Is myocardial fatty acid metabolism different between hypertrophic cardiomyopathy and hypertensive hypertrophy?

To investigate characteristics of fatty acid metabolism in hypertrophic cardiomyopathy (HCM), we performed myocardial imaging with 123I-iodophenyl-3-methylpentadecanoic acid (BMIPP) in 24 HCM patients, 13 patients with hypertensive hypertrophy (HT) and 10 normal subjects. Rest myocardial imaging with 123I-BMIPP was obtained at 20 minutes and 3 hours after 123I-BMIPP injection. Rest 201Tl imaging was also performed. In addition to ordinary tomography, whole body imaging was performed to calculate %Uptake (percentage of cardiac uptake of the isotope to total injected dose). As global indexes of fatty acid metabolism, we calculated two parameters; Uptake Ratio (%Uptake of 123I-BMIPP normalized by myocardial perfusion) and WOR (percent reduction of myocardial 123I-BMIPP within 3 hours). Regional abnormality was evaluated by visual assessment of ordinary tomograms and by BMIPP/Tl map. BMIPP/Tl map was made from Bull's-eye maps of 123I-BMIPP and 201Tl, and it represented 123I-BMIPP uptake normalized by myocardial perfusion of each pixel which constructed the image. %Uptake of 123I-BMIPP was not different among three groups. Uptake Ratio was significantly (p<0.001) different among three groups; normal (1.13±0.08)>HT (1.03±0.08)>HCM (0.87±0.09). WOR of 123I-BMIPP was accerelated in HCM (12.7±4.7%) and HT (10.2±2.9%) compared with normal (5.1±3.1%) (p<0.01). In HCM patients, by visual assessment, regional abnormality of 123I-BMIPP distribution was found in 17 of 24 patients (71%) including 3 patients with equivocal abnormality. In HT patients, only equivocal abnormality was observed in 23%. In BMIPP/Tl map, abnormality was observed in 92% of HCM and 8% of HT. Although global myocardial fatty acid metabolism was equally disturbed both in HCM and HT, regional abnormality of fatty acid metabolism was observed preferetially in HCM. This indicated myocardial fatty acid metabolism was not identical between HCM and HT. (author)