Septal Reduction in Hypertrophic Cardiomyopathy
What are the long-term outcomes after myectomy and alcohol septal ablation (ASA) in hypertrophic cardiomyopathy (HCM)?
The study authors performed a systematic review and meta-analysis of HCM studies with a follow-up period of at least 3 years. The primary outcomes included all-cause mortality and (aborted) sudden cardiac death (SCD). Secondary outcomes were periprocedural complications, left ventricular outflow tract gradient, New York Heart Association functional class after 3 months, and re-intervention. Pooled estimates were calculated using a random-effects meta-analysis.
This meta-analysis included 11 ASA cohorts (n = 2,013 with a mean follow-up period of 6.2 years) and 16 myectomy cohorts (n = 2,791 with a mean follow-up period of 7.4 years). They found that long-term mortality was similar after ASA (1.5% per year) when compared to myectomy (1.4% per year, p = 0.78). The rate of aborted SCD (including appropriate implantable cardioverter-defibrillator shocks) was 0.4% per year after ASA and 0.5% per year after myectomy (p = 0.47). Permanent pacemaker was implanted in 10% after ASA compared to 4.4% after myectomy (p < 0.001). There was no increased long-term risk of life-threatening arrhythmias after ASA, and ASA was still effective for the relief of symptoms in the majority of patients (92%) without the need for pacemaker implantation in most (90%). Subsequent intervention was required in 7.7% of ASA patients when compared to 1.6% of myectomy patients (p = 0.001).
The authors concluded that long-term mortality and aborted SCD rates were similar in ASA and myectomy patients. However, ASA patients were twice as likely to have a permanent pacemaker and 5 times the risk of requiring additional septal reduction when compared to myectomy patients.
This is an important study because it defines the natural history of HCM after septal reduction. It is unclear how many individuals in either group were continued on beta-blockers. These data should help patients decide whether they would want to avoid a thoracotomy and instead opt for an increased risk of permanent pacemaker implantation and possibly additional septal reduction. As imaging techniques offer better resolution and percutaneous techniques evolve, it is possible that ASA may emerge as the procedure of choice.
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