Key result
Low-volume institutions (1-24 procedures) were associated with higher odds of mitral-valve replacement during septal myectomy compared to high-volume centers (OR 2.7; 95% CI 2.3-3.2; p<0.05).
Why the study?
ACC guidelines emphasize procedural volume for improving outcomes after septal myectomy, but data measuring the impact of institutional volume on the need for mitral-valve replacement during septal myectomy were lacking.
Does high institutional volume of septal myectomy reduce the rate of concomitant mitral-valve replacement in patients with hypertrophic cardiomyopathy?
Observational (n=6,207)
Yes
Does high institutional volume of septal myectomy reduce the rate of concomitant mitral-valve replacement in patients with hypertrophic cardiomyopathy?
Odds Ratio: 2.7 (95% CI 2.3–3.2)
p-value: p=<0.05
Patients undergoing septal myectomy for hypertrophic cardiomyopathy at lower-volume centers have more than 2.5 times the odds of requiring concomitant mitral-valve replacement compared to those treated at guideline-endorsed high-volume centers.
May warrant referral to high-volume centers for septal myectomy; leaves open need for confirmatory studies on volume effects.
OBJECTIVE: Mitral regurgitation (MR) induced by systolic anterior motion in patients with hypertrophic cardiomyopathy (HCM) can frequently be abolished with a proficient septal myectomy (SM) without the need for mitral-valve replacement (MVR). ACC guidelines stress the importance of volume in improving outcomes after SM, but there is a lack of data measuring the impact of volume on the need for MVR during SM. This study was designed to assess the impact of institutional volume on MVR rates using national outcomes data. METHODS: The Nationwide Inpatient Sample was queried from 1998 to 2011 and a total of 6,207 patients had a diagnosis of HCM and a procedure code for SM. Outcomes were compared between patients who underwent SM (group I) and SM and MVR (group II). Furthermore, patients were stratified into 3 groups based on the number of SMs at the performing institution: low experience (1-24 cumulative SMs), medium experience (25-49 SMs), and high experience (>50 SMs). These patients underwent multivariable analysis to determine the impact of institutional volume on MVR rate. RESULTS: The total MVR rate was 26%. Perioperative outcomes were worse, i.e., there were higher rates of mortality, kidney injury, and urinary complications, in group II than in group I. Only 37.6% of patients were operated on at institutions meeting the guideline criteria of >50 cumulative SMs. When compared to patients in the high-experience group, patients in the low- (OR 2.7, 95% CI 2.3-3.2, p < 0.05) and medium-experience (OR 3.0, 95% CI 2.5-3.6, p < 0.05) groups were more likely to undergo MVR. CONCLUSION: Compared to reports from SM reference centers, national data suggest that MVR rates are quite high at SM. Patients undergoing SM at centers that do not meet the guideline standard have >2.5× the odds of undergoing MVR compared to those operated on at guideline-endorsed centers.
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Polanco et al. (2020) conducted an observational in Hypertrophic cardiomyopathy (n=6,207). Low institutional volume (1-24 septal myectomies) vs. High institutional volume (>50 septal myectomies) was evaluated on Mitral-valve replacement (MVR) (OR 2.7, 95% CI 2.3-3.2, p=<0.05). Low-volume institutions (1-24 procedures) were associated with higher odds of mitral-valve replacement during septal myectomy compared to high-volume centers (OR 2.7; 95% CI 2.3-3.2; p<0.05).
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