Diagnosis of early myocarditis after respiratory or gastrointestinal tract viral infection: insights from cardiovascular magnetic resonance

BACKGROUND: The diagnosis of myocarditis continues to be a challenging task in clinical practice. The purpose of our study was to investigate cardiovascular magnetic resonance imaging in the diagnostic workup of ambulatory patients with the suspicion of early myocarditis after respiratory or gastrointestinal tract viral infection. The need for accurate diagnosis of early myocarditis arises from the low diagnostic accuracy of routine clinical tests. METHODS: We examined 67 consecutive patients with symptoms of weakness, palpitations, and fatigue after respiratory or gastrointestinal tract infection. We compared these patients to 31 controls. ECG-triggered, T2-weighted, fast-spin-echo triple inversion recovery sequences and delayed enhancement imaging were obtained in all patients, as well as functional parameters of left ventricular function and dimensions. In addition, in 25 patients and 10 controls, ECG-triggered, T1-weighted, multi-slice spin-echo images were obtained in axial orientation. RESULTS: We found a significant difference between patients with suspected myocarditis and controls in T2-global myocardial signal intensity. In addition, the ratio of global myocardial signal intensity/muscle signal intensity was 2.3 ± 0.4 in patients and 1.8 ± 0.3 in controls, which was highly significant (p < 0.001). In 23 patients, a pathological late enhancement pattern was seen, but only in one of the controls. There was no significant difference in T1-signal parameters. CONCLUSION: Cardiovascular magnetic resonance technique is able to detect early myocardial involvement after respiratory or gastrointestinal tract infection.