Separating Acute Rheumatic Fever from Nonrheumatic Streptococcal Myocarditis

Streptococcal pharyngitis has been historically complicated with systemic involvement manifesting as acute rheumatic fever, which is a serious condition that can lead to permanent damage to heart valves. A recent association between streptococcal pharyngitis and nonrheumatic heart disease is emerging in literature. We present a case of nonrheumatic streptococcal myocarditis diagnosed using cardiac MRI.

A 25-year-old male, presented with complaints of sore throat, nonproductive cough, fever, pleuritic chest pain, and progressive dyspnea for four days. The patient had elevated troponins at presentation of 0.47 (ng/L) that peaked at 4.0 (ng/L). ECG showed sinus rhythm and ST elevations in leads V2, V3, V4, and V5. NT-Pro-BNP was 1740. Transthoracic echocardiogram (TTE) showed reduced ejection fraction (EF) of 37% and global hypokinesis. The rapid strep test was positive for group A streptococcus and C-reactive protein was elevated at 161. Cardiac MRI demonstrated an EF of 53% and edema in the anterior wall without delayed gadolinium enhancement. Cardiac catheterization showed normal coronaries.

According to modified Jones criteria, the patient did not meet the full major or minor criteria to be diagnosed with acute rheumatic fever. The course of the nonrheumatic myocarditis is favorable and includes a full recovery of cardiac function, no involvement of cardiac valves, or long-term use of antibiotics.

It is crucial to make a separate distinction between acute rheumatic fever and nonrheumatic myocarditis because this will have huge implications on management and long-term use of antibiotics. Cardiac imaging modalities can aid in distinction between the two disease entities.