Procedural durability and arrhythmic outcomes of septal reduction therapies in obstructive hypertrophic cardiomyopathy: an umbrella review of meta-analyses
A Menezes Junior, A C Simao, M B G De OliveiraAbstract
Background/Introduction
Obstructive hypertrophic cardiomyopathy (oHCM) is treated with septal reduction therapies (SRT), primarily septal myectomy (SM) and alcohol septal ablation (ASA). Beyond efficacy, the long-term safety profile, particularly concerning arrhythmic outcomes such as permanent pacemaker implantation (PPI) and sudden cardiac death (SCD), is a critical determinant in the choice between these procedures. Multiple meta-analyses present conflicting evidence and unresolved controversies regarding these key safety endpoints.
Purpose
To synthesize the comparative evidence between ASA and SM, focusing on procedural durability (reoperation risk) and arrhythmic outcomes (PPI and SCD), by conducting an umbrella review and formally assessing the certainty of the evidence using the GRADE approach.
Methods
An umbrella review of meta-analyses was conducted, adhering to PRISMA and Cochrane guidelines. A systematic search of four databases was performed. Methodological quality was assessed (AMSTAR 2), and study overlap was quantified (CCA). Quantitative synthesis used a random-effects model, harmonizing all effect estimates into the equivalent odds ratio (eOR). The overall certainty of evidence for each outcome was systematically assessed using the GRADE approach.
Results
Six meta-analyses (33 unique primary studies; 12,860 participants) were included, with a very high degree of overlap (CCA 40%). Regarding arrhythmic outcomes, the risk of permanent pacemaker implantation was significantly higher with ASA compared to SM [eOR 1.86 (95% CI 1.35–2.56); p < 0.05]. However, the certainty of evidence was classified as very low due to substantial heterogeneity (I² = 57.6%). For sudden cardiac death, the evidence was also of very low certainty [eOR 1.52 (0.79–2.91)], indicating no reliable difference. For procedural durability, high-certainty evidence (GRADE) indicated that ASA was associated with a significantly higher risk of future reoperations compared with SM [eOR (95% CI) 9.37 (6.82–12.87); p < 0.05; I² = 0%]. Crucially, for all mortality outcomes, including SCD, the certainty of evidence was consistently classified as very low, as shown in Figure 1.
Conclusion(s)
High-certainty evidence supports SM as the more durable intervention for oHCM treatment, with a reduced need for reinterventions. Conversely, the evidence for arrhythmic outcomes (PPI and SCD) and other mortality endpoints is of very low certainty, precluding the affirmation of superiority of one technique over the other. The clinical choice should prioritize the higher durability of SM, while acknowledging that current evidence does not reliably demonstrate a difference in long-term survival or arrhythmic risk.Figure 1.Primary Outcomes