Longer Follow-up ‘Reassuring’ for New-Onset LBBB After TAVR—With Caveats

PARIS, France—Longer-term follow-up data should “partially reassure” physicians concerned about the development of new-onset persistent left bundle branch block (LBBB) after TAVR for the treatment of aortic stenosis.

Although roughly one in five patients developed the conduction disturbance, there was no difference in clinical outcomes at 3 years, including mortality or hospitalizations for heart failure, between the patients with new-onset LBBB and those who did not develop LBBB. There was, however, a higher rate of permanent pacemaker implantation, as well as a reduction in left ventricular ejection fraction, among those who developed LBBB.

“I would say, yes, it is reassuring, but on the other hand we confirmed what was already known, that these patients are more prone to severe conduction issues requiring a pacemaker during follow-up,” senior investigator Josep Rodés-Cabau, MD (Quebec Heart and Lung Institute/Laval University, Quebec City, Canada), told TCTMD. “I would say one of the important messages is that these conduction issues requiring a pacemaker seem to be mainly occurring during the first year. After the first year, the risk of pacemaker is not much different from those patients without the conduction issue.”

The clinical impact of LBBB after TAVR is a regular topic of debate and there are limited data available regarding the long-term clinical consequences of the conduction defect. The incidence of LBBB ranges depending on the study, the type of device used, implantation techniques, and patient comorbidities, according to the investigators, but the data suggest the incidence is higher with the self-expanding heart valves as opposed to the balloon-expandable devices.

The new study, which was presented at EuroPCR 2019 by Chekrallah Chamandi, MD (Quebec Heart and Lung Institute/Laval University), and published simultaneously in JACC: Cardiovascular Interventions, included 1,415 consecutive patients who underwent TAVR with a balloon-expandable device (Sapien, Sapien XT, or Sapien 3; Edwards Lifesciences) or a self-expanding valve (CoreValve or Evolut R; Medtronic) at nine centers between 2007 and 2015. The final analysis included 1,020 cases, as 395 patients were excluded after a failure to successfully implant the valve, conversion to surgery, procedural death, or, in the majority of cases, the implantation of a permanent pacemaker during the initial hospitalization.

Risk of Pacemaker Highest in First Year

New-onset LBBB occurred in 461 patients immediately after the procedure, and of these, LBBB persisted in 212 patients (20.1%). The incidence of LBBB was significantly higher among patients who received the self-expanding CoreValve/Evolut R devices compared with the balloon-expandable heart valves.

At 3 years, there was no significant difference in all-cause mortality, cardiovascular mortality, sudden cardiac death, or hospitalizations for heart failure between those who developed LBBB after TAVR and those who did not. The development of new-onset LBBB was associated with a significantly increased risk of permanent pacemaker implantation compared with patients without LBBB (15.5% versus 5.4%; HR 2.45; 95% CI 1.37-4.38) and this risk was highest in the first year (HR 3.77; 95% CI 2.06-6.90). The median time for pacemaker implantation was 8 months. After the first year, rates of pacemaker implantation were similar in the LBBB and no-LBBB groups.

To TCTMD, Rodés-Cabau said the increased risk of pacemaker implantation in the first year has clinical implications. “Let’s say we want to do some kind of monitoring, such as continuous ECG monitoring, in these types of patients,” he said. “The study tells us [monitoring] can be relatively limited. Maybe the first year or maybe even the first weeks after the procedure where the risk really peaks.” 

Regarding the echocardiographic findings, left ventricular ejection fraction increased over time in patients who did not develop LBBB after TAVR and “slightly decreased” in patients with new-onset LBBB. As a result, the between-group difference was statistically significant.

Regarding the clinical impact of new-onset LBBB, Rodés-Cabau said the issue isn’t settled. At just 3 years, their study might not be long enough to fully assess the effect of LBBB on clinical outcomes. He pointed out that other studies, including a recent analysis of PARTNER 2, have shown new-onset persistent LBBB can lead to an increased risk of death. However, two large meta-analyses failed to show an association between LBBB after TAVR and the risk of death at 12 months.

Nonetheless, Rodés-Cabau said that with LBBB, “it’s only a matter of time” before it adversely affects left ventricular function, which can lead to heart failure hospitalizations and mortality.

It’s reassuring in this elderly cohort of patients, there doesn’t appear to be a signal [of increased clinical events], but it may be a completely different ballgame in the younger patients. Janarthanan Sathananthan

“The differences [between studies] are difficult to explain, but in this population we have been treating, at least up to date, there are so many confounders, so many comorbidities that can impact mortality,” said Rodés-Cabau. “It’s very difficult to have definite results about the real impact of these conduction issues. The group that will be very interesting will be the low-risk group because these patients are not supposed to die in the 2 years after TAVR.”

The bottom line is that physicians and researchers need to continue to monitor individuals who develop persistent LBBB following TAVR. “A word of caution,” said Rodés-Cabau. “This is not a completely benign issue.”

What About Low-risk Patients?

Janarthanan Sathananthan, MBChB (St. Paul’s Hospital, Vancouver General Hospital, Canada), who was not involved in the study, noted that the average age of patients included in the analysis was 80 years, and that these individuals likely had a higher incidence of pre-existing conduction issues.

“But in younger patients, there may be some potential concerns, particularly since the pacer rates have always been particularly higher than surgery,” said Sathananthan. “In somebody that is going to live for 30 or 40 years, what are the implications of that? It’s reassuring in this elderly cohort of patients, there doesn’t appear to be a signal [of increased clinical events], but it may be a completely different ballgame in the younger patients. It’s something we’re going to continue to learn about as we get more data from PARTNER 3 and other studies.”

The PARTNER 3 trial, which included low-risk patients (mean age 73 years), is planned for 10-year follow-up, he noted. While one of the big questions is valve durability, such extended follow-up will allow researchers to assess the impact of LBBB on long-term clinical outcomes.  

In an editorial, Ron Waksman, MD, and Jaffar Khan, BMBCh (MedStar Washington Hospital Center, Washington, DC), also point out that the study was limited to elderly TAVR patients who were considered ineligible or at high risk of surgery. A short life expectancy could have “masked the impact of new-onset persistent LBBB,” they write. “Whether this data will hold for the younger intermediate- and low-risk population with higher life expectancy is in doubt.” Future studies, with predefined criteria for permanent pacemaker implantation, including a systematic recording of the implanted pacemaker, is warranted in these low- and intermediate-risk patients, according to Waksman and Khan.  

Regarding the slight decrease in left ventricular ejection fraction observed in these patients with new-onset LBBB, Sathananthan said it’s not known if this has any impact on long-term mortality. “We just don’t know,” he said. “It’s a very grey zone.”

Sathananthan said they recently performed an analysis of pacemaker implantation rates based on device type, noting there are clear differences between technologies, with the lowest rate observed with the balloon-expandable devices. “In addition to all of this, whether TAVR is the right decision, people will need to start thinking what is the right device to put in, with pacemaker rates being an important consideration.”