HISTORY, CURRENT ILLNESS AND PHYSICAL EXAMINATION

History
No known drug allergies. Social background: self-employed. Lives with his family. Family history: father diagnosed with sarcoidosis and "large heart". Paternal grandfather died of sudden cardiac death at the age of 74. Personal history: no cardiovascular risk factors. No previous cardiovascular history. Other history: keratoconus. Asthma. No surgical history. No home medication.

Current illness
39-year-old patient who, after aerobic physical exercise (bicycle route), began to feel dizzy and sweaty. She initially improved after eating an apple, but later started sweating again, with general malaise and nausea. He reported associated palpitations. No anginal or pleuritic chest pain. On arrival at the ED, sustained monomorphic ventricular tachycardia was recorded and electrical cardioversion at 200 J was performed, which was effective. No previous similar symptoms.

Physical examination
Temperature 36oC, heart rate 67 bpm, blood pressure 106/59 mmHg, basal oxygen saturation 97%. Conscious, oriented and cooperative, eupneic at rest.
Pulmonary auscultation: preserved vesicular murmur with no added noise. Cardiac auscultation: rhythmic heart sounds without audible murmurs. Abdomen soft, depressible, not painful on palpation. Lower extremities without oedema.

COMPLEMENTARY TESTS
CBC: haemoglobin 13.5 g/dl, MCV 93 fl, MCH 30 pg, leukocytes 10,987/μl, platelets 186,000/μl. Biochemistry: glucose 101 mg/dl, urea 24 mg/dl, creatinine 0.84 mg/dl, sodium 140 mmol/l, potassium 4.2 mmol/l, lactate dehydrogenase 153 U/l, alkaline phosphatase 41 U/l, aspartate aminotransferase 28 U/l, alanine aminotransferase 28 U/l, gamma-glutamyltransferase 22 U/l, total bilirubin 1.3 mg/dl, direct bilirubin 0.5 mg/dl, total protein 69 g/l, albumin 44 g/l, total cholesterol 138 mg/dl, HDL-cholesterol 54 mg/dl, LDL-cholesterol 70 mg/dl, triglycerides 69 mg/dl, HbA1C 5.5%, thyrotropin (TSH)1.27 mU/l, serum IgG 11.11 g/l, serum IgA 1.64 g/l, serum IgM 0.79 g/l. Ultrasensitive troponin T (normal < 14) on arrival and at 3 hours: 187 -> 66 ng/l. Coagulation: INR 1.1, prothrombin rate 81%, partial thromboplastin time 28.80 s, D-dimer 555 ng/ml. Electrocardiogram (ECG): on arrival at the ED: monomorphic ventricular tachycardia with BRD morphology and superior axis. Baseline ECG: sinus rhythm. QRS with low voltages in limb leads, negative T wave V3-V6, I, aVL, II, III and aVF. Chest X-ray: slightly increased cardiothoracic index, no signs of heart failure. Transthoracic echocardiogram at discharge: severely dilated right ventricle (RV) with depressed systolic function. Left ventricle (LV) slightly dilated without hypertrophy, mild LV systolic dysfunction due to global hypokinesia, without segmental contractility abnormalities. No valvular heart disease, no pericardial effusion. 3D angio-CT reconstruction of coronary arteries: coronary arteries without lesions. Cardiac magnetic resonance (CMR): 4-chamber cine gradient-echo sequence (SSFP) (video 2): Dilated and hypocontractile LV with moderate systolic dysfunction. RV dilatation with global hypocontractility, ejection fraction 36%. Gradient echo sequence (SSFP) cine, centred in the RV outflow tract (video 3): Areas of dyskinesia and hypocontractility are seen in the RV outflow tract. Late gadolinium enhancement sequence, 4-chamber (A) and short axis (B): uptake at the level of the LV lateral wall in mid and apical segments and in the RV inferior wall at mid level, compatible with fibrosis. Immunology: antinuclear antibodies: negative. Neutrophil anti-cytoplasmic antibodies in vasculitis: negative. Genetics: homozygous carrier of the pathogenic variant p.T335A in the DSG2 gene.

CLINICAL COURSE
Non-syncopal sustained monomorphic ventricular tachycardia, with clinical involvement and acceptable haemodynamic tolerance. Electrical cardioversion to sinus rhythm. A transthoracic echocardiogram was performed in the emergency department prior to admission to cardiology, showing mild LV dysfunction and significant dilatation of the RV. As part of the study and in order to rule out underlying coronary artery disease that could justify the arrhythmia, a CT scan of the coronary arteries was performed without lesions, showing RV dilatation with irregular contour. Studies were completed with a CMR compatible with arrhythmogenic cardiomyopathy, predominantly of the RV, although the LV was also affected. Finally, an implantable cardioverter defibrillator was implanted for secondary prevention. Stable throughout admission, he was discharged without incident with neurohormonal treatment with bisoprolol and ramipril. During follow-up, the patient remained without clinical incidents or device therapies. A genetic test was requested, which was positive in homozygosis for the pathogenic variant p.T335A in the desmoglein 2 gene (DSG2).

DIAGNOSIS
Arrhythmogenic cardiomyopathy with biventricular involvement: moderate LV and RV systolic dysfunction.
Episode of non-syncopal sustained monomorphic ventricular tachycardia.
ICD implantation for secondary prevention.
Homozygous carrier of pathogenic variant in desmoglein 2 gene.
