Relook at lipoprotein (A): independent risk factor of coronary artery disease in north Indian population

Association of lipoprotein (a) with coronary artery disease in a South Asian population: A case-control study

Introduction

Coronary artery disease (CAD), the leading cause of mortality worldwide, is characterised by an earlier onset and more severe disease in South Asians as compared to Western populations.

Methods

This is an observational study on 928 individuals who attended three tertiary care centres in Kerala, India from 2014-to 2017. The demographic, anthropometric, behavioural factors and the lipoprotein (Lp(a)) and cholesterol values were compared between the two groups and across disease severity. The Chi-square test was used to compare the categorical variables and independent sample t-test for the continuous variables. Multivariable logistic regression was performed to investigate the association of demographic, clinical and behavioural factors with the disease. Odds ratios are presented with a 95% confidence interval. In individuals below 50 years, two logistic regression models were compared to investigate the improvement in modelling the association of the independent factors and Lp(a) with the occurrence of the disease.

Results

We included 682 patients in the diseased group and 246 patients treated for non-coronary conditions in the control group. Those in the control group were significantly younger than in the diseased group(p<0.002). Significantly more patients were diabetic, hypertensive, tobacco users and consumers of alcohol in the diseased group. Multivariable logistic regression on data from all age groups showed that age (OR = 2.55, 95% CI 1.51–4.33, p = 0.01), diabetes (OR = 3.71, 95% CI 2.42–5.70, p = 0.01), hypertension (OR = 3.03, 95% CI 2.12–4.34, p = 0.01) and tobacco use (OR = 5.44, 95% CI 3.39–8.75, p = 0.01) are significantly associated with the disease. Lp(a) (OR = 1.22, 95% CI 0.87–1.72) increased the odds of the disease by 22% but was not statistically significant. In individuals below 50 years, Lp(a) significantly increased the likelihood of CAD (OR = 3.52, 95% CI 1.63–7.57, p = 0.01). Those with diabetes were seven times more likely to be diseased (OR = 7.06, 95% CI 2.59–19.21, p = 0.01) and the tobacco users had six times the likelihood of disease occurrence (OR = 6.38, 95% CI 2.62–15.54, p = 0.01). The median Lp(a) values showed a statistically significant increasing trend with the extent/severity of the disease in those below 50 years.

Conclusion

Age, diabetes, hypertension and tobacco use appear to be associated more with the occurrence of coronary artery disease in adults of all ages. Lipoprotein(a), cholesterol and BMI categories do not seem to be related to disease status in all ages. However, in individuals below 50 years, diabetes, tobacco use and lipoprotein (a) are significantly associated with the occurrence of the disease.

Elevated Lipoprotein A in South Asians and the Associated Risk of Cardiovascular Disease: A Systematic Review

BACKGROUND

South Asians have a premature risk of cardiovascular disease and increased lipoprotein A which enhances their risk.

METHODS

This systematic review evaluates the role of elevated lipoprotein A in cardiovascular disease risk for South Asians. It discusses the pathophysiology, clinical studies, and treatment of elevated lipoprotein A using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses method.

RESULTS

A total of 72 articles was incorporated which consisted of clinical studies, case-control and cohort studies, meta-analysis, reviews, and editorials. Cardiovascular disease and myocardial infarction occurs prematurely in South Asians, which is further enhanced with an elevated lipoprotein A.

CONCLUSIONS

South Asians with an elevated lipoprotein A have an increased risk of coronary artery disease so they should have early enactment of lifestyle modification and aggressive medical management.

