HISTORY, CURRENT ILLNESS AND PHYSICAL EXAMINATION
42-year-old male, with no known cardiovascular risk factors. History of heart murmur in childhood, operated on for pectus excavatum and diaphragmatic hernia. Under treatment with ibandronic acid and calcium carbonate.
He was initially assessed at his reference hospital for a murmur, and the echocardiogram showed a slightly dilated left ventricle (LV) with slightly depressed systolic function (LVEF) (45% according to Simpson), a myxomatous mitral valve with prolapse of both leaflets leading to mild insufficiency, a right ventricle (RV) of normal size, but with an aneurysmal and akinetic apex and depressed systolic function, and aortic root at the upper limit of normality. In view of these findings, he was referred for specific consultation of familial heart disease for suspected arrhythmogenic right ventricular cardiomyopathy (ARVC).
At the first visit, the patient was asymptomatic from the cardiovascular point of view. Physical examination revealed a marfanoid appearance, with rhythmic heart tones and a systolic murmur II/VI in the mitral focus radiating to the axilla, with preserved vesicular murmur, no additional sounds on pulmonary auscultation and no oedema in the lower extremities.
During outpatient follow-up, he began to experience dyspnoea on moderate exertion.
To complete the study, Holter-ECG, cardiac magnetic resonance, transesophageal echocardiogram and genetic study were performed.

COMPLEMENTARY TESTS
Electrocardiogram (ECG) in consultation: sinus rhythm with incomplete right bundle branch block and a deflection from S to pseudoR > 55 ms.
The 24-hour Holter showed ventricular extrasystoles originating from the RV outflow tract with a density of 3% (6,935 beats) and a burst of non-sustained ventricular tachycardia (NSVT) with RV outflow tract morphology of 11 beats, totally asymptomatic.
Cardiac MRI showed a non-dilated RV with apical hypertrabeculation with dyskinetic movement of the free and apical anterior wall, with doubtful linear fibrofatty infiltration at that level and moderately depressed right systolic function (RVEF 36%). The left ventricle was slightly dilated, with apical hypertrabeculation associated with lateral mid-apical hypocontractility and mildly depressed systolic function (LVEF 48%).
Transesophageal echocardiogram showed a myxomatous mitral valve with prolapse of both leaflets with mild insufficiency, aortic root at the high limit of normality and mild LV systolic dysfunction.
The genetic study identified him as a heterozygous carrier of a mutation in the fibrillin 1 gene associated with Marfan syndrome (NC_000015.9 mutation: g. 48737574delC), with no mutations in the genes related to arrhythmogenic RV dysplasia. In view of these findings and given the patient's phenotype and clinical manifestations, we diagnosed Marfan syndrome and extended the genetic study to his children, who were found to be carriers, one of whom was also affected with mild aortic dilatation.

CLINICAL EVOLUTION
In view of the findings of the complementary tests and despite the fact that the genetic test for arrhythmogenic RV dysplasia was negative, we considered that the patient had this diagnosis, since he had one major criterion (anterior and apical RV dyskinesia with dysfunction < 40%) and 3 minor ones (> 500 VSD on Holter, NSVT with RV outflow tract morphology and deflection from S to pseudoR > 55 ms on the electrocardiogram).
Given the results of the complementary tests and the history of asymptomatic non-sustained ventricular tachycardia, it was decided to implant an automatic defibrillator (ICD) for primary prevention, in addition to medical treatment with beta-blockers and angiotensin-converting enzyme inhibitors (ACE inhibitors).
Since ICD implantation, the patient has had no shocks and remains in New York Heart Association (NYHA) functional class II during follow-up visits.

DIAGNOSIS
Biventricular arrhythmogenic cardiomyopathy with mild left and moderate right dysfunction, with mild left ventricular dilatation, anterior and apical RV dyskinesia and negative genetic study for RV arrhythmogenic cardiomyopathy.
Marfan syndrome; heterozygous carrier of mutation in the fibrillin 1 gene.
