Cardiovascular Risk in Diabetes Mellitus: Complication of the Disease or of Antihyperglycemic Medications.

Cardiovascular disease is the principal complication and the leading cause of death for patients with diabetes (DM). The efficacy of antihyperglycemic treatments on cardiovascular disease risk remains uncertain. Cardiovascular risk factors are affected by antihyperglycemic medications, as are many intermediate markers of cardiovascular disease. Here we summarize the evidence assessing the cardiovascular effects of antihyperglycemic medications with regard to risk factors, intermediate markers of disease, and clinical outcomes.

A quantitative measure of diabetes risk in community practice impacts clinical decisions: the PREVAIL initiative.

BACKGROUND AND AIMS: While predictive tools are being developed to identify those at highest risk for developing diabetes, little is known whether these assays affect clinical care. METHODS AND RESULTS: Thirty sites who used the PreDx(®) (Tethys BioScience, Emeryville, CA) abstracted clinical information from baseline clinic visits prior to a PreDx test and from the most recent visit at time of abstraction. All visits occurred between May 2008-April 2011 (median follow-up 198 days, IQR 124-334). The primary analysis was the influence of the PreDx test (5-year diabetes prediction) on subsequent care; descriptive statistics were used to summarize baseline and follow-up variables. Overall 913 patients with 2 abstracted visits were included. Relative to baseline, median SBP decreased 1.5 mmHg (p = 0.039), DBP decreased 2 mmHg (p < 0.001), LDL-C decreased 4 mg/dL (p = 0.009), and HDL-C increased 2 mg/dL (p < 0.001) at follow-up. Behavioral or lifestyle counseling was not significantly different from baseline to follow-up (71.2% vs. 68.1% (p = 0.077), but BMI was lower by 0.2 kg/m(2) at follow up (p = 0.013). At follow-up, more patients were prescribed metformin (13.7% vs. 9.7%, p < 0.001). A higher PreDx score was significantly associated with metformin prescription (p = 0.0003), lifestyle counseling (p = 0.0099), and a lower BMI at follow-up (p = 0.007). CONCLUSION: The use of a prognostic test in patients perceived to be high risk for diabetes was associated with a modest but significant increase in the prescription of metformin and lifestyle interventions and a reduction in BMI.

Non-traditional risk factors predict coronary calcification in chronic kidney disease in a population-based cohort.

The increased burden of cardiovascular disease in chronic kidney disease cannot be explained by traditional risk factors alone. Here, we evaluated the impact of non-traditional factors on the association of chronic kidney disease with coronary artery calcification using logistic regression among 2672 Dallas Heart Study patients of whom 220 had chronic kidney disease. The prevalence of coronary calcification significantly increased across all chronic kidney disease stages and this remained independently associated with coronary calcification after adjusting for traditional factors. The calcium x phosphorus product, homocysteine, and osteoprotegerin each diminished the magnitude of association between kidney disease and coronary calcification. After adjustment for these, the association between kidney disease and coronary calcification was no longer significant with the effects most prominent in the stages 3-5 subgroup. Our study has identified three non-traditional independent predictors of coronary calcification that diminished the association between chronic kidney disease and coronary calcification. These factors may represent novel mechanistic links warranting further investigation.

A 30-year follow-up of the Dallas Bedrest and Training Study: I. Effect of age on the cardiovascular response to exercise.

BACKGROUND: Cardiovascular capacity declines with aging, as evidenced by declining maximal oxygen uptake (VO(2)max ), with little known about the specific mechanisms of this decline. Our study objective was to assess the effect of a 30-year interval on body composition and cardiovascular response to acute exercise in 5 healthy subjects originally evaluated in 1966. METHODS AND RESULTS: Anthropometric parameters and the cardiovascular response to acute maximal exercise were assessed with noninvasive techniques. On average, body weight increased 25% (77 versus 100 kg) and percent body fat increased 100% (14% versus 28%), with little change in fat-free mass (66 versus 72 kg). On average, VO(2)max decreased 11% (3.30 versus 2.90 L/min). Likewise, VO(2)max decreased when indexed to total body mass (43 versus 31 mL. kg(-1). min(-1)) or fat-free mass (50 versus 43 mL/kg fat-free mass per minute). Maximal heart rate declined 6% (193 versus 181 bpm) and maximal stroke volume increased 16% (104 versus 121 mL), with no difference observed in maximal cardiac output (20.0 versus 21.4 L/min). Maximal AV oxygen difference declined 15% (16.2 versus 13.8 vol%) and accounted for the entire decrease in cardiovascular capacity. CONCLUSIONS: Cardiovascular capacity declined over the 30-year study interval in these 5 middle-aged men primarily because of an impaired efficiency of maximal peripheral oxygen extraction. Maximal cardiac output was maintained with a decline in maximal heart rate compensated for by an increased maximal stroke volume. Most notably, 3 weeks of bedrest in these same men at 20 years of age (1966) had a more profound impact on physical work capacity than did 3 decades of aging.

A 30-year follow-up of the Dallas Bedrest and Training Study: II. Effect of age on cardiovascular adaptation to exercise training.

