Bruce P. Hamilton

Effect of intensive treatment of hyperglycaemia on microvascular outcomes in type 2 diabetes: an analysis of the ACCORD randomised trial

BACKGROUND Hyperglycaemia is associated with increased risk of cardiovascular complications in people with type 2 diabetes. We investigated whether reduction of blood glucose concentration decreases the rate of microvascular complications in people with type 2 diabetes. METHODS ACCORD was a parallel-group, randomised trial done in 77 clinical sites in North America. People with diabetes, high HbA(1c) concentrations (>7.5%), and cardiovascular disease (or >or=2 cardiovascular risk factors) were randomly assigned by central randomisation to intensive (target haemoglobin A(1c) [HbA(1c)] of <6.0%) or standard (7.0-7.9%) glycaemic therapy. In this analysis, the prespecified composite outcomes were: dialysis or renal transplantation, high serum creatinine (>291.7 micromol/L), or retinal photocoagulation or vitrectomy (first composite outcome); or peripheral neuropathy plus the first composite outcome (second composite outcome). 13 prespecified secondary measures of kidney, eye, and peripheral nerve function were also assessed. Investigators and participants were aware of treatment group assignment. Analysis was done for all patients who were assessed for microvascular outcomes, on the basis of treatment assignment, irrespective of treatments received or compliance to therapies. ACCORD is registered with ClinicalTrials.gov, number NCT00000620. FINDINGS 10 251 patients were randomly assigned, 5128 to the intensive glycaemia control group and 5123 to standard group. Intensive therapy was stopped before study end because of higher mortality in that group, and patients were transitioned to standard therapy. At transition, the first composite outcome was recorded in 443 of 5107 patients in the intensive group versus 444 of 5108 in the standard group (HR 1.00, 95% CI 0.88-1.14; p=1.00), and the second composite outcome was noted in 1591 of 5107 versus 1659 of 5108 (0.96, 0.89-1.02; p=0.19). Results were similar at study end (first composite outcome 556 of 5119 vs 586 of 5115 [HR 0.95, 95% CI 0.85-1.07, p=0.42]; and second 1956 of 5119 vs 2046 of 5115, respectively [0.95, 0.89-1.01, p=0.12]). Intensive therapy did not reduce the risk of advanced measures of microvascular outcomes, but delayed the onset of albuminuria and some measures of eye complications and neuropathy. Seven secondary measures at study end favoured intensive therapy (p<0.05). INTERPRETATION Microvascular benefits of intensive therapy should be weighed against the increase in total and cardiovascular disease-related mortality, increased weight gain, and high risk for severe hypoglycaemia. FUNDING US National Institutes of Health; National Heart, Lung, and Blood Institute; National Institute of Diabetes and Digestive and Kidney Diseases; National Institute on Aging; National Eye Institute; Centers for Disease Control and Prevention; and General Clinical Research Centers.

Beneficial effects of metoprolol in heart failure associated with coronary artery disease: a randomized trial.

OBJECTIVES This clinical trial was performed to determine the safety and clinical impact of titrated metoprolol therapy in patients with heart failure, documented coronary artery disease and a low ejection fraction. BACKGROUND Despite known cardiodepressant effects, long-term use of beta-adrenergic antagonists appears to be beneficial in patients with idiopathic dilated cardiomyopathy. However, this therapy has not been critically evaluated in patients with heart failure and coronary artery disease. METHODS In 50 patients with heart failure, known coronary artery disease and an ejection fraction < or = 0.40, we examined the impact of metoprolol therapy in a 6-month double-blind, placebo-controlled randomized trial, assessing the frequency of heart failure exacerbations and changes in symptoms (New York Heart Association functional class), ejection fraction and exercise duration. Placebo-treated patients who completed 6-month follow-up studies then underwent a trial with metoprolol therapy (crossover group). RESULTS Metoprolol was titrated to a mean maximal dose of 87 mg/day (range 25 to 100) without serious adverse reactions. During double-blind therapy, use of a beta-blocker was associated with a significant reduction in the number of hospital admissions (4% vs. 32%, p < 0.05), overall improved functional class (p = 0.02), increased ejection fraction (4 +/- 7% [mean +/- SD] compared with 0 +/- 6%, p < 0.05) and a greater increase in exercise duration (193 +/- 276 vs. 38 +/- 213 s with placebo, p < 0.01). Crossover outcome paralleled the favorable impact seen during randomized metoprolol therapy. CONCLUSIONS Cautious use of titrated metoprolol appears to be safe and beneficial when added to standard heart failure therapy in patients with dilated cardiomyopathy associated with coronary artery disease.

