Relationship of lipoprotein(a) with intimal medial thickness of the carotid artery in Type 2 diabetic patients in south India

OBJECTIVE

The objective of this study was to investigate the association of lipoprotein(a) [Lp(a)] levels with intimal medial thickness (IMT) in Type 2 diabetic patients in south India.

STUDY DESIGN

We studied 587 consecutive Type 2 diabetic patients at the M.V. Diabetes Specialities Centre, Chennai. The mean age of the study group was 55 +/- 10 years and 71.2% were males. IMT of the right common carotid artery was determined using high-resolution B mode ultrasonography. Lp(a) levels were measured using ELISA. Since the frequency distribution of Lp(a) was skewed, Lp(a) values were log transformed and the geometric mean was used for statistical analysis. The tertiles of IMT were determined to analyse the association of Lp(a) and other factors with IMT.

RESULT

The mean Lp(a) level in the study patients was 18.9 +/- 3.1 mg/dl (geometric mean +/- sd) and the mean IMT of the study subjects was 0.93 +/- 0.19 mm (mean +/- sd). The prevalence of carotid atherosclerosis (defined as IMT > 1.1 mm) among subjects with elevated Lp(a) levels > 20 mg/dl was significantly higher compared with those with Lp(a) levels </= 20 mg/dl (26.9% vs. 16.3%, P = 0.003). Lp(a) levels increased with increase in tertiles of IMT (anova, P < 0.05). Pearson correlation analysis of carotid IMT with other cardiovascular risk factors revealed strong correlation of IMT with age (P < 0.0001), duration of diabetes (P < 0.0001), systolic blood pressure (P < 0.0001), diastolic blood pressure (P = 0.006), LDL-cholesterol (P = 0.023), HbA1c (P = 0.017) and Lp(a) (P < 0.0001). Multiple logistic regression analysis showed age (P = 0.010), LDL-cholesterol (P = 0.032) and Lp(a) (P = 0.021) to be associated with carotid atherosclerosis.

CONCLUSION

The results suggest that Lp(a) has a strong association with IMT of carotid arteries in Type 2 diabetic subjects in south India.

Coronary artery disease epidemic in Indians: a cause for alarm and call for action

Coronary artery disease (CAD) rates in urban areas in India are now 4-fold higher than in the United States (US) although the rates were similar in 1968. Both overseas and resident Indians have the highest rates of CAD, although almost half of them are life-long vegetarians. When compared to Whites, Blacks, Hispanics and other Asians, CAD rates among Indians worldwide are two to four times higher at all ages and five to ten times higher in those < 40 years of age. Although CAD is a fatal disease with no known cure, it is also highly predictable, preventable, and treatable. During the past 30 years, CAD rates halved in the US, Australia, Canada, France, Japan, and Finland. These vast reductions in CAD mortality are attributed to nationwide changes in specific risk factors that were identified through epidemiological research and addressed through population-based interventions, rather than extensive use of expensive technology. Reduction in risk factors explains most of the decline with modest contributions from advances in treatment. Ironically, the CAD rates doubled in India during the same period, primarily due to dietary changes associated with epidemiological transition from a rural sustenance economy to an urban market oriented economy. The impact of such changes appears to be greater in Indians than in other populations due to a genetic predisposition. Significant decline of CAD is readily achievable in India, by adopting a combined population-wide and high-risk primary prevention strategy. This requires concerted action by the medical profession, govemment, media, and the public.

