Mechanical ventricular assist devices (VADs) have led to survival in patients who develop postcardiotomy cardiogenic shock (PCCS) refractory to conventional therapies. To elicit determinants of survival, the authors reviewed records of 26 patients at our institution who required Pierce-Donachy VADs for PCCS. Thirteen patients were weaned from ventricular assistance (50%), nine (34.6%) achieved long-term survival, and 17 died. Survivors and those that died were equivalent in terms of age, sex, NYHA class, type of operation, and preoperative hemodynamics. Ventricular assist pumping was established earlier in survivors (P = 0.006) although aortic cross-clamp and total cardiopulmonary bypass times were equivalent between the groups. The development of biventricular failure was significantly associated with the inability to wean from mechanical circulatory assistance. Despite an equal incidence of biventricular failure, survivors had milder forms of this entity and all patients with severe biventricular failure requiring a biventricular assist device failed to wean and ultimately died (N = 5). Of all complications, inadequate cardiac output was a significant determinant of weaning. Perioperative myocardial infarction and renal failure were found to be univariate determinants of survival. Inadequate cardiac output and biventricular failure preclude weaning from mechanical circulatory assistance. Survival is associated with the expeditious establishment of assist pumping, and with the avoidance of irreversible perioperative myocardial injury and renal failure.