Lipoprotein(a): An underrecognized genetic risk factor for malignant coronary artery disease in young Indians

Malignant coronary artery disease (CAD) refers to a severe and extensive atherosclerotic process involving multiple coronary arteries in young individuals (aged <45 years in men and <50 years in women) with a low or no burden of established risk factors. Indians, in general, develop acute myocardial infarction (AMI) about 10 years earlier; AMI rates are threefold to fivefold higher in young Indians than in other populations. Although established CAD risk factors have a predictive value, they do not fully account for the excessive burden of CAD in young Indians. Lipoprotein(a) (Lp(a)) is increasingly recognized as the strongest known genetic risk factor for premature CAD, with high levels observed in Indians with malignant CAD. High Lp(a) levels confer a twofold to threefold risk of CAD-a risk similar to that of established risk factors, including diabetes. South Asians have the second highest Lp(a) levels and the highest risk of AMI from the elevated levels, more than double the risk observed in people of European descent. Approximately 25% of Indians and other South Asians have elevated Lp(a) levels (≥50 mg/dl), rendering Lp(a) a risk factor of great importance, similar to or surpassing diabetes. Lp(a) measurement is ready for clinical use and should be an essential part of all CAD research in Indians.

Risk factor profiling and study of atherosclerotic coronary plaque burden and morphology with coronary computed tomography angiography in coronary artery disease among young Indians

BACKGROUND

With a decade earlier manifestation of coronary artery disease (CAD) and paucity of data characterizing coronary plaque with coronary computed tomography angiography (CTA) among CAD patients in India, the study aimed to analyze patient characteristics and coronary plaque burden and morphology in young Indian patients with CAD.

METHODS

Serial coronary CTA was performed in 96 CAD patients. Among 60 patients ≤40years, risk factor and coronary plaque analysis done using a 256- slice CT in 33 patients with acute coronary syndrome (ACS) was compared with 27 patients with chronic stable angina (CSA). Univariate and multivariate analysis was performed, for factors predicting ACS as an outcome among young CAD patients. In addition, quantitative and morphologic plaque characteristics were compared among those ≤40years and >40years.

RESULTS

Among 60 subjects ≤40years of age, 77% had dyslipidemia, 70% high lipoprotein(a), 53.33% elevated hs-CRP and 73.33% raised homocysteine. hs-CRP (9.33 vs. 3.33, p value=0.01) and serum triglycerides (178.67 vs. 141.42, p value=0.03) were markedly raised in patients with ACS. Statistically significant number of patients in the ACS group had positive remodelling (ACS, 69.7% vs. CSA, 14.8%; p value<0.001), low attenuation plaque (ACS, 63.6% vs. CSA, 11.1%; p value<0.001), spotty calcification (ACS, 36.4% vs. CSA, 3.7%; p=0.002) and non-calcified plaque (ACS, 69.7% vs. CSA, 11.1%; p<0.001). On multivariate analysis, only lipoprotein (a) >30mg/dL and composite vulnerability score maintained a predictive value for ACS in patients ≤40years. Statistically significant number of patients in the younger age group had higher mean total plaque volume (66.17±41.31mm³ vs. 44.94±49.07mm³; p=0.03), remodelling index (1.5±0.27 vs. 1.08±0.38; p=0.0001). Comparing culprit lesion characteristics of ACS patients in the two age groups, positive remodelling (95.8% vs. 70.5%, p=0.02), spotty calcification (50% vs. 11.7%, p=0.01) and non-calcified plaque (95.8% vs. 70.5%, p=0.02) were significantly more frequent in patients ≤40years.

CONCLUSION

ACS in young Indians is characterized by a higher prevalence of both conventional and newer risk factors. In addition, culprit lesions in young ACS patients are more frequently characterized by coronary plaques with high risk morphological features. This may have implications in terms of preventive strategies to identify this high-risk group.

Lipoprotein(a) and lipid profiles of patients awaiting coronary artery bypass graft; a cross sectional study

Background

Lipoprotein(a) (Lp(a)) excess is an independent risk factor of coronary artery disease (CAD) and have shown wide ethnic variations. Further, lipid parameters used in the assessment and management of risk factors for CAD may not reflect accurately the disease or severity if the patients are on pharmacological interventions when compared to Lp(a). Lp(a) levels of Sri Lankan CAD patients awaiting coronary artery bypass graft are not documented.

