TAVR Experiences Identifying Risks for Stroke, LBBB, and Perivalvular Leak

October 24, 2012

MIAMI, Florida — With experiences in transcatheter aortic-valve replacement (TAVR) growing worldwide, new data are emerging to identify various predictors of adverse clinical outcomes, including the risk of cerebrovascular events, left bundle branch block (LBBB), and perivalvular aortic regurgitation. In one study presented today at TCT 2012, investigators identified some mechanical factors associated with a higher rate of acute cerebrovascular events in a large cohort of patients undergoing transcatheter valve replacement.

Dr Luis Nombela-Franco (Quebec Heart and Lung Institute, Laval University, Quebec City, QC) said that the occurrence of cerebrovascular events following TAVR remains one of the most worrisome complications associated with the interventional procedure. Published data suggest that the 30-day stroke risk with TAVR is approximately 3.5%.

Speaking during the morning session [1], Nombela-Franco presented data from five clinical centers performing TAVR and reported the incidence of acute and subacute cerebrovascular events was 2.7% and 2.4%, respectively. Importantly, the use of balloon postdilation and valve dislodgment/embolization were two risk factors associated with a higher rate of acute cerebrovascular events, those events occurring within the first 24 hours, whereas the presence of atrial arrhythmias was the main cause of subacute events.

"We probably postdilate patients less now than we have in previous cases," said Nombela-Franco.

Postdilation and Risk of Cerebrovascular Events

The analysis included data on the timing, predictive factors, and prognostic value of cardiovascular events in 1081 patients undergoing TAVR with balloon-expandable and self-expandable devices.

Early cerebrovascular events, defined as a transient ischemic attack, minor stroke, or major stroke occurring within 30 days, occurred in 54 patients (5.1%). Of these, nine patients had a transient ischemic attack and 45 patients had a stroke (4.2%), including 30 with a major stroke (2.8%) and 15 patients with a minor stroke (1.4%). The majority, 54%, of these events occurred within 24 hours, while the remainder occurred between one and 30 days. For late cerebrovascular events, with patients followed for a median of 12 months, there were 35 events, including 13 transient ischemic attacks and 22 strokes. Of these late strokes, 18 were major, including six hemorrhagic strokes, and four were minor strokes.

In a multivariate-adjusted risk model, valve dislodgment/embolization (hazard ratio [HR] 4.36; p=0.024) and the use of balloon postdilation (HR 2.46; p=0.034) were associated with increased risks of acute cerebrovascular events occurring within the first 24 hours. For subacute events, occurring between one and 30 days, the presence of diabetes, severely calcified aortas, and new-onset atrial fibrillation (AF) were each associated with a more than twofold increased risk of events. For late cerebrovascular events, chronic AF, peripheral vascular disease, and cerebrovascular disease were also associated with a twofold increased risk of late cerebrovascular events.

The chair of the morning session, Dr Wesley Pedersen (Minneapolis Heart Institute Foundation, MN), said the findings have clinical relevance, particularly as clinicians are questioning the risks of postdilation in patients with paravalvular insufficiency. One of the scheduled discussants, however, said that postdilation is not performed randomly and that many of these patients, specifically those with moderate to severe paravalvular leaks, require it.

"You're not postdilating just for the fun of it," said Dr Vinod Thourani (Emory University, Atlanta, GA). "You're postdilating because you have a paravalvular leak. It's a balance between a paravalvular leak and the potential of a 2% to 3% increased risk of stroke." He added that he is not comfortable leaving patients with moderate to severe paravalvular regurgitation and will postdilate these patients despite the risks.

TAVR and Perivalvular Regurgitation

In a second study, Dr Eric van Belle (Hôpital Cardiologique, Lille, France) presented data on perivalvular regurgitation and its impact on clinical outcomes from the FRANCE 2 registry, one of the largest registries of TAVR patients [3]. van Belle presented data on 2769 patients and reported that 15% had moderate to severe aortic regurgitation (grade >2) following successful TAVR. The presence of aortic regurgitation was associated with a twofold increase in the risk of death at one year.

At one year, the rate of death among patients with aortic regurgitation grade > 2 was 25% compared with 10% among patients with mild or no aortic regurgitation.

The use of a self-expandable device and the transfemoral approach were both associated with an increased risk of aortic regurgitation, with each variable associated with a twofold increased risk. The rate of aortic regurgitation >2 was 21.9% in patients treated with a self-expandable device via the femoral artery and 10.7% among patients treated with the same device via a nonfemoral artery. Similarly, the rate of aortic regurgitation was 13.9% among patients treated with a balloon-expandable device via the femoral artery and 8.0% for patients treated with a balloon-expandable device via a nonfemoral artery.

"Postprocedure aortic regurgitation after TAVR is a major issue," said van Belle, "and it could be avoided, especially when there is no significant aortic regurgitation at baseline or when a nonfemoral-artery approach is used. For balloon- and self-expandable devices, the benefit of the nonfemoral artery approach on the rate of aortic regurgitation suggests that a good axial control of the device at the time of the delivery is key to reduce the rates of aortic regurgitation."

van Belle noted that predictors of aortic regurgitation with the balloon-expandable device included the diameter of aortic annulus and diameter of the prosthesis, but these variables had no impact when a self-expandable device was used.

Other TAVR Analyses at TCT 2012

In other studies presented during the TAVR roundup, van Belle reported data suggesting that the presence of mild to moderate mitral regurgitation at baseline had no impact on one-year mortality rates among patients treated with TAVR in the FRANCE 2 registry [3]. In an analysis of the PARTNER A trial, Dr Sammy Elmariah (Massachusetts General Hospital, Boston) presented data showing that the failure of left ventricular function to improve in the first six months after TAVR increases the risk of all-cause mortality at one year [4].

And finally, Dr Marina Urena (Laval University, Quebec City) showed that 30% of patients with no prior conduction disturbances develop LBBB following TAVI with a balloon-expandable valve [5]. The depth of the prosthesis and baseline QRS duration were associated with a significant 37% and 24% increased risk of persistent LBBB, respectively, while the occurrence of new-onset LBBB was associated with a sixfold increased risk of the need for a permanent pacemaker (HR 5.99; p<0.001). In addition, persistent LBBB was associated with a reduction in left ventricular ejection fraction and poorer functional status at one year.

None of the investigators have any reported conflicts of interest.