Dissociation between structural injury and functional recovery: implications for clinical outcomes in acute myocarditis
L Lorenzo Alves, J Goncalves, T Branco, B Viana, E Andrade, S Amorim, R Rodrigues, M VasconcelosAbstract
Background
Risk stratification in acute myocarditis remains challenging. Although left ventricular functional recovery is often considered reassuring, the prognostic relevance of persistent myocardial scar despite recovered function is poorly defined.
Purpose
To evaluate whether a combined structure–function phenotypic approach based on left ventricular function and myocardial scar improves clinical risk stratification in acute myocarditis.
Methods
We conducted a retrospective observational study including consecutive patients admitted with acute myocarditis to a tertiary referral centre between January 2016 and November 2025. Cardiac magnetic resonance (CMR) was performed during the acute phase and repeated during follow-up when available. Functional recovery was defined as normalization of left ventricular ejection fraction (LVEF), while structural involvement was assessed by persistence of late gadolinium enhancement (LGE). Patients were classified into four structure–function phenotypes according to recovery of LVEF and LGE persistence. Clinical events included cardiovascular rehospitalisation, persistent ventricular dysfunction, device implantation, heart transplantation, or all-cause death.
Results
Among 138 patients, recovery of left ventricular systolic function occurred in 114 (82.6%). Patients without functional recovery had a greater myocardial scar burden, with higher LGE extent compared with recovered patients (p=0.050). However, neither the presence nor the extent of persistent LGE alone was associated with adverse clinical events (p>0.60). Complete structure–function phenotyping was available in 36 patients. The most frequent phenotype was recovery of LVEF without persistent LGE (58.3%), followed by recovery of LVEF with persistent LGE (30.6%). Persistent LVEF dysfunction, with or without LGE, was uncommon (each 5.6%). Event rates were similar among patients with recovered LVEF irrespective of LGE persistence (19.0% vs 18.2%), whereas patients without functional recovery experienced markedly higher event rates (50%), regardless of LGE status.
Conclusions
In acute myocarditis, recovery of left ventricular function and residual myocardial scar are dissociable phenomena. While greater scar burden is associated with failure of functional recovery, persistent LGE alone does not independently predict adverse clinical events. Combined structure–function phenotyping identifies distinct prognostic subsets and demonstrates that patients with recovered ventricular function have similarly favourable outcomes irrespective of residual scar, supporting the primacy of functional recovery in risk stratification and follow-up.BoxplotFor image description, please refer to the figure legend and surrounding text.BarFor image description, please refer to the figure legend and surrounding text.