Worldwide differences in primary prevention implantable cardioverter defibrillator utilization and outcomes in hypertrophic cardiomyopathy

Abstract

Aims Risk stratification algorithms for sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) and regional differences in clinical practice have evolved over time. We sought to compare primary prevention implantable cardioverter defibrillator (ICD) implantation rates and associated clinical outcomes in US vs. non-US tertiary HCM centres within the international Sarcomeric Human Cardiomyopathy Registry. Methods and results We included patients with HCM enrolled from eight US sites (n = 2650) and five non-US (n = 2660) sites and used multivariable Cox-proportional hazards models to compare outcomes between sites. Primary prevention ICD implantation rates in US sites were two-fold higher than non-US sites (hazard ratio (HR) 2.27 [1.89–2.74]), including in individuals deemed at high 5-year SCD risk (≥6%) based on the HCM risk-SCD score (HR 3.27 [1.76–6.05]). US ICD recipients also had fewer traditional SCD risk factors. Among ICD recipients, rates of appropriate ICD therapy were significantly lower in US vs. non-US sites (HR 0.52 [0.28–0.97]). No significant difference was identified in the incidence of SCD/resuscitated cardiac arrest among non-recipients of ICDs in US vs. non-US sites (HR 1.21 [0.74–1.97]). Conclusion Primary prevention ICDs are implanted more frequently in patients with HCM in US vs. non-US sites across the spectrum of SCD risk. There was a lower rate of appropriate ICD therapy in US sites, consistent with a lower-risk population, and no significant difference in SCD in US vs. non-US patients who did not receive an ICD. Further studies are needed to understand what drives malignant arrhythmias, optimize ICD allocation, and examine the impact of different ICD utilization strategies on long-term outcomes in HCM.

Ventricular arrhythmia and sudden cardiac death in hypertrophic cardiomyopathy: From bench to bedside

“…Prophylactic ICDs for high-SCD-risk patients have reduced the disease-related mortality by more than ten times, to attain a mortality rate of 0.5% per year. The five-year and ten-year survival rates (confined to HCM deaths) were 98 and 94%, respectively, which are not different from the expected all-cause mortality rate in the general U.S. population ( 17 ).…”

Implantable defibrillators in primary prevention of genetic arrhythmias. A shocking choice?

“…Compared with the conservative approach of many European countries, the current threshold for decision to implant an ICD in the USA is lower. 111 …”

Sudden cardiac death in hypertrophic cardiomyopathy: time to change the narrative

“…In this edition of the Journal, Nauffal and colleagues [6] shine a light on one of the murkier points of contention; namely, perceived differences in the approach to risk stratification in the US and Europe. Their study uses retrospective data from the SHaRe consortium-a voluntary registry involving specialist cardiomyopathy centres in North America, Europe and several other countries-that have provided important insights into disease natural history [2,7] .…”