Prolonged QT interval and coronary artery bypass mortality due to heart failure.

QT-interval prolongation has been shown to predict mortality in coronary artery disease and heart failure. To assess the prognostic value of QT interval for death due to low cardiac output after coronary artery bypass grafting, the QT interval was measured in 3 consecutive beats on the preoperative electrocardiogram (leads II and V(4)) in 30 patients who died perioperatively due to heart failure and a control group of 168 randomly matched hospital survivors during the same 3-year period. Mean corrected QT interval was significantly longer in the patients who died compared to the control group (480.7 +/- 96.2 vs. 425.4 +/- 21 ms). Among the variables evaluated, QT prolongation was the only independent predictor of perioperative death. In patients admitted for coronary artery bypass grafting, QT interval measurement is a simple clinical tool that may identify patients with a greater probability of a troublesome operative course.