Clinical Characteristics and Outcomes of Patients with Nonrheumatic Streptococcal Pharyngitis-Associated Myocarditis

Background: Reports of nonrheumatic streptococcal pharyngitis-associated myocarditis (SPAM) are rare, and its incidence, pathophysiology, and clinical features remain unclear. We evaluated the clinical course and outcome of patients diagnosed with nonrheumatic SPAM, with a particular focus on differentiating it from other etiologies of myocarditis. Methods: Seventy-nine consecutive individuals (age 32 ± 9 years, 71 men) with clinically diagnosed SPAM were evaluated. None satisfied the revised Jones criteria for diagnosis of acute rheumatic fever. Results: Average onset of symptoms prior to hospitalization was 5.44 ± 5.16 days, all had sore throat and were treated with antibiotics for 10 days; Clinical presentation was characterized by chest pain (91%), fever (90%), electrocardiographic ST-segment elevation (80%), and biochemical evidence of myocyte necrosis (100%). In 27 cases, coronary angiography was performed and in all either normal or nonsignificant coronary artery disease was found. Cardiac magnetic resonance imaging was done in 61 cases and demonstrated subepicardial late gadolinium enhancement (90%) predominantly in the lateral (85%) and inferior (75%) sides. Conclusions: Nonrheumatic SPAM may not be as infrequent as thought and should be considered in the differential diagnosis of acute ST-segment elevation myocardial infarction, especially in young male patients with sore throat and fever.