Key result
Compared to high-volume centers, low institutional case volume was associated with a significantly higher adjusted risk of in-hospital mortality after aortic valve replacement (OR 2.31) and mitral valve replacement (OR 2.29).
Why the study?
There are only a handful of published studies evaluating the volume-outcome relationship in heart valve surgery.
Does lower institutional case volume increase mortality in adults undergoing aortic or mitral valve replacement?
Observational (n=12,959)
Yes
Does lower institutional case volume increase mortality in adults undergoing aortic or mitral valve replacement?
Odds Ratio: 2.31 (95% CI 1.73–3.09)
Absolute Event Rate: 8.3% vs 2.6%
p-value: p=<0.001
Lower-volume centers show higher AVR/MVR mortality; leaves open whether volume-based referral improves outcomes.
BACKGROUND: There are only a handful of published studies regarding the volume-outcome relationship in heart valve surgery. We evaluated the association between institutional case volume and mortality after aortic valve replacement (AVR) and mitral valve replacement (MVR). METHODS: Two separate cohorts of all adults who underwent AVR or MVR, respectively, between 2009 and 2016 were analyzed using a Korean healthcare insurance database. Hospitals performing AVRs were divided into three groups according to the average annual case volume: the low- (< 20 cases/year), medium- (20-70 cases/year), and high-volume centers (> 70 cases/year). Hospitals performing MVRs were also grouped as the low- (< 15 cases/year), medium- (15-40 cases/year), or high-volume centers (> 40 cases/year). In-hospital mortality after AVR or MVR were compared among the groups. RESULTS: In total, 7875 AVR and 5084 MVR cases were analyzed. In-hospital mortality after AVR was 8.3% (192/2318), 4.0% (84/2102), and 2.6% (90/3455) in the low-, medium-, and high-volume centers, respectively. The adjusted risk was higher in the low- (OR 2.31, 95% CI 1.73-3.09) and medium-volume centers (OR 1.53, 95% CI 1.09-2.15) compared to the high-volume centers. In-hospital mortality after MVR was 9.3% (155/1663), 6.3% (94/1501), and 2.9% (56/1920) in the low-, medium-, and high-volume centers, respectively. Compared to the high-volume centers, the medium- (OR 1.97, 95% CI 1.35-2.88) and low-volume centers (OR 2.29, 95% CI 1.60-3.27) showed higher adjusted risk of in-hospital mortality. CONCLUSIONS: Lower case volume is associated with increased in-hospital mortality after AVR and MVR. The results warrant a comprehensive discussion regarding regionalization/centralization of cardiac valve replacements to optimize patient outcomes.
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Nam et al. (2022) conducted an observational in Aortic and mitral valve replacement (n=12,959). Low institutional case volume vs. High institutional case volume was evaluated on In-hospital mortality after aortic valve replacement (OR 2.31, 95% CI 1.73-3.09, p=<0.001). Compared to high-volume centers, low institutional case volume was associated with a significantly higher adjusted risk of in-hospital mortality after aortic valve replacement (OR 2.31) and mitral valve replacement (OR 2.29).
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