Impaired fibrinolysis and increased fibrinogen levels in South Asian subjects

The efficacy and safety of intravenous administration of tranexamic acid in patients undergoing cardiac surgery: Evidence from a single cardiovascular center

BACKGROUND

The current study was performed to systemically review the efficacy and safety of tranexamic acid (TXA) in patients undergoing cardiac surgery at a single large-volume cardiovascular center.

METHODS

A computerized search of electronic databases was performed to identify all relevant studies using search terms till December 31st, 2021. The primary outcomes were postoperative blood loss and the composite incidence of mortality and morbidities during hospitalization. Secondary outcomes included postoperative massive bleeding and transfusion, postoperative recovery profiles, coagulation functions, inflammatory variables, and biomarkers of vital organ injury.

RESULTS

Database search yielded 23 qualified studies including 27,729 patients in total. Among them, 14,136 were allocated into TXA group and 13,593 into Control group. The current study indicated that intravenous TXA significantly reduced total volume of postoperative bleeding in both adult and pediatric patients, and that medium- and high-dose TXA were more effective than low-dose TXA in adult patients (P < .05). The current study also demonstrated that intravenous TXA, as compared to Control, remarkably reduced postoperative transfusion incidences and volume of red blood cell and fresh frozen plasma, and reduced postoperative transfusion incidence of platelet concentrates (PC) (P < .05) without obvious dose-effects (P > .05), but TXA did not reduce PC transfusion volume postoperatively in adult patients (P > .05). For pediatrics, TXA did not significantly reduce postoperative transfusion incidence and volume of allogenic red blood cell, fresh frozen plasma and PC (P > .05). Additionally, the current study demonstrated that intravenous TXA did not influence the composite incidence of postoperative mortality and morbidities in either adults or pediatrics during hospitalization (P > .05), and that there was no obvious dose-effect of TXA in adult patients (P > .05).

CONCLUSIONS

This current study suggested that intravenous TXA significantly reduced total volume of postoperative bleeding in both adult and pediatric patients undergoing cardiac surgery at the single cardiovascular center without increasing the composite incidence of mortality and morbidities.

Generalizability of the REDUCE-IT trial to South Asians with cardiovascular disease

BACKGROUND

South Asians (SAs) represent ∼25% of the world's population and account for >50% of global cardiovascular (CV) deaths, yet they continue to be underrepresented in contemporary clinical trials. The REDUCE-IT study demonstrated in a high-risk and predominantly White population that icosapent ethyl (IPE) lowered major adverse cardiovascular events by 25%. We sought to determine the generalizability of these results to a high-risk population of SAs with established CV disease living in Canada.

METHODS

This was a cross-sectional observational study of 200 statin-treated SAs (≥45 years) with atherosclerotic CV disease (ASCVD) (NCT05271591). SA ethnicity was self-identified as being of Anglo-Indian, Bangladeshi, Bengali, Bhutanese, Goan, Gujarati, Indian, Jatt, Kashmiri, Maharashtrian, Malayali, Nepali, Pakistani, Punjabi, Sindhi, Sinhalese, Sri Lankan, Tamil, Telugu, or other SA. ASCVD was defined as the presence of coronary, carotid, or peripheral atherosclerosis.

FINDINGS

Mean age of the cohort was 67 years, where 82% were men and 57% had diabetes. The predominant ASCVD phenotype was coronary artery disease (94%). Mean (SD) baseline LDL-C and triglycerides were 1.70 (0.8) mmol/L and 1.42 (1.0) mmol/L, respectively. Three-quarters were on high-intensity statin therapy. According to the Health Canada/Canadian Cardiovascular Society Guidelines and FDA-approved indication, 33% and 25% of the participants were, respectively, eligible for IPE.

CONCLUSIONS

A large proportion of high-intensity, statin-treated, high-risk patients with ASCVD and of self-reported SA ethnicity are eligible for IPE. These data have important translational implications for SAs who are at a disproportionately higher risk of CV morbidity and mortality.

FUNDING

This study was funded by an unrestricted grant provided by HLS Therapeutics Inc, Canada.

Tranexamic acid reduces postoperative blood loss in Chinese pediatric patients undergoing cardiac surgery: A PRISMA-compliant systematic review and meta-analysis

BACKGROUND

Tranexamic acid has been increasingly used for blood conservation in cardiac surgery. However, the evidence supporting the routine use of tranexamic acid in Chinese pediatric patients undergoing cardiac surgery remains weak. This meta-analysis aimed to systematically review the efficacy of tranexamic acid when applying to Chinese pediatric patients undergoing cardiac surgery.

PARTICIPANTS

Chinese pediatric patients undergoing cardiac surgery.

INTERVENTIONS

Tranexamic acid or control drugs (saline/blank).

METHODS

PUBMED, Cochrane Library, EMBASE, China National Knowledge Infrastructure (CNKI), Wanfang Data, and VIP Data till May 4, 2021, database search was updated on August 1. Primary outcomes of interest included postoperative bleeding, allogeneic transfusion, and reoperation for bleeding. Secondary outcomes of interest included postoperative recovery. For continuous/dichotomous variables, treatment effects were calculated as weighted mean difference (WMD)/odds ratio and 95% confidence interval.