Lipoprotein(a) in coronary heart disease: a case-control study

To determine the significance of lipoprotein(a) levels in coronary heart disease patients, a case-control study was performed with 48 newly diagnosed coronary heart disease patients and 23 controls who were evaluated using clinical history and biochemical examination. Lipoprotein(a) was measured by quantitative latex-enhanced immunoturbidimetric method. Geometric means of biochemical parameters were obtained. Comprehensive lipid tetrad index was calculated using a previously validated formula. There was no significant difference in prevalence of diabetes, hypertension and smoking in cases and controls. Dietary intake of calories, fats, fatty acids and antioxidant vitamins was also similar. The levels of fasting glucose, cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol and triglycerides were not significantly different in cases and controls (p > 0.05). Low-density lipoprotein/high-density lipoprotein ratio (4.33 +/- 1.5 vs 4.29 +/- 1.8) and total cholesterol/high-density lipoprotein ratio (6.59 + 1.7 vs 6.69 +/- 2.2) were similar. The mean lipoprotein(a) levels were significantly greater in cases (11.95 +/- 2.8 mg/dL, range 1-102 mg/dL) as compared to controls (6.68 +/- 3.4 mg/dL, range 1-73 mg/dL) (t = 2.08, p = 0.041). As compared to controls, in coronary heart disease cases, mean lipoprotein(a) levels in patients upto 50 years (10.27 +/- 2.8 vs 7.27 +/- 3.4 mg/dL) as well as those over 50 years (12.99 +/- 2.9 vs 4.91 +/- 3.5 mg/dL) were significantly more (p < 0.05). Coronary heart disease patients had a slightly greater prevalence of high lipoprotein(a) levels, 20 mg/dL or more (31.3 vs 13.0%; chi 2 = 2.83, l-tailed p < 0.05). Comprehensive lipid tetrad index (total cholesterol x triglycerides x lipoprotein(a) divided by high-density lipoprotein cholesterol) was also slightly higher in cases (14688.2 +/- 3.6) than in controls (8358.2 +/- 4.3) (t = 1.68, 1-tailed p < 0.05). This study shows that lipoprotein(a) levels are significantly more in both younger and older coronary heart disease patients as compared to controls.

Lipoprotein(a) is an independent risk factor for coronary artery disease in NIDDM patients in South India

OBJECTIVE

Asian Indians have been reported to have very high prevalence rates of coronary artery disease (CAD) in the absence of traditional risk factors. Recently, elevated levels of lipoprotein(a) [Lp(a)] have been reported to be associated with premature CAD in migrant Asian Indians. However, there are very little data regarding Lp(a) in CAD patients from the Indian subcontinent and virtually none in individuals with NIDDM. The objective of this study was to assess the role of Lp(a) as a marker for CAD in South Indian NIDDM patients.

RESEARCH DESIGN AND METHODS

We estimated serum Lp(a) in 100 control subjects, 100 NIDDM patients without CAD, and 100 NIDDM patients with CAD. Lp(a) values were transformed into natural logarithms. Statistical analysis included Student's t test, one-way analysis of variance, and chi2 test. Multiple logistic regression analysis was used to identify associations with CAD.

RESULTS

Lp(a) levels were significantly higher in NIDDM patients with CAD compared with NIDDM patients without CAD and control subjects (geometric mean 24.6, 15.1, and 19.4 mg/dl, respectively, P < 0.05). Results of logistic regression analysis showed that Lp(a), age, and HDL were associated with CAD. In NIDDM patients with CAD, there was no correlation between Lp(a) and serum cholesterol, triglyceride, or HDL cholesterol levels, but there was a weak association with LDL cholesterol and systolic blood pressure.

CONCLUSIONS

The data suggests that serum Lp(a) is an independent risk factor for CAD in NIDDM patients in South India.

Elevated lipoprotein(a) levels in South Asians in North America

This report demonstrates that South Asians living in North America have elevated levels of Lp(a) compared with North American whites. Elevated Lp(a) levels may account, in part, for the tendency of South Asians to develop premature coronary heart disease (CHD).

Cooking oils, cholesterol and CAD: facts and myths

Elevated blood cholesterol is the strongest risk factor for coronary artery disease, and dietary excess of saturated fats is its largest contributor. Contrary to common belief, the contribution of dietary cholesterol to blood cholesterol is small. As a matter of fact, one need not consume cholesterol to have high blood cholesterol. Most vegetable cooking oils are low in saturated fats and are "heart healthy" with the important exception of tropical oils, such as coconut and palm oil, which are very rich in saturated fats. Though these oils contain no cholesterol, their cholesterol-raising potential is similar to or higher than most animal fats. Liberal use of these oils should be discouraged.

