed as predictors. Other covariates included chronic diseases, such as diabetes mellitus, hypertension, hyperlipidemia, atrial fibrillation, chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), peripheral artery occlusive disease (PAOD), gout, and malignancy. In addition, the patient history of cardiovascular diseases, such as HF, myocardial infarction (MI), cerebral vascular accident, and previous treatment, such as percutaneous coronary intervention (PCI) and coronary artery bypass grafting, were also defined as covariates.
2.4. Statistical analysis
We compared the clinical characteristics between the study groups using a χ2 test for categorical variables, an independent sample t test for continuous variables, and the Kruskal–Wallis test for the median values. A Kaplan–Meier analysis was conducted to estimate the cumulative mortality rate. Logistic regression was employed to compare the primary and secondary outcomes for 30-day or in-hospital death between STEMI and NSTEMI. In a further subgroup analysis, a multivariate Cox proportional hazards model was developed to identify the factors associated with overall mortality for patients with cardiogenic shock of STEMI or NSTEMI. The results are presented as adjusted odds ratio (OR) for logistic regression or adjusted hazard ratio (HR) for the Cox model with corresponding 95% confidence intervals (CIs).
3. Results
A total of 1175 patients with AMI complicated by cardiogenic shock were enrolled in our study. Of these, there were 715 patients with STEMI and 460 patients with NSTEMI. In our study population, compared with NSTEMI, patients with STEMI complicated by cardiogenic shock were younger (65.68 ± 14.05 years vs 70.70 ± 12.99 years, P < .001), men (73.29% vs 60.87%, P < .001), and had fewer underlying chronic diseases, such as diabetes mellitus, hypertension, hyperlipidemia, atrial fibrillation, COPD, CKD, PAOD, gout, and malignancy (Table 1). Moreover, patients with STEMI were less likely to have a history of cardiovascular diseases, such as HF, MI, cerebral vascular accident, or PCI. Primary outcomes were defined as the 30-day mortality or mortality at index hospitalization (Table 2). Mortality at index hospitalization was 14.83% for the STEMI group and 21.09% for the NSTEMI group (OR: 1.54, 95% CI: 1.13–2.08, P = .006). The 30-day mortality was 14.27% for the STEMI group and 19.13% for the NSTEMI group (OR: 1.42, 95% CI: 1.04–1.94, P = .028). The new-onset dialysis rate during index hospitalization was higher in the NSTEMI group (3.08% vs 8.04%, OR: 2.75, 95% CI: 1.50–4.73, P < .001). Also, pneumonia and sepsis were higher in the NSTEMI group. No difference was observed between the 2 groups for patients with cerebral vascular accident during the admission period. However, the major and GI bleeding rates were higher in the STEMI group (2.66% vs 0.22%, P = .014; 3.36% vs 0.22%, P = .007; respectively).
Table 1.
Baseline clinical characteristics of the patients.
