Association between Myocardial Triglyceride Content and Cardiac Function in Healthy Subjects and Endurance Athletes

Abstract

Ectopic fat accumulation plays important roles in various metabolic disorders and cardiovascular diseases. Recent studies reported that myocardial triglyceride (TG) content measured by proton magnetic resonance spectroscopy (1H-MRS) is associated with aging, diabetes mellitus, and cardiac dysfunction. However, myocardial TG content in athletes has not yet been investigated. We performed 1H-MRS and cardiac magnetic resonance imaging in 10 male endurance athletes and 15 healthy male controls. Serum markers and other clinical parameters including arterial stiffness were measured. Cardiopulmonary exercise testing was also performed. There were no significant differences in clinical characteristics including age, anthropometric parameters, blood test results, or arterial stiffness between the two groups. Peak oxygen uptakes, end–diastolic volume (EDV), end–systolic volume (ESV), left ventricular (LV) mass, peak ejection rates and peak filling rates were significantly higher in the athlete group than in the control group (all P<0.02). Myocardial TG content was significantly lower in the athlete group than in the control group (0.60±0.20 vs. 0.89±0.41%, P<0.05). Myocardial TG content was negatively correlated with EDV (r = −0.47), ESV (r = −0.64), LV mass (r = −0.44), and epicardial fat volume (r = 0.47) (all P<0.05). In conclusion, lower levels of myocardial TG content were observed in endurance athletes and were associated with morphological changes related to physiological LV alteration in athletes, suggesting that metabolic imaging for measurement of myocardial TG content by 1H-MRS may be a useful technique for noninvasively assessing the “athlete’s heart”.

Evaluation of Myocardial Triglyceride Accumulation Assessed on ¹H-Magnetic Resonance Spectroscopy in Apparently Healthy Japanese Subjects

“…In previous reports, the myocardial TG content has been shown to positively correlate with LV mass weight per LV volume according to the degree of LV hypertrophy (4). Furthermore, we recently reported that athletes exhibit lower myocardial TG levels (13). We also included several endurance athletes in the present study; however, similar trends were obtained after excluding these subjects (data not shown).…”

“…Cardiac magnetic resonance imaging (MRI) and 1 H-MRS were conducted on a MAGNETOM Avanto 1.5-Tesla MRI system (Siemens Medical Solution, Erlangen, Germany), as previously reported (13). In brief, each subject rested in the supine position with a belt placed around the upper part of the abdomen in order to minimize respiratory movements.…”

“…The areas under the curves for the water and lipid peaks were quantified according to standard line-fitting procedures (Siemens Syngo Spectroscopy, Siemens Medical Solution). The myocardial TG levels are expressed as the lipid to water ratios (%) (13,(19)(20)(21).…”

“…In addition, progressive caloric restriction has been shown to induce a dose-dependent increase in the myocardial TG content (11), whereas endurance training reduces this parameter (12). We recently reported that the myocardial TG content is significantly lower in endurance athletes than in healthy subjects (13).…”

Exercise mediated protection of diabetic heart through modulation of microRNA mediated molecular pathways

“…Using proton magnetic resonance spectroscopy ( 1 H-MRS), Sai et al [144] demonstrated a marked reduction in myocardial triglyceride content and a significant improvement in cardiac function in endurance athletes who were exercising for 5 days a week. In contrast, Schrauwen-Hinderling et al [145] showed that combined endurance and strength training 3 times per week for 12 weeks improved insulin sensitivity, VO 2max , LVEF and cardiac output in obese T2DM individuals without altering the cardiac lipid content.…”