Coronary heart disease and its risk factors in first-generation immigrant Asian Indians to the United States of America

The prevalence of coronary heart disease (CHD) and its risk factors in first-generation Asian Indian immigrants to the United States of America (US) were compared with those of the native Caucasian population. A total of 1688 Asian Indian physicians and their family members (1131 men and 557 women, age > or = 20 years) completed a questionnaire and in 580 subjects serum lipoproteins were determined. The age-adjusted prevalence of myocardial infarction and/or angina was approximately three times more in Asian Indian men compared to the Framingham Offspring Study (7.2% versus 2.5%; P < 0.0001) but was similar in women (0.3% versus 1%; p = 0.64). Asian Indians had higher prevalence of noninsulin-dependent diabetes mellitus (NIDDM; 7.6% versus 1%; p < 0.0001) but markedly lower prevalence of cigarette smoking (1.3% versus 27%; p < 0.0001) and obesity (4.2% versus 22%; p < 0.0001). Hypertension was less prevalent in Asian Indian men 14.2% versus 19.1%, p < 0.008) but similar in women (11.3% versus 11.4%). The prevalence of elevated total a low-density lipoprotein (LDL) cholesterol levels was similar in men [17% versus 23.4% (p = 0.24) and 13.7% versus 22.3% (p = 0.22), respectively] but lower in women [15% versus 26.1% (p = 0.018) and 14.3% versus 19.6% (p = 0.047) respectively]. The mean levels of high-density lipoprotein (HDL) cholesterol were less in younger (30-39 years) Asian Indian men (mean: 0.98 versus 1.18 mmol/l; p < 0.001) and middle-aged (30-59 years) women (mean: 1.24 versus 1.45 mmol/l; p < 0.001). The prevalence of hypertriglyceridaemia was similar in men (18.5% versus 11.3%), but higher in Asian Indian women (8.3% versus 4.1%, p = 0.02). To conclude, immigrant Asian Indian men to the US have high prevalence of CHD, NIDDM, low HDL cholesterol levels and hypertriglyceridaemia. All these have "insulin resistance" as a common pathogenetic mechanism and seem to be the most important risk factors.

Physico-chemical properties of low density lipoproteins in normolipidemic Asian Indian men

The present study investigated whether a predisposition to high frequency of small, dense low density lipoproteins (LDL) could be an additional coronary risk factor in migrant Asian Indians. Ninety-three normolipidemic (fasting plasma cholesterol levels < or = 240 mg/dl and triglyceride levels < or = 250 mg/dl) adult Asian Indian men residing in the U.S. were compared to a group of 59 Caucasian men for the prevalence of LDL electrophoretic patterns A and B (size of major LDL peak > or = 255 A for LDL pattern A and < 255 A for LDL pattern B). Compared to the Caucasians, the Asian Indians had larger LDL size (mean +/- SD; 260.1 +/- 12.8 A vs 267.7 +/- 11.4 A, respectively; p = 0.0002), an increased frequency of LDL pattern A (59% vs 85%, respectively) and a lower frequency of LDL pattern B (41% vs 15%, respectively) (p = 0.0005). The difference in LDL size in the two study groups persisted after adjusting for the various confounding variables, such as age, plasma triglycerides, high-density lipoprotein cholesterol and dietary habits. We conclude that compared to Caucasians, Asian Indian men have larger LDL particles and a lower prevalence of LDL phenotype B in the presence of normolipidemia. Therefore, we exclude a genetic predisposition to atherogenic LDL phenotype as a factor contributing to the high incidence of coronary heart disease in migrant Asian Indians.

Malignant coronary artery disease in young Asian Indians: thoughts on pathogenesis, prevention, and therapy. Coronary Artery Disease in Asian Indians (CADI) Study

Asian Indians have the highest rates of coronary artery disease (CAD) of any ethnic group studied, despite the fact that nearly half of this group are life-long vegetarians. CAD occurs early in age and generally follows a malignant course. Although the incidence of classic risk factors is low, high triglyceride and low high-density lipoprotein cholesterol levels, high lipoprotein(a) levels, hyperinsulinemia, and apple-type obesity all show a substantial prevalence in this population. Aggressive modification of life style beginning before adolescence seems justified in view of the malignant nature of CAD in this population. Pharmacologic intervention similar to that of secondary prevention of CAD seems justified as primary prevention in high-risk Asian Indians.