Fragmented QRS as a predictor of arrhythmic events in patients with hypertrophic obstructive cardiomyopathy

This study aims to determine whether fragmented QRS (fQRS) in the surface electrocardiogram (ECG) at implantable cardioverter defibrillator (ICD) implant can predict arrhythmic events using appropriate therapy delivered by the ICD as a surrogate. Hypertrophic obstructive cardiomyopathy (HOCM) is a genetic disorder associated with life-threatening arrhythmias frequently requiring an ICD. Seeking a noninvasive method of risk stratification remains a challenge. This paper is a retrospective, multicenter study of patients with HOCM and ICD. Surface 12-lead ECGs were analyzed. Appropriate therapy was validated by a blinded Core Lab. Univariate and multivariate analyses were performed. A p value of < 0.05 was considered significant. We included 102 patients from 13 centers. Mean age at implant was 41.16 +/- 18.25 years, 52 % were male. Mean left ventricular ejection fraction was 61.56 +/- 9.46 % and two thirds had heart failure according to the New York Heart Association class I. Secondary prophylaxis ICD implantation was the indication for implant in 40.2 % of cases. About half received a single-chamber ICD. fQRS was present at the time of diagnosis in 21 and in 54 % at ICD implant. At a mean follow-up of 47.8 +/- 39.3 months, 41 patients (40.2 %) presented with appropriate therapy. In a multivariate logistic regression, predictors of appropriate therapy included fQRS at implant (odds ratio [OR], 16.4; 95 % confidence interval [CI], 3.6-74.0; p = 0.0003), history of combined ventricular tachycardia/fibrillation/sudden death (OR, 14.3; 95 % CI, 3.2-69.3; p = 0.001) and history of syncope (OR, 5.5; 95 % CI, 1.5-20.4; p = 0.009). Ten deaths (9.8 %) occurred during the follow-up. fQRS in the lateral location increased the risk of appropriate therapy (p < 0.0001). fQRS predicts arrhythmic events in patients with HOCM and should be considered in a model of risk stratification.