RESULTS

A database search yielded 15 randomized controlled trials including 1641 patients, where 8 studies were allocated into non-cyanotic congenital group, 5 were allocated into cyanotic congenital group, and the other 2 were allocated into combined cyanotic/non-cyanotic group. This meta-analysis demonstrate that tranexamic acid administration can reduce the postoperative 24 hours blood loss in non-cyanotic, cyanotic, and combined cyanotic/non-cyanotic patients, the red blood cell transfusion in non-cyanotic and cyanotic patients, and the fresh frozen plasma transfusion in non-cyanotic and combined cyanotic/non-cyanotic patients.

CONCLUSION

This meta-analysis demonstrates that tranexamic acid is highly effective in reducing the blood loss in Chinese pediatric cardiac surgery, but it behaves poorly when it comes to the transfusion requirement. To further confirm this, more well-designed and adequately-powered randomized trials are needed.

Managing cardiovascular disease risk in South Asian kidney transplant recipients

South Asians (SA) are at higher cardiovascular risk than other ethnic groups, and SA kidney transplant recipients (SA KTR) are no exception. SA KTR experience increased major adverse cardiovascular events both early and late post-transplantation. Cardiovascular risk management should therefore begin well before transplantation. SA candidates may require aggressive screening for pre-transplant cardiovascular disease (CVD) due to their ethnicity and comorbidities. Recording SA ethnicity during the pre-transplant evaluation may enable programs to better assess cardiovascular risk, thus allowing for earlier targeted peri- and post-transplant intervention to improve cardiovascular outcomes. Diabetes remains the most prominent post-transplant cardiovascular risk factor in SA KTR. Diabetes also clusters with other metabolic syndrome components including lower high-density lipoprotein cholesterol, higher triglycerides, hypertension, and central obesity in this population. Dyslipidemia, metabolic syndrome, and obesity are all significant CVD risk factors in SA KTR, and contribute to increased insulin resistance. Novel biomarkers such as adiponectin, apolipoprotein B, and lipoprotein (a) may be especially important to study in SA KTR. Focused interventions to improve health behaviors involving diet and exercise may especially benefit SA KTR. However, there are few interventional clinical trials specific to the SA population, and none are specific to SA KTR. In all cases, understanding the nuances of managing SA KTR as a distinct post-transplant group, while still screening for and managing each CVD risk factor individually in all patients may help improve the long-term success of all kidney transplant programs catering to multi-ethnic populations.

Increased resistance to tissue plasminogen activator-induced fibrinolysis in healthy subjects from Thailand

: There is significant variability in blood coagulation among world populations. In particular, there may exist important differences in regulation of the fibrinolytic system in Asian populations that contribute to diseases of thrombosis and hemostasis. To investigate this issue, we compared fibrinogen concentration, plasma clot formation, and fibrinolytic resistance of healthy Asian subjects from Hat Yai, Songkhla, Thailand (Thai) vs. healthy North American subjects from Seattle, Washington, USA (SEA). Citrated plasma samples were obtained from healthy adult volunteers. Fibrinogen concentration was measured in plasma by the method of Clauss to examine for baseline differences of fibrinogen concentration. Samples were then standardized to 2.8 mg/ml fibrinogen using physiological buffer for each sample prior to fibrinolytic testing using rotational thromboelastometry (ROTEM) to examine for differences of clot lysis not attributable to fibrinogen concentration alone. Clot lysis was examined with ROTEM extrinsic pathway activation in the presence of 0, 0.5, and 1.0 μg/ml of tissue plasminogen activator (tPA). Two-way repeated measures analysis of variance was used to determine the effects of tPA and study group on ROTEM parameters. N = 49 Thai samples were compared with N = 58 SEA samples. Mean (SD) fibrinogen concentration was significantly increased for the Thai group at 4.03 (0.79) mg/ml vs. the SEA group at 3.66 (0.70) mg/ml (t test P = 0.014). After standardization of all samples to equivalent fibrinogen concentration, there were no differences in clot formation between groups without tPA. There was a significant effect of increasing tPA concentration on all ROTEM parameters except for clotting time. There were significant individual differences for amplitude at 10 min and lysis onset time, where amplitude at 10 min was significantly increased and lysis onset time was significantly prolonged for Thai vs. SEA at tPA concentrations of 0.5 and 1.0 μg/ml. Variability in thrombosis and hemostasis in Asians vs. other populations is likely to involve differences of fibrinogen concentration and regulation of clot lysis.

Insulin resistance syndrome in South Asians

Although South Asians express increased features (conventional) of insulin resistance syndrome, these do not fully explain the increased mortality both from ischaemic heart disease and ischaemic stroke in South Asians compared to Whites. Thrombotic risk factors for vascular disease, as a part of insulin resistance syndrome in South Asians, are being investigated and are an important moiety. The management of the epidemic of ischaemic vascular disease in South Asians is a major global endeavour.

