Diagnosis of coronary artery disease in persons with diabetes mellitus

LV Mass as a Predictor of CVD Events in Older Adults With and Without Metabolic Syndrome and Diabetes

OBJECTIVES

The purpose of this study was to examine the prognostic significance of left ventricular (LV) mass for cardiovascular disease (CVD) events in older adults with and without metabolic syndrome (MetS) and diabetes mellitus (DM).

BACKGROUND

MetS and DM are associated with increased CVD risk, but it is unclear in these groups whether subclinical CVD as shown by increased LV mass improves risk prediction compared to standard risk factors in older individuals.

METHODS

We studied 3,724 adults (mean 72.4 ± 5.4 years of age, 61.0% female, 4.4% African-American) from the Cardiovascular Health Study who had MetS but not DM or had DM alone or had neither condition. Cox regression was used to examine the association of LV mass, (alone and indexed by height and body surface area [BSA]) as determined by echocardiography, with CVD events, including coronary heart disease (CHD), stroke, heart failure (HF), and CVD death, as well as total mortality. We also assessed the added prediction, discriminative value, and net reclassification improvement (NRI) for clinical utility of LV mass compared to standard risk factors.

RESULTS

Over a mean follow-up of 14.2 ± 6.3 years, 2,180 subjects experienced CVD events, including 986 CVD deaths. After adjustment for age, sex and standard risk factors, LV mass was positively associated with CVD events in those with MetS (hazard ratio [HR]: 1.4, p < 0.001) and without MetS (HR: 1.4, p < 0.001), but not DM (HR: 1.0, p = 0.62), with similar findings for LV mass indexed for height or BSA. Adding LV mass to standard risk factors moderately improved the prediction accuracy in the overall sample and MetS group from changes in C-statistics (p < 0.05). Categorical-free net reclassification improvement increased significantly by 17% to 19% in those with MetS. Findings were comparable for CHD, CVD mortality, and total mortality.

CONCLUSIONS

LV mass is associated with increased CVD risk and provides modest added prediction and clinical utility compared to standard risk factors in older persons with and without MetS but not with DM.

Adenosine transport blockade restores attenuated cardioprotective effects of adenosine preconditioning in the isolated diabetic rat heart: potential crosstalk with opioid receptors

Considering the reduced ability of cardiac fibroblasts to release adenosine and increased ability of interstitial adenosine uptake during diabetes mellitus, the present study investigated the effect of adenosine preconditioning and the existence of cross-talk with opioid receptor activation in the diabetic rat heart subjected to ischemia-reperfusion (I/R). Langendorff-perfused normal and streptozotocin (65 mg/kg, i.p., once)-administered diabetic (after 8-weeks) rat hearts were subjected to 30-min global ischemia and 120-min reperfusion. Myocardial infarct size using triphenyltetrazolium chloride staining, markers of cardiac injury such as lactate dehydrogenase (LDH) and creatine kinase (CK-MB) release, coronary flow rate (CFR) and myocardial oxidative stress were assessed. The diabetic rat heart showed high degree of I/R injury with increased LDH and CK-MB release, high oxidative stress and reduced CFR as compared to the normal rat heart. The adenosine preconditioning (10 μM) afforded cardioprotection against I/R injury in the normal rat heart that was prevented by naloxone (100 μM) pre-treatment. Conversely, adenosine preconditioning-induced cardioprotection was abolished in the diabetic rat heart. However, co-administration of dipyridamole (100 μM), adenosine reuptake inhibitor, markedly restored the cardioprotective effect of adenosine preconditioning in the diabetic rat heart, and this effect was also abolished by naloxone pre-treatment. The reduced myocardial availability of extracellular adenosine might explain the inability of adenosine preconditioning to protect the diabetic myocardium. The pharmacological elevation of extracellular adenosine restores adenosine preconditioning-mediated cardioprotection in the diabetic myocardium by possibly involving opioid receptor activation.