Cardiac insulin resistance in subjects with metabolic syndrome traits and early subclinical atherosclerosis
Objective:
Experimental evidence suggests that metabolic syndrome (MetS) is associated with changes in cardiac metabolism. Whether this association occurs in humans is unknown.
Research Design and Methods:
821 asymptomatic individuals from the PESA study (50.6[46.9-53.6] years, 83.7% male) underwent two whole-body 18F-FDG PET-MR 4.80.6 years apart. Presence of myocardial 18F-FDG uptake was evaluated qualitatively and quantitatively. No myocardial uptake was grade as 0, while positive uptake was classified in grades 1-3 according to target-to-background ratio tertiles.
Results:
156 participants (19.0%) showed no myocardial 18F-FDG uptake, and this was significantly associated with higher prevalence of MetS (29.0% vs 13.9%, p<0.001), hypertension (29.0% vs 18.0%, p=0.002), and diabetes (11.0% vs 3.2%, p<0.001), and with higher insulin-resistance index (HOMA-IR, 1.64% vs 1.23 %, p<0.001). Absence of myocardial uptake was associated with higher prevalence of early atherosclerosis (i.e. arterial 18F-FDG uptake, p=0.004).
On follow-up, the associations between myocardial 18F-FDG uptake and risk factors were replicated, and MetS was more frequent in the group without myocardial uptake. The increase in HOMA-IR was associated with a progressive decrease in myocardial uptake (p<0.001). In 82% of subjects, the categorization according to presence/absence of myocardial 18F-FDG uptake did not change between baseline and follow-up. MetS regression on follow-up was associated with a significant (p<0.001) increase in myocardial uptake.
Conclusions:
Apparently healthy individuals without cardiac 18F-FDG uptake have higher HOMA-IR and higher prevalence of MetS traits, cardiovascular risk factors, and early atherosclerosis. An improvement in cardiometabolic profile is associated with the recovery of myocardial 18F-FDG uptake at follow-up.