Review: Diabetes and cardiac disease in South Asians

South Asians have a higher prevalence of diabetes, coronary heart disease and cardiovascular death. Their predisposition to insulin resistance partly explains this excess risk. After immigration, the adoption of a western diet allied to increased sedentary behaviour leads to weight gain, hypertension and hyperlipidaemia, factors which in turn combine to amplify the chances of getting heart disease. Further contributory factors are increased sub-clinical inflammation, increased thrombogenic tendency and higher serum homocysteine levels. South Asians with diabetes might do as well as White people with respect to intensive glycaemic and blood pressure control. However, there is little evidence for measures to reduce cardiovascular risk as South Asians have not been included as a subgroup in most large trials. Future prospective studies, including studies on the prevention of diabetes and cardiovascular disease in this high-risk population, are therefore urgently required.

Hypertension, diabetes and cardiovascular risk in ethnic minorities in the UK

Mortality from coronary heart disease (CHD), stroke and end-stage renal failure (ESRF) is high in South Asian (Indo-Asian) migrants in the UK. This is associated with a high prevalence of diabetes and hypertension.

Mortality from stroke and ESRF is also high in migrants to the UK of black African origin. However, CHD mortality is low in this group. This pattern of mortality is also associated with a high prevalence of hypertension and diabetes.

Conventional risk factors, such as cigarette smoking and hypercholesterolaemia, are less prevalent in ethnic minority populations in the UK and unlikely to explain the differences seen between groups, although each risk factor is likely to contribute to the variation in vascular disease within each group.

Is hyperlipidemia a potential protective factor against intraoperative awareness in cardiac surgery?

Background

Intraoperative awareness is a dreaded complication that leads to psychological sequelae such as posttraumatic stress disorder, especially in patients undergoing cardiac surgery. This study investigated the incidence of awareness among patients receiving cardiac surgery and sought to identify the risk factors contributing to intraoperative awareness.

Methods

Patients with informed consent undergoing cardiac surgery from June to September in 2012 were enrolled. At least one structured interview was performed postoperatively with the modified Brice Interview Questionnaire to identify intraoperative awareness as confirmed awareness, possible awareness, and no awareness. Confirmed awareness events reported by patients were classified into different categories with the Michigan Awareness Classification Instrument. The questionnaire results were combined with the patient medical records. A logistic regression model was used to analyze the risk factors that may have led to intraoperative awareness.

Results

An estimated 2136 patients were included, and 1874 patients completed at least one interview. 83 patients (4.4 %) were identified as possible or confirmed awareness, among which 46 (2.5 %) reported confirmed awareness. Patients who experienced confirmed awareness were mostly of Class 1 and 2, 15 and 24 patients respectively, which represented isolated auditory and tactile perceptions. And 11 patients reported feelings of distress intraoperatively. Hyperlipidemia was associated with intraoperative awareness (OR = 0.499, 95 % CI = 0.252–0.989, p = 0.043) and using chi-square test, however, no significance was found with logistic regression.

Conclusion

Patients undergoing cardiac surgery are at high risk for intraoperative awareness. Distress is a common feeling in patients with intraoperative awareness. Hyperlipidemia is a potential protective factor for intraoperative awareness in cardiac surgery.

The Relationship of Metabolic Syndrome Traits with Beta-Cell Function and Insulin Sensitivity by Oral Minimal Model Assessment in South Asian and European Families Residing in the Netherlands

Background. There are different metabolic syndrome traits among patients with different ethnicities. Methods. We investigated this by studying 44 South Asians and 54 Europeans and classified them in three groups according to the occurrence of metabolic syndrome (MetS) and Type 2 Diabetes (T2D). Insulin sensitivity index (ISI), static, dynamic, and total beta-cell responsivity indices (Φ), and disposition indices (DIs) were calculated with the use of oral minimal model (OMM). Results. In both ethnicities, ISI was lower in the subgroup with MetS and T2D as compared to the subgroup without MetS nor T2D (P < 0.004). South Asians without MetS were more insulin resistant than Europeans without MetS (P = 0.033). In the South Asians, ISI, dynamic DI, and static DI were associated significantly (P < 0.006) with high-density lipoprotein cholesterol and triglycerides. In the Europeans, ISI was associated with waist-to-hip ratio (P = 0.005) and systolic and diastolic blood pressure (P < 0.005), while static DI was related to the systolic blood pressure (P = 0.005). Conclusions. MetS was linked with insulin resistance and reduced capacity to handle glucose regardless of ethnicity. ISI and DIs were associated with lipid traits in South Asians and with blood pressure in Europeans suggesting that insulin resistance enhances different metabolic syndrome traits among different ethnicities.

Cerebrovascular disease in South Asia - Part II: Risk factors and prevention

In South Asian countries, conventional vascular risk factors like hypertension, diabetes mellitus, cardiac disease, smoking, obesity, atrial fibrillation are the dominant ones, while other aetiologies like rheumatic heart disease, infective meningitis-related infarcts and postpartum cerebral venous thrombosis also constitute a big fraction. This review discusses the evidence of prevalence of various risk factors in South Asian countries and possible measures to combat the rising burden of cerebrovascular disease. The last part of the review discusses prevention and identification of risk factors that are unique to or especially found in patient population of South Asia.

