HISTORY, CURRENT DISEASE AND PHYSICAL EXAMINATION
We present the case of a 47-year-old male diagnosed with HCM at the age of 44 years, following a family screening after his 7-year-old daughter presented with a recovered sudden death. Genetic testing showed a troponin I mutation (TNNI3) in the index case, our patient being a carrier. At the time of diagnosis, he was oligosymptomatic from the cardiovascular point of view: he reported NYHA functional class I-II and denied symptoms of palpitations, chest pain, dizziness or syncope.

COMPLEMENTARY TESTS
ECG: sinus rhythm. Narrow QRS with -30o axis. Left ventricular overload voltage criteria.
CBC: Hb 13 g/dl, Cr 1 mg/dl, normal ions, NT-proBNP 1,000 pg/ml.
Chest X-ray: cardiomegaly. Mild vascular redistribution to upper fields.
Echocardiogram: LV of normal diameter with moderate asymmetric septal hypertrophy (15 mm) with no obstruction across the left ventricular outflow tract, no systolic anterior motion of the mitral valve. Mild left ventricular systolic dysfunction (EF 48-50 %) and grade 1 diastolic dysfunction. Dilated left atrium (67 mm).
Cardiac magnetic resonance imaging (MRI): late gadolinium enhancement irregularly distributed in the medial wall of the entire septum, anterior wall and free wall of the right ventricle. IVS 15 mm. Severe left atrial dilatation.
Ergometry: sinus rhythm during recording. Supraventricular extrasystoles and ventricular extrasystoles (with BRDHH morphology) isolated.

EVOLUTION
After the studies performed, an intermediate risk of sudden death was estimated (HCM 5-year SCD rate 4.7%), and ICD implantation was decided for primary prevention of sudden death.
After a stable period of 3 years, he reported progressive clinical worsening in the last 6 months, presenting deterioration of functional class (CF NYHA III/IV). Physical examination revealed elevated jugular venous pressure and crackles on pulmonary auscultation. Laboratory tests showed elevated NT-proBNP up to 5,000 pg/ml, with the rest of the parameters in the normal range.
The electrocardiogram was in sinus rhythm. A control echocardiogram was performed, which showed LV with moderate asymmetric septal hypertrophy, which had not progressed, with deterioration of LV systolic function (EF 40-45%). No dynamic gradient was observed in the LV outflow tract.
He also had grade 3 diastolic dysfunction, with evidence of elevated filling pressures.
Ergospirometry was performed, showing peak oxygen consumption of 16 ml/min/kg (57% of predicted) and right heart catheterisation, with evidence of postcapillary pulmonary hypertension (pulmonary capillary pressure: 24 mmHg, systolic pulmonary pressure of 55 mmHg, mean pulmonary artery pressure 32 mmHg). RV end-diastolic pressure was 16 mmHg. Neurohormonal treatment was started and, due to severe dilatation of the left atrium and thrombotic risk in case of falling into atrial fibrillation, oral anticoagulation was also started.
The evolution in the following year was unfavourable despite optimal medical treatment, presenting dyspnoea on minimal exertion, with two admissions for decompensation of heart failure. A new determination of oxygen consumption was performed, estimating VO2 max of 12 ml/kg/min. Given the significant and progressive limitation of his functional capacity, he was referred to a reference centre as a candidate for heart transplant, undergoing a pre-transplant study and is currently on the waiting list for elective transplant.

DIAGNOSIS
Non-obstructive hypertrophic cardiomyopathy. Mutation in the troponin I 3 gene (TNNI3).
Recovered sudden death in first-degree relative. ICD carrier.
Mild left ventricular dysfunction. Stage D heart failure. NYHA functional class III/IV. Candidate for elective heart transplant.
