Late Conduction Defects After TAVR: Finding ‘Sweet Spot’ for Early Discharge

In an era where hospitals are discharging patients earlier and earlier after transcatheter aortic valve replacement, researchers are warning physicians to be cautious about the development of late conduction abnormalities that require implantation of a permanent pacemaker.

An ECG analysis performed after the procedure could help identify individuals who are at risk of conduction abnormalities developing more than 48 hours post-TAVR, they add. In a study of TAVR patients treated at a single center in Italy, individuals with baseline right bundle branch block (RBBB) and increases in the PR interval were more likely to develop late conduction abnormalities requiring a permanent pacemaker following TAVR.

“All of us in high-volume centers are pushing to send our patients home earlier,” senior investigator Azeem Latib, MD (IRCCS San Raffaele Scientific Institute, Milan, Italy), told TCTMD. “We want to get them home on day one or day two. There is a push not to turn this into a PCI-type of procedure, but there are reduced costs to the healthcare system if patients go home earlier. For me, the biggest limitation for earlier discharge is knowing I’m not putting them at any risk by doing so.”

Conduction abnormalities, such as high-degree atrioventricular (AV) block, requiring a permanent pacemaker remain one of the limitations of TAVR, but there has been a lot of research aimed at identifying predictors of the need for a permanent device.

Although most conduction abnormalities develop during or early after TAVR, there are instances in which high-degree AV block occurs more than 48 hours after valve replacement. The predictors of late or delayed conduction abnormalities are less well characterized and pose a clinical conundrum, particularly since these conduction disturbances can occur when the patient has already been discharged from hospital, said Latib.

“In clinical observation, we were seeing patients on day three, day four, or day five—patients we were about to discharge—with advanced AV block,” said Latib. “If we had discharged the patient 2 days ago, they’d have gone into AV block at home and had a complication.”

Christopher Meduri, MD (Piedmont Heart Institute, Atlanta, GA), who was not involved in the study, agreed the development of late conduction abnormalities is a relevant issue given that hospitals have gravitated toward faster discharge following TAVR. In their practice, if a patient is identified as being at high risk for late conduction abnormalities, physicians will send them home with an external 24-hour cardiac monitor, Meduri said. “We have not had a patient have a catastrophic event, but we have seen late heart block, sometimes even a week later [after TAVR].”

Late Pacemakers in 7% to 9% of Patients

Published in the August 13, 2018, issue of JACC: Cardiovascular Interventions, the new analysis included 740 patients treated at a single center between 2007 and 2015. Of these, 78 patients already had a permanent pacemaker and 51 patients received one within 48 hours of TAVR. Of the remaining 611 patients, 54 patients (8.8%) developed an advanced conduction abnormality requiring permanent pacemaker ≥ 48 hours of the procedure.

Individuals who required a late pacemaker had a wider QRS interval, had a higher prevalence of baseline RBBB, and were more likely to receive a self-expanding valve. In the multivariate analysis, baseline RBBB and an increasing PR interval (each 10-ms increase from baseline) were both associated with an increased risk of developing delayed conduction abnormalities requiring a permanent pacemaker.

A second study, also published in JACC: Cardiovascular Interventions, evaluated the utility of immediate post-TAVR 12-lead ECG parameters to identify conduction defects occurring within 30 days in 467 patients who underwent percutaneous valve replacement at a single center in Denmark. Overall, conduction abnormalities developed in 7.5% of patients within 30 days of TAVR.

Led by Troels Jørgensen, MD (Copenhagen University Hospital, Denmark), the investigators determined that removing the temporary pacemaker immediately after TAVR was safe in patients without RBBB who were in normal sinus rhythm and had normal PR and QRS intervals. No conduction defects occurred in these patients within 30 days of TAVR. In addition, the temporary pacemaker could be safely removed in patients in atrial fibrillation with a QRS interval less than 140 ms.

In an editorial, Tamim Nazif, MD, Shmuel Chen, MD, and Susheel Kodali, MD (Columbia University Irving Medical Center, New York NY), say the two studies confirm the occurrence of “delayed” high-degree conduction disturbances in 7% to 9% of patients without a prior pacemaker after TAVR. They also reinforce the usefulness of ECG parameters at different time points to predict these conduction defects and that patients with normal PR and QRS intervals are not at a significant risk of “subsequent, dangerous conduction disturbances.”  

That said, Nazif and colleagues point out that more research is needed because all the studies to date are relatively small, retrospective, single-center analyses. The studies have also not been able to integrate other important aspects of TAVR, such as valve type and depth of implantation, with ECG findings in clinical decision-making algorithms.  

Patient Would Have Gone Home

To TCTMD, Latib pointed out that the number of patients who required a late pacemaker was nearly the same as those who had a device implanted within 48 hours. In total, seven patients developed high-degree conduction defects requiring a pacemaker on day two and eight patients on day three. However, 12 patients had a permanent pacemaker implanted on day five and 11 patients on day six.

“In many centers, those patients would have already been sent home,” said Latib.

In evaluating the ECG before discharge to identify baseline RBBB, increases in the PR interval, or a widening of the QRS interval, physicians might be able to better identify at-risk patients. Such patients can be kept in the hospital or sent home with a monitoring device where physicians can track them closely for the next 7 to 10 days, said Latib.

Latib highlighted the recently published MARE study, which was led by Josep Rodės-Cabau, MD (Laval University, Quebec City, Canada). In that study of 103 consecutive patients with left bundle branch block (LBBB) following TAVR, investigators implanted a cardiac monitor (Reveal LINQ, Medtronic) on day four to assess the occurrence of significant arrhythmias. The majority of arrhythmic events were silent (77%), but 19 patients had a change in treatment as a result of the ECG data and nine patients required a permanent pacemaker for high-degree AV block.

To TCTMD, Meduri said they have been discharging patients early for nearly 4 years but they have had to incorporate risk-stratification tools to identify who might be at risk for developing late conduction defects. “A lot of the predictors described in the paper, such as right bundle branch block, we’re all very knowledgeable that that is a big risk factor,” he said. “With the PR interval, the delay, I don’t think I’ve even looked at specific numbers, but it could be very helpful.”

Meduri said the challenge with evaluating patients at risk for late conduction abnormalities is identifying those at highest risk. “You might tend to get a little gun-shy,” he said. “You see all of these potential predictors—in which the vast majority of time the patient is fine—and it’s easy to start saying we should revert back to holding a lot of them for a longer period of time. It’s all about trying to find that sweet spot.”

The use of 24-hour monitoring in patients potentially at risk for late high-degree AV block is a compromise between holding the patients in hospital and sending them home too early. “It’s our way of saying, ‘We’ve got good monitoring and we don’t think there is a risk of an extremely catastrophic event, but there might be later heart block,’” said Meduri. He added that they will also hold off on beta-blockers during the period the patient is monitored in order to hopefully facilitate faster ventricular escape beats if he or she develops AV block.