Impact of transapical beating-heart septal myectomy on left atrial remodeling and atrioventricular coupling in hypertrophic obstructive cardiomyopathy.

Background: Assessment of left atrial (LA) functional strain and atrioventricular coupling is increasingly recognized as critical in patients with hypertrophic obstructive cardiomyopathy (HOCM), associated with adverse atrial remodeling and malignant arrhythmia. The effect of transapical beating-heart septal myectomy (TA-BSM) on the improvement of LA function and atrioventricular coupling remains uncertain.

Methods: The patients with HOCM who underwent TA-BSM in Tongji Hospital between April 2022 and October 2023 were prospectively investigated. The LA structure parameters (diameters and volumes), functional parameters (total LA emptying fraction [LAEF], total strain [εs], peak positive strain rate [SRs], passive LAEF, passive strain [εe], peak early negative strain rate [SRe], active LAEF, active strain [εa], and late peak negative strain rate [SRa]), and the left atrioventricular coupling index (LACI) obtained using CMR before and after TA-BSM were compared. The Pearson or Spearman correlation analysis was used to investigate the relationships between LA parameters and LACI. The univariate and multivariate linear regression analyses were used to identify variables associated with the rate of change in strains.

Results: A total of 133 patients [median (Q1, Q3), 48 (35.0, 57.5) years; 92 males] were evaluated. Further, 133 healthy participants matched for age and sex were included as controls. The LA size, reservoir function (total LAEF, εs, and SRs), conduit function (passive LAEF, εe, and SRe), and booster function (active LAEF, εa, and SRa) were worse than control group but improved to various degrees after TA-BSM (all P < 0.05). The subgroup with poor atrioventricular coupling had greater rate of change of εs, εa, and SRa postoperatively (all P < 0.001). LACI was highly correlated with strain and strain rate before TA-BSM, which decreased slightly postoperatively. In multivariable regression analysis, preoperative LACI was highly correlated with the rate of change of εs (adjusted β = -0.449, P < 0.001), εe (adjusted β = -0.285, P < 0.001), and εa (adjusted β = -0.286, P = 0.001).

Conclusion: LA reverse remodeling was confirmed by CMR in HOCM after TA-BSM and LACI may be a potential factor affecting LA strain improvement and expected to be an effective indicator for long-term monitoring of postoperative left heart function.