Types of fat in the heart
Research type
Research Study
Full title
Myocardial Lipid Compartments in Type 2 Diabetes (Types of fat in the Heart)
IRAS ID
339891
Contact name
Dana Dawson
Contact email
Sponsor organisation
University of Aberdeen
Clinicaltrials.gov Identifier
., .
Duration of Study in the UK
1 years, 11 months, 31 days
Research summary
Research Summary
Athletes are super healthy compared to patients with type 2 diabetes, but both have increased fat storage in muscle: the so-called “athlete’s paradox”. It is likely that this fat has different characteristics in athletes and patients with type 2 diabetes. We previously showed that a high level of storage and usage of the so-called “bad” (saturated) fat inside the leg muscles is a sign of better health, which was surprising and unexpected. In this work we wish to obtain essential pilot data to allow us to extend our investigation to the heart muscle, which works continuously and is under higher demand for energy production. Having perfected the imaging sequence to obtain data form the hearts of n=15 healthy volunteers, we now wish to scan 15 patients with type 2 diabetes to see if the balance of saturated/unsaturated fat in their heart muscle tracks with the findings we previously observed in their skeletal muscle.
Summary of Results:
Introduction
Ectopic skeletal muscle intramyocellular lipid storage is a direct contributor to insulin resistance in type 2 diabetes. We have previously demonstrated that the unsaturated intramyocellular lipid fraction is increased in the skeletal muscle of type 2 diabetes patients compared to age/sex matched healthy controls. There is very little known about the amount and saturation of their myocardial intramyocellular lipids.
Purpose
We aim to investigate the total amount and relative proportions of saturated and unsaturated intramyocellular lipid fractions in the myocardium of patients with type 2 diabetes compared to healthy controls.
Methods
Fifteen type 2 diabetes patients and 13 age and sex-matched healthy controls underwent ECG, Echocardiography and cardiac magnetic resonance imaging screening prior to cardiac ¹H-magnetic resonance spectroscopy on a 3T Philips Achieva MRI scanner. Standard cardiac views and cine imaging were acquired to guide voxel placement in the mid-ventricular septum during diastolic phase. Cardiac ¹H-magnetic resonance spectroscopy was performed with a prospectively ECG-triggered, respiratory-navigated, free-breathing single-voxel point-resolved spectroscopy. Acquisition parameters were: spectral sampling points = 2048, sampling bandwidth = 1500 Hz, repetition time = 1 beat, echo time = 30 ms, averages = 128, nominal voxel size = 15 x 40 x 25 mm. Prior to acquisition, 1st order shimming was performed over the voxel area using the vendor supplied projection-based method. In lipids, protons in saturated single bonds display different precessional characteristics compared to those attached to unsaturated double/triple bonds, due to variations in electron density and shielding effects. Spectra were analysed in LCModel, to fit and quantify the most abundant intramyocellular (IMCL) saturated (0.9 and 1.3 ppm) and unsaturated (2.1 ppm) lipid peaks relative to creatine levels. The unsaturation index was calculated as follows Unsaturation Index = IMCL21/(IMCL09+ IMCL13+ IMCL21).
Results
Participants had an average age of 62 years for type 2 diabetics and 26 years for healthy controls. Mean BMI was 30 for type 2 diabetes and 21 for healthy controls. Cardiac ¹H-magnetic resonance spectroscopy was successfully acquired in 11 type 2 diabetes patients and 13 healthy controls. The unsaturation index was higher in type 2 diabetes patients compared to healthy controls (0.316±0.037 versus 0.204±0.018, p<0.01).Conclusion
¹H-magnetic resonance spectroscopy demonstrates higher unsaturated intramyocellular lipid fractions in the myocardium of type 2 diabetes patients. These findings advance our understanding of lipotoxicity in the diabetic myocardium.REC name
South Central - Oxford A Research Ethics Committee
REC reference
24/SC/0228
Date of REC Opinion
19 Jul 2024
REC opinion
Favourable Opinion