Predictive factors of hemodynamic collapse after coronary artery bypass grafting: a case-control study

OBJECTIVE: Sudden hemodynamic collapse after coronary artery bypass graft (CABG) surgery is a complication with high morbidity and mortality. The aim of this study was to explore factors possibly predictive of this major complication. DESIGN: Retrospective case-control study. SETTING: University hospital, department of cardiothoracic surgery. PARTICIPANTS: Between 1988 and 1999, of 8,807 CABG patients, a total of 76 (0.9%) suffered hemodynamic collapse after CABG surgery unrelated to pericardial tamponade or bleeding. Preoperatively matched patients (by age, sex, New York Heart Association classification, number of diseased vessels, left ventricular ejection fraction, and diabetes) served as a control group (n = 76). INTERVENTIONS: Patients with sudden cardiovascular collapse underwent emergency reopening of the sternotomy and open cardiac massage (OCM group). Several pre-, intra-, and postoperative variables were compared, and significant parameters in match-pair analysis were further tested with regression techniques. MEASUREMENTS AND MAIN RESULTS: Of the 76 OCMs, 57 (75%) occurred during the first 5 postoperative hours. In-hospital mortality was 46% (35 of 76) versus 0% in controls; 5-year survival was 49% versus 95%. In the OCM group, cardiopulmonary bypass (CPB) time was significantly prolonged (p = 0.0024), and cardiac index (p = 0.05) and the first acid-base values after CPB were lower (pH, p = 0.0057; BE, p = 0.0014). Postoperative myocardial ischemia appeared in 33% of patients in the OCM group and in 8% of controls (p < 0.0001). OCM-group patients more frequently required postoperative inotropic (epinephrine, p = 0.0002) and mechanical support (intra-aortic balloon pump, p = 0.005). Regression analysis revealed a correlation between cardiopulmonary resuscitation risk and low cardiac index, postoperative ischemia, and low pH level. CONCLUSION: Inadequate tissue perfusion, postoperative myocardial ischemia, and increased need for inotropic and mechanical support preceded hemodynamic collapse. Interventions to improve tissue perfusion and to prevent and treat myocardial ischemia may result in a more favorable outcome.