Insulin, Indian origin and ischaemic heart disease

Serum Apo A-1 and Its Role as a Biomarker of Coronary Artery Disease

Objectives

To evaluate the role of apolipoprotein(Apo A-1) as a biomarker of coronary artery disease (CAD) and its comparison with the traditional marker high-density lipoprotein (HDL).

Methodology

One hundred patients proven to have coronary artery disease by angiography were recruited and their serum biomarkers were compared with 100 normal individuals adjusted for age and sex.

Result

The mean +/-standard deviation (SD) value of plasma Apo A-1 levels in the normal individuals were observed to be 207.42 +/- 41.35 (mg/dL) against 90.69 +/- 20.77 (mg/dL) in the cardiac patients. On the other hand the serum HDL levels were 52.93 +/-33.58 (mg/dL) in the normal individuals and 37.86 +/- 23.19 (mg/dL) in the cardiac patients. Both of these differences were statistically significant (p < 0.001). For Apo A-1, a large proportion of patients (85%) were found to be in the abnormal range when compared to the control group in which only 7% had an abnormal value. For HDL, a majority (70%) of the cardiac patients had abnormal values while 40% of the normal individuals also had abnormal values. The sensitivity of Apo A-1 for detecting CAD was 85%, while for HDL, it was only 69%. Similarly, the specificity of Apo A-1 for detecting CAD was 93%, while for HDL, it was 60%. When plotted on a receiver operating characteristic (ROC) curve, Apo A-1 had a much larger area under the curve when compared to HDL.

Conclusion

This study suggests that Apo A-1 may, in fact, be more sensitive than HDL as a predictor of CAD. However, to completely elucidate its role as a biomarker, to set target serum levels and to increase its clinical use, further studies are required.

Effect of pioglitazone and its combination with statins in coronary artery disease patients with hyperinsulinemia

The objective of the study was to demonstrate the effect of pioglitazone and pioglitazone in combination with statin on East Indian patients with hyperinsulinemia and hyperlipidemia. It was a randomized, placebo-controlled, double-blind study with a parallel-group design comprising 83 patients. Patients of either sex with cardiac complications, including hyperlipidemia and (or) diabetes mellitus with or without hyperinsulinemia, were enrolled. Patients over 70 years of age, with renal or hepatic failure, or with severe diabetes mellitus (total glucose >400 mg/dL) were excluded from the study. Enrolled patients were randomly assigned to 4 groups that received placebo, pioglitazone, atorvastatin, or both. Blood samples were collected before and after treatment for analysis of serum glucose, insulin, lipid profile, apolipoprotein (apo) A1, apo B, and fibrinogen. Data were compared with that of patients with normal insulin or hyperinsulinemia. The patients with hyperinsulinemia receiving only pioglitazone showed a significant decrease in insulin levels compared with those with normal insulin levels. These patients also showed a significant increase in HDL levels. However, no significant change was observed in patients treated with both atorvastatin and pioglitazone. Pioglitazone was also found to increase significantly the apo A1 levels in patients with hyperinsulinemia, but there was no significant increase in patients given both atorvastatin and pioglitazone. Our data suggests that pioglitazone should be given preferably to the patients with hyperinsulinemia and statin should not be coadministered.

Correlation of lipoprotein (a) to angiographically defined coronary artery disease in Indians

Lipoprotein (a) [Lp(a)] levels have been correlated with angiographically defined coronary artery disease (CAD). Pattern of Lp(a) distribution in various racial groups is different. To study this relationship in Indian patients, plasma levels of Lp(a) and other lipid values were assessed in 101 patients undergoing coronary arteriography. Lp(a) concentration was higher in CAD group (n = 77) compared to normal coronary artery group (n = 24) (26.83 +/- 22.09 mg/dl vs. 15.07 +/- 14.61 mg/dl, P < 0.05). Lp(a) values had graded association with CAD. In Lp(a) quartile of < 5 mg/dl, 66.7% patients had CAD; in Lp(a) quartile of 5-25 mg/dl, 69.0% had CAD; Lp(a) quartile of 26-75 mg/dl, 87.5% had CAD; and in Lp(a) quartile of > or = 76 mg/dl, all patients had CAD. High density lipoprotein (HDL) cholesterol was higher in the normal coronary artery group as compared to CAD group (45.25 +/- 8.26 mg/dl vs. 41.83 +/- 16.47 mg/dl; NS). In HDL quartile of < 35 mg/l, 88.9% patients had angiographically defined CAD. Plasma values of total cholesterol, triglycerides (TG), apolipoprotein-A1 (Apo-A1), apolipoprotein-B (Apo-B), low density lipoprotein (LDL) cholesterol, LDL/HDL cholesterol ratio and Apo A1/B ratio were not significantly different in the groups with normal coronary arteries and CAD. Our results indicate that the measurement of Lp(a) provides a better marker for predicting the presence of angiographically defined CAD as compared to traditional measures.

