How Should We Diagnose Myocarditis, and Is its Recognition Really Clinically Relevant? ∗

Although the clinical spectrum of acute myocarditis varies from cardiogenic shock to asymptomatic electrocardiographic abnormalities during community viral outbreaks, its 3 most common clinical presentations are chest pain mimicking acute myocardial infarction, ventricular arrhythmias, and heart failure due to new-onset dilated cardiomyopathy (DCM) (1,2). Cardiac magnetic resonance (CMR) imaging has proven extremely valuable for assessment of clinically suspected myocarditis, by virtue of its ability to detect myocardial inflammation, myocardial edema, necrosis, and fibrosis (3). Several imaging sequences can accurately identify tissue characteristics associated with both acute and chronic myocarditis. Myocardial T1 (the spin-lattice longitudinal relaxation time) is shortened by increased interstitial space (e.g., scar, diffuse fibrosis, or infiltration) after administration of gadolinium-based contrast. T2-weighted (the spin-spin transversal relaxation time) mapping is used to detect myocardial edema, whereas early enhancement is felt to display capillary leakage and myocardial hyperemia. Contrast imaging with gadolinium enables detection of early capillary leakage based on T1-weighted early enhancement and accurate diagnosis of myocardial fibrosis based on late enhancement (LGE). LGE is frequently observed in patients with acute myocarditis in a pattern that is distinctive from ischemic myocardial injury (3). Recently, novel quantitative T1 and T2 mapping techniques, i...
Source: Journal of the American College of Cardiology - Category: Cardiology Source Type: research