The Relationship Between Electrocardiographic Findings and Cardiac Magnetic Resonance Results in Patients with Acute Myocarditis: A Retrospective Analysis

<i>Background and Objectives:</i> Electrocardiography (ECG), though non-specific, is widely applied as a valuable tool in the diagnostic work-up of acute myocarditis. Cardiac magnetic resonance (CMR) has become a key non-invasive tool. This study assessed the association of ECG findings (at baseline), echocardiographic parameters, circulating biomarkers, and CMR imaging features (myocardial edema and late gadolinium enhancement-LGE) in patients with acute myocarditis. <i>Materials and Methods</i>: This single-center, retrospective observational study included 86 patients admitted with acute myocarditis from January 2021 to December 2024. Data collected included demographics, clinical presentation, ECG, echocardiography, biomarkers (CRP, troponin I), and CMR imaging performed during hospitalization and at the six-month follow-up. Based on ECG findings, patients were stratified into three groups: no ST elevation or T-wave abnormalities (NSTG, <i>n</i> = 27), T-wave abnormalities (TWAG, <i>n</i> = 24), and ST elevation (STEG, <i>n</i> = 35). <i>Results</i>: We enrolled 86 patients (median age: 26 years; 87.2% male), and the most frequent CMR findings were either LGE (80.2%) and/or myocardial edema (75.6%). The prevalence of edema and LGE was higher in the STEG (both 91.2%) compared to TWAG (65.2%, 77.3%, respectively) and NSTG (57.7, 65.4%, respectively) (<i>p</i> < 0.05). Peak troponin levels were also higher in the STEG than other groups (<i>p</i> = 0.005). In logistic regression analysis, TWAs were independently associated with both edema (OR = 3.15, 95% CI: 1.078-9.189, <i>p</i> = 0.036) and LGE (OR = 3.93, 95% CI: 1.256-12.276, <i>p</i> = 0.019). Biomarkers were associated with lower LVEF in univariate analysis, but not in multivariate models. <i>Conclusions</i>: ECG abnormalities, particularly STE and TWA, are common in acute myocarditis and significantly associated with CMR findings. Although CMR remains essential for definitive diagnosis and risk stratification in acute myocarditis, ECG may serve as a valuable initial screening tool in the context of a multimodal diagnostic approach.