Hypertrophic Obstructive Cardiomyopathy Complicated by Severe Midventricular Obstruction Treated with Percutaneous Transluminal Septal Myocardial Ablation Using Simultaneous Contrast Imaging with Left Ventriculography and Coronary Angiography: A Case Report

Background Hypertrophic obstructive cardiomyopathy (HOCM) is a genetic cardiac disease characterised by left ventricular hypertrophy that induces left ventricular outflow tract obstruction (LVOTO), which occurs in approximately 25% of patients with hypertrophic cardiomyopathy (HCM), and, less commonly, a midventricular obstruction (MVO). Percutaneous transluminal septal myocardial ablation (PTSMA) treatment for HOCM has become an established therapy to alleviate LVOTO. Case Summary A 78-year-old woman with HOCM and severe MVO underwent PTSMA using simultaneous contrast imaging with left ventriculography (LVG) and coronary angiography (CAG). After the procedure, the pressure gradient between the aorta and left ventricular apex improved from 140 to 35 mmHg at rest and from 195 to 40 mmHg at post-extra-systolic potentiation. The residual pressure gradient in the left ventricular mid-ventricle and left ventricular outflow tract was 15 and 10 mmHg, respectively. Her clinical condition improved significantly, and she remained well without any symptoms. Discussion MVO is relatively rare, occurring in approximately 5–10% of patients with hypertrophic cardiomyopathy; therefore, it is substantially underdiagnosed or missed, leading to suboptimal treatment in a high proportion of patients. Thus, physicians should consider the possibility of MVO when evaluating patients with HCM to avoid overlooking it. Confirmation and clarification of the detailed anatomical relationship between MVO/LVOTO and effective septal branches using contrast imaging with LVG, CAG, and occlusion tests might be essential for achieving effective clinical outcomes in patients with HOCM concomitant with MVO.