Aims: Poor data exist about cardiac magnetic resonance (CMR) findings in a large sample of acute myocarditis with different clinical presentations (heart failure, arrhythmias, and infarct-like presentation).
Methods: Five hundred and forty-three in-patients with a clinical suspected of acute myocarditis confirmed by CMR were enrolled. The clinical indications to perform CMR were chest pain and/or dyspnea and/or palpitations, or effort intolerance/malaise in the last month; elevated troponin and/or new ventricular dysfunction, and/or new ECG abnormalities; and suspected inflammatory cause. CMR examination has permitted to identify epicardial and mid-layer distribution of late gadolinium enhancement (LGE) and to quantify left ventricular (LV) and right ventricular (RV) volumes, and ejection fraction.
Results: According to the main clinical pattern of presentation, three groups were categorized: heart failure (heart failure group; 35 patients, 6.4%), arrhythmias (arrhythmias group; 24 patients, 4.4%), and infarct-like (infarct-like group, 484 patients, 89.2%).Heart failure group and arrhythmias group had significantly higher LV volumes and number of LGE segments and lower LV and RV ejection fraction than the infarct-like group.Epicardial LGE in the LV inferolateral wall was the most frequent LGE location in each group. Mid-layer LV septal LGE showed a greater prevalence in the heart failure (52%) and arrhythmias (47%) groups than in the infarct-like group (27%, P < 0.0001).
Conclusion: In patients with CMR-detected acute myocarditis, heart failure, and arrhythmias have both a higher prevalence of LV and RV dysfunction, segments with LGE, and septal LGE with respect to the infarct-like group.