What is the clinical evidence from this study?

Study design: Cohort. Population: Hypertrophic obstructive cardiomyopathy (HOCM) (n=174). Intervention: Septal myectomy vs. Preoperative baseline. Primary outcome: Left atrial active strain (εa) reflecting booster function (p=<0.001).

What does this research mean for the field?

Septal myectomy in patients with hypertrophic obstructive cardiomyopathy significantly improves left atrial reservoir and booster function, with the extent of improvement in active strain being associated with minimum left atrial volume index and the reduction in left ventricular outflow tract pressure gradient. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

February 1, 2023Open Access

Reverse remodeling of left atrium assessed by cardiovascular magnetic resonance feature tracking in hypertrophic obstructive cardiomyopathy after septal myectomy

Q: What are the key findings of this study?

In patients with hypertrophic obstructive cardiomyopathy, septal myectomy significantly improved left atrial booster function, with active strain increasing from a median of 9.9% to 14.3%.

Q: What does this research mean for the field?

Septal myectomy in patients with hypertrophic obstructive cardiomyopathy significantly improves left atrial reservoir and booster function, with the extent of improvement in active strain being associated with minimum left atrial volume index and the reduction in left ventricular outflow tract pressure gradient. Novelty: ClaimNovelty.INCREMENTAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Key Result

In patients with hypertrophic obstructive cardiomyopathy, septal myectomy significantly improved left atrial booster function, with active strain increasing from a median of 9.9% to 14.3%.

Study Design

Type

Cohort (n=174)

Multicenter

Structured PICO

Does surgical septal myectomy improve left atrial structural and functional remodeling assessed by CMR feature tracking in patients with hypertrophic obstructive cardiomyopathy?

Population

88 patients with hypertrophic obstructive cardiomyopathy (HOCM) meeting surgical indications (severe symptoms/syncope despite optimal medical therapy, resting/provoked LVOT gradient ≥50 mmHg), mean age 44.1, 52% male, single-center (China). 86 healthy controls included for comparison.

Intervention

Surgical septal myectomy (extended Morrow procedure)

Comparator

Preoperative baseline (self-controlled) and 86 healthy controls

Outcome

Left atrial (LA) structural and functional remodeling assessed by CMR feature tracking, specifically the rate of change of active strain (εa)surrogate

Septal myectomy in patients with hypertrophic obstructive cardiomyopathy leads to significant reverse remodeling of the left atrium, particularly improving booster function, which correlates with the relief of LVOT obstruction.

Main Result

Absolute Event Rate: 14.3% vs 9.9%

p-value: p=<0.001

Limitations

Retrospective study design with potential selection bias due to exclusion of patients without pre- or postoperative CMR.
Small sample size from a single center.
Lack of prognostic analysis due to the small number of hard clinical events and short-term follow-up.
Inter-scan reproducibility was not tested.
Left atrial size was measured by bi-plane method rather than three-dimensional assessment.
Only transmitral E/A < 1 was available among parameters of diastolic dysfunction.

Abstract

BACKGROUND: Assessing the structure and function of left atrium (LA) is crucial in hypertrophic obstructive cardiomyopathy (HOCM) because LA remodeling correlates with atrial fibrillation. However, few studies have investigated the potential effect of myomectomy on LA phasic remodeling in HOCM after myectomy using cardiovascular magnetic resonance (CMR) feature tracking (FT). This study aims to evaluate the LA structural and functional remodeling with HOCM after myectomy by CMR-FT and to further investigate the determinants of LA reverse remodeling. METHODS: In this single-center study, we retrospectively studied 88 patients with HOCM who received CMR before and after myectomy between January 2011 and June 2021. Preoperative and postoperative LA parameters derived from CMR-FT were compared, including LA reservoir function (total ejection fraction EF, total strain εs, peak positive strain rate SRs), conduit function (passive EF, passive strain εe, peak early negative strain rate SRe) and booster function (booster EF, active strain εa, late peak negative strain rate SRa). Eighty-six healthy participants were collected for comparison. Univariate and multivariate linear regression identified variables associated with the rate of change of εa. RESULTS: Compared with preoperative parameters, LA reservoir function (total EF, εs, SRs), booster function (booster EF, εa, SRa), and SRe were significantly improved after myectomy (all P < 0.05), while no significant differences were observed in passive EF and εe. Postoperative patients with HOCM still had larger LA and worse LA function than healthy controls (all P < 0.05). After analyzing the rates of change in LA parameters, LA boost function, especially εa, showed the most dramatic improvement beyond the improvements in reservoir function, conduit function, and volume. In multivariable regression analysis, minimum LA volume index (adjusted β = - 0.39, P < 0.001) and Δleft ventricular outflow tract (LVOT) pressure gradient (adjusted β = - 0.29, P = 0.003) were significantly related to the rate of change of εa. CONCLUSIONS: index and ΔLVOT might be potential factors associated with the degree of improvement in εa.

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