Table 2.

Diagnostic criteria for clinically suspected myocarditis

Newly abnormal 12-lead electrocardiography, Holter monitoring, and/or stress testing, any of the following: •First- to third-degree atrioventricular block •Bundle branch block •ST/T-wave change (ST-segment elevation or non–ST-segment elevation, T-wave inversion) •Sinus arrest •Ventricular tachycardia or fibrillation and asystole •Atrial fibrillation, supraventricular tachycardia •Low QRS voltage •Frequent premature ventricular contractions

Markers of myocardial injury •Troponin I/troponin T

Functional and structural abnormalities on cardiac imaging

Echocardiography, angiography, and/or CMR: •Regional or global systolic or diastolic dysfunction, with or without left ventricular dilation •Increased wall thickness •Pericardial effusion •Intracavitary thrombi

Tissue characterization by CMR (updated Lake Louise criteria∗) •Edema •Hyperemia or capillary leak (early gadolinium enhancement) •Irreversible injury (necrosis, scar; late gadolinium enhancement)

CMR, cardiac magnetic resonance.

Modified from Caforio et al.³⁰ with permission from Oxford University Press.

^∗Clinically suspected myocarditis if > 1 clinical presentation and > 1 diagnostic criteria from different categories, in the absence of (1) angiographically detectable coronary artery disease (coronary stenosis > 50%) and (2) known preexisting cardiovascular disease or extracardiac causes that could explain the syndrome (eg, valve disease, congenital heart disease, hyperthyroidism). Suspicion is higher with higher number of fulfilled criteria. If the patient is asymptomatic, > 2 diagnostic criteria should be met.