Pattern of Left Ventricular Diastolic Dysfunction and QTc Prolongation in Adult Nigerians with Chronic Heart Failure

Abstract

Abnormalities of left ventricular diastolic function are known in patients with chronic heart failure but their relationship with QT interval has not been well studied, particularly in Nigeria. This study is therefore aimed at determining the relationship between pattern of diastolic dysfunction and QT interval. 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 25mm/sec and a rhythm strip (lead II) at 50mm/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 for clinical outcome. 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 during the study period. When patients with mild to moderate diastolic dysfunction (impaired relaxation and pseudo-normalization) were compared with severe form (restrictive pattern), the mean QTc was significantly longer in the latter group (0.493±0.029) than in the former (0.468±0.037) P=0.0001. Significant positive correlation was observed between QTc and stage of diastolic dysfunction (r = 0.318, P = 0.002). The data suggest that QTc may predict severity of diastolic dysfunction and by extension death in this group of patients.

Keywords: Diastolic dysfunction, QTc, mortality, chronic heart failure

Nigerian Medical Practitioner Vol. 53 (4) 2008: pp. 57-61