LOS ANGELES – Aortic valve interventions rose sharply in the United Kingdom during a recent 5-year period, largely due to a spike in procedures among elderly patients, researchers reported at the annual meeting of the Society of Thoracic Surgeons.
In the study, the combined U.K. Cardiac Surgical and Transcatheter Aortic Valve Implantation (TAVI) Registries – known as SATIRE for short – the team analyzed data from 37,020 patients nationwide who underwent aortic valve interventions (excluding balloon valvuloplasty) between 2006 and 2010.
Results showed that the annual number of these procedures increased by 32% over the course of the study, with about half of the increase due to procedures among patients aged 80 years and older, reported lead investigator Dr. Neil E. Moat, a cardiac surgeon and codirector of the Transcatheter Valve Programme at the Royal Brompton Hospital in London.
Overall, the annual number of aortic valve interventions increased during the study period, from 6,217 in 2006 to 8,201 in 2010. This was driven largely by a near doubling in interventions among patients aged 80 years or older, from 1,055 to 2,035.
"In 2010, 25% of all aortic valve interventions in the U.K. were performed in patients aged 80 or over," Dr. Moat noted.
By type of intervention, there was an increase in the annual number of TAVIs (from none to 749) and conventional surgeries (from 6,217 to 7,252), although the latter stabilized toward the end of the period.
"This is the first time in the whole history – 35 years of collecting U.K. cardiac surgical data – that these numbers have plateaued," he commented.
As of 2010, TAVIs accounted for 9% of all aortic valve interventions studied.
Not surprisingly, patients undergoing TAVI surgery were older than their counterparts undergoing conventional surgery, had a higher risk profile, and had poorer postoperative survival, but their lengths of hospital stay were statistically indistinguishable.
Importantly, two scores used in Europe to predict mortality after such interventions showed differential performance.
"The logistic EuroSCORE does not predict operative outcomes of surgery or TAVI" and should not be used, Dr. Moat advised. "The EuroSCORE II is probably quite good for conventional surgery but again is rather poor for predicting mortality outcomes from TAVI. And I suppose on this side of the pond, you will be pleased to hear that the STS [U.S. Society of Thoracic Surgeons] score is far better than either of these European scores in our population."
In the discussion after the presentation of the study, Dr. Paul A. Kurlansky, a cardiothoracic surgeon from Miami, remarked, "Maybe our risk score is better on this side of the pond, but we do not have the merging of databases that you guys have over there [in the U.K.], or the completion of them. One opportunity that I was wondering if you had taken or are planning to take advantage of is the ability to do propensity score matching or use other statistical tools in order to really match patients so that you can compare outcomes."
"That’s a very interesting question and something that we have debated long and hard," Dr. Moat replied, citing reservations given by the study’s statisticians. "They are very firm in their belief that whilst you can apply those statistical techniques, they are actually not valid because you have so much confounding by indication that [you are unable] to propensity-match populations. So it’s a deliberate decision not to pursue that."
Main analyses in the study used prospectively collected registry data for 35,392 patients undergoing conventional surgery – either aortic valve replacement (AVR) alone or combined with coronary artery bypass grafting (CABG) – and 1,628 TAVIs.
"Because [the registries] are national and publicly funded, they are free from any commercial bias. These are mandatory registries and therefore free of any selection bias," Dr. Moat pointed out. Furthermore, there is good standardization of definitions and long-term follow-up of mortality.
"All cardiac surgical procedures and all TAVIs in the U.K. are entered into national registries hosted by the National Institute for Cardiovascular Outcomes Research. The data set and databases of all of these registries are designed to be compatible and comparable," he added.
Overall, compared with patients undergoing surgery, patients undergoing TAVI were on average older and had a higher risk profile in terms of cardiovascular measures and comorbidities, although there was substantial overlap.
The median postoperative length of stay was 8 days after conventional surgery and 7 days after TAVI. "Despite the TAVI patients being older and at increased risk, there was no difference in postoperative length of stay. If anything, it was marginally lower in the TAVI group," Dr. Moat commented. The distribution of length of stay was also much the same. "You see a substantial numbers of these elderly, frail, and high-risk patients [in the TAVI group] being discharged before day 6," he added.