Log in to MyACC
Volume vs. Outcome Thresholds for TAVI
Quick Takes
- The current analysis from the TVT registry simulated data to compare TAVI outcomes based on volume thresholds vs. outcome thresholds.
- Findings show that shifting care to sites with the best outcomes, but not to sites performing higher volume (≥50 TAVIs per year) reduced adverse TAVI events (over 1,200 adverse events) compared with observed outcomes.
- This came at the cost of increased driving distance. Findings did not differ based on race.
Study Questions:
What is the association between volume thresholds versus spoke-and-hub implementation of outcome thresholds with transcatheter aortic valve implantation (TAVI) outcomes and geographical access?
Methods:
This cohort study included patients who enrolled in the US Society of Thoracic Surgeons/American College of Cardiology (STS/ACC) Transcatheter Valve Therapy (TVT) registry. Site volume and outcomes were determined from a baseline cohort of adults undergoing TAVI between July 1, 2017, and June 30, 2020. Within each hospital referral region, TAVI sites were categorized by volume (<50 or ≥50 TAVIs per year) and separately by risk-adjusted outcome on the STS/ACC TVT 30-day TAVI composite during the baseline period (July 2017–June 2020). Outcomes of patients undergoing TAVIs from July 1, 2020, to March 31, 2022, were then modeled as though the patients had been treated at 1) the nearest higher volume (≥50 TAVIs per year) or 2) the best outcome site within the hospital referral region. The primary outcome was the absolute difference in events between the adjusted observed and modeled 30-day composite of death, stroke, major bleeding, stage III acute kidney injury, and paravalvular leak. Data are presented as the number of events reduced under the above scenarios with 95% Bayesian credible intervals (CrIs) and median (interquartile range [IQR]) driving distance.
Results:
The overall cohort included 166,248 patients with a mean (standard deviation) age of 79.5 (8.6) years; 74,699 (47.3%) were female and 6,657 (4.2%) were Black; 158,025 (95%) were treated in higher-volume sites (≥50 TAVIs) and 75,088 (45%) were treated in best-outcome sites. Modeling a volume threshold, there was no significant reduction in estimated adverse events (−34; 95% CrI, −75 to 8), while the median (IQR) driving time from the existing site to the alternate site was 22 (15-66) minutes. Transitioning care to the best outcome site in a hospital referral region resulted in an estimated 1,261 fewer adverse outcomes (95% CrI, 1,013-1,500), while the median (IQR) driving time from the original site to the best site was 23 (15-41) minutes. Directionally similar findings were observed for Black individuals, Hispanic individuals, and individuals from rural areas.
Conclusions:
In this study, compared with the current system of care, a modeled outcome-based spoke-and-hub paradigm of TAVI care improved national outcomes to a greater extent than a simulated volume threshold, at the cost of increased driving time. To improve quality while maintaining geographic access, efforts should focus on reducing site variation in outcomes.
Perspective:
The current analysis from the TVT registry simulated data to compare TAVI outcomes based on volume thresholds versus outcome thresholds. Findings show that shifting care to sites with the best outcomes, but not to sites performing higher volume (≥50 TAVIs per year) reduced adverse TAVI events (over 1,200 adverse events) compared with observed outcomes. This came at the cost of increased driving distance. Findings did not differ based on race. Findings support the idea that prioritizing outcome thresholds will be more likely to improve TAVI-related outcomes than using volume thresholds.
Clinical Topics: Cardiac Surgery, Geriatric Cardiology, Invasive Cardiovascular Angiography and Intervention, Valvular Heart Disease, Cardiac Surgery and VHD, Interventions and Structural Heart Disease
Keywords: Acute Kidney Injury, Cardiac Surgical Procedures, Geriatrics, Heart Valve Diseases, Hemorrhage, Outcome Assessment, Health Care, Quality of Health Care, Stroke, STS/ACC TVT Registry, Transcatheter Aortic Valve Replacement
< Back to Listings
