Cardiovascular

Improvement in mitral regurgitation after alcohol septal ablation in hypertrophic obstructive cardiomyopathy: a retrospective cohort study.

Damlin A, Rück A, et al. • BMC cardiovascular disorders • 2026

Cohort PubMed 42966866 DOI 10.1186/s12872-026-06952-w

TL;DR

Among patients with at least moderate mitral regurgitation before alcohol septal ablation, MR severity generally improved at follow-up, potentially due to septal reduction and LVOT enlargement, which may have reduced SAM.

Key Findings

Results

About 14% of patients undergoing alcohol septal ablation had at least moderate mitral regurgitation at baseline.

154 patients who underwent ASA at Karolinska University Hospital (2009-2021) were included in this retrospective cohort.
21 patients (14%) had at least moderate MR at baseline.
Mean follow-up was 4.0 ± 3.9 years, with follow-up extending until 2025.

Results

Most patients with at least moderate baseline MR improved to mild MR or less after ASA.

90% (n = 19) of the 21 patients with at least moderate MR at baseline improved to mild MR or less.
Overall, 19 patients (12%) had improved MR grade, 128 (83%) had unchanged MR grade, and 7 (4.5%) had increased MR grade.

Results

Patients whose MR improved or remained unchanged had a greater reduction in LVOT peak pressure gradient than patients whose MR worsened.

Improved MR group: LVOT peak gradient fell from 137.5 to 4.8 mmHg between baseline and last follow-up.
Unchanged MR group: gradient fell from 57.0 to 25.0 mmHg.
Increased MR group (n = 7): gradient changed from 57.0 to 51.0 mmHg (p = 0.003).
Differences in continuous values were tested with Kruskal-Wallis and categorical values with Fisher's exact test.

Conclusions

The authors suggest MR improvement after ASA is potentially due to septal reduction and LVOT enlargement reducing SAM.

SAM of the mitral leaflets due to septal hypertrophy narrowing the LVOT is the primary mechanism of MR in hypertrophic obstructive cardiomyopathy.
MR improvement coincided with marked LVOT gradient reduction, consistent with reduced SAM.
The study was retrospective and observational, so the mechanism is inferred rather than directly demonstrated.

What This Means

This study looked at 154 patients with hypertrophic obstructive cardiomyopathy, a condition in which a thickened heart muscle wall blocks blood flow out of the heart, who had alcohol septal ablation at a Swedish hospital. The procedure shrinks the thickened wall. Researchers examined whether leaky mitral valve (mitral regurgitation) changed afterward, using ultrasound exams before the procedure, at one year, and at the latest follow-up (average about 4 years). About 1 in 7 patients (21 people) had moderate or worse leakage before the procedure. Of these, 90% improved to mild leakage or less. Patients whose valve leakage improved or stayed the same had larger drops in the pressure gradient across the blocked outflow area than the few patients (7) whose leakage worsened. This suggests that opening up the outflow tract may reduce abnormal movement of the mitral valve leaflets that causes leakage. The study was retrospective and done at a single center, with small numbers in some groups, so it cannot prove cause and effect. The findings suggest that alcohol septal ablation may help valve leakage in patients with this condition, but larger and prospective studies would be needed to confirm this.

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Citation

Damlin A, R&#xfc;ck A, Mustafic M, Jand&#xe9;r R, Rickenlund A, Eriksson M, et al.. (2026). Improvement in mitral regurgitation after alcohol septal ablation in hypertrophic obstructive cardiomyopathy: a retrospective cohort study.. BMC cardiovascular disorders. https://doi.org/10.1186/s12872-026-06952-w

Key Findings

What This Means

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