Prospective Study of Adenosine on Atrioventricular Nodal Conduction in Pediatric and Young Adult Patients After Heart Transplantation

Abstract

Background: Supraventricular tachycardia is common after heart transplantation. Adenosine, the standard therapy for treating supraventricular tachycardia in children and adults without transplantation, is relatively contraindicated after transplantation because of a presumed risk of prolonged atrioventricular block in denervated hearts. This study tested whether adenosine caused prolonged asystole after transplantation and if it was effective in blocking atrioventricular nodal conduction in these patients.

Methods: This was a single-center prospective clinical study including healthy heart transplant recipients 6 months to 25 years of age presenting for routine cardiac catheterization during 2015 to 2016. After catheterization, a transvenous pacing catheter was placed and adenosine was given following a dose-escalation protocol until atrioventricular block was achieved. The incidence of clinically significant asystole (≥12 seconds after adenosine) was quantified. The effects of patient characteristics on adenosine dose required to produce atrioventricular block and duration of effect were also measured.

Results: Eighty patients completed adenosine testing. No patient (0%; 95% confidence interval, 0-3) required rescue ventricular pacing. Atrioventricular block was observed in 77 patients (96%; 95% confidence interval, 89-99). The median longest atrioventricular block was 1.9 seconds (interquartile range, 1.4-3.2 seconds), with a mean duration of adenosine effect of 4.3±2.0 seconds. No patient characteristic significantly predicted the adenosine dose to produce atrioventricular block or duration of effect. Results were similar across patient weight categories.

Conclusions: Adenosine induces atrioventricular block in healthy pediatric and young adult heart transplant recipients with minimal risk when low initial doses are used (25 μg/kg; 1.5 mg if ≥60 kg) and therapy is gradually escalated.

Clinical trial registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02462941.

Keywords: adenosine; tachycardia, supraventricular; transplantation.

Conflict of interest statement

Disclosures

The authors have no conflicts to disclose.

© 2017 American Heart Association, Inc.

Figures

Figure 1. Adenosine Study Consort Diagram

All cardiac transplant patients 6 months – 25 years at Morgan Stanley Children’s Hospital undergoing routine cardiac catheterization from July 2015 until April 2016 were recruited. After 166 patients were screened, 135 were eligible and 80 underwent adenosine testing. *RV rescue pacing was the primary outcome. †AV block was the secondary outcome. Abbreviations: (AV) Atrioventricular, (CC) Cardiac Catheterization, (HTx) Heart Transplant, (RV) Right Ventricle.

Figure 2. Adenosine Testing After Heart Transplant

Figure 2A. Adenosine Testing Protocol Patients

Figure 2. Adenosine Testing After Heart Transplant

Figure 2A. Adenosine Testing Protocol Patients

Figure 3. Cumulative Response to Adenosine Testing

Graph of all patients (N=80) demonstrating the relationship of adenosine dose to atrioventricular (AV) block. The bars represent the percentage of patients that achieved AV block at each dose. The line represents the cumulative percentage of AV block by dose.