A simplified approach for evaluating sustained slow pathway conduction for diagnosis and treatment of atrioventricular nodal reentry tachycardia in children and adults

• Published in: Advances in medical sciences Vol. 63; no. 2; pp. 249 - 256
• Main Authors: Sledz, Janusz, Labus, Michal, Mazij, Mariusz, Klank-Szafran, Monika, Karbarz, Dariusz, Ludwik, Bartosz, Kusa, Jacek, Deutsch, Karol, Szydlowski, Leslaw, Mscisz, Adrian, Spikowski, Jerzy, Morka, Aleksandra, Kameczura, Tomasz, Swietoniowska-Mscisz, Aleksandra, Stec, Sebastian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-09-2018
• Subjects: Ablation; Adult; Atrioventricular nodal reentry tachycardia; Case-Control Studies; Child; Children; Coronary Sinus - pathology; Diagnosis; Electrocardiography; Female; Heart Conduction System - pathology; Humans; Male; Pacing; Tachycardia, Atrioventricular Nodal Reentry - diagnosis; Tachycardia, Atrioventricular Nodal Reentry - therapy; Pacing; Diagnosis; Children; Ablation; Atrioventricular nodal reentry tachycardia
• ISSN: 1896-1126; 1898-4002
• DOI: 10.1016/j.advms.2018.01.001

During incremental atrial pacing in patients with atrioventricular nodal reentrant tachycardia, the PR interval often exceeds the RR interval (PR > RR) during stable 1:1 AV conduction. However, the PR/RR ratio has never been evaluated in a large group of patients with pacing from the proximal coronary sinus and after isoproterenol challenge. Our study validates new site of pacing and easier method of identification of PR > RR.
A prospective protocol of incremental atrial pacing from the proximal coronary sinus was carried out in 398 patients (AVNRT-228 and control-170). The maximum stimulus to the Q wave interval (S-Q = PR), SS interval (S-S), and Q-Q (RR) interval were measured at baseline and 10 min after successful slow pathway ablation and after isoproterenol challenge (obligatory).
The mean maximum PR/RR ratios at baseline were 1.17 ± 0.24 and 0.82 ± 0.13 (p < 0.00001) in the AVNRT and controls respectively. There were no PR/RR ratios ≥1 at baseline and after isoproterenol challenge in 12.3% of the AVNRT group and in 95.9% of the control group (p < 0.0001). PR/RR ratios ≥1 were absent in 98% of AVNRT cases after slow pathway ablation/modification in children and 99% of such cases in adults (P = NS). The diagnostic performance of PR/RR ratio evaluation before and after isoproterenol challenge had the highest diagnostic performance for AVNRT with PR/RR > = 1 (sensitivity: 88%, specificity: 96%, PPV-97%, NPV-85%).
The PR/RR ratio is a simple tool for slow pathway substrate and AVNRT evaluation. Eliminating PR/RR ratios ≥1 may serve as a surrogate endpoint for slow pathway ablation in children and adults with AVNRT.