Praveen Sharma*, Purvi Purohit and Rashmi Gupta 1

Transcription

1 Indian Journal of Biochemistry & Biophysics Vol. 50, October 2013, pp Cardiac risk factors in descendants of parents with history of coronary artery disease (CAD) : An evaluation focusing on small dense low density lipoprotein cholesterol (sdldlc) and high density lipoprotein cholesterol (HDLc) Praveen Sharma*, Purvi Purohit and Rashmi Gupta 1 Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur , India 1 Department of Biochemistry, SMS Medical College, Jaipur , India Received 10 June 2013, revised 19 September 2013 The risk of coronary artery disease (CAD) in descendants with positive family history of CAD was evaluated in either one of or both the parents among 71 selected families. Subjects were grouped as parents and descendants without and with CAD and descendants spouses without CAD or family history of CAD. All subjects were examined for anthropometric characteristics, fasting blood sugar, serum lipids, lipoprotein sub-fractions, insulin, insulin resistance and pancreatic beta cell function. The results were subjected to statistical analysis by using the analysis of variance (ANOVA). Metabolic syndrome (MetS) was prevalent in the 83% descendants with CAD and 54.6% parents with CAD. The traditional risk factors were observed in both parents and descendants with CAD. Metabolic risk factors, including hypertriglyceridemia, low HDLc levels and hyperglycaemia had a higher frequency in the descendants with CAD. ANOVA showed significant F ratio for the anthropometric characteristics, hypertension, serum lipids, small dense (sd) LDLc levels, HDL2c levels and HDL3c levels in the descendants parents with CAD and CAD + diabetes mellitus (DM), as compared to those without CAD. The descendants without CAD, but with a positive family history had central adiposity, hypertension and had lower HDL levels and elevated sdldlc levels. Multiple analyses of variance showed that sdldlc and waist circumference were the most potent risk factors for prevalence of CAD. Thus, we conclude that a positive family history of CAD along with central adiposity and elevation of sdldlc levels appear to be important factors in the assessment of CAD risk in humans. Keywords: Coronary artery disease, Diabetes mellitus, Total cholesterol, HDL2c, HDL3c, HOMA-β, Insulin resistance, LbLDLc, sdldlc, Metabolic syndrome, Phospholipid, Hypertension, Insulin, Triglycerides, Waist circumference, Waist hip ratio. Cardiovascular diseases (CVDs) are not confined to a particular geographical region, age, sex and socioeconomic status. Heart diseases have already reached epidemic proportions in the third world countries. CAD is a leading cause of morbidity and mortality and was responsible for 7.2 million deaths in 2008, according to the World Health Organisation *Corresponding author praveensharma55@gmail.com Mobile: Abbreviations: ANOVA, Analysis of variance, ApoB, apolipoprotein B; ATP III, Adult treatment panel III; BMI, body mass index; CAD, coronary artery disease; DBP, diastolic blood pressure; DM, diabetes mellitus; FBS, fasting blood sugar; HC, hip circumference; HDLc, high density lipoprotein cholesterol; HDL2c HDL3c sub-fractions; HOMA-β, Pancreatic secretory function; IR, insulin resistance; Lb LDLc, large buoyant low density lipoprotein; LDLc, low density lipoprotein; MANOVA, multiple analysis of variance; MetS, metabolic syndrome; PL, phospholipids; SBP, Systolic blood pressure; sd LDLc, small dense low density cholesterol; SI, serum insulin; TC, total cholesterol; TG, triglycerides; WC, waist circumference; WHR, waist hip ratio. (WHO) report 1. It is predicted that more than half the worldwide CVD burden will be borne by the Indian subcontinent in the next decade. The highest age-standardised CVD death rates (per 100,000) in the world among the middle-aged population (30-69 yrs) are recorded in this region (>400). Disease burden, as well as the mortality from cardiovascular morbidities are projected to grow rapidly and relentlessly among the Asian Indian population 2. There has been an alarming increase in the incidence of CAD in younger individuals in developing countries 1. Asian Indians have been consistently shown to have a higher prevalence of premature CAD, as compared to the Europeans 3. Heart diseases are rising in Asian Indians 5-10 yrs earlier than in other communities around the world. Besides dietary indiscretions and sedentary lifestyles practiced by most of the South Asians 4, high prevalence of metabolic syndrome(mets), diabetes, insulin resistance (IR) and other pro-atherogenic

