Worldwide differences in primary prevention implantable cardioverter defibrillator utilization and outcomes in
Victor Nauffal1, Peter Marstrand2, Larry Han3
1Department of Medicine, Brigham and Women's Hospital, Cardiovascular Medicine Division, 75 Francis Street, Boston, MA 02115, USA.
Insights
Primary prevention implantable cardioverter defibrillators (ICDs) are implanted more often in US hypertrophic cardiomyopathy (HCM) centers. US patients received fewer appropriate ICD therapies, suggesting a lower-risk population, with no difference in sudden cardiac death for those not receiving ICDs.
Area of Science:
- Cardiology
- Genetics
- Public Health
Background:
- Hypertrophic cardiomyopathy (HCM) poses a risk of sudden cardiac death (SCD).
- Risk stratification for SCD and implantable cardioverter-defibrillator (ICD) use varies globally.
- Differences in clinical practice for SCD prevention in HCM are not well understood across regions.
Purpose of the Study:
- To compare primary prevention ICD implantation rates in US versus non-US tertiary HCM centers.
- To evaluate associated clinical outcomes, including appropriate ICD therapy and SCD incidence.
- To analyze regional differences in ICD utilization for SCD risk stratification in HCM.
Main Methods:
- Retrospective analysis of patients from the Sarcomeric Human Cardiomyopathy Registry.
- Inclusion of 2650 patients from eight US sites and 2660 from five non-US sites.
- Multivariable Cox-proportional hazards models to compare outcomes between US and non-US centers.
Main Results:
- Primary prevention ICD implantation rates were twofold higher in US sites compared to non-US sites.
- Higher implantation rates in US sites were observed even for patients at high 5-year SCD risk (≥6%).
- Appropriate ICD therapy rates were lower in US recipients, and SCD incidence did not differ between US and non-US non-recipients.
Conclusions:
- US centers implant primary prevention ICDs more frequently in HCM patients across the SCD risk spectrum.
- Lower appropriate ICD therapy rates in the US suggest implantation in lower-risk populations.
- Further research is needed to optimize ICD allocation and understand drivers of arrhythmias in HCM.
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.
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