Shortening of the PR interval in pericarditis after coronary bypass surgery

Background: Pericarditis, following pericardiotomy, is a well-known complication of cardiac surgery. The diagnosis of postpericardiotomy pericarditis (PP) is based on the electrocardiography (ECG) changes - the ST segment elevation in combination with a depression of the PR interval. However, in some cases, the ECG changes are difficult to distinguish from the changes associated with ST segment elevation acute coronary syndrome. In such cases, the diagnosis of pericarditis is made by excluding acute coronary syndrome, for which additional expensive diagnostic tests are performed. Aims: the purpose of the study is to identify a pattern in the change in the PR interval, which is detected in patients with acute pericarditis who underwent pericardiotomy during coronary bypass surgery. Methods: The observational study included 47 patients after coronary bypass surgery. We compared ECG of two groups of patients after coronary artery bypass grafting - 25 patients who demonstrated the ECG signs of acute pericarditis and 22 patients without those. Results: In most patients with PP after coronary bypass surgery, the characteristic ECG signs of acute pericarditis were accompanied by a transient shortening of the PR interval by 0.04 sec. Conclusion: The absence of such dynamics in patients after coronary artery bypass grafting without the ECG signs of pericarditis may indicate that a transient shortening of the PR interval may be an additional easily available ECG sign of acute PP.