Atrial fibrillation: to map or not to map?

Atrial fibrillation (AF) is the most frequently encountered cardiac dysrhythmia and is associated with significant morbidity and mortality. The incidence of early, new onset AF after cardiac surgery ranges from 15 to 65%. A variety of pre-, intra- or post-operative factors modifying electrical properties of atrial tissue may give rise to AF. In this thesis, we examined 1) characteristics of post-operative atrial ectopy and AF (PoAF) and 2) the relation between electrical parameters assessed with high resolution mapping, atrial ectopy and PoAF. High resolution epicardial mapping of the entire atria enabled identification and quantification of the spatial distribution of intra-atrial conduction abnormalities. Mapping was first performed during sinus rhythm. Thereafter, AF was induced by rapid electrical atrial stimulation. During the post-operative period, both AF episodes and atrial ectopy, including single premature beats, couplets and runs, were identified and characterized by semi-automatically rhythm analysis of more than 42 million heart beats. Long lines of conduction block at Bachmann’s Bundle were associated with development of AF. Both frequencies and burdens of atrial dysrhythmia were assessed. Episodes of PoAF were transient, with a short duration. There were large intra- and inter-individual differences in durations, frequencies and burdens of PoAF episodes despite similar clinical profiles of the patients. Successful induction of intra-operative AF was not related with development of early, de novo or late PoAF. The occurrence of atrial ectopy in patients with PoAF was significant higher compared to patients without PoAF. Also, the frequency and burden of atrial ectopy varied between patients with similar clinical profiles. The outcomes of this thesis emphasize the need for an individualized diagnosis of the arrhythmogenic substrate underlying AF and subsequently a patient tailored therapy for AF.

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