LBBB Remains Problematic 1 Year Post-TAVI: TVT Registry

New left bundle branch block (LBBB) following TAVI has grown less common over the past decade, but the conduction disturbance remains a substantial complication associated with worse morbidity, mortality, and quality of life over 1 year, according to US registry data.

The overall incidence of new LBBB among more than 200,000 TAVI patients enrolled in the Society of Thoracic Surgery (STS)/American College of Cardiology (ACC) TVT Registry was 16.3% between 2016 and 2022, decreasing from 19.9% to 14.4% over the years (P < 0.001). Still, patients with LBBB were at greater risk of experiencing death, rehospitalization, need for permanent pacemaker, worse quality of life, and lower left ventricular ejection fraction compared to those without.

“It’s long been recognized that conduction disturbances, especially heart block and new left bundle branch block, are the most frequent complication of TAVR, and increasingly there’s been evidence that left bundle branch block, in particular, is associated with adverse late clinical outcomes,” senior author Tamim M. Nazif, MD (NewYork Presbyterian/Columbia University Irving Medical Center, New York, NY), told TCTMD. “However, most of that evidence comes from much smaller data sets. The TVT Registry is unique in that it gives us a much larger real-world sample where we can investigate that.”

The analysis is one of the first to “look at patient-reported health status and showed that was worse as well at 1 year,” said Nazif, adding that the overall findings support continued efforts to reduce LBBB.

Commenting on the study for TCTMD, Josep Rodés-Cabau, MD, PhD (Laval University/Quebec Heart & Lung Institute, Canada), said the results confirm prior smaller studies and lauded the large size of the analysis.

The drop in LBBB seen over time is likely related to efforts that have been made to implant TAVI devices higher in the aorta, but that doesn’t always solve the problem, he said. “Are we going to be able to decrease these incidents below 10%? I’m not sure. Sometimes even if you implant the valve in a very high position, you will still have this conduction problem. But in any case, it is reassuring.”

1-Year Outcomes

The study, published online last week in Circulation: Cardiovascular Interventions with first author Nickpreet Singh, MD (NewYork Presbyterian/Weill Cornell Medical Center), included 202,533 patients (mean age 78.5 years; 48.7% female) undergoing elective TAVI who lacked previous conduction defects. Surgical risk as assessed on-site was low for 21.1% of patients, intermediate for 38.8%, and high for 39.7%. Mean Kansas City Cardiomyopathy Questionnaire overall summary score (KCCQ-OS) was 51.6 at baseline, and 85.8% of patients had an LVEF of at least 50%.

Among the 156,350 patients with 1-year data, those with LBBB had higher risks than those without the complication of all-cause mortality (9.2% vs 7.6%; adjusted HR 1.19; 95% CI 1.13-1.25), hospital readmission (28.6% vs 23.5%; adjusted HR 1.23; 95% CI 1.19-1.28), and need for new pacemaker (7.1% vs 2.1%; adjusted HR 3.50; 95% CI 3.26-3.76).

At 1 year, patients with new LBBB had lower KCCQ-OS scores (adjusted difference -1.7 points) and LVEF (adjusted difference -2.8%; P < 0.001 for both). The conduction disturbance was also associated with longer median hospital length of stay (P < 0.001) and a lower likelihood of being alive and well at 1 year (adjusted OR 0.88; 95% CI 0.83-0.94).

More to Uncover

While the data don’t indicate a need for specific practice changes, Nazif highlighted how the field has made “meaningful improvements over time,” by not only understanding how the depth of implant can affect outcomes, but also through changes to devices themselves that have reduced conduction disturbances.

“We know that there’s certain modifiable procedural techniques—the choice of the valve, the sizing of the valve, and especially depth of implantation—that may reduce the rates of new left bundle branch block,” he said. “This study reaffirms how important it is to continue to understand those modifiable risk factors and apply them in our practice.”

While LBBB rates are waning, the complication remains a problem in real-world practice, Rodés-Cabau said. “We need to continue developing these skills in terms of improving the valve positioning.”

LBBB can occur after SAVR as well, Nazif noted, but it’s a more common problem following TAVI. Need for permanent pacemaker also used to be vastly more common in TAVI compared with SAVR, but he specified that these “rates have come closer together.”

Part of the reasoning for this shift, he continued, could be that “complete heart block leading to pacemaker [is] an urgent complication in the immediate postoperative period that requires an immediate response.” On the other hand, LBBB “is a little more subtle in that it doesn’t have an immediate consequence, but it appears to have this long-term consequence” that deserves more attention.

Ambulatory monitoring for these patients has become more common, according to Nazif, but there’s no current intervention that can help once LBBB has developed.

“As we move into younger, lower-risk patients, it’s going to be increasingly important to understand how these conduction disturbances—both pacemaker and new LBBB—impact even much longer-term outcomes,” he said. “I’d like to see longer-term analyses, looking at perhaps 5- or even 10-year outcomes related to conduction disturbances. That’s going to be revealing.”

Moreover, Nazif said he’d like to see more research designed to understand the mechanisms by which LBBB causes late adverse outcomes. Those might include the progression of heart block, worsening heart failure, or ventricular arrhythmias, he suggested.