Volume-outcome relationship with transfemoral transcatheter aortic valve implantation (TAVI): insights from the compulsory German Quality Assurance Registry on Aortic Valve Replacement (AQUA)

Aims: Previous studies have shown lower rates of in-hospital complications and mortality for patients undergoing surgical aortic valve replacement (sAVR) in high-volume compared with lower-volume hospitals. It was the aim of our study to analyse whether there is a similar volume-outcome relationship for transcatheter aortic valve implantation (TAVI), which is increasingly used in clinical practice. Methods and results: We analysed all patients with non-emergent transfemoral (TF) TAVI procedures performed in 2014 in 87 German hospitals. We used the German Aortic Valve score 2.0 to calculate the ratio of observed versus expected (O/E) in-hospital mortality. A total of 9,924 patients (age 81.4 +/- 1.1 years, 45.3% male, median log EuroSCORE 18.81%, IQR 4.55) were included. Average observed mortality was 4.3 +/- 3.3%, while the expected average mortality was 5.4 +/- 1.4% (mean O/E ratio: 0.8). Average in-hospital mortality was 5.6 +/- 5.0% (range, 0 to 16.7%) in the lowest volume group of hospitals performing < 50 TF-TAVI annually compared to 2.4 +/- 1.0% (range, 0.5 to 3.7%) in the highest volume hospitals with >= 200 TF-TAVI procedures per year. There was a continuous, statistically significant association of lower O/E ratios with increasing TF-TAVI volumes (p < 0.001), but without a clear-cut threshold. Major complications, neurologic events, and rates of new pacemaker implantation were not different between low-and high-volume hospitals. Conclusions: Across the spectrum of hospital volumes from 11 to 415 patients undergoing TF-TAVI per year in Germany, there was a continuous, statistically significant association of lower average observed as well as risk-adjusted in-hospital mortality with increasing TF-TAVI volumes.