Prolonged QTc affects short-term and long-term outcomes in patients with normal left ventricular function undergoing cardiac surgery.

Abstract

Although it is known that preoperative decreased left ventricular ejection fraction (LVEF) is a risk for morbidity and mortality after cardiac surgery, there are no reliable markers of risk in patients with preserved LVEF. This study examines whether a prolonged QTc interval is associated with adverse outcomes in patients with preoperative LVEF greater than 40% undergoing cardiac surgery. A retrospective chart review of patients who had cardiac surgery at St. Paul's Hospital in Vancouver, Canada, between 2004 and 2009, who had a preoperative LVEF greater than 40%, was undertaken. We tested for association of preoperative prolonged QTc interval with mortality and morbidity using unadjusted and adjusted analyses. Five-hundred and fifty-five patients with a preoperative LVEF greater than 40% were included in the study; 496 (89.4%) had cardiopulmonary bypass and the remainder were off pump. Preoperative prolonged QTc was associated with increased mortality at 30 days (P < .01), 90 days (P < .01), and 8 years (P < .01), and these results remained significant after adjusting for the clinical variables significantly associated with mortality (8-year odds ratio, 2.42; 95% confidence interval, 1.34-4.34; P = .003). Similar results were found when the analysis was restricted to the more homogeneous group of patients undergoing on-pump coronary artery bypass (CABG, n = 408). Prolonged QTc was also associated with prolonged intensive care unit stay (P = .02), prolonged hospital stay (P < .01), development of atrial arrhythmias (P = .02), and low cardiac output syndrome (on-pump CABG, P = .02). In patients undergoing cardiac surgery and a preoperative LVEF greater than 40%, a prolonged QTc interval is associated with increased short-term and long-term mortality and increased perioperative morbidity, and therefore should be considered when assessing risk preoperatively.