A Method for Evaluating the Success of Slow Pathway Ablation: PR>RR Finding During Rapid Atrial Pacing

Atrioventricular nodal reentrant tachycardia (A VNRT) occurs ın patients with dua! atrioventricular (AV) nodal physiology. However, dua! AV nodal physiology cannot be demonstrated in a signifıcant proportion of patients w ith A VNRT. During rapid atrial pacing at the maximum rate with consistenı 1:1 AV conduction, PR interval often exeecds the pacing cycle Jength in patients with A VNRT. This finding, deseribed as PR>RR, was proposed to be consistent with antegrade slow pathway conduction and useful method for evaluating the success of slow pathway ablation in patients with A VNRT and without demosırable dua! AV nodal physiology. The purpose of this prospective study was to determine the diagnostic value of the PR>RR find ing as an indicator of antegrade slow pathway conduction and A VNRT. The PR and RR intervals were measured during rapid atrial pacing at the maximum rate with consistent 1:1 AV conduction in 2 groups of patients. Group 1: patients w ith A VNRT (n=20) and Group 2: control subjects (n=2 1 ). Radiofrequency catheter ablation of the slow pathway was performed in all Group 1 patients. After slow pathway ablation, the study protocol was repeated in Group 1 patients. PR>RR finding was present in ıo of 20 Group 1 patients (50%) and 2 of 2ı Group 2 patients (9.5%, p=0.006). After slow pathway ablation, PR>RR finding was no longer preseni in any Group ı patients. The finding of PR>RR had a sensitiviıiy of 50 % for A VNRT, a specificity of 90%, a negative predictive value of 66% and a positive predictive value of 84%. In conclusion, although the sensiıivity of PR>RR finding for AVNRT is low, because of its high specificity and positive predictive value, this finding may be usefuı for evaluating the success of slow pathway ablation in patients with A VNRT in whom tachycardia inducıion is not reproducibe and dua! AV nodal physiology cannot be demonstrated.