Postoperative atrial fibrillation: The role of the inflammatory response

Abstract

Objective Abnormal atrial conduction has been shown to be a substrate for postoperative atrial fibrillation (POAF). This study aimed to determine the relationship between the location of the atrial reentry responsible for POAF, and degree of atrial inflammation. Methods Normal mongrel dogs (n = 18) were divided into 3 groups: anesthesia alone (anesthesia), lateral right atriotomy (atriotomy), and lateral right atriotomy with anti-inflammatory therapy (steroid). Conduction properties of the right and left atria (RA and LA) were examined 3 days postoperatively by mapping. Activation was observed during burst pacing–induced AF. The RA and LA myeloper-oxidase activity was measured to quantitate the degree of inflammation. Results Sustained AF (>2 minutes) was induced in 5 of 6 animals in the atriotomy group, but in none in the anesthesia or steroid groups. All sustained AF originated from around the RA incision. Three of these animals had an incisional reentrant tachycardia around the right atriotomy and 2 had a focal activation arising from the RA during AF. The LA activations in these animals were passive from the RA activation. The RA activation of the atriotomy group was more inhomogeneous than that of the anesthesia group (inhomogeneity index: 2.0 ± 0.2 vs 1.0 ± 0.1, P<.01). Steroid therapy significantly normalized the RA activation after the atriotomy (1.2 ± 0.1, P<.01). The inhomogeneity of the atrial conduction correlated with the myeloperoxidase activity (r = 0.774, P<.001). Conclusions Reentrant circuits responsible for POAF are dependent on the degree of inflammation and rotate around the atriotomy. Anti-inflammatory therapy decreased the risk of postoperative AF.

Factors associated with postoperative atrial fibrillation and other adverse events after cardiac surgery

“…[1][2][3] Cardiac surgery is associated with direct and indirect myocardial injuries that are potential stimuli for adverse atrial remodeling and may increase arrhythmic risk. 1,2,4,5 Thus, it is unsurprising that high rates of atrial fibrillation occur after cardiac surgery. However, there are scant contemporary data on how various surgery characteristics contribute to this risk, limiting the development of effective predictive and preventive measures.…”

Temporal Dispersion of Atrial Activation Causes Postoperative Atrial Fibrillation

“…Another mechanism of PoAF is the spatial inhomogeneity of the atrial conduction. It has been described that surgical manipulation raises the inhomogeneity of the atrial conduction after surgery, resulting in PoAF 7,17 . A nonuniform dispersion of the refractoriness in the atria makes some patients vulnerable to the development of PoAF 18,19 .…”

“…Studies have proven that there are multiple factors inducing PoAF after cardiac surgery. The causes of PoAF are described to be atrial inflammation, excessive production of catecholamines, autonomic nervous system dysfunction, and interstitial mobilization of fluid with resultant changes in the volume, pressure, and neurohumoral environment [7][8][9] . The spatial inhomogeneity of the atrial conduction has been shown to be one of the causes of PoAF in an animal study 7 .…”

Risk Factors of Recurrence of Atrial Fibrillation (AF) After AF Surgery in Patients With AF and Mitral Valve Disease

“…The blanking period was defined as the first 30 days after the surgery because postoperative atrial fibrillation (POAF) could occur within 30 days after the surgery and usually disappear within 30 days after the surgery. 16,17 Therefore, POAF within 30 days after the surgery was excluded from this study. All patients were discharged on warfarin.…”

“…The blanking period was defined first 30 days after surgery because POAF occurs within 30 days after surgery and disappears within 30 days after surgery. 16,17 Therefore, POAF within 30 days after surgery was excluded from this study. If the patients had previously had POAF, recurrence of AF was detected even though sinus rhythm was maintained after the POAF terminated.…”