Associated factors and clinical implications of dynamic changes in late gadolinium enhancement after acute myocarditis

Abstract Funding Acknowledgements Type of funding sources: None. Background Although follow-up cardiac magnetic resonance (CMR) is often performed after acute myocarditis (AM), the prognostic implications of dynamic changes in late gadolinium enhancement (LGE) are unknown. Purposes To determine the prognostic implications of dynamic LGE changes after acute AM. Methods In a two-centre study, 204 consecutive hemodynamically stable patients (mean age 35±16 years, 78.9% males) with a CMR-based diagnosis of AM were included and underwent repeat CMR 3–12 months after diagnosis. Quantitative LGE was expressed as percent of left ventricular (LV) myocardium. The primary endpoint was the occurrence of major adverse cardiac events (MACE) at median 7.3[IQR:5.7–8.7] years. Results Compared to index CMR, there was an increase in LV ejection fraction (EF) (59% vs. 55%,p<0.001) and a decrease in LGE extent (7.6% vs. 12.0%,p<0.001) at follow-up (mean 5.7±2.6 months after index CMR). LGE persisted in 175 patients at follow-up (85.8%). LGE decreased by ≥50% from baseline in 94 patients (46%), by <50% in 86(42%) and increased in 24(12%). Female gender (OR[95%CI]=3.27[1.17–9.12],p = 0.023), low baseline LVEF (OR[95%CI]=0.93[0.88–0.98] per %,p = 0.010) and LGE involving both septal and lateral walls (OR[95%CI]=4.64[1.77–12.17],p = 0.002) were independently associated with increased LGE. By multivariate Cox analysis, only acute heart failure at inclusion (HR[95%CI]=3.11[1.02–9.20],p = 0.044), baseline LVEF (HR[95%CI]=0.95[0.89–0.99] per %,p = 0.028), a <50% LGE decrease (HR[95%CI]=2.17[1.23–3.88],p = 0.021) and an increase in LGE (HR[95%CI]=4.12[1.47–11.52],p = 0.004) were significantly associated with MACE. Conclusion After AM, LGE persists at 6 months in the vast majority of patients but tends to decrease. A <50% decrease or an increase in LGE are associated with MACE, indicating that follow-up CMR is relevant for risk stratification.