Clinical Characteristics and Outcomes of Patients with Acute Myocarditis: Insightsfrom the Myocarditis Registry of an Advanced Heart Failure Center in Middle East

Aims: Acute myocarditis (AM) is an inflammatory heart disease caused by infections, immune system activation, or medications. We report retrospective outcomes of patients admitted with AM who have elevated high-sensitive cardiac troponin levels and cardiac magnetic resonance imaging (cMRI) or histopathological findings. Methods: From January 2016 to January 2024, 133 patients with suspected AM and recent onset of symptoms (within 30 days) were screened. After exclusions, 85 patients (median age 34 (27-48) years; 29.4% female) were included. Results: At presentation, 39 patients (46%) exhibited a left ventricular ejection fraction (LVEF) of < 50%. Chest pain was the most common symptom (63.5%), while 15 (17.6%) presented with cardiogenic shock. cMRI was performed in 68 patients (80%), revealing myocardial edema in 42 (61.7%) and late gadolinium enhancement (LGE) in 60 patients (88.1%). Mid-wall enhancement was the most frequent (50%), followed by sub-epicardial (35%), and the mean time to cMRI was five days. Histopathological data were available for three patients presenting with cardiogenic shock, showing lymphocytic myocarditis for which they received corticosteroid therapy. Major adverse cardiovascular events (MACE) occurred in 16.4% (n=14). One-year follow-up data were available for 81 patients (95.2%); echocardiography in 40 patients indicated persistent LV dysfunction (LVEF <50%) in 11. Of the 13 patients who had repeat cMRI, 12 showed persistent LGE. Three patients (3.4%) were readmitted. Conclusions: This is the first registry-based report on AM in the Middle East-Gulf region. It reveals higher rates of left ventricular dysfunction, cardiogenic shock, and MACE. Limitations include a small sample size, lack of genetic testing, and a short follow-up duration.