Association between resolution of fragmented QRS and response to cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) has been recommended for patients with symptomatic heart failure and a wide QRS. Fragmented QRS (fQRS) on a 12-lead electrocardiography (ECG) has been shown to predict cardiac events. We aimed to investigate the relationship between resolution of fQRS and response to CRT.

Sixty-seven consecutive patients (38 men, mean age 65 ± 11) with left bundle branch block and fQRS on ECG undergoing CRT were studied. The presence of fQRS was assessed using standardized criteria. Echocardiographic response to CRT was defined by a ≥15% reduction in left ventricular end-systolic volume (LVESV) and resolution of fQRS was defined as decrease in number of leads with fQRS on ECG at 6 months follow-up.

Thirty-nine patients (58%) had response to CRT. LVESV significantly decreased from 150 ± 64 to 100 ± 48 in responders (P = 0.001). There was not any significant decrease in nonresponders (LVESV; from 157 ± 70 to 153 ± 66, P = 0.45). The number of leads with fQRS was decreased from 4.4 ± 1.8 to 1.7 ± 1.6 in responder patients (P < 0.001). The number of leads with fQRS was not significantly changed in nonresponders. (4.2 ± 2.2 vs. 5.1 ± 2.4, P = 0.06). In multivariate analysis, significant associates of response to CRT was evaluated adjusting for etiology of cardiomyopathy, baseline QRS width, left ventricular ejection fraction, number of leads with fQRS and resolution of fQRS. Resolution of fQRS was the only predictor of response to CRT (OR 0.018, 95% CI, 0.004-0.083, P < 0.001).

After adjusting for potential confounders, resolution of fQRS, is associated with response to CRT.