| Characteristics | All | STEMI | NSTEMI | P value |
|---|---|---|---|---|
| N = 1175 | N = 715 | N = 460 | ||
| Age, yr* | 67.65 ± 13.86 | 65.68 ± 14.05 | 70.70 ± 12.99 | <.001 |
| Gender† | ||||
| Male | 804 (68.43) | 524 (73.29) | 280 (60.87) | <.001 |
| Female | 371 (31.57) | 191 (26.71) | 180 (39.13) | |
| Treatment | ||||
| IABP use† | 274 (23.32) | 175 (24.48) | 99 (21.52) | .243 |
| ECMO use† | 68 (5.79) | 49 (6.85) | 19 (4.13) | .051 |
| ECMO days* | 2.50 ± 0.95 | 2.35 ± 0.93 | 2.89 ± 0.94 | .033 |
| PCI† | 481 (40.94) | 296 (41.40) | 185 (40.22) | .688 |
| CABG† | 99 (8.43) | 56 (7.83) | 43 (9.35) | .361 |
| Intubation† | 182 (15.49) | 100 (13.99) | 82 (17.83) | .076 |
| Inotropes treatment† | ||||
| Dopamine | 716 (60.94) | 502 (70.21) | 214 (46.52) | <.001 |
| Dobutamine | 162 (13.79) | 107 (14.97) | 55 (11.96) | .144 |
| Norepinephrine | 474 (40.34) | 238 (33.29) | 236 (51.30) | <.001 |
| Epinephrine | 288 (24.51) | 168 (23.50) | 120 (26.09) | .314 |
| Comorbidity† | ||||
| OHCA | 81 (6.89) | 61 (8.53) | 20 (4.35) | .006 |
| Diabetes | 348 (29.62) | 155 (21.68) | 193 (41.96) | <.001 |
| Insulin-requiring | 289 (24.6) | 109 (15.24) | 180 (39.13) | <.001 |
| Hypertension | 484 (41.19) | 240 (33.57) | 244 (53.04) | <.001 |
| Hyperlipidemia | 347 (29.53) | 182 (25.45) | 165 (35.87) | <.001 |
| Atrial fibrillation | 52 (4.43) | 24 (3.36) | 28 (6.09) | .026 |
| COPD | 177 (15.06) | 75 (10.49) | 102 (22.17) | <.001 |
| CKD | 230 (19.57) | 75 (10.49) | 155 (33.7) | <.001 |
| ESRD on dialysis | 134 (11.4) | 37 (5.17) | 97 (21.09) | <.001 |
| PAOD | 80 (6.81) | 28 (3.92) | 52 (11.3) | <.001 |
| Gout | 140 (11.91) | 61 (8.53) | 79 (17.17) | <.001 |
| Malignancy | 104 (8.85) | 53 (7.41) | 51 (11.09) | .030 |
| Previous HF | 212 (18.04) | 90 (12.59) | 122 (26.52) | <.001 |
| Previous MI | 181 (15.4) | 85 (11.89) | 96 (20.87) | <.001 |
| Previous CVA | 219 (18.64) | 100 (13.99) | 119 (25.87) | <.001 |
| Previous PCI | 146 (12.43) | 63 (8.81) | 83 (18.04) | <.001 |
| Previous CABG | 22 (1.87) | 10 (1.4) | 12 (2.61) | .135 |
| Lab median (IQR)‡ | ||||
| Hb | 12.45 (4) | 13.2 (3.7) | 11.2 (3.6) | <.001 |
| Cr | 1.47 (1.24) | 1.36 (0.92) | 1.725 (2.46) | <.001 |
| Na | 138 (5) | 138 (5) | 138 (6) | .007 |
| K | 4 (0.9) | 3.9 (0.8) | 4 (1) | .056 |
| ALT | 41 (63) | 51 (88) | 31 (40) | <.001 |
| CRP | 44.36 (110.2) | 44.4 (109.2) | 44.36 (112.4) | .705 |
| Index admission days* | 12.73 ± 11.04 | 12.19 ± 10.79 | 13.56 ± 11.39 | .038 |
ALT = alanine aminotransferase, CABG = coronary artery bypass grafting, CKD = chronic kidney disease, COPD = chronic obstructive pulmonary disease, Cr = serum creatinine, CRP = C-reactive protein, CVA = cerebral vascular accident, ECMO = extracorporeal membrane oxygenation, ESRD = end-stage renal disease, Hb = serum hemoglobin, HF = heart failure, IABP = intra-aortic balloon pump, IQR = interquartile range, K = serum potassium, MI = myocardial infarction, Na = serum sodium, NSTEMI = non-ST-segment elevation myocardial infarction, OHCA = out-of-hospital cardiac arrest, PAOD = peripheral artery occlusive disease, PCI = percutaneous coronary intervention, STEMI = ST-segment elevation myocardial infarction.
t test.
χ2 test.
Kruskal–Wallis test.
Table 2.
