There are very few prospective clinical studies of the frequency and outcome of atrial fibrillation in the context of pericarditis. The early reports in the English literature showed that atrial fibrillation was uncommon in acute pericarditis (≤7% of cases) and was associated with underlying structural heart disease of the myocardium, valves or coronary arteries.1 It is also known that PQ-segment depression (a marker of atrial pericarditis) is associated with the occurrence of atrial fibrillation in acute Q-wave myocardial infarction.2 A small prospective study of subacute pericarditis shows that atrial fibrillation may be common in tuberculous pericardial effusion (∼25% of cases) associated with left ventricular dysfunction and high N-terminal pro-brain natriuretic peptide levels.3 Pericarditis-associated atrial fibrillation is a transient condition that remits spontaneously within 6 weeks of treatment with antituberculosis medication in patients tuberculous pericardial effusion.3 By contrast, chronic constrictive tuberculous pericarditis is associated with persistent atrial fibrillation in 8% of cases, and usually occurs with a calcified pericardium.4

Imazio et al5 report probably the first and largest study of the natural history of atrial fibrillation associated with acute pericarditis to date. They conducted a prospective study of the frequency and prognosis of atrial fibrillation or flutter in 822 consecutive patients with acute pericarditis who presented to two cardiology referral centres in Athens, Greece and Torino, Italy between January 2006 and June 2014. The diagnosis of acute pericarditis was based on standard criteria, and pericarditis-associated atrial fibrillation or flutter was defined as a first episode of the …