Among patients undergoing transcatheter aortic valve replacement (TAVR), an intraprocedural electrophysiology study (EPS) can identify those at risk of early and delayed high-grade atrioventricular (AV) block post-TAVR, according to a new study. These findings were presented by Roger J. Laham, MD, of the Beth Israel Deaconess Medical Center, Boston, as late-breaking science Thursday at the Transcatheter Cardiovascular Therapeutics (TCT) 2023 conference. Laham presented in place of his colleague, Alfred Buxton, MD. Despite advancements in valve technologies over the years, AV conduction abnormalities (AVCA) remain a frequent complication, occurring in about 5% of 28% of patients undergoing TAVR. With expanding TAVR indications, this becomes more relevant when younger and low-risk patients are considered for TAVR. The investigators noted that the mechanisms underlying AVCA are not fully understood. Although EPS has been proposed for risk stratification, optimal timing of EPS remains unknown and previously published data on His-Bundle recordings are based on relatively smaller studies. Furthermore, indications for pacing in the absence of persistent complete heart block (CHB) or second degree Mobitz type 2 block are not well defined. Study details The study investigators aimed to clarify the mechanisms of AVCA following TAVR and understand the utility of intraprocedural EPS to risk-stratify with regard to high-grade AVCA following TAVR. The study included 399 consecutive patients who underwent TAVR between May 2021 and March 2023 at Beth Israel Deaconess. Those with pre-existing permanent pacemaker (PPM) or defibrillator were excluded. EPS were performed immediately before and after the TAVR procedure under the guidance of an electrophysiologist. This included placement of electrode catheter in the right atrium to induce Wenckebach at a cycle length of 600 milliseconds, followed by recording of proximal His-Bundle electrogram and positioning of a catheter in the right ventricle for rapid pacing during TAVR and recording retrograde conduction afterward. The electrophysiologist continuously monitored surface and intracardiac electrocardiograms (ECGs) during the procedure. Patients with any AVCA were discharged with 2 weeks of mobile cardiac monitor. The patients had mean age of 78.4 ± 8 years and were 56% male. Baseline first-degree AV block (PR interval >200 milliseconds) was present in 24% of the patients, right bundle branch block (RBBB) in 12%, and left bundle branch block (LBBB) in 5% of the patients. Most (89.5%) patients in the study received the Edwards Sapien 3 valve and rest of the patients received the Evolut. Thirty-six patients underwent valve-in-valve TAVR of which 23 patients received Sapien 3 and 13 received Evolute. EPS showed that AVCA was present in one patient prior to TAVR (2:1 AV block), in 60 patients during peri-implant period (2 patients had prolonged PR interval, 2 had Wenckebach, 5 had Mobitz type 2 AV block, and 51 had complete heart block [CHB]), and in 26 patients at the end of the procedure. Median duration of the AV block was 1 minute (range: 0.13-140 minutes). Twenty patients needed PPM either at the end of the TAVR or at some point during initial hospitalization [length of stay: median 1 day (range: 1-10 days)].Twenty patients developed CHB or Mobitz type 2 block after discharge with median time from TAVR to AV block being 4 days (range: 1-12 days). All-cause mortality was reported in five patients (one peri-procedural death and four late deaths with median time from procedure to death being 14 months). Baseline RBBB on surface ECG predicted post-TAVR CHB during initial hospitalization (p=0.0020), whereas post-TAVR PR interval of >300 milliseconds predicted CHB both during initial hospitalization (p=0.0043) as well as after discharge (p=0.0051). Interestingly, baseline RBBB was not associated with CHB after discharge (p=0.93). The investigators found that several parameters on EPS, such as post-TAVR HV interval (from the onset of His to the onset of ventricular activation; p<0.0001), post-HV interval ≥80 milliseconds (p=0.0146), post-HV interval ≥90 milliseconds (p=0.0003), baseline AH interval (from atrial signal to the onset of His; p=0.0036), and post AH interval (p=0.0095)were associated with CHB after discharge. Furthermore, post-TAVR HV interval ≥80 milliseconds (p=0.0160) and ≥90 milliseconds (p=0.0004) were associated with CHB after discharge, whereas post-TAVR HV interval (p=0.16) was not predictive. Putting the study findings in perspective, Laham concluded that intraprocedural EPS can be performed by interventional cardiologists to assess AV node and His-Bundle conduction abnormalities and predict the risk of early and delayed CHB following TAVR. The study investigators also noted that preexisting RBBB predicts risk for peri-TAVR, but not delayed, CHB, and that new LBBB at discharge was not predictive of delayed CHB as well. Comments Panelists at a TCT news conference noted that the study findings primarily represent TAVR patients receiving balloon-expandable Sapien valves and may not be extended to patients receiving other valve types. Responding to a question from news conference moderator Roxana Mehran, MD, of the Icahn School of Medicine at Mount Sinai, New York, about the key message of the study, Laham reiterated that interventional cardiologists doing TAVR can perform quick EPS measuring AH and HV intervals to identify patients at risk of early and delayed CHB. Responding to a reporter’s question during a TCT news conference about whether investigator’s institutional policies are to routinely do EPS in all TAVR patients, Laham said it is important to have multidisciplinary discussions and planning before each case with involvement of electrophysiologists for guidance and supervision. Photo Caption: Roger J. Laham, MD, speaks during a news conference Thursday at the Transcatheter Cardiovascular Therapeutics (TCT) conference in San Francisco. Photo Credit: Jason Wermers/CRTonline.org