Asian indians and insulin resistance syndrome: global perspective

Insulin resistance syndrome (IRS) is a crucial factor in causation of type 2 diabetes mellitus (T2DM) in Asian Indians. Approximately one-fifth of the migrant Asian Indians have evidence of metabolic syndrome. Furthermore, insulin resistance as estimated by homeostatic model assessment (HOMA-IR) was reported to be present in one-fifth of children and young adult Asian Indians with normal body mass index (BMI) and ~45-67% of those having high BMI. The cause(s) of such high prevalence of IRS in Asian Indians is not clear; however, inherent genetic predisposition, physical inactivity, excess regional body fat, and factors associated with migration may play an important role. It is important that lifestyle factor modification to prevent IRS and T2DM in Asian Indians should start in early childhood.

Childhood body mass index and adult pro-inflammatory and pro-thrombotic risk factors: data from the New Delhi birth cohort

OBJECTIVE

Weight gain and growth in early life may influence adult pro-inflammatory and pro-thrombotic cardiovascular risk factors.

METHODS

Follow-up of a birth cohort in New Delhi, India, whose weight and height were measured every 6 months until age 21 years. Body mass index (BMI) at birth, during infancy (2 years), childhood (11 years) and adulthood (26-32 years) and BMI gain between these ages were analysed in 886 men and 640 women with respect to adult fibrinogen, high-sensitivity C-reactive protein (hsCRP) and plasminogen activator inhibitor-1 (PAI-1) concentrations.

RESULTS

All the pro-inflammatory/pro-thrombotic risk factors were higher in participants with higher adiposity. In women, BMI at birth and age 2 years was inversely related to fibrinogen (P = 0.002 and 0.05) and, after adjusting for adult adiposity, to hsCRP (P = 0.02 and 0.009). After adjusting for adult adiposity, BMI at 2 years was inversely related to hsCRP and PAI-1 concentrations (P < 0.001 and 0.02) in men. BMI gain between 2 and 11 years and/or 11 years to adulthood was positively associated with fibrinogen and hsCRP in women and with hsCRP and PAI-1 in men.

CONCLUSIONS

Thinness at birth or during infancy, and accelerated BMI gain during childhood/adolescence are associated with a pro-inflammatory/pro-thrombotic state in adult life. An altered inflammatory state could be one link between small newborn/infant size and adult cardiovascular disease. Associations between pro-inflammatory markers and childhood/adolescent BMI gain are probably mediated through adult adiposity.

Obesity-related non-communicable diseases: South Asians vs White Caucasians

South Asians are at higher risk than White Caucasians for the development of obesity and obesity-related non-communicable diseases (OR-NCDs), including insulin resistance, the metabolic syndrome, type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD). Rapid nutrition and lifestyle transitions have contributed to acceleration of OR-NCDs in South Asians. Differences in determinants and associated factors for OR-NCDs between South Asians and White Caucasians include body phenotype (high body fat, high truncal, subcutaneous and intra-abdominal fat, and low muscle mass), biochemical parameters (hyperinsulinemia, hyperglycemia, dyslipidemia, hyperleptinemia, low levels of adiponectin and high levels of C-reactive protein), procoagulant state and endothelial dysfunction. Higher prevalence, earlier onset and increased complications of T2DM and CHD are often seen at lower levels of body mass index (BMI) and waist circumference (WC) in South Asians than White Caucasians. In view of these data, lower cut-offs for obesity and abdominal obesity have been advocated for Asian Indians (BMI; overweight >23 to 24.9 kg m(-2) and obesity ≥ 25 kg m(-2); and WC; men ≥ 90 cm and women ≥ 80 cm, respectively). Imbalanced nutrition, physical inactivity, perinatal adverse events and genetic differences are also important contributory factors. Other differences between South Asians and White Caucasians include lower disease awareness and health-seeking behavior, delayed diagnosis due to atypical presentation and language barriers, and religious and sociocultural factors. All these factors result in poorer prevention, less aggressive therapy, poorer response to medical and surgical interventions, and higher morbidity and mortality in the former. Finally, differences in response to pharmacological agents may exist between South Asians and White Caucasians, although these have been inadequately studied. In view of these data, prevention and management strategies should be more aggressive for South Asians for more positive health outcomes. Finally, lower cut-offs of obesity and abdominal obesity for South Asians are expected to help physicians in better and more effective prevention of OR-NCDs.

Effects of aprotinin on short-term and long-term outcomes after coronary artery bypass grafting surgery

BACKGROUND

Recent studies demonstrated that aprotinin use would increase the short-term and long-term mortality and complications after coronary artery bypass grafting (CABG). This study was to investigate effects of aprotinin during isolated primary CABG on short-term and long-term outcomes in Chinese patients.

