Table 1.
Demographic and clinical characteristics of the study population, n = 4,217
| Characteristics | Patients with nadir platelet ≤ 74 × 109/L (n = 428) | Patients with nadir platelet > 74 × 109/L (n = 3789) | P value |
|---|---|---|---|
|
| |||
| Demographics | |||
| Age categories, years | < 0.0001 | ||
| <55 | 44 (10.3) | 810 (21.4) | |
| 55–64 | 105 (24.5) | 1186 (31.3) | |
| 65–74 | 147 (34.4) | 1200 (31.7) | |
| 75–84 | 115 (26.9) | 551 (14.5) | |
| >84 | 17 (3.9) | 42 (1.1) | |
| Race | 0.771 | ||
| White | 329 (76.9) | 2900 (76.5) | |
| African American | 74 (17.3) | 706 (18.6) | |
| Hispanic | 3 (0.7) | 20 (0.5) | |
| Asian | 6 (1.4) | 32 (0.8) | |
| American Indian | 16 (3.7) | 127 (3.4) | |
| Other | 0 | 4 (0.1) | |
| Female sex | 153 (35.8) | 1020 (26.9) | 0.0001 |
|
| |||
| Medical history* | |||
| EuroSCORE-related variables | |||
| Chronic obstructive pulmonary disease | 74 (17.3) | 550 (14.5) | 0.126 |
| Peripheral vascular disease | 87 (20.3) | 618 (16.3) | 0.035 |
| Cerebrovascular accident | 43 (9.7) | 366 (10.1) | 0.798 |
| Previous cardiac surgery | 7 (1.6) | 31 (0.8) | 0.089 |
| Serum creatinine > 2 mg/dL | 36 (8.4) | 191 (5) | 0.003 |
| Critical preoperative state | 14 (3.3) | 53 (1.4) | 0.003 |
| Unstable angina pectoris | 50 (11.7) | 415 (10.9) | 0.648 |
| Left ventricular function | < 0.0001 | ||
| Normal | 168 (39.2) | 1918 (50.6) | |
| Moderate dysfunction | 192 (44.9) | 1526 (40.3) | |
| Severe dysfunction | 68 (15.9) | 345 (9.1) | |
| Recent myocardial infarction | 113 (26.4) | 950 (25.1) | 0.548 |
| Pulmonary hypertension | 7 (1.6) | 22 (0.6) | 0.012 |
| Emergency cardiac surgery | – | – | – |
| Post-infarct septal rupture | – | – | – |
| Average logistic EuroSCORE, % | 5.0 [2.7–10.1] | 3.0 [1.6–5.8] | < 0.0001 |
| Diabetes mellitus | 162 (37.4) | 1416 (37.8) | 0.846 |
|
| |||
| Laboratory tests results | |||
| Preoperative: | 1.1 [0.9–1.4] | 1.0 [0.9–1.2] | < 0.0001 |
| Serum creatinine, mg/dL | |||
| Platelet count, 109/L | 170.7 ± 58.2 | 227.8 ± 69.3 | < 0.0001 |
| Hemoglobin, g/dL | 12.7 ± 1.9 | 13.1 ± 1.9 | 0.007 |
| Postoperative | |||
| Nadir platelet count, 109/L | 59.9 ± 12.9 | 134.7 ± 41.9 | < 0.0001 |
| Nadir hemoglobin, g/dL | 8.7 ± 1.1 | 8.9 ± 1.2 | < 0.0001 |
|
| |||
| Preoperative medications† | |||
| Acetylsalicylic acid | 277 (66.3) | 2432 (65.1) | 0.649 |
| Alpha-receptor blockers | 24 (5.7) | 221 (5.9) | 0.883 |
| Angiotensin converting enzyme inhibitors | 180 (43.1) | 1578 (42.3) | 0.756 |
| Angiotensin II receptor antagonist | 38 (9.1) | 348 (9.3) | 0.877 |
| Beta-receptor blockers | 254 (60.8) | 2166 (58) | 0.281 |
| Calcium-channel blockers | 76 (18.2) | 710 (19) | 0.679 |
| Clopidogrel | 65 (15.6) | 499 (13.4) | 0.217 |
| Diuretics | 157 (37.6) | 1108 (29.7) | 0.0009 |
| Nitrates | 150 (35.9) | 1123 (30.1) | 0.015 |
| Statins | 213 (51) | 1949 (52.2) | 0.627 |
| Warfarin | 27 (6.5) | 139 (3.7) | 0.007 |
|
| |||
| Intraoperative characteristics | |||
| Year of surgery | 0.046 | ||
| 2001 | 97 (22.7) | 655 (17.3) | |
| 2002 | 77 (18) | 605 (16) | |
| 2003 | 44 (10.3) | 480 (12.7) | |
| 2004 | 36 (8.4) | 376 (9.9) | |
| 2005 | 48 (11.2) | 353 (9.3) | |
| 2006 | 30 (7) | 361 (9.5) | |
| 2007 | 34 (7.9) | 331 (8.7) | |
| 2008 | 34 (7.9) | 313 (8.3) | |
| 2009 | 28 (6.5) | 315 (8.3) | |
| Duration of cardiopulmonary bypass, minutes | 146.7 ± 55.6 | 122.2 ± 39.9 | < 0.0001 |
| Duration of aortic cross clamp, minutes | 76.4 ± 32.3 | 67.6 ± 27.9 | < 0.0001 |
| Intraoperative insertion of intra-aortic balloon pump | 97 (22.7) | 259 (6.8) | < 0.0001 |
|
| |||
| Intraoperative medications | |||
| Aminocaproic acid | 297 (69.4) | 2981 (78.7) | < 0.0001 |
| Aprotinin | 106 (24.8) | 648 (17.1) | < 0.0001 |
| Epinephrine | 269 (62.9) | 1682 (44.4) | < 0.0001 |
| Norepinephrine | 51 (11.9) | 169 (4.5) | < 0.0001 |
| Vasopressin | 84 (19.6) | 404 (10.7) | < 0.0001 |
| Nitroprusside | 187 (43.7) | 1506 (39.8) | 0.114 |
| Nitroglycerin | 304 (71) | 2745 (72.4) | 0.534 |
| Esmolol | 15 (3.5) | 106 (2.8) | 0.406 |
| Metoprolol | 278 (64.9) | 2624 (69.3) | 0.069 |
|
| |||
| Perioperative blood product use within 2 days, unit | |||
| Red blood cells | 5 [3–8] | 2 [0–4] | < 0.0001 |
| Fresh frozen plasma | 1 [0–4] | 0 [0–1] | < 0.0001 |
| Platelets | 1 [0–3] | 0 [0–1] | < 0.0001 |
| Cryoprecipitate | 0 [0–0] | 0 [0–0] | 0.0004 |
Values are expressed as mean ± standard deviation, median [interquartile range], or n (%).
*
The definitions of these risk factors were based on the definitions used by the European System for Cardiac Operative Risk Evaluation (EuroSCORE) scoring system.19
†
Due to missing numbers (%), preoperative medication use was computed for n = 418 patients in the 10th percentile group with a nadir platelet count ≤ 74 × 109/L, and for n = 3733 patients with a nadir platelet count > 74 × 109/L.