The utility of rapid atrial pacing immediately post-TAVR to predict the need for pacemaker implantation
Selected in JACC: Cardiovascular Interventions by M. Alasnag
The investigators proposed rapid atrial pacing (RAP) to further risk-stratify patients for post-TAVR PPI. Atrial pacing can be easily performed during the TAVR procedure since a temporary pacemaker (TPM) is routinely positioned in the right ventricle during valve implantation.
References
Authors
Krishnaswamy A, Sammour Y, Mangieri A, Kadri A, Karrthik A, Banerjee K, Kaur M, Giannini F, Pagliaro B, Ancona M, Pagnesi M, Laricchia A, Weisz G, Lyden M, Bazarbashi N, Gad M, Ahuja K, Mick S, Svensson L, Puri R, Reed G, Rickard J, Colombo A, Kapadia S, Latib A.
Reference
JACC: Cardiovascular Interventions. DOI: 10.1016/j.jcin.2020.01.215
Published
15 April 2020
Link
Read the abstractReviewer
My Comment
Why this study? – the rationale/objective
Although transcatheter aortic valve replacement (TAVR) has been an established treatment option for inoperable, high risk, and intermediate symptomatic severe aortic stenosis for many years, an Achilles Heel of TAVR has always been accurately predicting permanent pacemaker implantation (PPI). PPI in itself carries a higher cost, morbidity and mortality following TAVR. Several factors have been identified that increase the likelihood for a PPI including, pre-existing right bundle branch block (RBBB), intraprocedural complete heart block (CHB), left ventricular outflow tract calcification, new left bundle branch block (LBBB), and use of self-expandable valves (SEV). However, they are not sufficient in many instances. Delayed conduction defects have been reported including sudden cardiac death thereby warranting longer observation periods or a lower threshold for implanting a PPI, both which are not ideal.
The investigators proposed rapid atrial pacing (RAP) to further risk-stratify patients for post-TAVR PPI. Atrial pacing can be easily performed during the TAVR procedure since a temporary pacemaker (TPM) is routinely positioned in the right ventricle during valve implantation.
How was it executed? – the methodology
This is a prospective study that was conducted in two centers (Cleveland Clinic Foundation (Cleveland, Ohio) and Ospedale San Raffaele (Milan, Italy)). TAVR was performed using standard protocol with rapid ventricular pacing through a TPM for the valve deployment. After completion of the valve deployment, the TPM was withdrawn to the right atrium, and atrial pacing was performed at rates of 70 to 120 beats/min (or until AVB was observed) in 10 beats/min increments for a total of 20 beats at each increment. The Wenckebach phenomenon was defined as progressive PR prolongation with pacing followed by a blocked QRS complex. The patients were then followed for clinical outcomes, including a need for PPI on the basis of the presence or absence of RAP-induced Wenckebach AVB. Those with pre-existing pacemakers, underlying atrial fibrillation, or develop CHB that did not resolve by the end of the procedure were excluded. Transient CHB was still included.
Baseline characteristics, pre-procedural echocardiographic parameters, CT based annular sizing, electrocardiographic conduction intervals before (within 24 h) and after (within 24 h) TAVR, valve type, and clinical follow-up were all collected and reported.
What is the main result?
A total of 284 patients were enrolled over an approximately 1-2 year period. The mean age was 81 years and women were 45% of the total. Mean STS was 5.57. Coronary artery disease (CAD) was present in 60% of the total studied population. End-stage renal disease was significantly more frequent in those who did not develop the Wenckebach phenomenon during RAP compared with those who did (3.2% vs. 0%; p = 0.038). Baseline echocardiographic characteristics were similar in both groups as well as annular size, and valve type and size used. LVEF was 56% in the total studied population. There was a higher rate of pre-TAVR first-degree AVB in the Wenckebach group (36.7% vs. 16.8%; p < 0.001). Severe LVOT calcification was similar in both groups (16-17%).
Moderate sedation was employed in 92.3%. No complications of the rapid atrial pacing were detected particularly pericardial effusion or tamponade. Major adverse events including stroke and mortality were similar. Hospital stay was also similar ranging between 2.3-2.4 days for both groups. The 30-day clinical outcomes did not differ among the two groups.
Most importantly, there was a higher rate of PPI within 30 days of TAVR in those who developed Wenckebach AVB (13.1% vs. 1.3%; p < 0.001), with a negative predictive value for PPI in the group without Wenckebach AVB of 98.7%. More patients who underwent TAVR with a SEV required PPI than those receiving a BEV (15.9% vs. 3.7%; p = 0.001). This rate was lower in patients who did not develop Wenckebach AVB (2.9% and 0.8%).
Rapid atrial pacing after TAVR to risk stratify those in need of permanent pacemaker implantation
Illustration credit: JACC: Cardiovascular Interventions
Critical reading and the relevance for clinical practice
As many of us adopt early discharge protocols, identifying patients at risk of high-grade AV block becomes a key determinant. Rapid atrial pacing as a test of the underlying conduction system appears both safe and feasible in this study. The RAP was performed by the TAVR operator and didn't require an electrophysiologist. Many structural interventionalists may not have the confidence or expertise to interpret the results. Additionally, the rate of 120 bpm may not be an adequate stressor in many cases. RAP is not definitive and patients may still need longer monitoring (even as an outpatient with a loop recorder).
The older age studied (age 81 years) is very reassuring. Approximately 60% had underlying coronary artery disease and 85% had hypertension. It is unknown how many of those with CAD or hypertension required AV nodal blocking agents, in particular, Beta Blockers for their underlying disease. These agents are also often prescribed in those with impaired LV systolic function; however, the mean EF in this cohort was 56%. It is difficult to extrapolate the value of RAP on patients taking such agents and those with impaired LV systolic function from this study.
In spite of the small numbers and non-randomized design of the study, it was able to identify those who need PPI or at least necessitate further monitoring. With larger randomized cohorts, I'm optimistic RAP will prove valuable in reducing unnecessary PPI and propel early discharge post TAVR.
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