METHODS

We studied 5,103 consecutive Chinese patients who underwent isolated primary CABG from 1999 to 2005. Of all the patients, 4,122 received aprotinin during operation (aprotinin group) and 981 received no aprotinin or other antifibrinolytic therapy (control group). Short-term and long-term mortality and major complications were analyzed with multivariate regression analysis. Propensity adjustment method was used to minimize the selection bias between the two groups, and propensity matching method was used to yield two well-matched groups for further comparison.

RESULTS

Blood loss after operation was significantly reduced in the aprotinin group compared with the control group (p < 0.001). Aprotinin use was neither associated with the perioperative mortality (p = 0.45, relative risk, 1.34) or major complications, nor was it associated with long-term mortality (p = 0.21, relative risk, 1.26) and major adverse cardiac and cerebrovascular events (p = 0.82, relative risk, 0.98). After propensity adjustment for the baseline characteristics, we obtained similar results. In addition, comparison between the two well-matched groups showed no significant difference either in baseline characteristics or in short-term and long-term outcomes.

CONCLUSIONS

Aprotinin use during isolated primary CABG reduced blood loss significantly, but was not associated with short-term or long-term mortality and complications. Aprotinin use in relatively low-risk CABG patients was effective and safe in a Chinese (Asian) population.

Prevalence of metabolic syndrome and associated risk factors in Asian Indians

OBJECTIVE

This study examined the association between metabolic syndrome, lifestyle behaviors, and perception and knowledge of current health and cardiovascular disease (CVD) among Asian Indians in the US.

METHOD

The sample comprised of 143 adult Asian Indians recruited through health fairs for survey and bioclinical measures.

RESULTS

The prevalence of metabolic syndrome was 32%, much higher than other ethnic groups, did not vary by gender but increased with age. Respondents had high physical inactivity and poor knowledge of CVD risk factors. Dietary behavior, age, number of years lived in the US, self-rated physical and mental health and BMI were significant predictors and explained 40.1% of variance in metabolic syndrome score. Poorer physical health status had the greatest predictive influence on metabolic syndrome.

CONCLUSION

Asian Indians are a high risk group for CVD.

Vascular risk factors in South Asians

South Asians originate from the Indian sub-continent (India, Pakistan, Bangladesh, Sri Lanka and Nepal) and represent one fifth of the world's population. Several studies suggested that South Asians have an increased risk of developing coronary heart disease (CHD) when compared with European populations. We review the role of traditional and emerging risk factors in the increased CHD risk in South Asians. The high prevalence of insulin resistance and type 2 diabetes mellitus in South Asians may be a major cause for their elevated vascular risk. However, other established and emerging risk factors are also overrepresented in South Asians. Large-scale prospective studies could determine the relative contribution of established and emerging vascular risk factors in South Asians. There is an urgent need for trials in South Asians that will evaluate clinical outcomes following treatment of these risk factors.

Relation between soluble intercellular adhesion molecule-1, homocysteine, and fibrinogen levels and race/ethnicity in women without cardiovascular disease

Although certain markers of inflammation and hemostasis are elevated in persons at risk of future cardiovascular events, data assessing the relation between inflammatory and hemostatic markers of vascular risk and race/ethnicity are limited. Thus, in a cross-sectional analysis of the Women's Health Study (WHS), baseline soluble intercellular adhesion molecule-1 (ICAM-1), homocysteine, and fibrinogen were measured in 23,687 women without a history of cardiovascular disease. In 22,677 white, 242 Hispanic, 428 black, and 340 Asian women, the distribution of median ICAM-1 levels was significantly lower in black (311.9 ng/ml, interquartile range [IQR] 220.1 to 380.0) and Asian (312.7 ng/ml, IQR 267.3 to 362.3) women than white (343.1 ng/ml, IQR 301.9 to 394.9) and Hispanic (351.9 ng/ml, IQR 305.9 to 404.2) women (p <0.001). Although homocysteine was marginally lower in Asian women (p = 0.05), fibrinogen was higher in black women than their counterparts. After controlling for body mass index, hypertension, diabetes, smoking, alcohol use, family history of myocardial infarction, education, hormone use, and lipids, ICAM-1 remained significantly lower in black and Asian women. Meanwhile, homocysteine was lower in Asian women and fibrinogen remained higher in black women than their counterparts. In conclusion, this cross-sectional analysis shows that baseline fibrinogen, ICAM-1, and homocysteine vary by self-reported race/ethnicity.

Indices of angiogenesis, platelet activation, and endothelial damage/dysfunction in relation to ethnicity and coronary artery disease: differences in central versus peripheral levels

BACKGROUND

We hypothesized that indices of angiogenesis (vascular endothelial growth factor (VEGF), angiopoietins (Ang-1 and -2), platelet activation (soluble P-selectin)) and endothelial damage/dysfunction (von Willebrand factor (vWf)) would be more deranged in South Asians than in white Europeans when measured within the coronary sinus or coronary artery per se (that is, intracardiac sampling of blood supplying and draining the heart), as compared to measurements from the peripheral venous system.

METHODS

To test this hypothesis, we performed a cross-sectional study of 87 subjects undergoing cardiac catheterization, where 43 were South Asian and 44 were white European.

