QTc duration and QRS fragmentation on baseline ECG relate to sustained ventricular tachyarrhythmia and sudden cardiac death in hypertrophic cardiomyopathy

Abstract

Purpose: The presence of prolonged QTc and QRS fragmentation (fQRS) on baseline ECG was studied in patients with hypertrophic cardiomyopathy (HCM) and related with occurrence of ventricular tachyarrhythmias or sudden cardiac death (VTA/SCD). Methods: A total of 195 clinical HCM patients was studied (52±13 years, 61% male). On a standard 12-lead ECG, QTc duration was calculated by Bazett's formula; fQRS was defined as presence of various RSR' patterns, R or S notching and/or >1 additional R wave in any non-aVR lead in patients without pacing or typical (in)complete bundle branch block. Study endpoint comprised SCD or sustained VTA (tachycardia or fibrillation) documented on ECG or, in baseline implantable cardioverter defibrillator (ICD) recipients [n=58 (30%)], by appropriate ICD therapies (shock/ATP) for VTA. QT prolonging drug recipients were excluded. Results: After a median follow up of 5.7 years (IQR 2.7-9.1), 26 (13%) patients experienced VTA (n=22) or SCD (n=4). Kaplan-Meier time to survival free of VTA/SCD showed worse survival in patients with QTc≥440 ms (p=0.017) or fQRS in ≥3 territories (inferior, lateral, septal and/or anterior) (p=0.004) (Figure). Multivariate regression analysis showed that both QTc ≥440 ms (β=2.4, p=0.034, 95% CI 1.07-5.58) and fQRS in ≥3 territories (β=3.4, p=0.007 95% CI 1.54-14.9) were independently associated with VTA/SCD. Excluding secondary prevention ICD recipients (n=13), likelihood ratio test indicated that assessment of QTc and fQRS on top of conventional SCD risk factors provided incremental value to predict occurrence of VTA/SCD (p=0.034). ![Figure][1] Kaplan Meier survival curve. Conclusion: QTc duration and presence of fQRS relate to occurrence of VTA/SCD in HCM patients, independently of conventional SCD risk factors, and therefore may have an impact on preventive treatment strategies. [1]: pending:yes