Case presentation: A 39-year-old male presents at emergency room for pain at the level of the right calf for almost 12h, along with paresthesia. From his personal pathological history can be retained the diagnosis of non-obstructive hypertrophic cardiomyopathy at the age of 30 years, without further follow-ups, the patient being lost from the annual recommended check-ups. The subject has a history of sudden cardiac death (SCD) in the family, namely the death of his only sister at 33-years-old. Clinical examination shows a patient with altered general status, regulated heart sounds, without murmurs, pulse 100/bpm, blood pressure 100/62 mmHg. The entire right lower limb is cold with pulses absent in the common femoral, popli-teal and peroneal artery and present in the left lower leg. The electrocardiogram detects sinus tachycardia at 100 bpm. The suspicion of acute lower limb ische-mia is raised and a Doppler ultrasound is performed detecting thrombotic occlusion of the right common femoral artery. Treatment with unfractionated heparin is initiated and Fogarty thrombo-embolectomy is performed urgently with favorable subsequent evolu-tion and correct flows in the arterial lower right limb axis. Cardiac echocardiography reveals a dilated left ventricle, with predominantly septal hypertrophy, se-vere systolic dysfunction with ejection fraction 20-25% and diffuse hypokinesia, old apical thrombus, severe left atrium dilation, mild mitral regurgitation and right ventricle free-wall hypertrophy. The case is interpreted as a biventricular non-obstructive hypertrophic cardi-omyopathy with evolution towards dilatation and seve-re ventricular dysfunction. On ECG Holter is detected non-sustained ventricular tachycardia with paroxystic episodes of atrial fibrillation. It is decided the implant of a cardiac defibrillator in primary prevention of SCD with resynchronization function. MRI reveals areas of extended transmural myocardial fibrosis with expansion of the interstitial space on a non-ischemic pattern. The patient received treatment with acenocoumarin, ß1-blocker, angiotensin-converting enzyme inhibitors and mineralocorticoid receptor antagonists. Genetic testing is applied using next-generation sequencing on MiSeq, with an extended panel, namely TruSi-ght Cardio Sequencing Kit highlighting a pathogenic mutation in myosin-binding protein C (MYBPC3), NM_000256.3: c.1252A> T, a missense mutation, resulting in a truncated variant of MYBPC3. A hetero-zygous mutation of factor V Leiden (NM_000130.4 (F5): c.1601G> A) is also identified. It was realized the cascade genetic family screening for the pathogenic mutation of MYBPC3.

Particularity of the case: The peculiarity of the case is the diagnosis of acute lower limb ischemia with thromboembolic mechanism in a young patient with sarco-meric hypertrophic cardiomyopathy in dilatation stage with severe systolic dysfunction and paroxysmal atrial fibrillation. Although, there are no studies to show associations between heterozygous mutations of factor V Leiden and arterial thrombosis, this can predispose to arterial occlusions as unveiled on small series and case-reports. The constellation of genetic mutations can importantly influence the therapeutic management, or evenly anticipate the patient’s evolution.