The role of infarction-associated pericarditis on the occurrence of atrial fibrillation

Aims Transient atrial fibrillation is a relatively common arrhythmia in the early phase of acute Q-wave myocardial infarction. However, the role of infarction-associated pericarditis on the genesis of atrial fibrillation is controversial. This study was designed to examine the relative importance of infarction-associated pericarditis among other clinical variables on the genesis of transient atrial fibrillation in patients with acute myocardial infarction. Methods and results Three hundred and ninety-eight patients with acute Q-wave myocardial infarction were examined carefully by means of auscultation, ECG, two-dimensional echocardiography and haemodynamic measurements. The diagnosis of pericarditis was made on the basis of pericardial rub detected during the first 3 days after admission. At least 0·5mm of PQ-segment depression from a TP segment lasting more than 24h in both limb and precordial leads was considered diagnostic of PQ-segment depression. Atrial fibrillation was present in 76 patients (19%). Sixteen (42%) of 38 patients with PQ-segment depression had atrial fibrillation, whereas 23 (30%) of 77 patients with pericardial rub had atrial fibrillation. Based on ten clinical variables, multivariate analysis was performed to determine the important variables related to the occurrence of atrial fibrillation. PQ-segment depression (chi-square=4·10, P<0·05) was selected with age (chi-square=10·52, P<0·005), the number of left ventricular segments with advanced asynergy (chi-square=7·73, P<0·01) and pericardial effusion (chi-square=7·95, P<0·005) as important factors related to atrial fibrillation. Patients with PQ-segment depression had a significantly higher pulmonary capillary wedge pressure than those without it. Conclusion Among patients with infarction-associated pericarditis, those with PQ-segment depression represent atrial involvement associated with extensive myocardial damage and hence, PQ-segment depression is one of the clinical signs related to the occurrence of atrial fibrillation in acute Q-wave myocardial infarction.