Expert Consensus Gives Initial Guidance on Post-TAVR Conduction Disturbances

A new consensus document released this week, complete with treatment algorithms, hopes to reduce the number of potentially deadly conduction disturbances following TAVR, including new-onset left bundle branch block (LBBB) and need for permanent pacemaker (PPM) implantation.

The expert committee responsible for pulling the document together acknowledges that conduction disturbances remain an unconquered challenge in the domain of percutaneous valve therapies.

“It's a very humble step forward in order to provide some kind of guidance [in] a field that has been really quite chaotic, I would say, in the last 10 years,” lead author Josep Rodés-Cabau, MD (Laval University, Quebec City, Canada), told TCTMD. “Nobody knows exactly what to do, and we have to recognize that the data we had to provide some guidance was really scarce and [more is] badly needed.”

Commenting on the paper for TCTMD, Troels H. Jørgensen, MD (Rigshospitalet, Copenhagen University Hospital, Denmark), said for research purposes, “it's nice that somebody finally tried to make uniform definitions—for example, for what are persistent conduction abnormalities after TAVR and what are delayed conduction abnormalities—because that's been very varied [from] study to study.” Clinically, most of the papers published so far seeking to show the optimal ways in which these patients should be followed up have been small, he added. Connecting them all in this way is “important work.”

Additionally, Nicolo Piazza, MD, PhD (McGill University Health Center, Montreal, Canada), who called this issue “the Achilles’ heel of TAVR,” told TCTMD that this paper is “a stepping stone in the right direction, and I think as time goes on this is going to be a good platform for future iterations and trying to tailor these algorithms on a more patient-specific level.” However, he did note that “we're dealing with a very heterogeneous population and algorithms tend to ignore heterogeneity.”

Algorithms by Group

Published in the August 27, 2019, issue of the Journal of the American College of Cardiology, by a multidisciplinary group of interventional cardiologists, electrophysiologists, and cardiac surgeons, the paper first defines a broad lists of conduction disturbances including LBBB, right bundle branch block (RBBB), varying degrees of atrioventricular block (AVB), procedural versus delayed events, and new-onset persistent issues.

It's a very humble step forward in order to provide some kind of guidance [in] a field that has been really quite chaotic. Josep Rodés-Cabau

The authors included data from several dozen studies of periprocedural conduction disturbances into multiple algorithms for how operators can move forward with patients presenting with varying degrees of problems following TAVR, stratifying them into five groups:

• Group 1: No ECG changes in patients without RBBB preprocedure
• Group 2: No ECG changes in patients with preexisting RBBB
• Group 3: ECG changes in patients with preexisting RBBB, LBBB, intraventricular conduction delay with QRS ≥ 120 ms or first-degree AVB
• Group 4: New-onset LBBB
• Group 5: High-degree AVB/complete heart block during the procedure

For procedural guidance, they advise continuous ECG monitoring, using venous access/temporary pacemaker, avoiding predilation, considering a valve type with a lower risk of conduction disturbances in high-risk patients, and minimizing depth of valve implantation.

For Group 1, the authors summarize that the temporary pacemaker is removed following the procedure and telemetry is used for 24 hours. If no new conduction disturbances arise, the patient can be sent home. Otherwise, the patient can be categorized Group 3-5 depending on what new issue arises.

Group 2 patients should keep their temporary pacemaker for at least 24 hours and can be sent home only after an additional 24 hours of telemetry and no further arrhythmias or ECG changes have occurred. High-degree AVB or complete heart block would necessitate PPM implantation, but other ECG changes over 2 days would reclassify these patients as Group 3.

The temporary pacemaker should also be maintained for 24 hours in Group 3 patients, according to the authors, who note that the occurrence of high-degree AVB or complete heart block at any time indicates need for PPM. If then the ECG changes regress to baseline or there are no further ECG changes, the patient can be discharged so long as there are no further changes on telemetry and ECG after another full day. Further ECG changes should warrant keeping the temporary pacemaker for an additional 24 hours, and those who still have further ECG changes putting them beyond where they stood at baseline should be followed more aggressively as they are now at higher risk for AVB.

