How electrically silent is the pericardium?

Acute pericarditis is a clinical inflamma-tory syndrome. The diagnosis is made when at least two of the following four criteria are present: (1) characteristic chest pain; (2) presence of pericardial friction rub; (3) ECG changes (up to 60% of patients); and (4) pericardial effusion (detected by imaging techniques in up to 60% of patients). 1 While it is commonly believed that diffuse ST segment elevation with concomitant ST depression in lead aVR (and V1) and with PR segment depression is typically detected in patients with acute pericarditis, this classic pattern is seen in less than 60% of patients. For example, Imazio et al 2 reported ST segment elevation in only 25% of their cohort of 240 patients with pericarditis. The classic ECG findings are seen mainly in the early phase (stage 1) of acute pericarditis and typically persist up to 2 weeks after symptom onset. 3 Later on, ST segment elevation resolves, and T waves become flat or inverted. These changes can persist for several weeks until complete resolution (stage 4). 3 However, it should be noted that similar ECG pattern with PR segment depression, diffuse ST elevation and ST depression in aVR can be seen with ‘early repolarisation’. 4 Thus, it could be that in some patients overdiag-nosis of acute pericarditis is made if diagnosis relies on the ECG in the presence of chest pain (that can be due to other aetiologies). the considered to be electric silent, inflammation limited to the not result in ST segment deviation. 1 3 Concomitant the 1 in