Institutional case volume and mortality after aortic and mitral valve replacement: a nationwide study in two Korean cohorts

• Published in: Journal of cardiothoracic surgery Vol. 17; no. 1; pp. 1 - 190
• Main Authors: Nam, Karam, Jang, Eun Jin, Jo, Jun Woo, You, Jiwon, Park, Jung-Bin, Ryu, Ho Geol
• Format: Journal Article
• Language: English
• Published: London BioMed Central Ltd 20-08-2022; BioMed Central; BMC
• Subjects: Analysis; Angina pectoris; Aorta; Aortic valve; Aortic valve replacement; Cardiac arrhythmia; Case volume; Coronary vessels; Endocarditis; Heart surgery; Heart valve diseases; Heart valves; Hospitals; Mitral valve; Mitral valve replacement; Mortality; Patients; Population; Review boards; Surgical prognosis; Variables; Veins & arteries; Volume-outcome relationship; South Korea
• ISSN: 1749-8090; 1749-8090
• DOI: 10.1186/s13019-022-01945-0

Abstract
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.