For the Group 4 and 5 patients with new LBBB and AVB, respectively, temporary pacing should also be continued for a day then followed by 24 hours of telemetry and daily ECG in those whom the complication resolves. A higher-degree LBBB or further ECG changes following a new-onset LBBB dictates a high-risk for AVB patient.

Recommendations for patients deemed at higher risk for AVB at the end of the varying algorithms include invasive electrophysiology (EP) studies to guide a PPM decision, continuous ECG monitoring at hospital discharge, and prophylactic PPM.

Not a ‘White or Black’ Problem

Conduction disturbances after TAVR are not a new issue, and yet they still plague the field as much today as they did in the initial trials, even as device iterations have evolved. Rodés-Cabau said a big challenge is that they can change over time. “The involuntary nature of these changes is what makes all these conduction issues a very complex phenomenon, because it's not something that you can see white or black,” he said. “Sometimes, yes, but many times it's very difficult, and when you look at the current guidelines, there are no clear recommendations.”

As Piazza observed, variability is an issue. “I don't think industry really understands what's causing these conduction disturbances other than the conduction disturbance literally being within millimeters of the aortic valve annulus,” he commented. “It's variable from patient to patient, and I think that's where some of the problems lie in creating a general rule when there's so much variability in such an anatomic structure that we implant against (ie, the aortic annulus versus the distance to the conduction system). That variability from patient to patient makes it difficult to create generalized rules or a strategy.”

One solution might be changing the sizing algorithms for TAVR valves, he suggested. “I think that we at times are oversizing the valves too much, meaning that we are putting in larger valves than needed in many patients. So instead of sizing at the aortic annulus level, maybe we should be sizing somewhere slightly above in the aortic valve leaflets—that will lead to a smaller valve size, same valve function perhaps and [the same] paravalvular leak rates, but with less stretch or less injury to the conduction system.” Patient selection and implant technique may also play a role, Piazza added.

With the recent US Food and Drug Administration expansion of TAVR to patients at low-risk for surgery, Jørgensen said these conditions should be of even greater concern. “When you look at patients that are expected to survive a longer time, then these conduction abnormalities might really start to show an impact,” he said.

“We don't know what implications of a TAVR system are in a 60-year-old because long-term data is nonexistent in these patients,” said Piazza. “We have 5-year data, 7-year data perhaps, on elderly patients receiving TAVR, but the truth is that we are lacking 10-year or longer-term data in the 60, 65, 75-year-old patients. And so now that the portal is open to implant this type of patients, I think it's going to be very critical that perhaps the FDA or some regulatory body or industry or physicians take it upon themselves to start a registry or some study to better understand [this issue].”

Rodés-Cabau said he would like to see two types of studies in the near future. The first would be a uniform validation of these algorithms in a large patient cohort. “Probably we will find some mistakes or some indications that we were wrong,” he ceded. Also, “every type of conduction disturbance will need a response,” so studies should focus on determining these in every subgroup of patients, especially determining if continuous ECG monitoring and EP studies can be used to identify patients at risk of sudden death.

We need to get to the bottom of this by conducting more robust studies with more precise data. Nicolo Piazza

Piazza said he’d also like to see more research in how implantable loop recorders can help track patients after TAVR. “There is a healing process in some, and there's a worsening process in others,” he said. “We don't understand who gets worse and who gets better and what are those predictors of improvement or decline. So maybe these wearables are going to provide us with more specific and accurate data, . . . because at the end of the day we are making decisions sometimes on an ECG, which is a snapshot at one time point, but this is a dynamic process.”

Ultimately, he is “baffled” at the problem, Piazza acknowledged. “It's been 11 years since we've exposed the problem, . . . and I can tell you that the pacemaker rates for an Evolut or CoreValve, despite the device iterations, have not changed in the hands of many. I think those people who say they have a change in permanent pacemaker rates, [that] has to do with them changing their indications and their thresholds.”

It’s unlikely that an answer will come in even the next 5 years, he concluded. “Physicians and industry have to step it up, . . . and we need to get to the bottom of this by conducting more robust studies with more precise data.”