Prognostic significance of QT interval prolongation in adult Nigerians with chronic heart failure.

BACKGROUND AND OBJECTIVES: 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.

MATERIALS AND METHOD: Ninety-six consecutive patients with heart failure were recruited with 90 age and sex-matched controls. All the subjects had a 12-lead electrocardiogram at a paper speed of 25 mm/sec and a rhythm strip (lead II) at 50 mm/sec. The latter was used to calculate the QTc using the Bazett's formula. Left ventricular systolic and diastolic functions were assessed using 2D guided M-mode and Doppler echocardiogram respectively. They were followed-up for six months.

RESULTS: 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 patients was similar to that of the controls (50.3 +/- 15) (P = 0.475). Twenty-eight (30.8%) patients died after 6 months 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, R2 = 0.17, P= 0.001).

CONCLUSION: QTc prolongation is a predictor of mortality in CHF and may be an important adjunct in risk stratification of patients with heart failure.