Prolonged QTc interval and high B-type natriuretic peptide levels together predict mortality in patients with advanced heart failure.

Abstract

The role of QTc interval prolongation in heart failure remains poorly defined. To better understand it, we analyzed the QTc interval duration in patients with heart failure with high B-type natriuretic peptide (BNP) levels and analyzed the combined prognostic impact of prolonged QTc and elevated BNP. QTc intervals were measured in 241 patients with heart failure who had BNP levels >400 pg/mL. QT interval duration was determined by averaging 3 consecutive beats through leads II and V4 on a standard 12-lead ECG and corrected by using the Bazett formula. QTc intervals were prolonged (>440 ms) in 122 (51%) patients and normal in 119 (49%). The BNP levels in these 2 groups were not significantly different (786+/-321 pg/mL in the prolonged QTc group versus 733+/-274 pg/mL in the normal QTc group, P=0.13). During 6 months of follow-up, 46 patients died, 9 underwent transplantation, and 17 underwent left ventricular assist device implantation. The deaths were attributed to pump failure (n=24, 52%), sudden cardiac death (n=18, 39%), or noncardiac causes (n=4, 9%). Kaplan-Meier survival rates were 3 times higher in the normal QTc group than in the prolonged QTc group (P<0.0001). On multivariate analysis, prolonged QTc interval was an independent predictor of all-cause death (P=0.0001), cardiac death (P=0.0001), sudden cardiac death (P=0.004), and pump failure death (P=0.0006). Prolonged QTc interval is a strong, independent predictor of adverse outcome in patients with heart failure with BNP levels >400 pg/mL.