Canadian TAVI Study Refines Patient Factors for Success

NEW YORK – Midterm results of a Canadian study of transcatheter aortic valve implantation (TAVI) have shown survival and cardiac event rates comparable to those of earlier studies, but the Canadian investigators have identified patient factors that can help in selecting appropriate patients for the procedure and further improve outcomes.

Dr. Josep Rodés Cabau of the Quebec Heart and Lung Institute in Quebec City, who is lead investigator of the Canadian study, reported results at the annual New York Cardiovascular Symposium. The study involved the implantation of the Edwards valve (Edwards Lifesciences) by either a transfemoral (TF) or transapical (TA) approach in 339 high-risk patients. Preliminary results, published last year (J. Am. Coll. Cardiol. 2010;55:1080-90), showed similar 30-day mortality for both approaches – 9.5% for TF vs. 11.3% for TA – according to Dr. Rodés Cabau.

He reported updated data that showed an overall survival rate of 76% at 1 year – 75% for TF and 77% for TA. At 2 years, that survival rate evened out somewhat – 68% overall, 68% for TF and 69% for TA. Dr. Rodés Cabau reported yet-to-be published data that showed the approaches had similar rates of new cerebral lesion formation, as measured by post-TAVI MRI: 66% for TF and 71% for TA.

However, the study also concluded that the TF or TA approach did not determine worse outcomes as much as patient factors, such as pulmonary hypertension, chronic obstructive pulmonary disease, or chronic kidney disease, or problems during the implantation procedure, such as hemodynamic issues or infection. "This points to the importance of patient selection if we want to improve the results associated with these procedures," Dr. Rodés Cabau said.

As in other studies of TAVI, the Canadian trial involved patients too frail for surgical aortic valve repair, he noted. Most subjects were in their 80s, and many had multiple comorbidities: About two-thirds had coronary artery disease, a third had pulmonary disease, a third had heart bypass surgery, a third had peripheral vascular disease, and more than half had some degree of renal dysfunction, he said.

Earlier studies of patients with these diseases had higher death and event rates than did recent studies, he noted. "When you look at the more recent studies, you see that the success of the procedure is systematically higher than 90%, and higher than 95% in many of these series," he said.

He also explained why the apical approach may have had a slightly higher 30-day mortality than did femoral catheterization across four series reported in 2010: "On whole, the transapical-approach patients had a higher 30-day mortality, probably because they have a logistical Euroscore higher than 25% in most of the series." In the Canadian study, the TA group had an average Euroscore of 29.4% vs. 25.8% for the TF group.

The Canadian study identified pulmonary hypertension and severe mitral valve regurgitation as two of the main factors associated with 30-day mortality, Dr. Rodés Cabau said. "In our institution, we have improved our patient selection based on our experience," he said.

The Canadian study also had a 30-day stroke rate and need for new pacemaker implantation comparable to those of the SOURCE (SAPIEN Aortic Bioprosthesis European Outcome) registry (Circulation 2010;122:62-9).

"For the type of patient we are treating nowadays, quality of life and functional status might be even more important than survival length," Dr. Rodés Cabau said. "In most cases, TAVI shows a considerable improvement in functional status. However, a significant number of patients, around 20%, do not improve much after these procedures – again, to enlighten that we may be picking some patients who are too sick to have the procedure."

Meanwhile, the results from cohort A of the PARTNER (Placement of Aortic Transcatheter Valve) trial, which compares TAVI (Edwards SAPIEN valve) and surgical aortic valve replacement for high surgical risk patients, should be available in 2011, Dr. Rodés Cabau said.

Dr. Rodés Cabau disclosed that he receives consulting fees or honoraria from AGA Medical and Edwards Lifesciences, and research grants from Boston Scientific.