RESULTS

South Asian participants were younger (P = 0.01) but had a lower rate of self-reported smoking (P = 0.01). The extent of coronary atherosclerosis, assessed using presence of lesions > 50%, number of vessels diseased and Gensini score, was comparable between the two ethnic groups (all P = NS). When samples were analysed from the coronary circulation or the femoral vein in relation to South Asian and white European ethnicity, there were no significant differences in the levels of VEGF, angiopoietins 1 and 2, soluble P-selectin and vWf levels between the two ethnic groups.

CONCLUSION

Indices of angiogenesis, platelet activation, and endothelial damage/dysfunction are comparable in South Asians and their white European counterparts. Our results suggest that their pathophysiological roles may be comparable in South Asians and white Europeans in the context of coronary artery disease.

Type 2 diabetes and cardiovascular risk in the UK south Asian community

A popular hypothesis for the greater prevalence of type 2 diabetes and cardiovascular disease in UK south Asians is that they have an increased susceptibility of developing insulin resistance in response to certain environmental factors, including obesity and adoption of a sedentary lifestyle. Insulin resistance is postulated as a central feature of the metabolic syndrome, culminating in type 2 diabetes, atherosclerotic vascular disease and CHD; a pathway potentially accelerated by migration/urbanisation. We describe and compare the prevalence of type 2 diabetes, cardiovascular disease and their associated risk factors in UK south Asian and white Caucasian populations to determine possible reasons for the increased preponderance of these diseases in south Asians, and highlight key evidence for optimal risk factor management. Finally, we describe a UK community-based programme that attempts to reduce the morbidity and mortality from type 2 diabetes and cardiovascular disease in south Asians through a new approach to management.

Effect of pioglitazone on insulin sensitivity, vascular function and cardiovascular inflammatory markers in insulin-resistant non-diabetic Asian Indians

AIMS

To determine the effects of pioglitazone (30 mg once daily for 16 weeks) on insulin sensitivity, insulin-mediated vasodilation, vascular inflammatory markers, fat distribution and lipids in Asian Indians and Caucasians of European ancestry.

METHODS

Cross-sectional study. Eighteen non-diabetic Asian Indians and 17 Caucasians of comparable age (34 +/- 3 vs. 36 +/- 3 years) and body mass index (26.0 +/- 1.2 vs. 24.7 +/- 1.0 kg/m(2)) had measurements of insulin sensitivity (M, insulin clamp at 6 pmol/kg per min), abdominal fat (computed tomographic scan at L4-L5), endothelial-dependent (reactive hyperaemia, RH) and -independent (0.4 mg sublingual nitroglycerin, TNG) vasodilation using brachial artery ultrasound before and after the 2-h clamp at baseline and after pioglitazone therapy.

RESULTS

Asian Indians were insulin resistant compared with Causasians during the baseline clamp (M = 25.6 +/- 1.7 vs. 41.1 +/- 2.2 micromol/kg per min, P < 0.0001) and improved significantly after pioglitazone (to 33.9 +/- 1.7 micromol/kg per min, P < 0.001). Vasodilatory responses to RH and TNG were similar in Asian Indians and Caucasians at baseline and did not change. Insulin-mediated vasodilation improved after pioglitazone in Asian Indians, but not in Caucasians, and correlated with the change in insulin sensitivity (r = 0.52, P = 0.03). C-reactive protein (CRP) was higher in Asian Indians vs. Caucasians (1.6 +/- 0.4 vs. 0.9 +/- 0.2 mg/l) and was negatively correlated with insulin sensitivity (r = -0.53, P = 0.02). In the Asian Indian group, CRP and plasminogen activator inhibitor-1 decreased and adiponectin increased after pioglitazone, but there were no significant changes in total or visceral fat.

CONCLUSIONS

These results demonstrate that insulin-resistant Asian Indians respond favourably to an insulin sensitizer with improvements in insulin sensitivity, cardiovascular and inflammatory risk markers, and vascular responses to insulin. These agents may have a role in decreasing the risk of diabetes and cardiovascular disease in this high-risk population.

CVD risk factors and ethnicity--a homogeneous relationship?

Current understanding of cardiovascular disease risk (CVD) is derived largely from studies of Caucasians of European origin. However, people of certain ethnic groups experience a disproportionately greater burden of CVD including coronary heart disease (CHD) and stroke. Adoption of a Westernised lifestyle has different effects on metabolic and vascular dysfunction across populations, e.g. South Asians have a higher prevalence of coronary heart disease (CHD) and cardiovascular mortality compared with Europeans. African-Americans demonstrate higher rates of CHD and stroke while African/Caribbeans in the UK have lower CHD rates and higher stroke rates than British Europeans. Other non-European groups such as the Chinese and Japanese exhibit consistently high rates of stroke but not CHD, while Mexican Americans have a higher prevalence of both stroke and CHD, and North American native Indians also have high rates of CHD. While conventional cardiovascular risk factors such as smoking, blood pressure and total cholesterol predict risk within these ethnic groups, they do not fully account for the differences in risk between ethnic groups, suggesting that alternative explanations might exist. Ethnic groups show differences in levels of visceral adiposity, insulin resistance, and novel risk markers such as C-reactive protein (CRP), adiponectin and plasma homocysteine. The marked differences across racial and ethnic groups in disease risk are likely due in part to each of genetic, host susceptibility and environmental factors, and can provide valuable aetiological clues to differences in patterns of disease presentation, therapeutic needs and response to treatment. Ongoing studies should increase understanding of ethnicity as a potential independent risk factor, thus enabling better identification of treatment targets and selection of therapy in specific populations.

