Detailed analysis of tachycardia cycle length aids diagnosis of the mechanism and location of atrial tachycardias

Abstract

Background Although the mechanism of an AT can usually be elucidated using modern high-resolution mapping systems, it would be helpful if the AT mechanism and circuit could be predicted before initiating mapping. Objective We examined if information gathered from the cycle length (CL) of the tachycardia can help predict AT-mechanism and its localization. Methods 138 activation maps of ATs including 8 focal-ATs, 94 macroreentrant-ATs and 36 localized-ATs in 95 patients were retrospectively reviewed. Maximal CL (MCL) and minimal CL (mCL) over a minute period were measured via a decapolar catheter in the coronary sinus. CL-variation and beat-by-beat CL-alternation were examined. Additionally, CL-respiration correlation was analyzed by the RhythmiaTM system. Results Both MCL and mCL were significantly shorter in macroreentrant-ATs (MCL = 288[253-348]ms, p = 0.0001; mCL = 283[243-341]ms, p = 0.0012), and also shorter in localized-ATs (MCL = 314[261-349]ms, p = 0.0016; mCL = 295[248-340]ms, p = 0.0047) compared to focal-ATs (MCL = 506[421-555]ms, mCL = 427[347-508]ms). An absolute CL-variation (MCL-mCL) < 24 ms significantly differentiated reentrant ATs from focal-ATs with a sensitivity = 96.9%, specificity = 100%, positive predictive value (PPV) = 100% and negative predictive value (NPV) = 66.7%. The beat-by-beat CL-alternation was observed in 10/138 (7.2%), all of which showed the reentrant mechanism, meaning that beat-by-beat CL-alternation was the strong sign of reentrant mechanism (PPV = 100%). Although the CL-respiration correlation was observed in 28/138 (20.3%) of ATs, this was predominantly in right-atrium (RA)-ATs (24/41, 85.7%), rather than left atrium (LA)-ATs (4/97, 4.1%). A positive CL-respiration correlation highly predicted RA-ATs (PPV = 85.7%), and negative CL-respiration correlation probably suggested LA-ATs (NPV = 84.5%). Conclusion Detailed analysis of the tachycardia CL helps predict the AT-mechanism and the active AT chamber before an initial mapping.

Transition mechanisms from atrial flutter to atrial fibrillation during anti‐tachycardia pacing therapy

“…AFL can also spontaneously transition to sinus rhythm by oscillations in cycle length 31 . In this case, autonomic nervous system fluctuations or changes in the loading conditions of the atrial tissue during respiration 32 may serve as extrinsic interventions.…”