Myocardial metabolism may offer further risk stratification in the management of patients with heart failure

Objectives Fatty acid oxidation is easily impaired under various pathological conditions.Iodine-123-BMIPP is a radioactive fatty acid tracer, which enables monitoring of myocardial fatty acid utilization. Myocardial accumulation of BMIPP is not only related with blood flow or fatty acid metabolism but also with intracellular ATP concentrations. The aim of this study is to evaluate the utility of assessing myocardial fatty acid metabolism in patients with congestive heart failure (HF) by BMIPP scintigraphy.

Methods Thirty-two patients with HF of NYHA II or III functional class were compared with 18 normal control subjects. The planer and SPECT images were obtained at 15 min after BMIPP injection (111 MBq). The ROI was placed on the heart (H) and mediastium (M), and the uptake ratio of the H/M was calculated. Plasma B-type natriuretic peptide was measured, and we estimated cardiac function such as left ventricular ejection fraction and early to-late diastolic mitral inflow velocity ratio by echocardiography.

Results Myocardial fatty acid metabolism was impaired in HF caused by various diseases. H/M was lower in HF compared to normal subjects(2.0±0.2 vs. 2.3±0.3,p<0.001). The degree of metabolic abnormality evaluated by BMIPP scintigraphy was closely related to the clinical severity of HF, including cardiac function. Kaplan-Meier analysis revealed that a lower H/M (<2.0) was related with an earlier progression of heart failure or arrhythmia and subsequent hospitalization. Altered myocardial metabolism was an independent and significant predictor of cardiac events in patients with HF. There was no death in the first hospitalization. However six patients died during subsequent hospitalization within 3 years (five cardiac deaths and one non-cardiac death).

Conclusions Evaluation of myocardial fatty acid metabolism with BMIPP may offer further risk stratification or prediction of outcomes in patients with HF caused by a variety of heart diseases