Ethnic differences in the management of coronary heart disease patients: lessons to be learned in indo-asians

OBJECTIVES

To examine the impact of ethnicity on the outcome of coronary artery bypass grafting (CABG) for myocardial revascularization.

SUBJECTS AND METHODS

We evaluated retrospectively 7,226 Caucasian (CC) and 650 Indo-Asian (IA) patients who underwent isolated first-time CABG surgery over 5 years. The relationship between ethnicity (IA vs. CC) and 30-day mortality, 6-month mortality and complications were analysed.

RESULTS

After adjustment for baseline characteristics, IA and CC patients had similar 30-day [IA/CC odds ratio (OR) 1.07; 95% confidence interval (CI) 0.84-1.35; p = 0.59] and 6-month mortality risk (IA/CC OR 1.10; 95% CI 0.91-1.34; p = 0.31). However, IA patients were more likely to experience complications following surgery (OR 1.28; 95% CI 1.14-1.45; p < 0.01).

CONCLUSION

Ethnicity does not appear to be a strong risk factor for adverse outcomes following CABG surgery in the IA patients. However, future studies are needed to elucidate the specific reasons for higher complication rates in IA patients and to devise strategies to reduce complications following the operation for these patients.

Insulin resistance syndrome (metabolic syndrome) and obesity in Asian Indians: evidence and implications

OBJECTIVES

This review describes prevalence, determinants, and possible pathophysiologic mechanisms and suggests management and research directions for insulin resistance syndrome (metabolic syndrome) in Asian Indians.

METHOD

We reviewed the topic using the terms Asian Indians, Asians, South Asians, and Indians coupled with the terms insulin resistance, hyperinsulinemia, metabolic syndrome, and obesity from the databases Pubmed (National Library of Medicine, Bethesda, MD, USA) and Current Contents (Institute for Scientific Information, Thomson Scientific, Philadelphia, PA, USA) and from non-indexed publications of the medical research and governmental institutions in India.

RESULTS

Asian Indians have a high prevalence of insulin resistance syndrome that may underlie their greater than normal tendency to develop diabetes mellitus and early atherosclerosis. Important reasons could be their excess body fat and adverse body fat patterning including abdominal adiposity even when the body mass index is within the currently defined normal limits. Some of these features have been reported at birth and childhood. Whether Asian Indians also have tendency to develop insulin resistance de novo, independent of total or regional adiposity, needs further investigation. Underlying genetic tendency or early-life adverse events may contribute to such a phenotype, but lifestyle factors alone or modulated by inherited factors appear to play an important role because obesity and dyslipidemia become worse with urbanization and migration. Systemic stress may contribute to insulin resistance syndrome in the intra-country and inter-country migrant Asian Indians.

CONCLUSIONS

High prevalences of excess body fat, adverse body fat patterning, hypertriglyceridemia, and insulin resistance beginning at a young age have been consistently recorded in Asian Indians irrespective of their geographic locations. These data suggest that primary prevention strategies should be initiated early in this ethnic group.

Specific elevation in plasma tissue plasminogen activator antigen concentrations in South Asians relative to Europeans

Elevated levels of haemostatic factors including tissue plasminogen activator (t-PA) antigen are associated with coronary heart disease in Europeans but data in South Asians are sparse. We performed a cross-sectional study of 111 healthy men and women aged 40-55 years (56 European and 55 Asian) frequency matched across a wide range of body mass index (17-34 kg/m2). All subjects had detailed adiposity and metabolic measurements, and five haemostatic factors were determined. South Asians had greater insulin resistance than Europeans (fasting insulin geometric mean, 7.1 versus 4.7 microU/ml, and 2-h insulin, 37.3 versus 14.1 microU/ml, respectively). There were no significant ethnic differences in the mean concentrations of fibrinogen, factor VII, von Willebrand factor, or fibrin D-dimer (P > 0.10). However, the t-PA antigen concentration was significantly elevated in South Asians compared with Europeans (mean, 10.6 versus 8.2 ng/ml, P = 0.001). t-PA correlated positively in both ethnic groups with features of the metabolic syndrome but the ethnic difference in t-PA persisted after adjustment for adiposity, metabolic and inflammatory variables (beta = 2.0, 95% confidence interval = 0.5-3.6, P = 0.012). We therefore hypothesize that elevated t-PA antigen may be a novel mechanism contributing to increased cardiovascular risk in South Asians.

