Volume-outcome relationships for transcatheter aortic valve replacement-risk-adjusted and volume stratified analysis of TAVR outcomes

OBJECTIVES: This purpose of the study was to evaluate TAVR outcomes at low, intermediate and high volume institutions. BACKGROUND: For the care of complex patients, volume-outcome effect is well described. The initial US TAVR experience was limited to a few centers of excellence. The impact of institutional volume on outcomes after TAVR has not been systematically studied. METHODS: Within the Banner Health system, TAVR is performed at 3 institutions-a low volume, an intermediate volume and a high volume institution. 181 consecutive patients undergoing TAVR within these 3 institutions were the study cohort. To adjust for bias and confounders between the 3 groups, risk-adjusted multivariate logistic regression and propensity score analysis was performed. The primary endpoint was a composite of mortality, dialysis-dependent renal failure, cerebrovascular accident, need for new permanent pacemaker and readmission within 30days. RESULTS: The primary endpoint was reached in 38.8% of patients at the high volume institution and 76.2% of patients at the low volume institution (p<0.01). Having a TAVR procedure at a larger volume institution was an independent predictor of having improved outcomes (OR 0.33, 95% CI 0.16-0.68; p=0.003). These improved outcomes after the TAVR procedure noted at the large volume institution were seen in the most complex patients: age ≥80years, BMI >30, diabetes, hypertension, prior CAD, CKD and NYHA class III/IV heart failure. CONCLUSIONS: High-risk patients undergoing TAVR at a large volume institution have better 30-day outcomes compared to outcomes at intermediate and low volume centers.