Operator Experience of Atleast 225 Procedures Associated With Improved TAVR Outcomes The Learning Curve and Annual Procedure Volume Standards for Optimum Outcomes of Transcatheter Aortic Valve Replacement

Findings from an international TAVR registry involving 16 centers and spanning over a decade have important implications for operator training and patient care at centers performing TAVR. The study, published in JACC Cardiovascular Interventions, is a testament to the learning curve that still exists with both greater procedural safety and lower mortality rates reported when TAVR is performed by experienced operators. Additionally, TAVR performed at low annual volume (<50 procedures) institutions is associated with decreased procedural safety and higher patient mortality. This stepwise improvement in patient outcomes bears important implications for operator training and patient care at centers performing TAVR.

Transcatheter aortic valve replacement (TAVR) is a complex procedure requiring significant technical expertise and experience in percutaneous and endovascular procedures. However, the information available about its learning curve characteristics and minimal annual volumes required for optimization of clinical outcomes of TAVR is limited, despite increasing use of this procedure across several institutions in the US. In the light of this, Waseef et al. analyzed data of 3403 patients participating in the international TAVR registry in order to determine the procedural learning curve and minimum annual institutional volumes associated with optimal clinical outcomes for transcatheter aortic valve replacement (TAVR). For TAVR learning curve characterization, all cases were chronologically ordered into initial (1 to 75), early (76 to 150), intermediate (151 to 225), high (226 to 300), and very high (>300). Furthermore, for comparative analysis, participating institutions were classified by annual TAVR case volume into low-volume (<50), moderate-volume (50 to 100), and high-volume (>100) groups. The primary outcomes measured were procedural and 30-day clinical outcomes. Multivariate regression analysis was performed for 30-day mortality and the early safety endpoint.

In their publication in JACC Cardiovascular Interventions, Waseef and his colleagues reported significantly higher all-cause mortality at 30 days for initial (odds ratio [OR]: 3.83; [CI]: 1.93 to 7.60), early (OR: 2.41; 95% CI: 1.51 to 5.03), and intermediate (OR: 2.53; 95% CI: 1.19 to 5.40) experience groups as compared with those with an experience of >300 cases. The high and very high groups had similar odds of patient survival. (4.8% versus 3.3%, P=0.525) The early safety endpoint too was significantly worse for all experience groups compared with the very high experience operators. The most experienced centers showed better outcomes in terms of the number of deaths, strokes, major bleeding, vascular complications, surgical conversions, and renal failures after TAVR. Significantly higher all-cause 30-day mortality (OR: 2.70; 95% CI: 1.44 to 5.07) and worse early safety endpoint (OR: 1.60; 95% CI: 1.17 to 2.17) was demonstrated in low annual volume (<50) TAVR institutions, whereas intermediate and high annual volume groups displayed no significant differences in patient outcomes.

Commenting on the importance of these findings and its worldwide implications, Dr. Salvatore Brugaletta, an Interventional Cardiologist from Barcelona, Spain stated, “So far, very few countries have a regulation which allows only some centers to perform TAVR in order to increase numbers of TAVR in these centers and improve the quality of care. Nevertheless, this is not true in many other countries, where many hospitals want to perform TAVR. For this reason, based on the findings of the present analysis, it does make much sense to concentrate human and economic resources in few high-level hospitals, in order not only to increase the quality of TAVR but also to save costs.” Indeed, the study can serve as a guide for optimal resource and technology distribution for TAVR as a minimum annual volume threshold is required to provide the best outcomes for patients. In an accompanying editorial, Dr. John Carroll, MD, of the University of Colorado School of Medicine in Aurora, said, “The findings are important in expanding and updating an existing evidence base for making health care policy decisions as well as informing professional society recommendations as to the organization of care to maximize the benefit and minimize complications for novel procedures like TAVR.”

Discussing his thoughts on future research in the field, he added, “There is no doubt that TAVR outcomes continue to improve, and this is related to multiple factors, including expansion to lower-risk patients, more experienced teams, improved technologies and techniques, and optimizing patient selection. With lower rates of mortality and major complications, the statistical analysis will become more difficult to show learning curves and volume–outcomes associations if a study focuses on single outcomes, or the number of cases is not very large. Therefore, future studies will need to have composite endpoints and a very large study population.”