Elevated concentrations of endogenous ouabain in patients with congestive heart failure.

BackgroundAn endogenous digitalis-like compound in mammals has long been postulated, but only recently has a substance indistinguishable from ouabain been identified in human plasma. Because of the potential significance of such a substance in patients with congestive heart failure, we sought to evaluate the pathophysiology of endogenous ouabain in these individuals. Methods and ResultsUsing an immunoassay, we determined plasma ouabain concentrations in 51 patients with heart failure and in 19 control subjects. Plasma ouabain concentrations in control subjects ranged from 0.16 to 0.77 nM (mean, 0.44±0.20 nM). In 19 matched heart failure patients receiving digoxin, the mean ouabain was significantly elevated at 1.59±2.2 nM (range, 0.17–8.76 nM, p < 0.05 versus control subjects). The ouabain concentration correlated inversely with both cardiac index (r = −0.62, p < 0.005) and mean arterial pressure (r = −0.51, p < 0.05). However, there was no correlation between ouabain and left ventricular filling (r = 0.19, NS) or right atrial pressures (r = 0.20, NS). In 16 heart failure patients not receiving digoxin, the mean ouabain was 1.52±2.58 nM. No relation between renal function and ouabain was detected. ConclusionsThe unanticipated lack of correlation of ouabain with atrial pressures indicates that volume is not the chief determinant of ouabain concentration in patients with congestive heart failure. However, the significant relations of plasma ouabain concentration with cardiac index and mean arterial pressure imply that endogenous ouabain may be an important homeostatic factor in humans.

Ouabain-induced hypertension in the rat: relationships among plasma and tissue ouabain and blood pressure.

Objectives To determine the steady-state dose-dependence of blood pressure, plasma and tissue ouabain during continuous infusion of ouabain in the rat, and to evaluate the adrenal dependence and effect of a high salt intake on this form of hypertension. Design and methods Ouabain was administered, via subcutaneous osmotic pumps, to normal and adrenalectomized male Sprague-Dawley rats for 5 weeks. Blood pressure, plasma renin and aldosterone, and circulating and tissue levels of ouabain were determined. Results Following a latent period, blood pressures and circulating ouabain were significantly elevated dose-dependently in glycoside-infused rats at 5 weeks. Upon withdrawal of the ouabain infusion, blood pressure and plasma ouabain levels normalized within 1 week. In rats that received 30

Effect of Intensive Compared With Standard Glycemia Treatment Strategies on Mortality by Baseline Subgroup Characteristics: The Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial

mUg ouabain/kg per day, the circulating, kidney, hypothalamic and anterior pituitary levels of ouabain were increased significantly (by 7-, 15-, 2.8− and 2.1-fold, respectively), whereas the content of other tissues tested was unchanged. Blood pressure and plasma levels of ouabain correlated with hypothalamic and kidney glycoside content in the infused rats. High-performance liquid chromatography of the adrenal, renal, hypothalamic and pituitary extracts showed one major peak of ouabain immunoreactivity, with a retention time equivalent to that of commercial ouabain. Plasma renin activity was normal, whereas aldosterone levels were increased significantly to 2.9− and sevenfold in rats that received 10 and 30

Angiotensin II Stimulates Secretion of Endogenous Ouabain From Bovine Adrenocortical Cells via Angiotensin Type 2 Receptors

mUg ouabain/kg per day, respectively. Dietary salt loading suppressed aldosterone and did not exacerbate hypertension. In bilaterally adrenalectomized rats the ambient circulating and kidney levels of ouabain were low and ouabain infusion raised glycoside levels and blood pressure significantly. Conclusions Prolonged infusion of ouabain in the normal rat raises the circulating, kidney, hypothalamic and anterior pituitary levels and induces a reversible hypertension with normal plasma renin activity. Although characterized by raised aldosterone levels, the hypertension does not require the adrenal glands and is not salt-sensitive. This model may be useful for exploring novel mechanisms of long-term regulation of blood pressure.

