Study confirms that volume matters for achieving lower in-hospital mortality after TAVI

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A study, published in EuroIntervention, provides further evidence that there is an inverse relationship between the number of transcatheter aortic valve implantation (TAVI) procedures a centre performs and in-hospital mortality. However, authors Kurt Bestehorn (Technical University of Dresden, Dresden, Germany) and others caution against setting minimum volume numbers

Bestehorn et al report that patients who undergo surgical aortic valve replacement at hospitals performing a high number of such procedures have lower in-hospital mortality, lower operative mortality and shorter hospital stays than those who undergo surgery at low-volume hospitals. They add that while small studies have indicated that an inverse relationship between hospital volume and outcomes also exists for TAVI, this finding needs to be confirmed in larger studies. “We have therefore analysed the TAVI dataset from the mandatory Germany Quality Assurance Registry on Aortic Valve Replacement (AQUA), comprising all TAVI procedures in Germany in 2014,” the authors note.

They identified 9,924 patients who underwent transfemoral TAVI at 87 hospitals across Germany in 2014. Of these 87 hospitals, 46 (53%) performed ≥100 cases per year—including 14 (16%) that performed ≥200 cases per year—and 41 performed fewer than 100 cases per year. Bestehorn et al comment: “Procedure times were significantly longer in lower volume hospitals and decreased with transfemoral TAVI workload, particularly with ≥100 procedures. The overall length of hospital stay as well as post TAVI procedure until discharge period was longer among hospitals with lower volume.”

Holger Eggebrecht

In-hospital mortality also increased with decreasing hospital volume, with the average in-hospital mortality being 5.6±5% for the hospitals performing the lowest number of procedures (fewer than 50 per year) and being 2.4±1% for hospitals performing the highest number of procedures (≥200). The authors comment: “There was a statistically significant association of lower average mortality with increasing transfemoral TAVI volumes (p<0.01).” They add that there was also a significant trend towards decreasing observed/expected mortality ratios with increasing hospital volume (p=0.001).

However, there were no significant differences between low- and high-volume hospitals in terms of major complications, including severe intraoperative complications requiring emergency cardiac surgery, neurologic complications, vascular complications, and rates of new pacemaker implantation.

According to Bestehorn et al, the German Cardiac Society now recommends a minimum of 50 TAVI procedures per year “to maintain appropriate standards to guarantee quality of care”. However, they say that “this requirement is of course arbitrary in the absence of any real data” and note that their study indicates that two of three German centres meet these requirements even though outcomes “varied widely”.

Furthermore, given the variability they observed, the authors comment that setting limits on centre volume “would not only deprive sties with lower volume but excellent outcomes from the opportunity to serve their patients in their own backyard but will also likely overwhelm the large volume centres and delay treatment.” They add that understanding how lower volume centres are able to produce good outcomes may benefit others, saying “this may potentially help minimise the variability and gap in outcomes observed among hospitals with different TAVI volumes”.

Study author Holger Eggebrecht (Cardioangiological Center Bethanien, Frankfurt, Germany) told Cardiovascular News: “For me it is important to stress that some smaller centres had great outcomes. Nevertheless beyond 100 TAVI procedures per year, the curve of observed/expected mortality ratio flattens and there are fewer differences, the results become more stringent, and there are fewer outliers to either side.”

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