Abstract 16484: Primary Prevention Implantable Cardioverter Defibrillator Utilization for Hypertrophic Cardiomyopathy in US vs Non-US: Findings From the Share Registry

Abstract

Introduction: Risk stratification for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) has evolved with notable differences in international practice trends and US vs European guidelines. Hypothesis: Utilization of primary prevention implantable cardioverter defibrillators (ICD) is higher in the US. Methods: We examined rates of primary prevention ICD implantation in 5,063 HCM patients in the international SHaRe registry from 2000 - 2020 (NUS=2,390; Nnon-US=2,673). Using multiple logistic regression we compared probability of ICD implantation for US vs non-US sites adjusting for standard SCD risk factors (Figure 1A). Interaction tests were performed to identify risk factors differentially associated with ICD implantation in US vs non-US sites after 2014 when the European Society of Cardiology (ESC) risk score was introduced. Results: The odds of ICD implantation were 3-fold higher in US sites [ORUS/non-US=3.11 (2.54 -3.81)] (Figure 1A). Odds remained similar after adjustment for ESC risk score [OR =3.17 (2.57 -3.91)]. Implantation rates were higher in the US throughout the study period with a notable drop in rates in both US and non-US sites after 2014 and a reduction in the magnitude of the difference in ICD utilization between US and non-US sites (ORUS/non-US (<2014) =4.20 (3.05-5.78) vs. ORUS/non-US (≥2014)=2.55 (1.89-3.44); pinteraction<0.001) (Figure 1B). Non-sustained ventricular tachycardia was a stronger predictor of ICD implantation in US sites [ORUS=4.9 (3.4-7.0) vs ORnon-US= 2.1 (1.2-3.6); pinteraction=0.005], whereas, left atrial diameter (> 40 mm) was a stronger predictor in non-US sites [ORNon-US=2.9 (2.1-4.0) vs ORUS=1.3 (1-1.6); pinteraction <0.001]. Conclusions: ICD utilization rates vary globally. In this study, primary prevention ICD utilization rates were 3-fold higher in the US despite adjustment for standard SCD risk factors. Further studies are needed to evaluate outcomes of these practice differences.