Myocardial ¹¹C-diacylglycerol accumulation and left ventricular remodeling in patients after myocardial infarction

Left ventricular (LV) remodeling after myocardial infarction (MI) is a maladaptive process that increases the risk of heart failure and death. The myocardial phosphoinositide cycle, which is located downstream from several neurohumoral factors, plays a crucial role in LV remodeling. Our animal studies demonstrated that 1-[1-¹¹C]butyryl-2-palmitoyl-rac-glycerol ( ¹¹C-DAG) can be used to visualize regions with an activated phosphoinositide cycle. Therefore, we examined whether myocardial ¹¹C-DAG accumulation assessed by PET is relevant to LV enlargement and systolic dysfunction in post-MI patients. Methods: We performed PET with ¹¹C-DAG in 13 post-anteroseptal MI patients and 4 healthy volunteers. We placed regions of interest on the noninfarcted myocardium and calculated the myocardium-to-left atrial (LA) chamber ratio of ¹¹C-DAG accumulation. Results: The myocardium-to-LA chamber ratio of ¹¹C-DAG was significantly higher in the post-MI patients (mean ± SD, 1.73 ± 0.35) compared with that of the healthy volunteers (mean ± SD, 1.25 ± 0.13; P < 0.05). In the post-MI patients, the myocardium-to-LA chamber ratio of ¹¹C-DAG was significantly correlated with the LV end-diastolic volume index (r = 0.79, P < 0.01) and the plasma concentration of brain natriuretic peptide (r = 0.85, P < 0.001) and negatively correlated with the LV ejection fraction (r = -0.69, P < 0.01). Conclusion: These findings suggest that the myocardial ¹¹C-DAG accumulation assessed by PET is relevant to LV enlargement, LV systolic dysfunction, and humoral activation in post-MI patients. This new imaging strategy based on intracellular signaling may contribute to the assessment and treatment of post-MI patients.