Role of atrial ischaemia in development of atrial fibrillation following coronary artery bypass surgery1

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Abstract
OBJECTIVE: Atrial fibrillation (AF) is a common complication aftercoronary artery bypass grafting (CABG) operations, occurring in 5 to 40% ofcases. A number of studies have implicated atrial ischaemia in the genesisof this arrhythmia. The aim of this study was to examine the relationshipbetween atrial coronary anatomy and the incidence of post operative atrialfibrillation. METHOD: To investigate a possible anatomical explanation tothe onset of AF after CABG, 25 patients with documented AF after CABG werematched and compared to 25 patients which remained in sinus rhythm (SR).All coronary angiograms were reported blindly by a cardiac radiologist withreference to the blood supply of the sino-atrial (SA) node andatrio-ventricular (AV) node before and after surgery. RESULTS: Univariateanalysis of risk factors did not identify any significant difference(Fisher exact test, P > 0.05) between the two groups in age, gender,left ventricular function, ischaemic time, number of vessels diseased orgrafted, renal dysfunction and withdrawal of beta-blockade. However,significant disease in the SA nodal artery was present in 2 patients of theSR group when compared to 9 in the AF group. Significant disease of AVnodal artery was present in only 4 patients of the SR group when comparedto 18 in the AF group. Comparison between the two groups showed asignificantly increased incidence of SA or AV nodal artery disease in theAF group, (SA: P = 0.018, AV: P = 0.0001). Mean hospital stay was 8.1 daysfor the SR group and 9.1 days in the AF group (P = 0.175). CONCLUSION:Obstructive disease in the SA nodal and AV nodal arteries is more common inpatients developing atrial fibrillation following coronary artery bypasssurgery than those who remain in sinus rhythm. If the incidence of AF couldbe predicted by the anatomical distribution of arterial disease thentargeting prophylaxis to this group may be possible.