Outcome after thrombolytic therapy of nine cases of myopericarditis misdiagnosed as myocardial infarction.

Anecdotal reports have suggested that cardiovascular complications may occur if thrombolytic therapy is performed in cases of pericarditis misdiagnosed as acute myocardial infarction. From 1980 to 1993, 47 cases of myopericarditis mimicking myocardial infarction have been admitted to our institution. The misdiagnosis was made because of clinical onset characterized by a typical chest pain, and/or localized ST segment elevation. Since 1987, nine (9/9 males, age 40 +/- 14 years) out of the 47 patients (19%) have been treated with a thrombolytic agent (streptokinase 4/9, rt-PA 5/9) followed by intravenous heparin. This treatment was started during the pre-hospital phase (2/9) and while in hospital (7/9). No pericardial rub was present; ST segment elevation was mainly localized in inferior and lateral leads; no Q wave developed; median creatine kinase rise was 268 units (range 38 to 1280), and only one patient had a small pericardial effusion. The mean level of fibrinogen after thrombolysis was 1.72 g.l-1 (range 0.10 to 4.50). In all cases, typical ECG changes were present suggesting pericarditis with a subsequent return to a normal ECG. No severe cardiac or pericardial complication or arrhythmia occurred; only one patient developed a non-compressive and resolvable pericardial effusion. Cardiac catheterizations (coronary and left ventricular angiographies) were normal when performed (5/9). Long-term follow-up (mean 46 +/- 29 months) was favourable without any coronary events. In conclusion, thrombolytic therapy was uncomplicated in our patients with myopericarditis simulating evolving myocardial infarction.