Characterization of pre-existing arrhythmogenic substrate associated with de novo early and late postoperative atrial fibrillation

Atrial fibrillation substrate development before, during and after cardiac surgery: Who is to blame for late post-operative atrial fibrillation?

“…Interestingly, calcium-handling abnormalities have been implicated in atrial conduction abnormalities in the setting of catecholaminergic polymorphic ventricular tachycardia [10], suggesting that the calciumhandling abnormalities present in patients that subsequently develop POAF [7,8] might also contribute to the observed conduction abnormalities [9,11] [2]. In agreement, age was the only independent factor associated with POAF in multivariable analysis in the study by Van Schie et al [9], suggesting that the observed conduction abnormalities may be age dependent. However, whether this is due to age-dependent remodeling, or due to a longer timeframe for comorbidity-related remodeling in older individuals is unknown.…”

“…In this issue of the International Journal of Cardiology, Van Schie et al [9] provide novel in vivo data supporting the presence of a pre-operative vulnerable functional substrate in patients that subsequently develop POAF. In this study, 263 patients with complete 5-year follow-up or persistent AF after cardiac surgery were included.…”

“…The previously reported fibrosis in patients developing POAF [2,6] likely contributes to the observed LA conduction abnormalities [9], but divergent data exist on RA structural remodeling [2,6] and no data are available from other regions due to limitations in human atrial tissue availability. Interestingly, calcium-handling abnormalities have been implicated in atrial conduction abnormalities in the setting of catecholaminergic polymorphic ventricular tachycardia [10], suggesting that the calciumhandling abnormalities present in patients that subsequently develop POAF [7,8] might also contribute to the observed conduction abnormalities [9,11] [2]. In agreement, age was the only independent factor associated with POAF in multivariable analysis in the study by Van Schie et al [9], suggesting that the observed conduction abnormalities may be age dependent.…”

“…Perhaps the most intriguing aspect of the study by Van Schie et al [9] is the nature of L-POAF. In particular, almost half of L-POAF episodes occurred >2 year after the surgery and one can question whether the occurrence of such AF episodes is actually influenced by the preceding surgery.…”

“…Distinguishing these different patient subgroups will be challenging due to limited options for direct measurement of atrial substrates after termination of E-POAF or during the peri-operative period. Van Schie et al [9] provide arguments for both components: All L-POAF episodes occurred in patients with E-POAF, suggesting that the surgery could have a strong (and potentially lasting) effect on the vulnerable substrate. On the other hand, patients with L-POAF also had more pre-existing remodeling, suggesting that their substrate might already be much closer to the threshold for developing AF, independent of surgery-related triggers.…”