# Comparison of morrow procedure and transapical beating-heart septal myectomy in patients with hypertrophic obstructive cardiomyopathy: a systematic review and meta-analysis

## TL;DR

This study compares two heart surgery techniques for treating hypertrophic obstructive cardiomyopathy and finds both are effective, though one is less invasive.

## Contribution

The study provides a systematic review and meta-analysis comparing two septal myectomy techniques for HOCM.

## Key findings

- Both surgical myectomy and TABSM similarly reduce left ventricular outflow tract pressure gradient.
- TABSM had lower long-term mortality and pacemaker implantation rates compared to surgical myectomy.
- Functional status improved in both groups, with younger age and higher study quality linked to better outcomes.

## Abstract

Transaortic surgical myectomy is the established gold-standard treatment for hypertrophic obstructive cardiomyopathy (HOCM). In contrast, the less invasive transapical beating-heart septal myectomy (TABSM) has recently gained attention as a potential alternative, although comparative evidence regarding their clinical outcomes remains limited.

To compare the efficacy and safety of surgical myectomy and TABSM in patients with HOCM.

A systematic search of PubMed, Web of Science, Cochrane Library, and ScienceDirect (January 2014–May 2025) identified 24 observational studies including 3,732 patients (2,824 surgical myectomy; 908 TABSM). The primary outcome was the change in left ventricular outflow tract pressure gradient (LVOTPG). Secondary outcomes included improvement in NYHA class, prevalence of moderate-to-severe mitral regurgitation (MR ≥ 2), short-term (30-day) and long-term mortality, and the rate of postoperative permanent pacemaker implantation. Random-effects meta-analysis and meta-regression were performed.

Both procedures achieved substantial and comparable reductions in LVOTG, with no significant between-group difference (p = 0.75). Functional status improved in both cohorts; younger age and higher study quality were independently associated with greater improvement in NYHA class (p < 0.05). Residual MR ≥ grade 2 decreased in both groups. 30-day mortality was low and similar between surgical myectomy and TABSM. Long-term mortality appeared lower after TABSM (≈2%) compared with surgical myectomy (≈6%); however, this finding should be interpreted cautiously due to substantial heterogeneity and shorter follow-up in TABSM studies. Pacemaker implantation occurred less frequently after TABSM than after surgical myectomy (≈2% vs. ≈6%; p = 0.03).

Both surgical myectomy and TABSM are effective and safe approaches for septal reduction in HOCM. While surgical myectomy remains the reference standard, TABSM represents a promising minimally invasive option, particularly in anatomically complex or reoperative cases. Prospective studies with standardized endpoints are required to guide individualized procedural selection and confirm long-term outcomes.

https://www.crd.york.ac.uk/PROSPERO/view/CRD420251075522, Identifier CRD420251075522.