atypical clinical forms with negative cardiac enzyme findings were also identified, and in these cases the contribution of cardiac MRI was of great importance. The fact that 2 of the 4 patients with endomyocardial biopsy had negative histologie findings was not surprising, even though the clinical presentation was typical of acute myocarditis, because the sensitivity of endomyocardial biopsy is between 30% and 50% because of sampling error.
However, polymerase chain reaction identified the streptococcal genomes in all 4 cases. Usually, streptococcal myocarditis has a benign prognosis, despite its initially dramatic presentation.However, some of our patients presented left ventricular impairment both at the initial evaluation and at the 3-month follow-up visit. This is a new finding that should caution cardiologists toward a more careful initial approach and a closer follow-up of patients with streptococcal myocarditis.