Abstract 14304: Does QRS Fragmentation Have a Role in Risk Stratification for Sudden Death in Hypertrophic Cardiomyopathy?

Background: Fragmentation of the QRS complex on 12-lead electrocardiogram (ECG) represents alterations of myocardial activation due to myocardial scarring and has been associated with increased risk for sudden death and adverse prognosis. However the clinical significance of this finding in hypertrophic cardiomyopathy (HCM) remains unresolved. Methods: Consecutive HCM patients evaluated from 2004 to 2020 were included and followed for 5.1 ± 4.1 years for outcomes including sudden death events (appropriate ICD interventions for VT/VF, cardiac arrest, or sudden death) and development of endstage heart failure requiring transplant. QRS fragmentation was defined as presence of an additional R wave or notching in the R or S wave in two contiguous ECG leads in the absence of bundle branch block. Results: Among 1929 HCM patients, 539 (28%) were identified with QRS fragmentation. As compared to patients without QRS fragmentation, patients with QRS fragmentation had similar baseline demographics including age (52±16 vs. 53±16, p=0.35), gender (60% vs. 61% male, p=0.51), ejection fraction (64 ± 6 vs. 64 ± 5, p=0.77) and presence of LV outflow obstruction (≥30mmHg at rest or provocation; 65% vs. 65%, p=0.9). While patients with QRS fragmentation had more substantial LV hypertrophy (19 ± 4 vs. 18 ± 4, p=0.001) as well as presence and extent of late gadolinium enhancement by cardiac MRI (64% vs. 56%, 6.3 ± 6 vs. 5 ± 5, p<0.01), there was no difference in other risk markers including syncope (9% vs 9%, p=0.89), family history of SD (8% vs. 6%, p=0.31), NSVT (10.5% vs. 8%, p=0.10). Over follow-up, patients with QRS fragmentation were at increased risk for sudden death events (5.6% vs. 2.2%, p<0.001) and development of end-stage heart failure requiring transplant (2.4% vs. 0.8%, p=0.007). However, sensitivity and positive predictive value of QRS fragmentation for predicting sudden death events (50% and 5.6%, respectively) as well as endstage heart failure (52% and 2.4%) is limited. Conclusion: In a large consecutive HCM cohort, QRS fragmentation on 12-lead ECG is associated with extreme HCM phenotype and a number of adverse consequences including sudden death events and endstage development, and represents a potential prognostic marker.