Relationship of diet, abdominal obesity, and physical activity to plasma lipoprotein levels in Asian Indian physicians residing in the United States

OBJECTIVE

To examine the relationship of total fat, saturated fat, carbohydrate and energy intake, leisure-time activity, waist-to-hip ratio (WHR), and body mass index to the prevalence of atherogenic plasma triglyceride (TG) and high-density lipoprotein cholesterol (HDL-C) levels in Asian Indians living in the United States. High plasma TG and low HDL-C levels have been documented in Asian Indians worldwide.

DESIGN

This exploratory study examined medical history, demographics, anthropometrics, plasma lipids levels, food intake frequency, and self-reported leisure-time activity.

SUBJECTS

153 Asian Indian male physicians (mean age=47 years) were recruited at two annual national conferences of the American Association of Physicians from India, with free medical assessments as incentives.

STATISTICAL ANALYSES PERFORMED

Correlational and multiple regression analyses were performed.

RESULTS

Subjects' diets averaged 56% energy from carbohydrate, 32% from total fat, and 8% from saturated fat. High total fat intake was associated with high WHR (r=.21, P<.01) and high total carbohydrate intake (grams per day) was associated with high TG level (r=.24, P<.05). Leisure-time activity averaged 136 minutes/week and negatively correlated with total plasma cholesterol level (r=.22, P<.01) and low-density lipoprotein cholesterol level (r=.25, P<.001).

APPLICATIONS

Dietitians should recommend moderate dietary carbohydrate intake and meal patterns with energy distributed throughout the day, in addition to decreasing fat consumption, to Asian Indian clients at risk for coronary artery disease. High carbohydrate intake and uneven diurnal distribution (no breakfast and large evening meals) are associated with high TG and low HDL-C levels in this population.

The risk of hospitalization for ischemic heart disease among Asian Americans in northern California

To supplement sparse data about ischemic heart disease in Asian Americans, hospitalization risk was prospectively examined in a group of Asian Americans living in Northern California. Analyses used Cox models with ischemic heart disease risk traits as covariables. With Whites as the referent category, relative risks by ethnic group were as follows: Chinese, 0.6 (P = .001); Japanese, 1.0 (P = .97); Filipinos, 1.0 (P = .95); South Asians, 3.7 (P < .001); other Asian Americans, 0.8 (P = .55). Thus, unexplained differences in ischemic heart disease risk exist among Asian-American ethnic groups, with Chinese Americans at lowest risk and persons of South Asian origin at highest risk.

Plasma levels of apolipoproteins A-1 and B in Indian patients with angiographically defined coronary artery disease

Apolipoproteins A-1 and B concentration were measured in 201 Indian patients (32 females; 169 males) undergoing elective diagnostic coronary arteriography in order to assess the predictive power of apolipoproteins as a 'marker' of coronary artery disease (CAD). This association was also compared to that of other traditional risk factors: age, hypertension, diabetes, family history, smoking and plasma levels of total cholesterol, triglycerides, low and high density lipoproteins. The apolipoprotein (Apo) A-1 levels averaged 82.9 +/- 18.9 mg/dl in the normal coronary group (n = 43) and 76.0 +/- 18.1 mg/dl in the group with coronary artery disease (n = 158). The average Apo B levels in the normal coronary group and coronary artery disease group were 67.8 +/- 17.7 mg/dl and 78.9 +/- 19.5 mg/dl, respectively. Overall Apo B and triglyceride levels (of all lipid measures) showed larger univariate difference between the normal group (no coronary artery disease) and the group with coronary artery disease. The variable with strongest predictive power for coronary artery disease was the ratio of Apo A-1 to Apo B. These findings were confirmed using multiple logistic regression analysis adjusting for age and other traditional risk factors. Our results indicate that the measurement of apolipoproteins A-1 and B provide a better marker for predicting the presence of coronary artery disease as compared to traditional lipid measures. Overall the levels of these apolipoproteins seem to be lower in Indian population as compared to those reported from the West.