Cardiac cell damage in hypertrophic cardiomyopathy evaluated by beta-methylbranched fatty acid analogue, iodine-123-15-(p-iodophenyl)-3-(R,S)- methylpentadecanoic acid (BMIPP) myocardial fatty-acid imaging and late gadolinium-enhanced contrast magnetic resonance imaging: Usefulness of combining the two techniques

Background: Late gadolinium-enhanced (LGE) magnetic resonance imaging (MRI) has been found to be a highly valuable imaging modality for myocardial characterization in cases of hypertrophic cardiomyopathy (HCM). In addition, abnormalities of BMIPP uptake have also been recognized in HCM. In this study, we hypothesized that abnormalities of fatty acid uptake and metabolism may be detected before fibrosis can be recognized on cardiovascular MRI in patients with HCM. Methods and Results: Twenty-four patients with HCM were examined by both BMIPP myocardial fatty acid imaging and LGE MRI, and the results of the two imaging methods were compared. BMIPP uptake abnormalities were recognized in 23 of the 24 HCM patients (95.8%) and 126 out of the 408 segments (30.9%) examined, and were most frequently located in the interventricular septum and anterior wall of the left ventricle, the inferior wall and apex of the heart. Areas of LGE were recognized in 18 of the 24 HCM patients (75%) and 50 of the 408 segments (12.2%) examined, and were most frequently located in the interventricular septum of the left ventricle. Double-positive results of both BMIPP uptake abnormalities and LGE were recognized in 18 of the 24 cases (75.0%) and 45 of the 408 segments (11.0%) examined. Double-positive results were noted most frequently in the interventricular septum of the left ventricle and the anterior wall. Conclusion: The areas showing BMIPP uptake abnormalities were more extensive than those showing LGE on MRI. In addition, the positivity rate for BMIPP uptake abnormalities in areas showing LGE on MRI was considerably higher than that of LGE positivity in areas positive for BMIPP uptake abnormalities. These results are not contradictory to our hypothesis. Therefore, differences between the examination methods in terms of the extent and positivity rate in cases of HCM may be related to the stage of progression of the cardiac muscle cell damage in cases of HCM. Thus, the use of both examinations together might be useful in the evaluation of the stage of disease progression in cases of HCM.