Sapien transcatheter aortic valve. Source: Edwards Lifesciences

CHICAGO—Non-cardiac co-morbidities, such as chronic obstructive pulmonary disease (COPD), chronic kidney disease (CKD), atrial fibrillation and frailty, are main predictors of late mortality after transcatheter aortic valve implantation (TAVI), suggesting that patients with these conditions merit closer evaluation and follow-up, according to the longest multicenter study on the clinical outcomes and valve durability with TAVI presented March 24 at the 61st annual American College of Cardiology’s (ACC) scientific session. However, in general, valve function remained stable at four years.

Most data on TAVI are limited to acute and one-year follow-up, and very few data exist on clinical outcomes and prognostic factors at longer-term follow-up, according to the study’s lead investigator Josep Rodés-Cabau, MD, from the department of cardiology at the Quebec Heart & Lung Institute in Quebec City. He added that very few data exist on the long-term durability of transcatheter valves.

Thus, the researchers set out to evaluate the long-term outcomes following TAVI using the Multicenter Canadian Experience study, with special focus on the causes and predictors of late mortality and valve durability

The study included 339 patients considered to be inoperable or at very high surgical risk who underwent TAVI at six Canadian medical centers between January 2005 and June 2009. The transfemoral approach was used in 48 percent of the patients, while the transapical approach was used in 52 percent of the patients. Also, the STS score for all patients was 9.8 percent—9 percent in the transfemoral arm and 10.5 percent in the transapical arm. 

Patients received a balloon-expandable valve (Cribier-Edwards, 57 patients), (Edwards Sapien, 275 patients), (Sapien XT, seven patients) and were then followed to determine both safety and efficacy. Clinical follow-up to determine safety was conducted in clinical visits and/or through phone contact, while efficacy follow-up was performed through echocardiography with central Echo Core Lab evaluation.

After the median three-year follow-up, 43.1 percent of the patients had died. Also, 10.4 percent of those patients died within 30 days of TAVI, and 32.4 percent died during the remainder of the follow-up period. Of those who died more than 30 days post-procedure, 67.3 percent died because of non-cardiac causes, including pulmonary causes (32.7 percent) and end-stage kidney disease (10 percent). In addition, 26.4 percent died of cardiac causes, and the cause of death was unknown in 7 percent of the patients. 

After examining the long-term data from those who died more than 30 days post-procedure, researchers determined that death was most often caused by COPD, CKD, atrial fibrillation and frailty. For the frailty definition, Rodés-Cabau acknowledged that there was no systematic, objective test about frailty, so the term could be somewhat subjective.

The causes of cardiac death at follow-up were cardiac failure (65.6 percent), sudden death (13.8 percent), MI (13.8 percent), endocarditis (3.4 percent) and post-mitral replacement (3.4 percent). Also, pulmonary hypertension determined a higher rate of peri-procedural death and remained a predictor of cardiac death at follow-up, he reported.

Of note, the stroke rate was quite low, at 2.3 percent within the first 30 days and 8 percent at 48 months. “This low of a stroke rate in a patient population that is PARTNER-like in terms of STS score is striking,” said study discussant Ted E. Feldman, MD, an interventional cardiologist at NorthShore University Health System in Chicago.

However, Rodés-Cabau suggested the stroke found in this study is similar to other registries outside the U.S. “The stroke rate in the PARTNER trials may have been higher because they used older versions of the catheters, whereas many patients in this study used a newer version of the Sapien valve,” he said.

Also, in the echocardiography exams showed that valve performance following TAVI was maintained throughout the follow-up period. Mild aortic regurgitation was frequent after the procedure but remained stable throughout the follow-up period. Rodés-Cabau reported that there were no cases of valve structural failure, and there were two cases of reintervention because of valve endocarditis, infection of the valves.

In summary, performing TAVI in this patient population was associated with a survival rate of 57 percent after a median follow-up of three years, with no differences between transfemoral and transapical approaches

“This study’s level of detail is fairly remarkable,” Feldman concluded.