The incidence of paroxysmal atrial arrhythmias during pericarditis is probably higher than is generally realized. James1 reported the appearance of atrial arrhythmias in 26 patients with pericarditis secondary to collagen disease, neoplasm, trauma, infection, or after myocardial infarction. Soffer2 noted that, in his series of patients with idiopathic pericarditis, transient atrial fibrillation appeared in 13%. This is the exact incidence recorded by Scherl3 in a study of 30 patients with idiopathic pericarditis.
Several morphologic features explain the occurrence of arrhythmias during the acute phase of pericarditis. Proximity of the diseased pericardium to the atria and the fact that the sinus node is located 1 mm or less beneath the atrial epicardium suggest that clinically significant involvement of these structures will occur in many patients with pericarditis. James1 described the results of histological study of the cardiac conduction system in 38 patients in whom pericarditis was found
PERICARDITIS AND ATRIAL ARRHYTHMIAS. JAMA. 1963;185(4):316-317. doi:10.1001/jama.1963.03060040100034