Outcome of Acute Myocarditis Patients

Study Questions:

What are the characteristics, in-hospital management, and long-term outcome of patients with acute myocarditis (AM)?

Methods:

This is a retrospective study of 684 patients with suspected AM and recent onset of symptoms (<30 days) screened between May 2001 and February 2017 from 19 Italian hospitals. The study authors included patients in the analysis who had no evidence of coronary artery disease (patients >50 years without available coronary angiography were excluded). Furthermore, patients aged >70 years were excluded, as potential confounders could not be completely ruled out at cardiac magnetic resonance (CMR) (i.e., Takotsubo or other conditions associated with the aging heart). The final study cohort was comprised of 443 patients (median age 34 years, 19.4% female) with AM diagnosed either by endomyocardial biopsy (EMB) or increased troponin plus edema and late gadolinium enhancement at CMR. Myocardial histology was available in 61 out of 443 (13.7%) patients (EMB in 56 cases, postmortem examination in four cases, and explanted heart in one case). The main study endpoint was the overall incidence of cardiac death and heart transplant (HTx). Secondary study endpoints were all-cause deaths and HTx, and a composite of major AM-related cardiac events that occurred after the acute phase. The latter combined endpoint included cardiac death and HTx (excluding in-hospital events), sustained ventricular arrhythmias treated with electrical shock or ablation, and symptomatic heart failure needing device implantation. In the patients with follow-up CMR, there was a prevalence of reduced left ventricular ejection fraction (LVEF), and evidence of LV dilation (considering the threshold of indexed LV end-diastolic volume of 105 ml/m2 and 95 ml/m2, for men and women, respectively).

Results:

The most frequent symptom at presentation was chest pain (86.6% of patients), followed by dyspnea (19.2%); 80.5% of patients had prodromal symptoms. An associated autoimmune disorder was observed in up to 7.2% of patients. Eosinophilic granulomatosis with polyangiitis and mixed connective tissue disease were the most frequently observed autoimmune or systemic inflammatory disorders. AM occurred more frequently in male subjects (about 80%), although women more frequently had complicated AM and were therefore at higher risk of complications. At presentation, 26.6% (n = 118 patients) had either LVEF <50%, sustained ventricular arrhythmias, or a low cardiac output syndrome, while 325 (73.4%) had no such complications. EMB was performed in 12.6% (56/443), and a baseline CMR was performed in 93.7% (415/443) of patients. Cardiac mortality plus HTx at 1 and 5 years were 3.0% and 4.1%, respectively. Cardiac mortality plus HTx were 11.3% and 14.7% in patients with complicated presentation, and 0% in uncomplicated cases (log-rank p < 0.0001). Major AM-related cardiac events after the acute phase (post-discharge death and HTx, sustained ventricular arrhythmia treated with electrical shock or ablation, symptomatic heart failure needing device implantation) occurred in 2.8% at 5-year follow-up, with a higher incidence in patients with complicated forms (10.8% vs. 0% in uncomplicated AM, log-rank p < 0.0001). Beta-adrenoceptor blockers were the most frequently employed medications both in complicated (61.9%) and uncomplicated forms (53.8%, p = 0.18). After a median time of 196 days, 200 patients had follow-up CMR, and 8/55 (14.5%) with complications at presentation had LVEF <50% compared with 1/145 (0.7%) of those with uncomplicated presentation.

Conclusions:

The authors concluded that overall serious adverse events after AM were lower than previously reported. However, patients with LVEF <50%, ventricular arrhythmias, or low cardiac output at presentation were at higher risk compared with uncomplicated cases that had a benign prognosis and low risk of subsequent LV systolic dysfunction.

Perspective:

This is an important study because it characterizes the natural history of myocarditis in a contemporary cohort of patients diagnosed with currently used technology including cardiac biomarkers, CMR, and EMB. The findings of this study should help design therapeutic clinical trials for myocarditis.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias, Cardiac Surgery and Heart Failure, Acute Heart Failure, Heart Transplant, Interventions and Imaging, Angiography, Magnetic Resonance Imaging, Nuclear Imaging

Keywords: Arrhythmias, Cardiac, Chest Pain, Coronary Angiography, Dilatation, Dyspnea, Edema, Gadolinium, Heart Failure, Heart Transplantation, Magnetic Resonance Imaging, Mixed Connective Tissue Disease, Myocarditis, Myocardium, Prodromal Symptoms, Receptors, Adrenergic, Stroke Volume, Troponin


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