Associations between insulin resistance and thrombotic risk factors in high-risk South Asian subjects

AIMS

There is recognized association of thrombotic factors to insulin resistance in White Europeans. South Asians are more insulin resistant compared with white Europeans and express increased metabolic features of insulin resistance. The aim of the study was to determine whether there was any relationship between insulin resistance and thrombotic risk factors in healthy South Asian subjects.

METHODS

Healthy South Asians (n = 185) clinically free from ischaemic heart disease, ischaemic stroke or peripheral vascular disease were randomly recruited. Partial correlations of homeostasis model assessment (HOMA) (surrogate of insulin resistance) were analysed with two fibrinolytic and five coagulation factors.

RESULTS

Age and gender-adjusted HOMA was significantly correlated to plasminogen activator inhibitor-1 (0.51, P = 0.0001), tissue plasminogen activator antigen (r = 0.40, P = 0.0001), fibrinogen (r = 0.28, P = 0.0001), von Willebrand factor (r = 0.17, P = 0.03), factor XIIa (r = 0.22, P = 0.006) factor VII antigen (r = 0.19, P = 0.02) and factor XIII B subunit (r = 0.30, P = 0.001).

CONCLUSIONS

Insulin resistance significantly clusters with fibrinolytic and coagulation factors in South Asians, which may contribute to high prevalence of vascular disease in this population.

Association between the risk of coronary artery disease in South Asians and a deletion polymorphism in glutathione S-transferase M1

South Asians living in Western societies show a greater risk of coronary artery disease (CAD) than the indigenous Caucasian population, probably related to the change to a Westernised lifestyle and an associated genetic susceptibility. Modulation of DNA damage and mutation caused by polymorphisms in detoxification enzymes, including the glutathione S-transferases (GSTs), is a well-established risk factor for tobacco-related carcinogenesis, and a similar change in cellular damage may be involved in the risk of vascular disease associated with tobacco smoking. In this study we examined whether polymorphisms in GST genes influence the risk of CAD in a case-control group of South Asians, following our recent observation of such an association in Caucasians from the same region of the UK. Blood was obtained from 170 patients of South Asian origin admitted for angiographic investigation of chest pain and from 203 controls. Patients were subdivided into those with and without previous acute myocardial infarction (AMI), and DNA was analysed for deletions in the GSTM1 and GSTT1 genes. An association was found between the prevalence of the GSTM1 null genotype and the risk of developing CAD in this study population. The frequency of the null genotype was 52.7% in healthy controls and 41.2% in patients (odds ratio [OR] 0.63, 95% confidence interval [95% CI] 0.42-0.95, p = 0.029). The effect was similar in subjects with or without a prior history of AMI. The association was also independent of smoking history, with both non-smokers and smokers showing a similar pattern of genotype distribution, the frequency of the null genotype being 51.2% in controls versus 37.0% in patients in 'never' smokers (OR 0.56, 95% CI 0.33-0.94, p = 0.037) and 60.0% in controls versus 46.2% in patients in 'ever' smokers (OR 0.57, 95% CI 0.25-1.28, p = 0.223). The association remained after adjusting for age, sex, body mass index and the presence or absence of stenosis. No significant associations were observed between the GSTT1 genotype and cardiovascular disease (chi(2) test, p > 0.1). The results of this study indicate that the GSTM1 null genotype is protective against both CAD and AMI. However, further study is required in order to elucidate the, as yet unexplained, mechanisms underlying this association.

Increased fibrinogen, von Willebrand factor and tissue plasminogen activator levels in insulin resistant South Asian patients with ischaemic stroke

The aim of this study was to determine differences in atherothrombotic risk factors in South Asian subjects with a history of ischaemic stroke and South Asian subjects free from personal and family history of clinically detectable stroke. Eighty South Asian patients with ischaemic stroke (confirmed on cranial computerised scan) and 80 South Asian controls with similar age and gender distributions were recruited at random. The frequency of hypertension (P=<0.0001), myocardial infarction (P=0.003) and diabetes mellitus (<0.0001) were significantly higher in stroke patients. Stroke patients had lower high-density lipoprotein cholesterol (0.95 vs. 1.1 mmol/l, P=<0.0001), higher plasma glucose (8.1 vs. 6.6 mmol/l, P=0.01) and trendwise higher HBA(1C) (6.4 vs. 6.0%, P=0.09). There was no difference in insulin levels but insulin resistance was significantly higher in stroke patients (3.75 vs. 2.66, P=0.01). Stroke patients showed elevated levels of fibrinogen (3.78 vs. 3.41 mg/dl, P=0.02), von Willebrand factor (1.78 vs. 1.50 IU/ml, P=0.006) and tissue plasminogen activator (12.8 vs. 11.3 ng/ml, P=0.04), but the differences did not persist after adjustment for glucose, triglycerides, HDL, WHR, and BMI. Higher levels of fibrinogen, von Willebrand factor and t-PA in South Asian stroke patients disappeared after adjustment for features of insulin resistance syndrome but persisted after adjustment for presence of diabetes, confirming that these changes are essentially dependant on features of insulin resistance syndrome. A prospective study would be required to elucidate the role of thrombotic risk factors in South Asians with ischaemic stroke.