Hypertrophic Cardiomyopathy in a Monozygotic Twin Pair: Similarly Different.

A 70-year-old female patient was admitted to our hospital because of atypical chest pain and fatigue. No relevant diseases were recorded in her previous medical history. During the physical examination, she presented with a mild systolic murmur. Her 12-lead ECG indicated right bundle branch block (Figure 1A), and blood pressure was normal. Initial blood test showed normal hs-Troponin T and D-dimer levels. Transthoracic echocardiography (TTE) revealed mild concentric left ventricular (LV) hypertrophy (end-diastolic interventricular septal thickness 14 mm; LV mass index, 96 g/m2) with septal bulging and mild aortic stenosis (transaortic mean gradient 18 mm Hg, calculated aortic valve area 1.8 cm2) because of valve calcification (Figure 2A; Video I in the Data Supplement). In addition, TTE showed a good LV and right ventricular systolic function, impaired LV relaxation, and minimal mitral and tricuspidal regurgitation (Video II in the Data Supplement). To rule out obstructive coronary artery disease, we performed coronary artery calcium score scan and prospectively ECG-triggered coronary computed tomography angiography using a 256-slice multidetector-row computed tomography. The total coronary artery calcium score was 340; the calcium score of the aortic valve was 731 (Figure 3A). The coronary computed tomography angiography depicted a left dominant coronary system (Figure 4A) and several calcified and partially calcified atherosclerotic plaques along the left anterior descending coronary artery, causing moderate stenosis and partially calcified plaques in the left circumflex coronary artery, causing mild stenosis. The patient was discharged with optimized medications.Figure 1. Twelve-lead ECG indicated right bundle branch block in twin A and left ventricular strain pattern in twin B .Figure 2. M-mode echocardiography shows systolic anterior motion of the mitral valve in twin B (arrows), which is absent in twin A .Figure 3. Volume-rendered images of the aortic root show aortic valve …