Outcomes for 30-day or index hospitalization mortality.
| Outcome | Number of event (%) | OR (95% CI)* | P value | |
|---|---|---|---|---|
| STEMI N = 715 | NSTEMI N = 460 | |||
| Primary outcomes | ||||
| 30 d or index hospitalization mortality | 106 (14.83) | 98 (21.30) | 1.56 (1.15–2.11) | .004 |
| 30 d mortality | 102 (14.27) | 88 (19.13) | 1.42 (1.04–1.94) | .028 |
| Mortality at index hospitalization | 106 (14.83) | 97 (21.09) | 1.54 (1.13–2.08) | .006 |
| Secondary outcomes | ||||
| New onset of dialysis | 22 (3.08) | 37 (8.04) | 2.75 (1.50-4.73) | <.001 |
| New onset of CVA | ||||
| Ischemic stroke | 9 (1.26) | 8 (1.74) | 1.39 (0.53–3.62) | .503 |
| Hemorrhagic stroke | 5 (0.70) | 1 (0.22) | 0.31 (0.04–2.66) | .285 |
| Major bleeding | 19 (2.66) | 1 (0.22) | 0.08 (0.01–0.60) | .014 |
| Gastrointestinal bleeding | 24 (3.36) | 1 (0.22) | 0.06 (0.01–0.47) | .007 |
| Pneumonia | 133 (18.60) | 109 (23.70) | 1.36 (1.02–1.81) | .035 |
| Sepsis | 139 (19.44) | 148 (32.17) | 1.97 (1.50–2.57) | <.001 |
CVA = cerebral vascular accident, NSTEMI = non-ST-segment elevation myocardial infarction, STEMI = ST-segment elevation myocardial infarction.
Ref. = SETMI.
One-year follow-up events for patients discharged from index hospitalization are displayed in Table 3. The prevalence of recurrent NSTEMI episodes was lower in the STEMI group (1.64% vs 4.41%, P = .013) for these patients. Readmission for HF (9.03% vs 12.95%, P = .057) and all-cause mortality (2.63% vs 4.13%, P = .202) had better trends of the STEMI group but failed to reach the significance. However, the requirement of percutaneous revascularization was higher in the STEMI group (9.52% vs 5.51%, P = .027). The overall 1-year cumulative mortality rate for patients with STEMI and NSTEMI was 17.06% and 24.13%, respectively, as shown in Figure 1.
Table 3.
Outcomes for 1-year follow-up cases.
| Outcome | Number of event (%) | HR (95% CI)* | P value | |
|---|---|---|---|---|
| STEMI N = 609 | NSTEMI N = 363 | |||
| CV outcome | ||||
| Myocardial infarction | ||||
| STEMI | 10 (1.64) | 4 (1.10) | 0.67 (0.21–2.13) | .497 |
| NSTEMI | 10 (1.64) | 16 (4.41) | 2.72 (1.24–6.00) | .013 |
| Revascularization | ||||
| PCI | 58 (9.52) | 20 (5.51) | 0.56 (0.34–0.94) | .027 |
| CABG | 4 (0.66) | 4 (1.10) | 1.68 (0.42–6.73) | .461 |
| Heart failure admission | 55 (9.03) | 47 (12.95) | 1.46 (0.99–2.15) | .057 |
| Death from any cause | 16 (2.63) | 15 (4.13) | 1.58 (0.78–3.20) | .202 |
| Neurologic outcome | ||||
| Ischemic stroke | 3 (0.49) | 1 (0.28) | 0.56 (0.06–5.36) | .613 |
| Hemorrhagic stroke | 1 (0.16) | 1 (0.28) | 1.68 (0.11–26.8) | .715 |
| Unspecified stroke | 9 (1.48) | 7 (1.93) | 1.31 (0.49–3.52) | .592 |
| Safety outcome | ||||
| Major bleeding | 3 (0.49) | 1 (0.28) | 0.56 (0.06–5.38) | .615 |
| GI bleeding | 4 (0.66) | 1 (0.28) | 0.42 (0.05–3.75) | .437 |
CABG = coronary artery bypass grafting, CV = cardiovascular, GI = gastrointestinal, HR = hazard ratio, NSTEMI = non-ST-segment elevation myocardial infarction, PCI = percutaneous coronary intervention, STEMI = ST-segment elevation myocardial infarction.
