Objectives Prolongation of the QRS duration (≥ 120 ms) has been suggested to be an independent risk factor for mortality in patients with heart failure. The purpose of this study was to examine the clinical baseline variables correlated with the QRS duration and the association between the QRS duration and survival in patients with dilated cardiomyopathy (DCM).
Methods A retrospective observational cohort study was undertaken in 1119 patients with DCM and a median follow-up of 3.5 years. Standard demographics, transthoracic echocardiography, and routine blood tests were obtained shortly after admission. All patients were subsequently divided into the following groups: QRS > 150 ms, QRS = 120-150 ms, and QRS < 120 ms. The outcome was assessed with all-cause mortality after admission. The correlates with QRS duration were assessed by multivariable linear regression, and the association between the QRS duration and all-cause mortality was assessed with multivariable Cox regression. Subgroups were also stratified by the left ventricular ejection fraction (LVEF) and NYHA functional classes.
Results Of the 1108 patient with DCM, 19.3% (n = 216) had QRS > 150 ms, 23.0% (n = 257) had QRS = 120-150 ms, and 57.7% (n = 646) had QRS < 120 ms. Age, disease course, left ventricle diameter and left atrium diameter were positively associated with the QRS duration, whereas the heart rate, LVEF, atrial fibrillation, and right ventricle diameter were negatively associated with the QRS duration. The all-cause mortality rates were highest in patients with QRS > 150 ms (33.3%), intermediate in those with QRS = 120-150 ms (33.1%), and lowest in those with QRS < 120 ms (17.2%) after the mean follow-up of 3.5 years, showing a significant difference in the all-cause morbidity risk among the QRS duration groups (log-rank χ2 = 42.811, P < 0.001). In the subgroup patients with LVEF ≤ 30% and NYHA III or IV, QRS prolongation was associated with a significant increase in the all-cause mortality rate. After adjustment for baseline variables, Cox regression analysis further revealed that the QRS, left atrium diameter and NYHA functional classes were independent predictors of all-cause mortality in patients with DCM.
Conclusions The QRS duration was correlated with age, LVEF, left ventricle diameter, left atrium diameter, right ventricle diameter and disease course. In addition, QRS prolongation is an independent predictor of increased all-cause mortality in patients with DCM.