Abstract Introduction Double-chambered right ventricle (DCRV) is a rare congenital heart defect with right ventricular outflow tract (RVOT) obstruction. The right ventricle (RV) is divided into anatomically proximal high-pressure and distal low-pressure chambers by abnormal muscle bundle. DCRV is frequently associated with others congenital heart defects, particularly ventricular septal defects (VSDs). Although its typically presents during childhood and adolescence, it can also present in adulthood. Case Presentation An 84-years-old woman was admitted to our hospital, in emergency department, with a 30-days history of worsening dyspnea and exercise intolerance. She was Ukrainian and did not speak Italian or English. The patient past medical history was unknow except for untreated bilateral glaucoma complicated by blindness. Vital signs were notable for tachycardia, tachypnea (respiratory rate, 28/minute), blood pressure of 118/76 mm Hg, SpO2 of 91%. Physical exam revealed left-sided parasternal systolic murmurs, abolished vesicular murmur at lung bases and jugular vein distension with hepatojugular reflux. The ECG showed atrial fibrillation. Chest X-ray showed moderate cardiomegaly, bilateral pleural effusions, and pulmonary congestion. Transthoracic echocardiography (TTE) was performed and revealed a normal-sized left ventricle with mildly reduced left ventricle ejection fraction (EF 48%), left atrial enlargement, biventricular hypertrophy with asymmetrical interventricular septal hypertrophy. Also, we found massive right atrium and enlarged right ventricle with reduced longitudinal contractility (TAPSE of 13 mm and tricuspid annular tissue Doppler S’ velocity = 7.0 cm/sec). Color flow Doppler in parasternal short-axis view revealed a turbulent systolic flow into the right ventricle. Continuous-wave spectral Doppler analysis showed a peak velocity of 5.6 m/ sec corresponding to a peak gradient of 120 mmHg. Real time 3D-TTE confirmed the of mid-ventricular obstruction due to abnormal trabecular tissue. Therapy including diuretics, beta-blockers and anticoagulants was started. Subsequently, a transesophageal echocardiography (TOE) confirmed the presence of an anomalous mid-ventricular muscle bundle and revealed an associated small sub-aortic ventricular septal defect (VSD) leading to the diagnosis of acute RV failure due to double-chambered RV with VSD and atrial fibrillation. Due to the high risk of complications, patient was considered not amenable for surgery. She was discharged on medical therapy. Conclusions We report a rare case of DCRV and VSD diagnosed in an elderly patient. Due to its rarity, DCRV continues to be misdiagnosed, especially in adulthood. Three-dimensional echocardiography and TOE were most useful tool to define diagnosis and pathophysiology in such an elderly and non-compliant patient.