Download this article's Factoid in PDF (& PPT for Gold Subscribers)

While persistent left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) does not indicate a greater risk of mortality, it is associated with a higher likelihood of pacemaker implantation, according to a study published online February 26, 2013, ahead of print in Circulation.

Luca Testa, MD, PhD, of Clinical Institute S. Ambrogio (Milan, Italy), and colleagues looked at 818 patients treated with the CoreValve bioprosthesis (Medtronic, Minneapolis, MN) at high-volume centers between 2007 and 2011 who did not present with LBBB or pacemaker at admission.

Mortality Not Affected

Within 48 hours after TAVR, 43.2% (n = 354) of patients developed new-onset LBBB, but the conduction abnormality only persisted in about half of those (n = 184) at discharge. Overall, 27.3% (n = 224) of patients developed persistent LBBB after TAVR through 30 days, while 72.7% (n = 594) did not.

At 30 days, overall mortality was 5.9%, with no differences between those who developed LBBB (6%) and those who did not (5.5%; P = 0.6). One-year mortality was 19.5% with no difference between the groups (P = 0.12).

Although patients with persistent LBBB had a higher rate of pacemaker implantation compared with those without the condition at 30 days (5% vs. 2%; P = 0.02), this difference was no longer significant at 1 year (18.2% vs. 17%; P = 0.09). Within 30 days of TAVR, pacemaker implantation was performed for advanced aortic valve block in 95% of patients with LBBB and 96% of those without the abnormality. At 1 year, those percentages fell to 78% and 80%, respectively.

Both the rates of hospitalization for heart failure and overall improvement in NYHA functional class were consistent between the 2 study groups at 30 days and 1 year.

Connection Between LBBB, Pacemaker ‘Unclear’

In an e-mail communication with TCTMD, Dr. Testa said he expected mortality to worsen with the presence of LBBB, “but it did not, presumably as a consequence of the very high baseline risk of patients undergoing [TAVR]. After more than 10 years since the first cases, this confirmed that the scenario of the [TAVR] patients is far from being completely elucidated.”

“The role of new-onset LBBB remains unclear” in regard to the increased short-term risk of pacemaker implantation, the authors say. “We hypothesize that the presence of LBBB might have an impact exclusively on ‘acute and early’ risk of progression to advanced [atrio-ventricular] block but not on the ‘late’ risk,” they write.

Dr. Testa suggested that ECG be routinely performed on patients implanted with CoreValve before discharge and at 1 month “in order to capture bradyarrhythmias which could require a [pacemaker] implantation.” 

But going forward, he said he would like to see “the advent of newer devices with the capacity of being fully retrievable (thus favoring an optimal deployment in most of the cases), and less traumatic for the membranous interventricular septum” in order to “minimize the risk of [atrio-ventricular] block requiring [pacemaker] implantation.”

Pacemaker Issue May Complicate Approval

This is not an “earth-shaking” paper, according to Peter C. Block, MD, of Emory University School of Medicine (Atlanta, GA). However, he told TCTMD in a telephone interview that “it’s reassuring [to know] that left bundle branch block does not have any long-term consequences as far as mortality is concerned, but the ongoing issue with CoreValve is that there is a very high percentage of patients who will need a pacer.”

The increased risk of pacemaker implantation in these patients will play an important part in the US Food and Drug Administration’s (FDA) evaluation of the CoreValve device, Dr. Block predicted. “If I were sitting on the FDA [panel], I would be seriously concerned about the additional cost for say a quarter of the patients because they will have to have pacemaker implantation after their very expensive transcatheter valve procedure,” he explained. “So we’re talking about a lot of money here.”

Testa L, Latib A, De Marco F, et al. Clinical impact of persistent left bundle branch block after transcatheter aortic valve implantation with CoreValve revalving system. Circulation. 2013;Epub ahead of print.

Related Stories:

• ADVANCE: TAVR with CoreValve Safe, Effective at 6 Months
• CoreValve Appears a Feasible Replacement for Failed Surgical Aortic Valves
• About One-Third of CoreValve Patients Require a Permanent Pacemaker