Effect of esmolol on oxidant status and antioxidant activity in acute myocardial infarction.

AIMS AND OBJECTIVES: The role of oxygen free radicals in reperfusion injury to the heart in myocardial infarction (MI) has been postulated. In this study, the clinical and antioxidant effects of esmolol, an ultra-short acting beta blocker in patients of acute MI was studied. MATERIAL AND METHODS: This was a randomized, double-blind, controlled, prospective study. Total 30 patients with acute MI were included. All patients were thrombolysed with streptokinase. Fifteen of these patients were randomly selected to receive esmolol while other 15 patients served as controls. The parameters compared at 0, 2 and 24 hours between the esmolol group and the controls were--malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPX). RESULTS: Patients with MI had 5.16 times higher MDA level at 0 hours (20.34 +/- 6.12 nmol/ml vs. 3.94 +/- 0.70 nmol/ml, p < 0.0001) than MDA level in normal healthy population. At 2 hours, patients with MI had 5.71 times higher MDA level compared to normal healthy population (22.51 +/- 5.51 nmol/ml vs. 3.94 +/- 0.70 nmol/ml, p < 0.0001). A statistically significant difference in MDA levels at 2 and 24 hours was observed in MI patients given esmolol (mean change 2.06 +/- 5.39 nmol/ml vs. -4.47 +/- 6.93 nmol/ml, p = 0.009). Esmolol infusion also caused significant difference in GPX level at 2 hours compared to controls (23.79 + 14.68 U/gm Hb vs 38.3 +/- 8.95 U/gm Hb, p = 0.003). CONCLUSION: Free radical levels are raised in patients with MI which may contribute to reperfusion injury. The antioxidant action of esmolol was clearly observed by significant difference in MDA level and GPX sparing effect. Large scale clinical trials may establish conclusively role of beta blockers as antioxidants as adjuvant to thrombolytic therapy in MI.

Insulin resistance, high prevalence of diabetes, and cardiovascular risk in immigrant Asians. Genetic or environmental effect?

OBJECTIVES: To compare the prevalence of diabetes, hyperinsulinaemia, and associated metabolic abnormalities in immigrant Asians, Asians in India, and native white British men. DESIGN: Case control study. SETTING: Wythenshawe Hospital, Manchester, United Kingdom, and Maulana Azad Medical School, New Delhi, India. SUBJECTS: Men with angiographically proved coronary artery disease; 83 British Asians, 87 white men, and 30 Indian Asians with age matched controls. INTERVENTIONS: Fasting lipid concentrations, serum glucose, and total insulin concentrations were measured in the fasting state and one and two hours after a 75 g glucose load by mouth. All subjects had a physical examination by the same observer. RESULTS: Asians in the United Kingdom and in India had a higher prevalence of diabetes and impaired glucose tolerance than the white British men. Patients in all three ethnic groups had higher total insulin concentrations than their controls in the fasting state and after the glucose load. British Asian and Indian Asian patients and controls had higher total insulin concentrations than the white men in the fasting state and after the glucose load. Total insulin concentrations were similar in British and Indian Asians, though fasting concentrations were higher in British Asians than Indian Asians. White men had similar cholesterol, lower triglyceride, and higher high density lipoprotein cholesterol concentrations than Asians in the United Kingdom and in India. British Asian patients had higher cholesterol concentrations and British Asian controls had higher triglyceride concentrations than the Indian Asian groups. Asian patients and controls were more active. British and Indian Asian patients had higher waist to hip ratios than controls. The waist to hip ratio was positively correlated with insulin and triglyceride concentrations and negatively correlated with the high density lipoprotein cholesterol concentration. Fasting insulin and high density lipoprotein concentrations were independent predictors of coronary artery disease in white men, whereas in British Asians the waist to hip ratio was the strongest independent predictor. In Indian Asians the waist to hip ratio and high density lipoprotein concentration were independent predictors of coronary artery disease. CONCLUSIONS: Central obesity in the subgroups of Asians studied showed a close association with hyperinsulinaemia and the risk of coronary artery disease. A predisposition to insulin resistance and its metabolic abnormalities in this group of Asians seems to be genetically determined, environmental changes after migration having only a small additional effect.