A Practical Criterion for the Rapid Detection of Single‐Loop and Double‐Loop Reentry Tachycardias

INTRODUCTION: Entrainment criteria for the diagnosis of reentrant atrial tachycardia can be difficult to apply and cannot detect double-loop reentry. We sought to develop and clinically test a new criterion for the diagnosis of single- and double-loop reentry. METHODS AND RESULTS: (1) Proposed criterion: after sequential overdrive pacing at 2 different locations and assessing the first ensuing beats of tachycardia, the difference in activation time recorded between 2 appropriate stationary positions changes by 1 or 2 tachycardia cycle lengths; a change of 2 tachycardia cycle lengths usually indicates double-loop reentry rather than only a single-loop. (2) Clinical testing: multiple overdrive pacing maneuvers were undertaken and analyzed in 5 patients with common flutter (single-loop reentry). In total, 23 pairs of overdrive pacing maneuvers were performed using electrodes in the coronary sinus and a distribution of positions in the right atrium. In 22/23 pairs of maneuvers, the change in Activation Difference was within 2.6 ± 12.4 milliseconds of the tachycardia cycle length, confirming single loop reentry. For double-loop reentry, the literature was reviewed and 3 cases of double-loop reentry were identified with sufficient data. In all of these cases, double-loop reentry was detected and also the zone containing the common isthmus was identified. CONCLUSION: The proposed criterion can diagnose single- and double-loop reentry atrial tachycardia using intracardiac recordings from any pair of well separated positions. The criterion does not require precise electrode placement or extensive activation mapping.