IntroductionThe excessive cardiovascular disease (CVD) burden associated with type 2 diabetes mellitus (T2D) is conventionally attributed to a clustering of traditional risk factors including hyperglycaemia, hypertension, dyslipidaemia and obesity. More recently, studies by our group and others have demonstrated that individuals with impaired glucose tolerance and T2D have increased triglyceride content within the myocardium. [1][2][3] This ectopic lipid deposition is purported to contribute to changes in cardiac structure and function frequently seen in individuals with glucose intolerance, referred to as 'diabetic cardiomyopathy'. 4,5 In animal models of obesity and T2D, thiazolidinedione (TZD) therapy attenuates myocardial triglyceride (mTG) deposition and normalises left ventricular (LV) systolic dysfunction. [6][7][8] As substantial controversy exists surrounding the cardiac effects of these commonly used glucose-lowering medications, 9,10 we conducted a nested imaging sub-study within a 6-month, randomised controlled clinical trial of rosiglitazone on cardiovascular performance. The sub-study assessed the effects of rosiglitazone on mTG content and its association with measures of cardiac structure and function in patients with T2D and increased CVD risk. Our a-priori hypothesis was that 6 months of rosiglitazone therapy would significantly reduce mTG content in patients with T2D, which would be associated with improved LV performance.
AbstractThis was a nested sub-study of a randomised placebo-controlled trial of the effect of 6 months of treatment with rosiglitazone added to existing therapy on myocardial triglyceride (mTG) content in patients with type 2 diabetes (T2D) and prevalent cardiovascular disease (CVD) or at least one additional risk factor. The primary endpoint, mTG content, was measured with cardiac 1 H-magnetic resonance spectroscopy. Of the 99 randomised participants selected for the imaging sub-study, 49 (48%) had complete and interpretable spectroscopy data (age = 58 years, duration of T2D = 9.5 years; 57% women and 69% non-white). There was no significant change in mTG in either group (−0.1 ± 0.6% and −0.05 ± 0.8% respectively) and the changes in mTG were not associated with changes in left ventricular structure or function. Compared with placebo, treatment with rosiglitazone for 6 months had no discernible effect on mTG or left ventricular function in this population with long-standing diabetes and CVD.
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Research design and methodsThis was a sub-study nested within a single-centre, prospective, randomised, double-blind, placebo-controlled, parallel-group trial evaluating the cardiovascular effects of rosiglitazone in patients with T2D and elevated CVD risk, with the study design and primary study results previously published (NCT00424762). 11,12 In the present sub-study, we assessed the effects of rosiglitazone on 1 H-magnetic resonance spectroscopy (MRS)-derived mTG content and MRI-derived measures of LV structure and function. The study protocol was approved by the UT Southw...