New Criteria to Demonstrate Entrainment and Macro-Re-Entry in Atrial Tachycardias

Recognition of entrainment and macro-re-entry in atrial tachycardia (AT) remains challenging with available criteria.

This study tested 2 novel conduction time-based criteria for identifying entrainment of macro-re-entrant AT.

Conduction times during overdrive atrial pacing were measured between 4 strategically positioned atrial electrodes. Criterion 1 compared conduction times from the same pacing and recording sites during sinus rhythm vs tachycardia at the same pacing rate; a significant difference implicated macro-re-entry. Criterion 2 compared conduction times from a pacing site to a recording site vs those in the reverse direction during tachycardia at the same pacing rate; a significant difference implicated macro-re-entry. Three groups were studied: macro-re-entrant AT, focal AT (real/simulated), and sinus rhythm (technical controls).

Of the 117 individuals studied, pacing maneuvers in 104 met inclusion criteria for the primary analysis. For Criterion 1, median (Q1-Q3) maximal conduction time differences were greater in macro-re-entrant AT (196 milliseconds [156-251 milliseconds]) than in focal AT (8 milliseconds [4-10 milliseconds]) or controls (12 milliseconds [8-23 milliseconds]) (P < 0.001). A cutoff of 60 milliseconds yielded 95% sensitivity and 100% specificity for detecting macro-re-entry. For Criterion 2, maximal conduction time differences were again greater in macro-re-entrant AT (182 milliseconds [139-222 milliseconds]) than in focal AT (12 milliseconds [11-17 milliseconds]) or sinus rhythm controls (18 milliseconds [13-27 milliseconds]) (P < 0.001). A cutoff of 63 milliseconds achieved 96% sensitivity and 100% specificity.

Conduction time analysis provides a robust and accurate approach for confirming entrainment and macro-re-entry in AT, improving diagnostic precision compared with existing criteria.