Ref. = SETMI.
Figure 1.
1-year cumulative mortality of STEMI and NSTEMI patients complicated with cardiogenic shock. NSTEMI = non-ST-segment elevation myocardial infarction, STEMI = ST-segment elevation myocardial infarction.
Subgroup analyses for predicting short-term mortality risk for STEMI or NSTEMI are shown in Tables 4 and 5, respectively. Age (HR: 1.67, 95% CI: 1.10–2.56, P = .017), ECMO (HR: 3.11, 95% CI: 1.79–5.39, P = .031), intubation (HR: 1.99, 95% CI: 1.23–3.10, P = .0.02), and female gender (Male HR: 0.64, 95% CI: 0.43–0.96, P = .031) showed predictive power in the multivariable analysis of the STEMI group, whereas revascularization showed a potential benefit but did not reach significance. For the NSTEMI group, age (HR: 2.66, 95% CI: 1.52–4.67, P = .001) and intubation (HR: 2.17, 95% CI: 1.39–3.37, P = .001) were significant risk factors for short-term mortality, whereas revascularization could be beneficial but did not reach significance in multivariate analysis. Subgroup analysis results for patients in different age groups are listed in Figure 2A and B. Compared with younger patients, those older than 55 years in the STEMI and NSTEMI groups had significantly higher mortality rates.
Table 4.
Subgroup analysis of predictors of 30-day or in-hospital mortality in STEMI.
| Variables | Univariate analysis | Multivariate analysis | ||||
|---|---|---|---|---|---|---|
| HR | 95% CI | P value | HR | 95% CI | P value | |
| Age, >65 yr | 1.91 | (1.27–2.86) | .002 | 1.67 | (1.10–2.56) | .017 |
| Male | 0.53 | (0.36–0.79) | .002 | 0.64 | (0.43–0.96) | .031 |
| Treatment | ||||||
| IABP use | 1.1 | (0.71–1.69) | .670 | – | – | – |
| ECMO use | 2.58 | (1.51–4.40) | .001 | 3.11 | (1.79–5.39) | <.001 |
| ECMO days | 0.61 | (0.34–1.08) | .089 | – | – | – |
| Intubation | 2.23 | (1.45–3.44) | .0003 | 1.99 | (1.28–3.10) | .002 |
| Revascularization | 0.35 | (0.23–0.54) | <.0001 | 0.45 | (0.18–1.12) | .085 |
| PCI | 0.35 | (0.22–0.56) | <.0001 | 0.76 | (0.29–2.03) | .589 |
| CABG | 0.75 | (0.35–1.63) | .472 | – | – | – |
| Comorbidity | ||||||
| Diabetes mellitus | 0.93 | (0.58–1.49) | .763 | – | – | – |
| Insulin-requiring | 1.06 | (0.63–1.78) | .834 | – | – | – |
| Hypertension | 1.38 | (0.94–2.03) | .104 | – | – | – |
| Hyperlipidemia | 0.94 | (0.60–1.46) | .775 | – | – | – |
| Atrial fibrillation | 2.06 | (0.96–4.43) | .065 | – | – | – |
| COPD | 1.32 | (0.75–2.32) | .333 | – | – | – |
| CKD | 1.2 | (0.67–2.15) | .537 | – | – | – |
| PAOD | 1.58 | (0.69–3.61) | .275 | – | – | – |
| Gout | 0.86 | (0.42–1.77) | .682 | – | – | – |
| Malignancy | 1.44 | (0.77–2.70) | .249 | – | – | – |
| Previous CABG | 0.7 | (0.10–4.98) | .719 | – | – | – |
| Dialysis | 1.76 | (0.89–3.49) | .105 | – | – | – |
Adjusted variable: age group, gender, ECMO use, intubation, revascularization, PCI.
