TNNI3 and hydrops fetalis: Clinical criteria•ACS-like•New or worsening HF•Chronic HF•Cardiogenic shock/Ventricular arrhythmiaDiagnostic testing•ECG/Holter/stress test with new abnormalities•New LV or RV structural or functional abnormality (echo/angiography/CMR)•Myocardiocytolysis markers (elevated cTnI or cTnT)•Diagnostic CMR (edema and injury meeting Lake Louise criteria (15)