Heart transplantation now provides an acceptable therapy for patients with severe end-stage heart disease. Although patient outcome has significantly improved both early and late after heart transplantation, early morbidity and mortality continues to affect overall survival and may be unpredictable. In an attempt to identify factors that may assist in predicting early outcome after orthotopic heart transplantation, we assessed allograft function in 16 patients in the immediate postoperative period, 30 minutes after weaning from cardiopulmonary bypass by measuring the fractional shortening of the left ventricle with transesophageal echocardiography. In addition, standard hemodynamic indexes of allograft function (arterial blood pressure, pulmonary capillary wedge pressure, mean pulmonary artery pressure, and cardiac output) were obtained at this early time point. Early outcome was assessed by the duration and peak dose of inotrope support required after transplantation, requirement for mechanical support, and the duration of stay in the intensive care unit. Left ventricular fractional shortening 30 minutes after cardiopulmonary bypass was significantly lower in those patients requiring inotropic support (28.4% +/- 4.6% versus 43.7% +/- 3.5%, p < 0.05), whereas hemodynamic variables failed to distinguish these groups. In those patients requiring inotropes, there was a significant negative correlation of fractional shortening with the peak dose (r = -0.87, p < 0.01) and the duration of inotropic support (r = -0.62, p < 0.05). The total ischemic time of the allograft (206 +/- 22 minutes, range 77 to 359) did not correlate with the subsequent fractional shortening, but patients requiring inotrope support after the operation had significantly longer ischemic times (259 +/- 22 versus 138 +/- 22 minutes, p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)