Methods

A cross sectional study was carried out with patients (n = 102) awaiting coronary artery bypass graft at a tertiary healthcare institution in Sri Lanka. Lp(a) was determined by immunoturbidimetric method (Konelab 20XT) and information on risk factors collected using a standardized questionnaire. The severity of CAD was determined by Gensini score. Lipid parameters and pharmacological treatment data were obtained from the Medical Records. Data were analysed using independent sample t-test, Pearson and Spearman tests respectively.

Results

Total cholesterol (TC), LDL cholesterol (LDLc) and HDL cholesterol (HDLc) of the total study sample (average ± SD) were, 150 ± 36 mg/dL, 92 ± 36 mg/dL and 34 ± 9 mg/dL respectively with no significant difference irrespective of being on pharmacological treatment or not. All lipid parameters were significantly high (p < 0.05) in females. The average Lp(a) was 50 ± 38 (SD) mg/dL with no significant difference in males or females independent of being on treatment (50 ± 39 mg/dL) or not (49 ± 39 mg/dL) and above the cut off value (30 mg/dL).

Conclusions

Despite pharmacological interventions 27 % of the study population had high LDLc and majority low HDLc. Mean Lp(a) was in excess irrespective of risk factors or being on treatment or not and is confirmed as an independent, potential marker for assessing the susceptibility for CAD especially in those with other intermediate risk factors but considered non-hyperlipidemic by conventional methods.

Vascular Disease in Young Indians (20-40 years): Role of Ischemic Heart Disease

Coronary Artery Disease (CAD) occurs at a younger age in Indians with over 50% of Cardiovascular Disease (CVD) mortality occurring in individuals aged less than 50 years. Although several risk factors have been suggested; smoking, dyslipidemia and hypertension are major risk factors in the young. In this review, we have pooled the current evidence on Ischemic Heart Disease (IHD) in young (20-40 years) and provided an opinion for the effective management of IHD in young Indians.

Conventional and Advanced Lipid Parameters in Premature Coronary Artery Disease Patients in India

BACKGROUND

Coronary artery disease (CAD) is the leading cause of death worldwide and has assumed alarming proportions in India with gradual increase in its incidence and prevalence over the last decade. India is in the middle of epidemic of coronary artery disease which is leading cause of hospital admissions, morbidity and mortality. In the Indian population, there is higher tendency to develop CAD at a younger age, which cannot be explained on the basis of conventional lipid parameters.

AIM

The purpose of this study is to find advanced lipid parameters which correlate better with premature CAD, as compared to the conventional lipid parameters.

MATERIALS AND METHODS

Thirty middle aged individuals suffering from premature CAD and 30 age and gender matched healthy individuals without any history of clinical evidence suggestive of CAD were studied. Fasting venous blood samples of all the subjects under study were collected after an overnight fasting and conventional lipid parameters and advanced lipid parameters (i.e. oxidized LDL, Lp (a), ApoA-1, small dense LDL, ApoB) were estimated. Correlation of conventional and advanced lipid parameters with premature CAD and among each other was calculated using Pearson correlation coefficient.

RESULTS

In our study the values of ox-LDL, sdLDL, Lp (a) and ApoB, total cholesterol, TG, LDL-C were significantly higher while HDL-C and Apo A1 and were significantly lower in cases than in controls. Advanced lipid parameters have higher correlation with premature CAD as compared to conventional lipid parameters. Ox-LDL show the highest correlation coefficient (r=+0.89) among these parameters followed by Lp (a) (r=+0.86) and ApoB (r=+0.79).

CONCLUSION

Advanced lipid parameters (i.e. oxidized LDL, Lp (a), ApoA-1, small dense LDL, ApoB) are better discriminator of premature CAD as compared to conventional lipid parameters (total cholesterol, triglycerides, low density lipoprotein and high density lipoprotein). Oxidised LDL, small dense LDL and lipoprotein (a) can explain occurrence of CAD in normolipidemic patients and proved to be better markers for explaining high degree of prematurity, morbidity and mortality of CAD in Indian population. They can prove to be better marker for early detection and intervention in premature CAD and site for targeted drug therapy.