Eosinophilic Myocarditis: Characteristics, Treatment, and Outcomes.

BACKGROUND: Eosinophilic myocarditis (EM) is an acute life-threatening inflammatory disease of the heart. Neither large case series nor clinical trials on this specific myocarditis have been reported.

OBJECTIVES: Based on a systematic revision of all published histologically proven cases, this study aimed to describe the clinical presentation, treatment, and outcome of EM.

METHODS: The study screened 443 manuscripts in MEDLINE and EMBASE on cases of EM published until June 2017. The authors identified 264 patients and included in the main analysis 179 patients admitted to hospital with histologically proven EM.

RESULTS: Median age was 41 years (interquartile range: 27 to 53 years) with similar prevalence in both sexes; pediatric cases (≤16 years of age) accounted for 10.1%. The main symptom at presentation was dyspnea (59.4%), with peripheral eosinophilia observed in 75.9%. Median left ventricular ejection fraction at presentation was 35% (interquartile range: 25% to 50%). The disorders most frequently associated with EM were hypersensitivity and eosinophilic granulomatosis with polyangiitis, which accounted for 34.1% and 12.8% of cases, respectively, whereas idiopathic or undefined forms accounted for 35.7% of cases. Steroids were administered in 77.7% of patients. A temporary mechanical circulatory support (n = 30) was instituted in 16.8% of patients. In-hospital death was 22.3% (n = 40), with the highest occurrence in the hypersensitivity form (36.1%; p = 0.026).

CONCLUSIONS: EM has a poor prognosis during the acute phase, despite a publication bias that could have led to an overestimation of mortality. Associated conditions are identified in approximately 65% of cases. Specific trials and multicenter registries are needed to provide evidence-based treatments to improve in-hospital outcome.