Myocardial strain overrules left ventricular ejection fraction and late gadolinium enhancement extent in predicting MACE in CMR-proven acute myocarditis

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac magnetic resonance (CMR) plays a major role in both the diagnostic process and prognostic stratification in acute myocarditis. Presence of late gadolinium enhancement (LGE) and left ventricular (LV) ejection fraction (EF) are known predictors of major adverse cardiovascular events (MACE). However, in daily clinical practice it remains challenging to distinguish ‘the good from the bad’. The prognostic value of CMR feature tracking (FT) derived strain, with respect to LGE and LVEF, remains unclear. Purpose To evaluate the incremental prognostic value of left atrial (LA) phasic function, LV and right ventricular (RV) strain using CMR-FT in patients with CMR-proven acute myocarditis. Methods In this multicenter observational study, patients with CMR-proven acute myocarditis were included and followed with regard to MACE including all-cause mortality (ACM), heart-failure hospitalizations (HFH), and life-threatening arrhythmias (LTA). Using FT-derived strain, LV global longitudinal strain (GLS), circumferential strain (GCS), and radial strain (GRS), RV GLS and LA phasic function were measured. Uni- and multivariable analysis including clinical and CMR parameters were performed to assess the association with MACE. Results A total of 162 patients were included (75% male, 41 ±17 years). MACE occurred in 29 patients (18%, ACM n = 18, HFH n = 7, LTA n = 11) during a median follow-up of 5.5 (2.2-8.3) years. Forty-six percent had a STEMI-like presentation (combination of chest pain, elevated troponin, and ST-elevation, n = 74). LGE was present in 90% of patients and mean LVEF was 51 ± 12%. Patients with LVEF <50% had a significantly worse prognosis compared to patients with LVEF ≥50% (p < 0.0001, Figure A). When we categorized the study population into subgroups of quartile values of LV GLS, patients with LV GLS worse than 18% had a significant worse outcome compared to the other subgroups (p < 0.05, Figure B). Subgroups of LGE extent did not show significantly different associations with outcome (p = 0.458, Figure C). Cox regression analysis showed that LV strain and LA phasic function were univariably associated with MACE, whereas RV GLS and LGE extent were not. All univariable associated strain parameters were separately included in a multivariable model, including age, sex, STEMI-like presentation, and LVEF. LV GLS (HR 1.08, p = 0.01), LV GCS (HR 1.15, p = 0.02), and LV GRS (HR 0.98, p = 0.02) were independent predictors of MACE. Conclusions LV strain parameters are independent and incremental predictors of prognosis in patients with acute myocarditis, while RV strain and LA phasic function are not. Therefore, LV strain is a promising novel parameter for risk stratification in acute myocarditis.