CABG = coronary artery bypass grafting, CKD = chronic kidney disease, COPD = chronic obstructive pulmonary disease, ECMO = extracorporeal membrane oxygenation, HR = hazard ratio, IABP = intra-aortic balloon pump, PAOD = peripheral artery occlusive disease, PCI = percutaneous coronary intervention, STEMI = ST-segment elevation myocardial infarction.
Table 5.
Subgroup analysis of predictors of 30-day or in-hospital mortality in NSTEMI.
| Variables | Univariate analysis | Multivariate analysis | ||||
|---|---|---|---|---|---|---|
| HR | 95% CI | P value | HR | 95% CI | P value | |
| Age, >65 yr | 2.99 | (1.72–5.19) | <.0001 | 2.66 | (1.52-4.67) | .001 |
| Male | 0.68 | (0.46–1.01) | .057 | – | – | – |
| Treatment | ||||||
| IABP use | 1.08 | (0.68–1.73) | .745 | – | – | – |
| ECMO use | 1.23 | (0.50–3.03) | .648 | – | – | – |
| ECMO days | 0.72 | (0.30–1.74) | .467 | – | – | – |
| Intubation | 2.03 | (1.31–3.14) | .002 | 2.17 | (1.39-3.37) | .001 |
| Revascularization | 0.37 | (0.24–0.57) | <.0001 | 0.73 | (0.33–1.63) | .445 |
| PCI | 0.37 | (0.23–0.60) | <.0001 | 0.52 | (0.22–1.23) | .135 |
| CABG | 0.75 | (0.36–1.56) | .447 | – | – | – |
| Comorbidity | ||||||
| Diabetes mellitus | 1.47 | (0.99–2.18) | .058 | – | – | – |
| Insulin-requiring | 1.38 | (0.93–2.06) | .111 | – | – | – |
| Hypertension | 1.35 | (0.91–2.03) | .140 | – | – | – |
| Hyperlipidemia | 1.33 | (0.89–1.99) | .166 | – | – | – |
| Atrial fibrillation | 1.57 | (0.76–3.23) | .224 | – | – | – |
| COPD | 1.36 | (0.87–2.14) | .177 | – | – | – |
| CKD | 1.82 | (1.22–2.71) | .003 | 1.28 | (0.83–1.98) | .271 |
| PAOD | 1.49 | (0.87–2.56) | .146 | – | – | – |
| Gout | 1.79 | (1.13–2.84) | .013 | 1.43 | (0.86–2.37) | .171 |
| Malignancy | 1.72 | (1.01–2.94) | .047 | 1.11 | (0.64–1.93) | .709 |
| Previous CABG | 0.74 | (0.18–2.99) | .670 | – | – | – |
| Dialysis | 1.52 | (0.98–2.37) | .064 | – | – | – |
Adjusted variable: age group, intubation, revascularization, PCI, CKD, gout, malignancy.
CABG = coronary artery bypass grafting, CKD = chronic kidney disease, COPD = chronic obstructive pulmonary disease, ECMO = extracorporeal membrane oxygenation, HR = hazard ratio, IABP = intra-aortic balloon pump, NSTEMI = non-ST-segment elevation myocardial infarction, PAOD = peripheral artery occlusive disease, PCI = percutaneous coronary intervention.
Figure 2.
Subgroup analysis of short-term mortality for different age groups in (A) STEMI, (B) NSTEMI. NSTEMI = non-ST-segment elevation myocardial infarction, STEMI = ST-segment elevation myocardial infarction.
