115: Prognostic value of CMR criteria for LV functional improvement in patients with acute myocarditis

Abstract

Standard diagnostic CMR criteria (“Lake Louise Criteria”) indicate acute myocarditis, if at least 2 out of the following 3 criteria are positive: (1) Myocardial edema/T2, (2) hyperemia/capillary leakage/early Gd enhancement ratio (EGE ratio) and (3) irreversible injury/late Gd enhancement (LGE). However, there is a lack of prognostic data using these criteria regarding LV functional improvement. We studied 37 patients referred for acute myocarditis during admissison and after a 12-month follow-up. CMR studies included T2-weighted and contrast-enhanced T1-weighted (EGE ratio and LGE) sequences. Global edema was defined as T2 SI ratio (normalized to skeletal muscle) of ≥2 and regional edema as a regional area of SI≥2SD, consisting of at least 10 conjoint pixels. LV function was analysed using long axis views. An increase by at least 5% was considered improvement. Out of a total of 37 patients, 29 met the CMR Lake Louise Criteria (LL+) and 8 did not (LL-). Baseline and 12-month EF were significantly lower in LL+ (53.2±8 vs. 62.2±5; p=0.007 and 58.9±4 vs. 62.9±5, p=0.0045 respectively). At follow up ejection fraction increased in LL+ but not in LL- groups (delta EF:5.7±9.8 vs. 0.7±2). The presence of global and/or regional myocardial edema was strongly associated with an increase of EF ≥5% (see table). Lack of EF increase (Δ EF< 5%) n=26 EF increase (Δ EF ≥ 5%) n=11 All patients n=37 p LL + 18 (69.2%) 11 (100%) 29 (78.3%) 0.040 Edema + 15 (57.7%) 11 (100%) 26 (70.0%) 0.009 EGE + 17 (65.3%) 11 (100%) 28 (75.6%) 0.051 LGE+ 17 (65.3%) 8 (72.7%) 25 (67.5%) 0.487 In a multivariate analysis, the presence of global and/or regional edema on admission was the only independent predictor of an increase of EF (beta=0.428, p=0.009) In patients with clinically suspected acute myocarditis, the presence of positive CMR Criteria is associated with LV function recovery. Myocardial edema as defined by CMR was the strongest parameter, indicating that the observed increase of EF may be due to recovery of reversibly injured myocardium.