Effect of intensive compared with standard glycemia treatment strategies on mortality by baseline subgroup characteristics: The ACCORD trial

OBJECTIVE To determine if baseline subgroups in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial can be identified for whom intensive compared with standard glycemia treatment had different effects on all-cause mortality. RESEARCH DESIGN AND METHODS Exploratory post hoc intention-to-treat comparisons were made between intensive and standard glycemia groups on all-cause mortality by subgroups defined by baseline characteristics. RESULTS There were few significant interactions between baseline characteristics and effects of intensive versus standard glycemia treatment on mortality: self-reported history of neuropathy (hazard ratio [HR] 1.95, 95% CI 1.41–2.69) versus no history of neuropathy (0.99, 0.79–1.26; P value for interaction 0.0008), higher A1C (A1C >8.5%: HR 1.64, 95% CI 1.22–2.22; A1C 7.5–8.4%: 1.00, 0.75–1.34; A1C <7.5%: 1.00, 0.67–1.50; P value for interaction 0.04), and aspirin use (HR 1.45, 95% CI 1.13–1.85, compared with 0.96, 0.72–1.27, in nonusers; P value for interaction 0.03). CONCLUSIONS We found a remarkable similarity of effect from intensive compared with standard glycemia treatment on mortality across most baseline subgroups. No differential effect was found in subgroups defined by variables anticipated to have an interaction: age, duration of diabetes, and previous history of cardiovascular disease. The three baseline characteristics that defined subgroups for which there was a differential effect on mortality may help identify patients with type 2 diabetes at higher risk of mortality from intensive regimens for glycemic control. Further research is warranted.

Clinical Outcomes by Race in Hypertensive Patients With and Without the Metabolic Syndrome: Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)

Angiotensin II stimulates secretion of corticosteroids and ouabain-like activity from adrenocortical cells. Distinct adrenocortical angiotensin II receptor subtypes (AT1, AT2) have been described, and the present studies investigated their roles in steroid secretion. Using primary bovine adrenocortical cell cultures under serum free conditions, angiotensin II stimulated the secretions of aldosterone, cortisol, and endogenous ouabain as verified by high-performance chromatography. The dose-response curves for stimulated steroid secretion were parallel with unitary slopes while the half-maximally effective concentrations of angiotensin II were 0.31 to 0.38 nmol/L for secretions of aldosterone and cortisol and 2.3 nmol/L for endogenous ouabain. The nonselective mammalian antagonist (Sar1-Ile8) angiotensin II blocked stimulated secretion of all three steroids without affecting basal output. In the presence of the AT1 antagonist DuP753, angiotensin II-stimulated secretions of aldosterone and cortisol were blocked while secretion of endogenous ouabain was unaffected. In the presence of the AT2 antagonist PD123319, both basal and angiotensin II-stimulated secretions of aldosterone and cortisol were normal while stimulated secretion of endogenous ouabain was inhibited. The secretion of endogenous ouabain was activated maximally by the AT2 agonist CGP42112 under conditions in which aldosterone secretion was unaffected. These results demonstrate that AT2 receptors stimulate secretion of endogenous ouabain from bovine adrenocortical cells. The specificity of AT1 and AT2 receptor stimulation indicates that separate signaling mechanisms having minimal cross talk control the adrenocortical secretions of corticosteroids and cardiac-active steroids. Adrenocortical AT2 receptors may be important in the adaptation to low salt diets and other conditions in which angiotensin II is increased.

