Fragmented narrow QRS complex: predictor of left ventricular dyssynchrony in non-ischemic dilated cardiomyopathy.

Background: Cardiac resynchronization therapy is an important therapeutic modality in drug refractory symptomatic patients of heart failure with wide QRS (≥120 ms) on electrocardiogram. However, wide QRS (considered as a marker of electrical dyssynchrony) occurs in only 30% of heart failure patients, making majority of drug refractory heart failure patients ineligible for resynchronization therapy. Significant numbers of patients with narrow QRS have echocardiographic evidence of left ventricular dyssynchrony.