Short term caloric restriction induces accumulation of myocardial triglycerides and decreases left ventricular diastolic function in healthy subjects

Abstract

Objective: Diabetes mellitus and obesity are associated with increased plasma non-esterified fatty acid (NEFA) levels, myocardial triglyceride accumulation and myocardial dysfunction. Because a very low calorie diet (VLCD) also increases plasma NEFA levels, we studied the effect of a VLCD on myocardial triglyceride (TG) content and cardiac function in healthy subjects.

Research Design and Methods: Fourteen healthy non-obese men underwent ¹H-magnetic resonance spectroscopy (MRS) to determine myocardial and hepatic triglyceride content, ³¹P-MRS to assess myocardial high-energy-phosphate metabolism (PCr/ATP), and MR imaging of myocardial function at baseline and after a 3-day VLCD.

Results: After the dietary intervention, plasma NEFA levels increased compared to baseline (from 0.5 ± 0.1 to 1.1 ± 0.1mmol/l, p< 0.05). Concomitantly, myocardial TG content increased by ∼55%, compared to baseline (from 0.38 ± 0.05 to 0.59 ± 0.06%, p< 0.05), whereas liver TG content decreased by ∼32% (from 2.2 ± 0.5 to 1.5 ± 0.4%, p< 0.05). The VLCD did not change myocardial PCr/ATP (2.33 ± 0.15 vs. 2.33 ± 0.08, p> 0.05) or systolic function. Interestingly, deceleration of the early diastolic flow across the mitral valve decreased after the VLCD (from 3.37 ± 0.20 to 2.91 ± 0.16ml/s² × 10^-3, p< 0.05). This decrease in diastolic function was significantly correlated with the increase in myocardial TG content.

Conclusions: Short-term VLCD induces accumulation of myocardial TG. In addition, VLCD decreases left ventricular diastolic function, without alterations in myocardial high-energy-phosphate metabolism. This study documents diet dependent, physiological variations in myocardial TG content and diastolic function in healthy subjects.