Acute myocarditis presenting as accelerated junctional rhythm in Graves’ disease: A case report

Table 2 Diagnostic criteria for myocarditis[8]

Examinations and presentations	Features
ECG/Holter/stress test	Newly abnormal 12 lead ECG and/or Holter and/or stress testing, any of the following: I to III degree atrioventricular block, or bundle branch block, ST/T wave change (ST elevation or non-ST elevation, T wave inversion), sinus arrest, ventricular tachycardia or fibrillation and asystole, atrial fibrillation, reduced R wave height, intraventricular conduction delay (widened QRS complex), abnormal Q waves, low voltage, frequent premature beats, supraventricular tachycardia
Myocardiocytolysis markers	Elevated TnT/TnI
Functional and structural abnormalities on cardiac imaging (echo/angio/CMR)	New, otherwise unexplained LV and/or RV structure and function abnormality (including incidental finding in apparently asymptomatic subjects): regional wall motion or global systolic or diastolic function abnormality, with or without ventricular dilatation, with or without increased wall thickness, with or without pericardial effusion, with or without endocavitary thrombi
Tissue characterization by CMR	Oedema and/or LGE of classical myocarditic pattern
Clinical presentationsa	Acute chest pain, pericarditic, or pseudo-ischaemic (1) New-onset (days up to 3 mo) or worsening of: Dyspnea at rest or exercise, and/or fatigue, with or without left and/or right heart failure signs; (2) Subacute/chronic (> 3 mo) or worsening of: dyspnea at rest or exercise, and/or fatigue, with or without left and/or right heart failure signs; (3) Palpitation, and/or unexplained arrhythmia symptoms and/or syncope, and/or aborted sudden cardiac death; and (4) Unexplained cardiogenic shock

^aIf the patient is asymptomatic, ≥ 2 diagnostic criteria should be met. Clinically suspected myocarditis if ≥ 1 clinical presentation and ≥ 1 diagnostic criteron from different categories, in the absence of: (1) Angiographically detectable coronary artery disease (coronary stenosis ≥ 50%); (2) known pre-existing cardiovascular disease or extra-cardiac causes that could explain the syndrome (e.g., valve disease, congenital heart disease, and hyperthyroidism) (see text). Suspicion is higher with higher number of fulfilled criteria. ECG: Electrocardiography; CMR: Cardiac magnetic resonance; LV: Left ventricle; RV: Right ventricle; LGE: Late gadolinium enhancement; TNI: Troponin I; TNT: Troponin T.