Comprehensive cardiovascular magnetic resonance in acute myocarditis: Association between mapping parameters and in-hospital severity.

BACKGROUND: Cardiovascular magnetic resonance (CMR) is central to the non-invasive assessment of suspected myocarditis. Although the diagnostic and longer-term prognostic value of CMR mapping has been established, its relationship with bedside markers of acute in-hospital disease severity remains less well defined. In this exploratory study, we evaluated associations between quantitative CMR tissue markers and laboratory as well as clinical markers of acute severity. METHODS: In this retrospective single-center study, adults with clinically suspected acute (peri-)myocarditis who underwent comprehensive CMR between October 2018 and March 2024 were analyzed. CMR comprised cine imaging, edema-sensitive sequences, native T1 and T2 mapping, extracellular volume (ECV) fraction mapping, and late gadolinium enhancement (LGE). Clinical data were retrospectively obtained from electronic medical records. CMR datasets were evaluated in consensus by two readers with six and nine years of CMR experience (Blinded for submission), who were blinded to clinical and outcome data. Associations were assessed using Spearman correlation with false-discovery-rate correction; NT-proBNP was available in 34/67 patients, peak hsTropT in 64/67 patients, and LGE extent in 53/67 patients. RESULTS: Sixty-seven patients (31.6 ± 13.0 years; 14/67 [20.9 %] female) were included. Global and maximum native T1, T2, and ECV fraction showed weak-to-moderate positive correlations with NT-proBNP (ρ = 0.40-0.60) and length of stay (ρ = 0.34-0.47). Left ventricular ejection fraction showed inverse correlations with maximum native T1, global and maximum T2, and LGE extent (ρ = -0.28 to -0.39). LGE extent correlated with peak high-sensitivity troponin T (ρ = 0.35) and length of stay (ρ = 0.35). Cardiogenic shock was associated with higher mapping values (ρ = 0.33-0.40); this exploratory finding was based on only six events and should be interpreted cautiously. CONCLUSIONS: In this exploratory single-center cohort, quantitative CMR mapping abnormalities paralleled biomarkers of myocardial stress and injury and length-of-stay-based markers of acute in-hospital severity in patients with suspected myocarditis. These hypothesis-generating findings support native T1, T2, and ECV fraction mapping as complementary markers within standardized CMR assessment. Prospective, multivariable studies with longitudinal follow-up are needed to define their independent prognostic value and clinical utility.