4. Discussion
In this study, the 30-day or index hospitalization mortality remained high in patients with Killip IV AMI, especially in NSTEMI patients, with a mortality rate of 21.30%. The outcome difference between STEMI and NSTEMI varied across studies. Upon comparing STEMI and NSTEMI patients with cardiogenic shock, the 30-day or index hospitalization mortality of the STEMI group was significantly lower than that of the NSTEMI group (14.83% vs 21.30%, P = .004). Moreover, the 1-year follow-up demonstrated worse overall survival outcomes for NSTEMI. AMI prognosis under different settings varied in previous studies. The OPERA registry from France included data from 2176 patients with STEMI or NSTEMI. A study based on this registry demonstrated higher in-hospital mortality (4.6% vs 4.3%) but a lower 1-year death rate (9.0% vs 11.6%) for STEMI.[3] In addition, a nationwide registry study in Korea showed that among patients with AMI, a higher 30-day cardiac death rate (8.5% vs 5.7%, respectively) and 1-year cardiac mortality (12.3% vs 9.5%, respectively) were seen in the STEMI group than in the NSTEMI group.[6] Furthermore, a report from Beijing demonstrated higher short-term mortality in the STEMI group than in the NSTEMI group (6.6% vs 5.3%, respectively).[7] However, these trials did not focus on AMI patients with cardiogenic shock.
Anderson et al ever conducted a registry of 235,541 patients with myocardial infarction in the United Stated to evaluate the short-term outcomes. 7.4% of these patients experience cardiogenic shock during the index admission period.[8] The mortality during index admission was 33.1% of the STEMI group and 40.8% of the NSTEMI group. Although the study enrolled more than 80% white people but only 2.2% Asian people, the higher short-term mortality rate of the NSTEMI group than STEMI was similar to our study. Patients with NSTEMI and STEMI have different characteristics. Also, their outcomes vary in different settings. The higher mortality rate of patients with NSTEMI could be related to the presence of more comorbidities. In our analysis, patients in the NSTEMI group were older than those in the STEMI group. Patients with NSTEMI had significantly more comorbidities, including diabetes, hypertension, dyslipidemia, COPD, CKD, PAOD, and gout. This underlying characteristic distribution was also similar to the previous large registry.[8]
Moreover, previous cardiovascular disease events were higher among patients with NSTEMI. The baseline differences between the STEMI and NSTEMI groups could influence the short-term outcome and 1-year results. In our study, under the setting of cardiogenic shock following AMI, the prognosis was worse for the NSTEMI group in both short-term and long-term follow-ups. AMI patients with cardiogenic shock could not survive NSTEMI and have an increased mortality rate because of underlying conditions.
Patients with cardiogenic shock in the NSTEMI group had higher risks of pneumonia, sepsis, and new-onset hemodialysis due to age and underlying comorbidities. Furthermore, for the 1-year outcome analysis, NSTEMI patients had a significantly higher rate of recurrent NSTEMI events and a marginally significant HF readmission rate. Our results are similar to those reported for patients with AMI complicated by cardiogenic shock from the Unites States Nationwide Readmissions Database, which showed a lower 30-day admission rate in the STEMI group (OR: 0.91, CI: 0.82–1.00, P = .042).[4] These results suggest that patients in the NSTEMI group require additional attention for long-term HF and care for ischemic heart disease.
In our analysis, patients with AMI complicated by cardiogenic shock had significant mortality risks during the first 30 days, similar to the IABP-Shock II trial. Studies showed that the first month after AMI was the most critical period for the patients, and the mortality curve could be flattened after that.[9] These suggested that the initial treatment and care of these patients are essential. Devices and inotropic agent support for these patients are used as life-saving implementations or measures, and ECMO-assisted cardiogenic shock showed promising short-term outcomes.[10] Previous reports revealed that ECMO use was usually limited in the first 2 weeks, especially in mortality cases.[11] These could also explain why the highest mortality risk occurred within the first 30 days.