BACKGROUND: Aerobic power declines with age. The degree to which this decline is reversible remains unclear. In a 30-year longitudinal follow-up study, the cardiovascular adaptations to exercise training in 5 middle-aged men previously trained in 1966 were evaluated to assess the degree to which the age-associated decline in aerobic power is attributable to deconditioning and to gain insight into the specific mechanisms involved. Methods and Results-- The cardiovascular response to acute submaximal and maximal exercise were assessed before and after a 6-month endurance training program. On average, VO(2max) increased 14% (2.9 versus 3.3 L/min), achieving the level observed at the baseline evaluations 30 years before. Likewise, VO(2max) increased 16% when indexed to total body mass (31 versus 36 mL/kg per minute) or fat-free mass (44 versus 51 mL/kg fat-free mass per minute). Maximal heart rate declined (181 versus 171 beats/min) and maximal stroke volume increased (121 versus 129 mL) after training, with no change in maximal cardiac output (21.4 versus 21.7 L/min); submaximal heart rates also declined to a similar degree. Maximal AVDO(2) increased by 10% (13.8 versus 15.2 vol%) and accounted for the entire improvement of aerobic power associated with training. CONCLUSIONS: One hundred percent of the age-related decline in aerobic power among these 5 middle-aged men occurring over 30 years was reversed by a 6-month endurance training program. However, no subject achieved the same maximal VO(2) attained after training 30 years earlier, despite a similar relative training load. The improved aerobic power after training was primarily the result of peripheral adaptation, with no effective improvement in maximal oxygen delivery.

Influence of diabetes mellitus on clinical outcomes across the spectrum of acute coronary syndromes. Findings from the GUSTO-IIb study. GUSTO IIb Investigators.

AIMS: We examined the characteristics, outcomes, and effects of hirudin vs heparin treatment of diabetic patients across the spectrum of acute coronary syndromes. METHODS AND RESULTS: We studied the 12,142 patients enrolled in the randomized GUSTO-IIb study. Diabetic patients (n=2175) were older, more often female, more often had prior cardiovascular disease, hypertension, and hyperlipidaemia, and less often were current smokers. Diabetic patients had a higher overall incidence of death or (re)infarction at 30 days (13.1% vs 8.5%, P=0.0001), whether they presented with ST-segment elevation (13.9% vs 9.9%, P=0.0017) or not (12.8% vs 7.8%, P=0.0001), and at 6 months (18.8% vs 11.4%, P=0.0001). Among diabetic patients, hirudin was associated with a tendency toward a lower risk of death or (re)infarction at 30 days (12.2% vs 13.9% with heparin) and 6 months (17.8% vs 20.2%). Diabetic patients had more major bleeding, stroke, heart failure, shock, atrioventricular block, and atrial arrhythmias, but no increased risk for ocular bleeding. CONCLUSIONS: Diabetic patients with acute coronary syndromes had worse 30-day and 6-month outcomes, particularly those without ST-segment elevation. The statistically non-significant trend toward improved outcomes with hirudin was similar among patients with and without diabetes, with a greater point estimate for the absolute difference in patients with diabetes.

Oral glycoprotein IIb/IIIa antagonists: new insights from the SYMPHONY trial.

Platelet aggregation plays a central role in the pathophysiology of acute coronary syndromes, and the platelet glycoprotein IIb/IIIa receptor has been identified as the critical final mediator of this process. Antagonists of this receptor used parenterally during both acute coronary syndromes and percutaneous coronary interventions reduce the likelihood of subsequent major cardiac complications. However, after the treatment period little further benefit accrues. Based on these observations and that of the significant benefit of aspirin in cardiovascular secondary prevention, oral glycoprotein IIb/IIIa receptor antagonists are being evaluated with the goal of extending the benefit of glycoprotein IIb/IIIa inhibition into chronic secondary prevention. This paper will review the results of the SYMPHONY study of one such oral agent, sibrafiban, and the current state of the oral glycoprotein IIb/IIIa inhibitor field.

Oral platelet glycoprotein IIb/IIIa inhibition.

Platelet aggregation plays a central role in the pathogenesis of thrombosis and the acute coronary syndromes. When given intravenously, potent selective antagonists of fibrinogen binding to the glycoprotein (GP) IIb/IIIa receptor, the final common pathway for platelet aggregation, have been effective in the treatment of acute coronary syndromes. Their benefit ceases, however, with the end of the infusion. Aspirin reduces the incidence of secondary vascular events by 25% to 30% after an acute coronary syndrome, and clopidogrel provides modest improvement over aspirin. However, both are relatively weak antiplatelet agents that each block only one of many pathways to platelet activation and surface membrane expression of the competent GP IIb/IIIa receptor. With the success of the intravenous GP IIb/IIIa antagonists in the acute setting, recent interest has focused on the potential benefit of oral GP IIb/IIIa antagonists used long-term for secondary prevention. The oral agents tested in phase III studies thus far have not performed up to expectations, however. The following paper reviews these studies and the implications of their results.

Determination of secondary structure in the initiation region of ovalbumin mRNA.

We have analyzed the secondary structure in the region surrounding the initiation codons of both cellular and synthetic versions of ovalbumin mRNA. RNase V1 cleavage sites and structure-dependent, chemically modified bases in cellular ovalbumin mRNA were determined by reverse transcription of hen poly A(+) RNA using ovalbumin-specific, synthetic DNA primers. These results indicate an extensive region of unpaired nucleotides preceding the initiation codon and a region of base-paired nucleotides including and following the initiation codon. A synthetic ovalbumin mRNA (SP65.OV) was prepared by run-off transcription of a cloned ovalbumin cDNA (pSP65.OV). Identical regions of hen ovalbumin and SP65.OV mRNAs gave identical patterns of structure-dependent base modifications. A computer program for determining RNA secondary structure was used to find a 5'-region structure for ovalbumin mRNA that is consistent with our data.