Association of QRS duration and outcomes after myocardial infarction: the VALIANT trial.

Background: Prolongation of the QRS duration has been shown to be associated with adverse outcomes among heart failure (HF) patients. The association of QRS duration with clinical outcomes in the post-myocardial infarction (MI) setting is less well defined.
Objectives: To assess the prognostic significance of QRS duration prolongation on initial electrocardiogram after acute MI.
Methods: QRS duration was measured in 403 patients with MI complicated by left ventricular dysfunction, signs or symptoms of HF, or both, who were enrolled in the Valsartan in Acute Myocardial Infarction (VALIANT) echo study. The cohort was divided into quartiles of QRS duration (<75 ms, 75-88 ms, 89-108 ms, >108 ms). The number of clinical events were determined and compared across the groups.
Results: Increasing QRS duration is associated with a higher incidence of HF, sudden death (SD), and cardiovascular (CV) death (P-trend <0.05) but not with stroke or recurrent MI. The univariate relative risks for HF, SD, and CV death with increasing QRS duration quartiles were 1.31 (95% CI, 1.06-1.64), 1.57 (95% CI, 1.03-2.40), and 1.31 (95% CI, 1.03-1.66), respectively, but QRS duration did not remain independently predictive of adverse outcome after adjusting for the 10 most predictive baseline covariates. Baseline end-diastolic and end-systolic volumes were larger and ejection fraction was lower in the higher QRS quartile groups.
Conclusions: Prolonged QRS duration, even within the normal range, is associated with larger ventricular volumes, reduced systolic function, and an increased risk for development of HF, SD, and CV death after MI but appears to be a marker, rather than an independent predictor, for increased risk.