Institutional Volume Thresholds and Risk-Adjusted Outcomes After Transcatheter Aortic Valve Replacement: Contemporary Evidence From the Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry.

BACKGROUND: The relationship between institutional volume and transcatheter aortic valve replacement outcomes is complex but vital for optimizing patient triage and developing effective care strategies. METHODS: The authors analyzed outcomes of patients undergoing transcatheter aortic valve replacement between January 2021 and February 2023 in the STS/ACC TVT (Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy) Registry at hospitals affiliated with the CommonSpirit Health network. Centers were categorized by annual TAVR volume as low (<100 cases per year), intermediate (100-300 cases per year), or high (>300 cases per year). Baseline risk assessment included the Society of Thoracic Surgeons score, an estimate of operative mortality risk. The primary outcome was major adverse cardiac and cerebrovascular events. Inverse probability of treatment weighting adjusted for baseline differences. RESULTS: Among 6663 patients, 58.6% were treated at high-volume centers. Patients treated at high-volume centers were older than those at intermediate- or low-volume centers (P<0.001). STS risk scores were highest at high-volume centers than at intermediate- and low-volume centers (P=0.005). After inverse probability of treatment weighting adjustment, high-volume centers remained associated with a reduced risk of major adverse cardiac and cerebrovascular events compared with both low-volume centers (adjusted hazard ratio [aHR], 0.40 [95% CI, 0.16-0.98]; P=0.047) and intermediate-volume centers (aHR, 0.56 [95% CI, 0.34-0.92]; P=0.021). Receiver operating characteristic analysis identified an annual procedural volume threshold of 314 cases as the empirical discriminator of MACCE (area under the curve, 0.77 [95% CI, 0.74-0.80]; P<0.001). CONCLUSIONS: Within this integrated health system, high-volume centers had better risk-adjusted outcomes despite treating higher-risk patients. The empiric volume threshold identified in this cohort should be validated in other settings.