Utility of vector flow mapping and [¹⁸F]fluorodeoxyglucose-positron emission tomography/computed tomography to assess left ventricular workload in obstructive hypertrophic cardiomyopathy

A 77-year-old female with exertional dyspnoea in spite of taking cibenzoline 300 mg/day, bisoprolol 5 mg/day, and verapamil 240 mg/day was referred to our hospital for further treatment of obstructive hypertrophic cardiomyopathy. Marked left ventricle (LV) hypertrophy (20 mm), systolic anterior motion (SAM) of anterior mitral leaflet, and a severe gradient at the LV outflow tract (LVOT) of 122 mmHg were observed on transthoracic echocardiography (see Supplementary data online, Videos S1 and S2; Panels A1–A4). Vector flow mapping (DAS-RS1; FUJIFILM Healthcare Co.) demonstrated multiple turbulent blood flow vectorial patterns inducing SAM, a prominent diastolic peak energy loss of 55.5 J/m³/s within the LV, and a decreased relative intraventricular pressure difference of 0.62 mmHg during isovolumic relaxation time (ΔP_IRT; see Supplementary data online, Video S3; Panels A5–A7). Fasting [¹⁸F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) combined with enhanced computed tomography (CT) demonstrated intense uptake into the posterior wall of the LV, indicating increased workload (Panels C1–C3). Our heart team decided to perform surgical myectomy rather than alcohol septal ablation. The patient underwent the extended myectomy through aortotomy and LVtomy under cardiopulmonary bypass. White fibrous endocardial muscles were removed from the septum (Panels D1 and D2). Marked hypertrophic free wall and hypertrophic papillary muscles especially were resected via the apical LV to suppress the turbulent blood flow for eliminating SAM (Panel D3). The resected myocardium weighed 3.6 g, and LV apical incision was repaired with a double-layered polytetrafluoroethylene felt strip (Panel D4). Histopathological examination revealed varying sizes of degenerated myocardium and endocardial and interstitial fibrosis (Panels E1–E4). Under taking cibenzoline 300 mg/day and carvedilol 20 mg/day, follow-up echocardiography confirmed resolutions of LVOT obstruction, mid-cavity obliteration, and SAM despite showing mild aortic and mitral regurgitation (see Supplementary data online, Videos S4 and S5; Panels B1–B4). Left ventricle thickness and LVOT pressure gradient were decreased to 14 mm and 34 mmHg, respectively (Panels B1–B4). Efficient flow dynamics reduced diastolic peak energy loss to 14.1 J/m³/s and increased ΔP_IRT to 1.98 mmHg (see Supplementary data online, Video S6; Panels B5–B7). FDG uptake was observed at the apical incision site of the LV, but not at the posterior wall (Panels C4–C6). Clinical symptoms were strikingly improved with uneventful peri-operative course. Vector flow mapping and FDG-PET/CT are useful to assess LV workload in obstructive hypertrophic cardiomyopathy. The authors are grateful to Dr. Atsuko Tahara, BS. Shin-ichiro Ito, Dr. Kodai Shibao, Dr. Munehisa Bekki, Dr. Akihiro Honda, Dr. Yasuyuki Zaima, and Prof. Jun Akiba (Kurume University School of Medicine), Dr. Seiya Kato (Saiseikai Fukuoka General Hospital), and Prof. Kojiro Furukawa (University of the Ryukyus) for their professional support in this study.

Supplementary data are available at European Heart Journal online.

All authors declare no disclosure of interest for this contribution.

No data were generated or analysed for or in support of this paper.