The number of short-term bleeding events, including major and GI bleeding, was significantly higher in the STEMI group. A previous study comparing the risk of bleeding in acute coronary syndrome (ACS) has shown a higher number of bleeding events in the STEMI group than in the NSTEMI group.[12] Patients with more comorbidities were thought to have a higher bleeding risk. However, their bleeding rate was lower, although patients in the NSTEMI group had more comorbidities and were older. This result may be partially explained by the use of different procedures or medications between the groups. In both groups, patients had similar rates of PCI and coronary artery bypass surgery; however, patients in the STEMI group had a higher rate of IABP (24.48% vs 21.52%, P = .2425) or ECMO (6.85% vs 4.13%, P = .0511). The use of the intravascular supporting system is associated with more extended coverage and higher serum levels of antithrombotic agents. Patients in the STEMI group had a higher intravascular supporting system-usage rate and potential higher potency antiplatelet or anticoagulation usage, resulting in more bleeding events.
Subgroup analysis showed the potential benefit of revascularization for patients with AMI complicated by cardiogenic shock. The debates on early revascularization in acute myocardial infarction complicated by cardiogenic shock had been discussed for decades.[13,14] PCI has been reported to be associated with lower mortality in AMI patients complicated by cardiogenic shock,[13,15] even in older patients who received percutaneous revascularization, with the benefit of decreasing the mortality rate by up to 50%.[16] Although our report showed that both groups benefited (STEMI, HR: 0.35, 95% CI: 0.23–0.54, P < .0001; NSTEMI, HR: 0.37, 95% CI: 0.24–0.57, P = .0001), the findings did not reach significance in multivariate analysis. Further studies about revascularization results in correlation to prognosis in AMI complicated with cardiogenic shock may provide more information in this field.
Furthermore, age was still a significant predictor for worse prognosis. The relationship of age with short-term outcomes was further analyzed. The risk significantly increased with age. When comparing patients older than 85 years with those younger than 55 years, the short-term risk increased 3.42-fold (HR 3.42, 1.69–6.94. P = .001) in the STEMI group and 7.32-fold (HR 7.32, 2.51–21.34, P < .001) in the NSTEMI group. Age remained an important risk factor for mortality among patients with AMI complicated by shock.[17] For older patients, this critical condition could lead to a poor prognosis. In addition to age, respiratory failure requiring intubation was a significant predictor of short-term mortality in the STEMI and NSTEMI groups. The ECMO usage rate was higher in the STEMI group; however, the use of ECMO was associated with higher mortality in this group. Despite using inotropic agents or other support, patients with ECMO may have worse outcomes because ECMO is reserved for patients requiring resuscitation.
Finally, among patients with STEMI-related shock, male gender could be a protective factor for short-term outcomes. This gender difference-related outcome has been observed in previous studies of ACS with cardiogenic shock.[18,19] Other studies focusing on STEMI with gender differences have also shown this phenomenon.[20,21] The possible causes include older age and more comorbidities in female patients with ACS. However, a further study on STEMI in younger patients showed worse short-term outcomes in female patients after adjustment for demographics, comorbidities, medications, and severity of coronary disease.[22] Furthermore, in the IABP-SHOCK II trial, no gender-related difference was seen in clinical outcomes after multivariable adjustment for baseline characteristics.[18] However, the IABP-SHOCK II trial included both STEMI and NSTEMI cases, and gender-associated outcome differences were less significant for NSTEMI in our study. Therefore, further studies are required to evaluate this phenomenon.
5. Limitations
In this database analysis study, we evaluated patients with AMI with cardiogenic shock. The retrospective design limited our ability to enroll patients randomly and might have caused selection bias. The claim-based database did not include personal information such as tobacco use, lifestyle, and family history of cardiovascular disease. Information on the daily physical activity was also unavailable in our database. Furthermore, the timing of ischemia onset to diagnosis and treatment is an essential issue of ACS. Clinically, the symptoms of ischemic onset of AMI could be several hours to days before patients presented themselves to the emergency department. However, this information could not be obtained in the research database. Besides, the diagnoses of comorbidities were based on ICD-9 or ICD-10 codes, and it was challenging to distinguish underlying disease severity. Type 2 MI could also exist in the study. Finally, we did not analyze detailed medication usage among different groups of patients, including different oral antihyperglycemic agents, antiplatelets, or anticoagulants, which could be associated with the differences in outcomes.
