AMSTERDAM – Transcatheter aortic valve replacement produced dramatically better 1-year survival, compared with surgical valve replacement, among high-risk patients with diabetes in a new, post hoc analysis of data collected in the first PARTNER trial.
The 145 patients with any type of diabetes who underwent transcatheter aortic valve replacement (TAVR) in the operable, cohort A of the first Placement of Aortic Transcatheter Valves (PARTNER) trial had an 18% all-cause mortality rate during 1-year follow-up, compared with a 27% rate among the 130 patients who underwent surgical aortic valve replacement (SAVR), a difference in this post hoc analysis that reached statistical significance.
Dr. Brian R. Lindman
The finding of a 9-percentage-point difference in mortality in the diabetic subgroup treated with TAVR, a 40% relative risk reduction compared with SAVR, contrasts with the overall, primary finding of the PARTNER I cohort A trial, which showed that TAVR and SAVR produced similar mortality rates in high surgical-risk patients after 1 year (N. Engl. J. Med. 2011;364:2187-98).
TAVR use in patients with diabetes also resulted in a statistically significant reduction in the 1-year incidence of renal failure requiring dialysis, a 4% rate compared with an 11% among the SAVR patients, Dr. Brian R. Lindman reported at the annual congress of the European Society of Cardiology. This also contrasted with the overall PARTNER results when patients without diabetes were included, which showed no difference in renal outcomes between TAVR and SAVR.
The results "raise the possibility that TAVR may be the preferred approach for patients with diabetes," said Dr. Lindman. But he cautioned that because this was a post hoc analysis, the results need confirmation in a prospective study.
Despite this caveat, Dr. Lindman said that the finding can’t be completely ignored when treatment options are discussed with patients who have severe aortic stenosis. "Going forward, I think this is something we’ll need to think about, and we might lean more toward TAVR for patients with diabetes. But we’d like to see some confirmatory evidence in the PARTNER II cohort A trial," he said in an interview. Investigators from the PARTNER II trial, which is randomizing patients with moderate surgical risk, have said that the cohort A results are expected in 2015.
"Although hypothesis-generating only, this result is good news for patients with diabetes," said Dr. William Wijns, codirector of the cardiovascular center at O.L.V. Hospital in Aalst, Belgium.
Dr. Lindman also cautioned that investigators collected limited data on patients’ diabetes status in PARTNER I. The data did not include information on diabetes type, hemoglobin A1c or blood glucose levels, or treatment received. He also acknowledged that the 42% prevalence of diabetes in the study cohort was unexpectedly high, but noted that if this meant that some patients with a questionable diabetes diagnosis entered the analysis, this should have diminished the mortality difference between TAVR and SAVR.
The 275 patients with diabetes in PARTNER I cohort A averaged 82 years of age, and just over a third were women. The subgroups of patients with diabetes randomized to TAVR and to SAVR showed no significant differences for any physiologic or cardiovascular measure or in the prevalence of various comorbidities.
The analysis also showed a statistically significant reduced rate of 1-year mortality in the subgroup treated with transfemoral TAVR compared with SAVR, and in the subgroup of patients with diabetes treated with transapical TAVR compared with SAVR. The 1-year rate of stroke was an identical 3.5% in the patients with diabetes treated with TAVR and in those treated with SAVR. Patients treated with SAVR had a higher incidence of a major bleeding event during follow-up compared with the TAVR patients, while the TAVR patients had a significantly higher rate of major vascular complications during follow-up. Both findings were consistent with the overall PARTNER I cohort A results, said Dr. Lindman, a cardiologist at Washington University in St. Louis.
The diabetes patients who underwent TAVR showed their striking reduction in 1-year mortality despite having the same problem with postprocedural aortic regurgitation as seen in the overall PARTNER I trial. At 6 months after treatment, 9% of the TAVR patients had moderate or severe aortic regurgitation, and 54% had mild regurgitation, compared with rates of 1% moderate or severe and 6% mild in the SAVR patients.
Dr. Lindman speculated that increased inflammation and oxidative stress in patients with diabetes may interact with the stresses of heart surgery to produce the excess mortality seen after SAVR in patients with diabetes. Results from prior studies had documented worsened survival in patients with diabetes who undergo heart surgery, he said.