BACKGROUND Cardiovascular magnetic resonance (CMR) imaging is commonly used to diagnose acute myocarditis. However, the natural history of CMR-based tissue markers and their association with left ventricular recovery is poorly explored. We prospectively investigated the natural history of CMR-based myocardial injury and chamber remodeling over 12 months in patients with suspected acute myocarditis. METHODS One hundred patients with suspected acute myocarditis were enrolled. All underwent CMR evaluations at baseline and 12 months, inclusive of T2 and late gadolinium enhancement. Blinded quantitative analyses compared left ventricular chamber volumes, function, myocardial edema, and necrosis at each time point using predefined criteria. The predefined primary outcomes were improvement in left ventricular ejection fraction ≥10% and improvement in the indexed left ventricular end diastolic volume ≥10% at 12 months. RESULTS The mean age was 39.9±14.5 years (82 male) with baseline left ventricular ejection fraction of 57.1±11.2%. A total of 72 patients (72%) showed late gadolinium enhancement at baseline with 57 (57%) having any T2 signal elevation. Left ventricular volumes and EF improved significantly at 12 months. Global late gadolinium enhancement extent dropped from 8.5±9.2% of left ventricular mass to 3.0±5.2% ( P=0.0001) with prevalence of any late gadolinium enhancement dropping to 48%. Reductions in global T2 signal ratio occurred at 12 months (1.85±0.3 to 1.56±0.2; P=0.0001) with prevalence of T2 ratio ≥2.0 dropping to 7%. Neither marker provided associations with the primary outcomes. CONCLUSIONS In clinically suspected acute myocarditis, significant reductions in tissue injury markers occur during the first 12 months of convalescence. Neither the presence nor extent of the investigated CMR-based tissue injury markers were predictive of our pre-defined function or remodeling outcomes at 12 months in this referral population.

中文翻译：

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急性心肌炎的心肌损伤和腔室重塑的自然史。

背景技术心血管磁共振（CMR）成像通常用于诊断急性心肌炎。然而，基于CMR的组织标志物的自然史及其与左心室恢复的关联研究很少。我们前瞻性调查了疑似急性心肌炎患者在12个月内基于CMR的心肌损伤和室重塑的自然史。方法招募了一百例疑似急性心肌炎的患者。所有患者均在基线和12个月时接受了CMR评估，包括T2和晚期enhancement增强。盲定量分析使用预定标准比较了每个时间点的左心室容积，功能，心肌水肿和坏死。预定义的主要结局是12个月时左心室射血分数改善≥10％，索引左心室舒张末期容积改善≥10％。结果平均年龄为39.9±14.5岁（男82岁），基线左心室射血分数为57.1±11.2％。共有72例患者（72％）在基线时表现出晚期late增强，其中57例（57％）的T2信号升高。12个月时左心室容积和EF明显改善。全球晚期late增强程度从左心室质量的8.5±9.2％降至3.0±5.2％（P = 0.0001），任何晚期enhancement增强的发生率均下降至48％。总体T2信号比率降低发生在12个月（1.85±0.3到1.56±0.2； P = 0.0001），T2比率≥2.0的患病率下降到7％。两种指标均未提供与主要结局的关联。结论在临床上可疑的急性心肌炎中，恢复期的前12个月内组织损伤标志物明显减少。在这个转诊人群中，研究的基于CMR的组织损伤标记物的存在或程度均不能预测我们在12个月时的预定功能或重塑结果。