Association between abnormal fatty acid metabolism and myocardial triglyceride accumulation in patients with chronic heart failure: a study using BMIPP and 1H-MRS

Abnormal energy metabolism in the myocardium has been reported in patients with heart failure. In particular, it is suggested that excessive myocardial fat accumulation in heart failure can lead to lipotoxicity, while disturbances in the uptake and breakdown of fatty acids may contribute to the worsening of heart failure. Recent advances in imaging techniques, such as proton magnetic resonance spectroscopy (1H-MRS) for directly evaluating myocardial fat accumulation and iodine-123-beta-methyl-P-iodophenyl-pentadecanoic acid (BMIPP) for assessing fatty acid uptake and breakdown disorders, have enabled clinical evaluation, but many aspects of their relationship and detailed mechanisms remain unclear.

This study aims to evaluate the relationship and clinical significance of myocardial fat accumulation and fatty acid uptake and breakdown disorders in patients with heart failure using BMIPP and 1H-MRS.

We included 33 consecutive patients with chronic heart failure, aged 20 years or older, who provided informed consent between September 2020 and January 2024. BMIPP and Magnetic Resonance Imaging (MRI, 1.5T MR scanner) were performed during the stable phase (mean interval 5.6 ± 9.0 days). BMIPP was imaged twice, early phase at 20 minutes and delayed phase at 180 minutes, with early H/M (heart-to-mediastinum ratio), delayed H/M, and washout rate (WR) measured from planar images and SPECT images, respectively. MRI cine imaging was used to measure various left ventricular parameters (LVEDV, LVESV, SV, LVEF, LV mass), and 1H-MRS was employed to measure myocardial triglyceride (MTG) accumulation. The relationship between BMIPP and MRS evaluation parameters and left ventricular function parameters in MRI and patient background factors (age, gender, TG, LDL, HDL, BS, HbA1c, IRI, HOMA-IR, proBNP) were evaluated.

There was no correlation between any of the BMIPP parameters (early H/M, delayed H/M, WR) and MTG. Additionally, none of the parameters correlated with left ventricular function parameters such as LVEF and LV mass measured by MRI or with patient background factors. However, a significant correlation was found only between MTG and IRI (r=0.641, p=0.0002) and HOMA-IR (r=0.589, p=0.001).

In patients with chronic heart failure, abnormalities in myocardial fatty acid metabolism and myocardial triglyceride accumulation may independently influence the pathophysiology of heart failure, potentially adding value to traditional severity assessment indicators of heart failure. In particular, myocardial triglyceride accumulation may be attributed to increased fatty acid uptake into the myocardium due to elevated insulin resistance in heart failure.