Study highlights disparity in TAVI outcomes based on procedural availability

Research has highlighted significant regional variations in the availability of transcatheter aortic valve implantation (TAVI) and patient outcomes between Ontario, Canada and New York State, USA.

PATIENTS IN NEW YORK enjoyed better TAVI accessibility and outcomes compared to those in Ontario. Furthermore, statistical analysis suggested that if the same New York residents were treated in Ontario, they would have experienced poorer outcomes. The findings are published in the Canadian Journal of Cardiology

According to current clinical guidelines, TAVI is preferred for patients who are considered high-risk or ineligible for surgical aortic valve replacement (SAVR) and a viable option for those at intermediate or low risk. Despite this, access to TAVI varies significantly across regions.

Lead investigator Harindra Wijeysundera (University of Toronto, Toronto, Canada), stated that the potential benefits of centralising TAVI procedures to a fewer number of specialised centers with potentially higher procedural volumes must be weighed against possible patient harms.

“In areas such as New York, there has been a rapid expansion of new TAVI centres, which has increased the capacity but resulted in relatively low volumes at some facilities. Because low operator-hospital volume is linked to poorer TAVI outcomes, this raises concerns about the potential for poorer post-procedural outcomes as a possible clinical consequence if TAVI availability becomes more widespread,” he said.

As there is limited knowledge on how these contrasting scenarios compare (potentially sicker patients before the procedure, but with better post-procedural outcomes due to to consider not only the native aortic valve anatomy, but also the metrics of the failing transcatheter heart valve (i.e. leaflets high, stent dimensions, skirt height etc.) and its mode of failure. The relation between the failing transcatheter heart valve and the aortic root anatomy will determine the risk of coronary obstruction, and thus guide the way we will implant the second valve (lower versus higher) and the degree of leaflets overhanging that we will accept. higher operator-hospital experience, versus less sick patients with shorter wait times, but potentially poorer post-procedural outcomes due to lower operator-volume experience), researchers conducted an observational, retrospective cohort study that compared outcomes between the two regions as a natural experiment. They aimed to examine whether differences in healthcare delivery in regions with high versus low access to TAVI translated to differences in post- procedural mortality and readmissions. All Ontario and New York State residents aged 18 years or older who underwent TAVI between January 2012, and December 2018 were identified. The primary outcomes were post-TAVI 30-day in-hospital mortality and all-cause readmissions.

How important is valve selection in redo TAVI? Do different features benefit the procedure?

More than the second valve, is perhaps the choice of the first valve that will influence the feasibility and the outcome of redo TAVI procedure. In fact the main difficulty of redo TAVI comes from the risk of coronary obstruction, which is highest when the first valve implanted is a supra-annular transcatheter heart valve. In fact, with the implantation of the second prosthesis inside the first transcatheter heart valve, the degenerated leaflets will be tilted up, thereby creating a “covered stent” which might impair coronary flow, particularly in the presence of a small aortic root. The higher the leaflet’s position of the first THV, the higher the risk of coronary flow impairment after redo TAVI. In this sense, if the first prosthesis implanted was a short frame THV, the redo TAVI procedure might be less cumbersome (independently from the choice of the second prosthesis, provided the latter is implanted with commissural alignment). On the other hand, treatment of a failing supra-annular transcatheter heart valve is likely to be best approached with the implantation of a short frame balloon-expandable valve, which can be implanted lower or higher based on the risk of coronary obstruction and the expected haemodynamic result of leaflets overhanging (more detrimental if the failing mechanism is a stenosis rather than regurgitation).

The study found significant differences in TAVI access rates between the two jurisdictions. Although there was no significant difference in the rate of readmission at 30 days between the two jurisdictions (14.6% in Ontario and 14.1% in New York State), the 30-day in-hospital mortality rate was higher in Ontario (3.1%) than in New York State (2.5%). To determine the potential impact of treatment in Ontario on New York patients, the investigators calculated the observed versus expected outcomes for New York patients had they been treated in Ontario.

Wijeysundera noted that the study results suggest that greater access to TAVI is linked with better outcomes, possibly due to early intervention in the disease trajectory.