Fragmented QRS predicts the arrhythmic events in patients with heart failure undergoing ICD implantation for primary prophylaxis: more fragments more appropriate ICD shocks.

Background: Fragmented QRS complex (fQRS) is associated with cardiovascular outcomes in various patient populations. Although there were clinical studies investigating the association of fQRS with arrhythmic events in patients with systolic heart failure, the results were conflicting regarding the association of implantable cardioverter defibrillator (ICD) shocks and fQRS. In this study, we aimed to evaluate the association between the presence and extent of fQRS with appropriate ICD shocks and/or all-cause mortality.
Methods: A total of 215 patients (age: 58.2 ± 11.6 years, 72.5 % male) with the diagnosis of left ventricular systolic heart failure in whom ICD had been implanted for primary prophylaxis were enrolled. Standard ECG evaluation revealed fQRS complex in 123 patients (57.2 %). The phenomenon of fQRS was defined as deflections at the beginning of the QRS complex, on top of the R wave, or in the nadir of the S wave similar to the definition in CAD.
Results: At mean 23.5 ± 12.1 months follow-up, all-cause mortality was observed in 45 (20.9 %) patients and 111 (51.6 %) patients experienced appropriate ICD shocks. Median number of ECG leads with fQRS were higher in patients with appropriate ICD shocks (3 [2-6] vs 1 [0-2], P < 0.001, respectively). The presence of fQRS (HR: 6.64, 95 % CI: 3.54-12.4, P < 0.001) and the number of leads with fQRS (HR: 1.35, 95% CI: 1.22-1.67) were found as independent predictors of appropriate ICD shocks. Additionally, there was a negative correlation between left ventricular ejection fraction and the number of leads with fQRS (r = -0.434, P < 0.001). Rates of all-cause mortality did not differ between the fQRS(+) (29 [24 % ]) and fQRS(-) (16 [17 % ]) groups (P = 0.27).
Conclusion: Our findings suggest that the presence and extent of fQRS complex on standard 12-lead ECG predicts appropriate ICD shocks in patients with left ventricular systolic heart failure who underwent ICD implantation for primary prophylaxis.
(© 2014 Wiley Periodicals, Inc.)