Intensive Glycemic Control Is Not Associated With Fractures or Falls in the ACCORD Randomized Trial

OBJECTIVE To determine if baseline subgroups in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial can be identified for whom intensive compared with standard glycemia treatment had different effects on all-cause mortality. RESEARCH DESIGN AND METHODS Exploratory post hoc intention-to-treat comparisons were made between intensive and standard glycemia groups on all-cause mortality by subgroups defined by baseline characteristics. RESULTS There were few significant interactions between baseline characteristics and effects of intensive versus standard glycemia treatment on mortality: self-reported history of neuropathy (hazard ratio [HR] 1.95, 95% CI 1.41–2.69) versus no history of neuropathy (0.99, 0.79–1.26; P value for interaction 0.0008), higher A1C (A1C >8.5%: HR 1.64, 95% CI 1.22–2.22; A1C 7.5–8.4%: 1.00, 0.75–1.34; A1C <7.5%: 1.00, 0.67–1.50; P value for interaction 0.04), and aspirin use (HR 1.45, 95% CI 1.13–1.85, compared with 0.96, 0.72–1.27, in nonusers; P value for interaction 0.03). CONCLUSIONS We found a remarkable similarity of effect from intensive compared with standard glycemia treatment on mortality across most baseline subgroups. No differential effect was found in subgroups defined by variables anticipated to have an interaction: age, duration of diabetes, and previous history of cardiovascular disease. The three baseline characteristics that defined subgroups for which there was a differential effect on mortality may help identify patients with type 2 diabetes at higher risk of mortality from intensive regimens for glycemic control. Further research is warranted.

Blood Pressure Control by Drug Group in the Antihypertensive and Lipid‐Lowering Treatment to Prevent Heart Attack Trial (ALLHAT)

BACKGROUND Antihypertensive drugs with favorable metabolic effects are advocated for first-line therapy in hypertensive patients with metabolic/cardiometabolic syndrome (MetS). We compared outcomes by race in hypertensive individuals with and without MetS treated with a thiazide-type diuretic (chlorthalidone), a calcium channel blocker (amlodipine besylate), an alpha-blocker (doxazosin mesylate), or an angiotensin-converting enzyme inhibitor (lisinopril). METHODS A subgroup analysis of the Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial (ALLHAT), a randomized, double-blind hypertension treatment trial of 42 418 participants. We defined MetS as hypertension plus at least 2 of the following: fasting serum glucose level of at least 100 mg/dL, body mass index (calculated as weight in kilograms divided by height in meters squared) of at least 30, fasting triglyceride levels of at least 150 mg/dL, and high-density lipoprotein cholesterol levels of less than 40 mg/dL in men or less than 50 mg/dL in women. RESULTS Significantly higher rates of heart failure were consistent across all treatment comparisons in those with MetS. Relative risks (RRs) were 1.50 (95% confidence interval, 1.18-1.90), 1.49 (1.17-1.90), and 1.88 (1.42-2.47) in black participants and 1.25 (1.06-1.47), 1.20 (1.01-1.41), and 1.82 (1.51-2.19) in nonblack participants for amlodipine, lisinopril, and doxazosin comparisons with chlorthalidone, respectively. Higher rates for combined cardiovascular disease were observed with lisinopril-chlorthalidone (RRs, 1.24 [1.09-1.40] and 1.10 [1.02-1.19], respectively) and doxazosin-chlorthalidone comparisons (RRs, 1.37 [1.19-1.58] and 1.18 [1.08-1.30], respectively) in black and nonblack participants with MetS. Higher rates of stroke were seen in black participants only (RR, 1.37 [1.07-1.76] for the lisinopril-chlorthalidone comparison, and RR, 1.49 [1.09-2.03] for the doxazosin-chlorthalidone comparison). Black patients with MetS also had higher rates of end-stage renal disease (RR, 1.70 [1.13-2.55]) with lisinopril compared with chlorthalidone. CONCLUSIONS The ALLHAT findings fail to support the preference for calcium channel blockers, alpha-blockers, or angiotensin-converting enzyme inhibitors compared with thiazide-type diuretics in patients with the MetS, despite their more favorable metabolic profiles. This was particularly true for black participants.