6. Conclusion
We demonstrated the outcomes of STEMI and NSTEMI complicated by shock. The results revealed that mortality remained high in patients with AMI complicated by cardiogenic shock. Moreover, compared with STEMI, NSTEMI was associated with a significantly higher mortality rate in short-term results. NSTEMI group also has a higher risk for recurrent NSTEMI at long-term follow-up. Furthermore, age and respiratory failure were the most significant risk factors for short-term mortality. Female gender was also a predictor of worse prognosis for STEMI with cardiogenic shock. Finally, revascularization showed a potential benefit for short-term outcomes but did not reach significance in multivariable analysis.
Acknowledgments
The authors thank the statistical assistance and wish to acknowledge the support of the Maintenance Project of the Center for Big Data Analytics and Statistics (Grant CLRPG3D0046) at Chang Gung Memorial Hospital for study design and monitor, data analysis, and interpretation.
Author contributions
CCC, ICH, MLT, and SHC conceived and designed the study. MLT, MJH, and VCW, drafted the manuscript. WCL and YTH collected, analyzed, interpreted the data, and performed the statistical analyses. All authors reviewed the manuscript.
Data curation: Wen-Ching Lan, Yu-Tung Huang.
Formal analysis: Wen-Ching Lan, Yu-Tung Huang.
Investigation: Ming-Lung Tsai, Ming-Jer Hsieh, Shang-Hung Chang.
Methodology: Ming-Lung Tsai, Ming-Jer Hsieh.
Project administration: Shang-Hung Chang.
Supervision: Chun-Chi Chen, I-Chang Hsieh.
Writing – original draft: Ming-Lung Tsai.
Writing – review & editing: Victor Chien-Chia Wu.
Supplementary Material
Abbreviations:
- ACS =
- acute coronary syndrome
- AMI =
- acute myocardial infarction
- CGRD =
- Chang Gung Research Database
- CI =
- confidence interval
- CKD =
- chronic kidney disease
- COPD =
- chronic obstructive pulmonary disease
- ECMO =
- extracorporeal membrane oxygenation
- GI =
- gastrointestinal
- HF =
- heart failure
- HR =
- hazard ratio
- IABP =
- intra-aortic balloon pump
- ICD =
- International Classification of Diseases
- MI =
- myocardial infarction
- NSTEMI =
- non-ST-segment elevation myocardial infarction
- OR =
- odds ratio
- PAOD =
- peripheral artery occlusive disease
- PCI =
- percutaneous coronary intervention
- STEMI =
- ST-segment elevation myocardial infarction.
This study was approved by the Chang Gung Memorial Hospital Institutional Review Board (201700965B0C502), and informed consent was waived because of the retrospective nature of the study and the analysis used anonymous clinical data.
This work was supported by a grant from Chang Gung Memorial Hospital for statistical assistance and open access (grant no: CMRPG3I0093). This funding body had no role in the design of this study and will not have any role during its execution, analyses, interpretation of the data, or decision to submit results.
The authors have no conflicts of interest to disclose.
The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
Supplemental Digital Content is available for this article.
How to cite this article: Tsai M-L, Hsieh M-J, Chen C-C, Wu VC-C, Lan W-C, Huang Y-T, Hsieh I-C, Chang S-H. Prognosis of patients with cardiogenic shock following acute myocardial infarction: The difference between ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction. Medicine 2022;101:36(e30426).
Contributor Information
Ming-Lung Tsai, Email: dogofly@gmail.com.
Ming-Jer Hsieh, Email: hsiehic@ms28.hinet.net.
Chun-Chi Chen, Email: mr3228@gmail.com.
Victor Chien-Chia Wu, Email: victorcwu@hotmail.com.
Wen-Ching Lan, Email: wenching1122@gmail.com.
Yu-Tung Huang, Email: anton.huang@gmail.com.
I-Chang Hsieh, Email: hsiehic@ms28.hinet.net.
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