Abstract 14023: Myocardial Perfusion Abnormalities: A Potential Biomarker for Ventricular Arrhythmias in Hypertrophic Cardiomyopathy Young Patients?

Abstract

Introduction: Despite progress in the field, risk stratification for sudden death in patients with hypertrophic cardiomyopathy (HCM) remains challenging. Although ventricular arrhythmias (VA) account for most of these events, the mechanisms responsible for cardiac arrest in HCM are not understood. Hypothesis: Abnormalities in myocardial perfusion may create an arrhythmogenic substrate in HCM patients. Methods/ Results: A 12-year-old boy was admitted to our department after an out-of-hospital cardiac arrest, with documented ventricular fibrillation while running. A non-obstructive asymmetric HCM was diagnosed with echocardiography (max LV wall thickness 32 mm). He had one conventional risk factor for SCD. Genetic testing revealed a heterozygous state for a MYH7 variation: p.Glu500Ala (NM_000257.3:c.1499A>C). This variation was classified as “probably pathogenic” (class 4 according to ACMG). His father and his 15-year-old brother were heterozygous for the same variant and were asymptomatic. The brother displayed a similar HCM phenotype. The patient received an implantable defibrillator and suffered from appropriate exercise-related shocks within 6-months despite sotalol therapy (160 mg bid). Because the VA occurred always when the patient was engaged in vigorous physical activity despite beta blocker and since he could not refrain from physical activity, thallium-201 myocardial scintigraphy was performed. To further understand the arrhythmogenic phenotype, his brother underwent the same investigation. Significant uptake perfusion defects in both initial and delayed images were evident in the proband (15%) but not in the asymptomatic brother. Treatment with antianginal drug (amlodipine 5 mg/day) was initiated. With 10 mg/day amlodipine was associated with a significant improvement of the scintigraphy (6% versus 15% perfusion defect). At a follow-up of 12 months, there was no recurrence of VA. Conclusions: Regarding HCM patients, the present report 1) strengthens the hypothesis that myocardial perfusion defects may identify patients at risk for VA, 2) suggests that tailored anti-ischemic prescription may be useful, and 3) underscores the need of prospective studies quantifying ischemia in HCM patients with exercise-induced VF.