Prolonged QRS duration in patients with heart failure: relation to exercise tolerance, diastolic function and aetiology.

BACKGROUND

In patients with chronic heart failure (CHF) QRS prolongation is a frequent finding and is related to increased morbidity and mortality. It is not clear if prolonged QRS in CHF of ischaemic origin (CAD) represents the same severity of the syndrome as in non-ischaemic (non-CAD) cardiomyopathy.

AIM: To assess the relationship between QRS duration and BNP levels, diastolic function and peak VO2 in patients with CAD CHF and non-CAD CHF.

METHODS

In 70 patients with left ventricular ejection fraction (LVEF) <45% [35 with left bundle branch block (LBBB)] echocardiography, cardiopulmonary exercise test and standard ECG were performed as well as BNP level was measured.

RESULTS

Peak VO2 was significantly lower, BNP level higher in patients with LBBB than those without LBBB. In the non-CAD CHF peak VO2 was significantly lower, whereas BNP levels and restrictive filling pattern prevalence higher in the group with LBBB than without LBBB, which was not seen in the CAD CHF group. A significant correlation between peak VO2 and BNP levels (r=-0.31; p=0.02), QRS duration (r=-0.27; p=0.02), and diastolic function parameter - DTE (r=0.28; p=0.02) was found. Peak VO2 was significantly lower in the CAD CHF than in non-CAD CHF. In multivariate regression analysis, LVEF (r=-0.32; p=0.012) and LVEDD (r=0.30; p=0.015) were independently associated with QRS duration.

CONCLUSION

In patients with CHF, QRS duration is independently related to LVEF and LVEDD. It seems that prolonged QRS may be a better predictor of more advanced CHF in patients with non-ischaemic rather than ischaemic cardiomyopathy.