麻豆传媒

An easy-to-do electrophysiological test, performed immediately after transcatheter aortic valve replacement (TAVR), could reliably rule out patients' future need for a pacemaker, researchers found.

Their approach involved withdrawing the temporary pacemaker from the right ventricle and placing it in the right atrium after valve implantation in TAVR. Rapid right atrial (RA) pacing was performed at 70-120 bpm and patients were assessed for Wenckebach atrioventricular block (AVB), defined as progressive PR prolongation with pacing followed by a blocked QRS complex.

The 45.8% of 284 patients who did develop Wenckebach AVB had a substantially higher rate of permanent pacemaker implantation (PPI) within 30 days of TAVR (13.1% vs 1.3%, P<0.001), according to researchers led by Amar Krishnaswamy, MD, of Cleveland Clinic, reporting online in .

Lack of Wenckebach AVB was associated with a negative predictive value (NPV) of 98.7% for 30-day PPI, study authors noted. Of the two patients who underwent PPI without Wenckebach, one did so because of new left bundle branch block (LBBB) with known low ejection fraction, and the other for a 2.5-second pause and known LBBB.

"Atrial pacing post-TAVR is easily performed and can help identify those patients who may benefit from extended rhythm monitoring. Those patients who did not develop pacing-induced Wenckebach AVB demonstrate an extremely low likelihood of PPI," the investigators concluded.

"The findings of our study have already been incorporated into our clinical practice," they said. "We now feel comfortable routinely discharging patients who develop transient CHB [complete heart block] during TAVR on the day after procedure if they do not demonstrate Wenckebach on their rapid atrial pacing study and no further episodes of high-degree conduction disease."

The reported 98.7% NPV of the Wenckebach test would "indeed allow for early discharge after an abbreviated period of additional ECG monitoring," agreed Tobias Reichlin, MD, and Thomas Pilgrim, MD, both of Bern University Hospital in Switzerland, in .

Such an approach is not possible for patients in atrial fibrillation at the time of TAVR, however, and may be affected by anesthesia choice, Reichlin and Pilgrim cautioned.

For now, the need for permanent pacemakers remains a major weakness of contemporary TAVR. Transcatheter valves are associated with PPI rates in the range of 5%-30% because of conduction disturbances and high-degree AVB, the editorialists said.

This is important as TAVR expands to lower-risk and younger patient populations.

To avoid late conduction block, some patients currently get a prophylactic pacemaker if they show conduction abnormalities on the post-TAVR ECG. A majority, however, are not in fact dependent on the device at follow-up, according to Krishnaswamy's group.

Their study was based on 284 consecutive TAVR patients, all without pre-existing pacemakers or underlying atrial fibrillation. Investigators allowed the inclusion of those with transient CHB during TAVR.

Study participants had undergone TAVR at two high-volume centers: Cleveland Clinic and Ospedale San Raffaelle in Milan, Italy. Operators opted for local anesthesia in 92% of patients.

People receiving self-expanding valves required PPI in 15.9% of cases, compared to 3.7% with a balloon-expandable valve (P=0.001). Among the subset of people who did not develop Wenckebach AVB, those figures went down to 2.9% and 0.8%, respectively, according to the authors.

"The Wenckebach phenomenon is the result of slowing at the A-H interval, while high-grade conduction block occurs at the H-V segment. The very high NPV among patients who did not develop Wenckebach at RA-pacing rates up to 120 bpm is therefore indicative of a reasonable test of the H-V interval," Krishnaswamy and colleagues explained.

Bias cannot not be excluded from the report given the selected patient population, the investigators acknowledged.

"Additionally, while the current study was performed at two high-volume sites, the number of patients with pacemaker implantation is still relatively small and a larger experience would provide more data for widespread clinical adoption," they noted.

"Further, other variables for PPI including valve calcification and depth of implantation were not analyzed in the current study but are known factors in predicting the need for PPI," they added.

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