Prognostic Significance Of QT Interval Prolongation In Adult Nigerians With Chronic Heart Failure.

Abstract

Prognostic survival studies for heart-rate corrected QT interval in patients with
chronic heart failure are few; although these patients are known to have a high risk of sudden cardiac death. This study was aimed at determining the mortality risk associated with prolonged QTc in Nigerians with heart failure. Ninety-six consecutive patientswith heart failurewere recruitedwith 90 age and sexmatched controls.All the subjects had a 12-lead electrocardiogramat a paper speed of 25mm/sec and a rhythm strip (lead II) at 50mm/sec.The latterwas used to calculate theQTc using the Bazett\'s formula. Left ventricular
systolic and diastolic functions were assessed using 2D guided M-mode and Doppler echocardiogram respectively.Theywere followed-up for sixmonths. Ninety-one patients and 90 controls completed the study. Five patients were lost to follow-up. The
mean age (51.9±16 years) of the patientswas similar to that of the controls (50.3±15) (P= 0.475).Twenty-eight (30.8%) patients died after 6months of follow-up against none of the controls.The mean QTc was significantly longer in the non-survivors (0.494±0.027) than in the survivors (0.462±0.035) (P = 0.0001). The percentage mortality in patients with prolonged QTc against those with normal QTc was 41% and 14% respectively (P =
0.001). In the stepwise regression analysis, QTc was an independent predictor of mortality (R = 0.412, R = 0.17, P= 0.001). QTc prolongation is a predictor of mortality in CHF and may be an important adjunct in risk stratification of patientswith heart failure.

Keywords: Chronic Heart Failure, QTc Prolongation, Mortality

Nigerian Journal of Clinical Practice Vol. 11 (4) 2008: pp. 336-341