The PR/RR interval ratio during rapid atrial pacing exceeded 1.0 in most AVNRT patients before ablation and decreased significantly to < 1.0 after slow pathway ablation (P < 0.00001).
Observational (n=57)
Does the PR/RR interval ratio during rapid atrial pacing indicate the presence of anterograde slow pathway conduction in patients with AVNRT?
A PR/RR interval ratio > 1.0 during rapid atrial pacing is a simple and useful indicator of slow AV nodal pathway conduction, particularly in AVNRT patients lacking classical dual AV nodal physiology.
p-value: p=< 0.00001
INTRODUCTION: Although the AV conduction curve in patients with AV nodal reentrant tachycardia (AVNRT) is usually discontinuous, many patients with this arrhythmia do not demonstrate criteria for dual AV nodal pathways. During rapid atrial pacing, the PR interval often exceeds the pacing cycle length when there is anterograde conduction over the slow pathway and AVNRT is induced. The purpose of this prospective study was to determine the diagnostic value of the ratio of the PR interval to the RR interval during rapid atrial pacing as an indicator of anterograde slow pathway conduction in patients undergoing electrophysiologic testing. METHODS AND RESULTS: The PR and RR intervals were measured during rapid atrial pacing at the maximum rate with consistent 1:1 AV conduction in four study groups: (1) patients with inducible AV nodal reentry and the classical criterion for dual AV nodal pathways during atrial extrastimulus testing (AVNRT Group 1); (2) patients with inducible AV nodal reentry without dual AV nodal pathways (AVNRT Group 2); (3) control subjects 60 years of age without inducible AV nodal reentry. For both groups of patients with inducible AV nodal reentry, AV conduction was assessed before and after radiofrequency ablation of the slow AV nodal pathway. Before slow pathway ablation, the PR/RR ratio exceeded 1.0 in 12 of 13 AVNRT Group 1 patients (mean 1.27 +/- 0.21) and 16 of 17 AVNRT Group 2 patients (mean 1.18 +/- 0.15, P = NS Group 1 vs Group 2). After slow pathway ablation, the maximum PR/RR ratio was 1.0 in only 3 of 27 patients with no relation to patient age. CONCLUSION: The ratio of the PR interval to the RR interval during rapid atrial pacing at the maximum rate with consistent 1:1 AV conduction provides a simple and clinically useful method for determining the presence of slow AV nodal pathway conduction. This finding may be particularly useful in patients with inducible AV nodal reentry without dual AV nodal physiology on atrial extrastimulus testing.
Baker et al. (Mon,) conducted a observational in AV nodal reentrant tachycardia (AVNRT) (n=57). PR/RR interval ratio measurement during rapid atrial pacing vs. Before vs after radiofrequency ablation of the slow AV nodal pathway, and vs control subjects was evaluated on PR/RR interval ratio during rapid atrial pacing at the maximum rate with consistent 1:1 AV conduction (p=< 0.00001). The PR/RR interval ratio during rapid atrial pacing exceeded 1.0 in most AVNRT patients before ablation and decreased significantly to < 1.0 after slow pathway ablation (P < 0.00001).
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