Key result
CS activation shift from eccentric to concentric identifies intra-atrial block at the mitral isthmus.
Why the study?
A change in coronary sinus activation pattern during ablation of orthodromic reciprocating tachycardia can lead to misinterpretation of accessory pathway presence or ablation success, requiring clarification of underlying mechanisms.
Case Report (n=1)
An abrupt change in coronary sinus activation pattern during ablation of an orthodromic reciprocating tachycardia should raise suspicion for intra-atrial block rather than a second accessory pathway.
A change in the coronary sinus (CS) activation pattern from an eccentric to a concentric pattern during the ablation of an orthodromic reciprocating tachycardia might falsely suggest the presence of a second (septal) accessory pathway (AP) during tachycardia or the successful ablation of the left lateral AP under ventricular pacing despite persistent and unaffected AP conduction. Complete or partial intra-atrial block should be suspected when an abrupt change in the atrial activation sequence is noted during catheter ablation at the posterolateral and lateral aspects of the mitral annulus. The correct anatomical position of the CS catheter plays a vital role in the differential diagnosis of this situation.
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Hidayet et al. (2022) conducted a case report in Narrow complex tachycardia (n=1). Electrophysiological study was evaluated. An abrupt change in the coronary sinus activation pattern from eccentric to concentric during narrow complex tachycardia was identified as an intra-atrial conduction block at the mitral isthmus level.
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