2 454 INDIAN J. BIOCHEM. BIOPHYS., VOL. 50, OCTOBER 2013 factors like dyslipidaemia, thrombotic tendencies and a positive family history increase the risk of an individual prone to premature CAD 5. India s greatest socioeconomic burden of the CVDs is amplified by the effects of these diseases on the productive workforce between yrs of age. The mean age for first incidence of an episode of acute myocardial infarction in Indians is 53 yrs. The CAD that manifests at a younger age can have devastating effects on the individual, family and society. A strategy involving prevention of the CVDs long before their onset will be more cost-effective than providing interventions at a stage when the diseases have progressed too far 6. The excess burden of premature CAD on the Asian Indians is due to their genetic susceptibility, which is magnified by the adverse effects of lifestyle factors associated with urbanization, affluence and changes in diet. Multiple studies have demonstrated the alarmingly high prevalence of CAD in the Asian Indian population worldwide. CVD has been reported as the cause of mortality in 40% of urban Indians and 30% of rural Indians and this trend has shown an exponential increase over time 2. The evidence indicates that apart from the high prevalence of diabetes mellitus (DM), all the other risk factors described predominantly for the Caucasians (Westerners) are comparatively rare among the Asian Indians, quite disproportionate to the high incidence of CAD 2. Little is known about the pathogenesis of atherosclerosis and CAD in Indians, who belong to diverse ethnic groups and geographical regions, but share the common problem of high mortality from CAD. Thus, the elevated chronic heart disease (CHD) in Asian Indians may require an explanation by the uncommon risk factors. Recent findings suggest that sdldlc appears as a risk factor along with the other well-recognised risk factors, such as the increased levels of plasma TG and ApoB, as well as the decreased HDLc levels 6. SdLDLc particles may be of particular importance, but clinical studies evaluating their predictive value for coronary atherosclerosis are few. Thus, in the present study, we have evaluated different routine and novel risk factors with special emphasis on sdldlc in individuals with established CAD and their first generation descendants with an aim to establish the most striking risk factor of CAD in these individuals. Materials and Methods Subjects The current study was conducted at the Department of Biochemistry, SMS Medical College, Jaipur & Jodhpur National University, Jodhpur, India. A total of 71 families participated in the study with 482 subjects. The subjects were grouped into two major groups: Group I: parents (142) and Group: II (209) descendants. Each group was further subdivided into two subgroups without and with established CAD. Age-matched descendant spouses (109) without any disease or family history served as control subjects. Informed consent was obtained from all participants and the study protocols were approved by the Institutional Ethical Committee. Subjects were interviewed for family history, dietary habits, lifestyle (sedentary, moderately active or active), and habit of smoking, tobacco chewing and alcohol consumption. They were examined anthropometrically and clinically by taking their weight, height, waist and hip circumference and measuring their blood pressure. Biochemical assays The following biochemical indices were analyzed in the subjects: Fasting blood sugar (GOD-PAP method), Total cholesterol (CHOD-PAP method), Triglycerides (GPO-PAP method), HDLc (direct homogenous method Kit of Randox), HDL2c (HDLc HDL3c = HDL2c), HDL3c (Precipitation method) 7, LDLc (Direct homogenous method Kit of Randox), SdLDLc 8, large buoyantlb LDLc (LDLc - sdldlc = LbLDLc), Phospholipids (Trinder method), Serum insulin (SI) (ELISA-Monobind, Inc. USA), HOMA-IR and HOMA-β and metabolic syndrome (MetS) prevalence was calculated based on Adult Treatment Panel (ATP III) guidelines National Cholesterol Education Program Statistical analysis The observations were subjected to continuous, descriptive statistics of mean ± SD, 95% CI etc. Significance was calculated using ANOVA and multivariate analysis of variance (MANOVA) was used to figure out the most potent CAD risk factor. All statistical analyses were done by using the Prism 5 software. Results and Discussion In developing nations like India, the increase in CAD is reaching epidemic proportions. India is now in the middle of a CAD epidemic and CAD is expected to be the leading cause of death and

3 SHARMA et al.: CARDIAC RISK FACTORS IN DESCENDANTS OF PARENTS 455 disability adjusted life years (DALYS) lost by the year Reports from India and abroad have demonstrated that Indians have a high propensity to CAD compared with other ethnic groups, despite lower prevalence of conventional risk factors 10. It is now known that CAD tends to occur early in the life of Indians 11 and is often seen that many young men are suddenly knock-down by heart attack in productive years of their life. An association of genetic factors of family history has also been shown to be strongly involved. The present study was conducted in 71 families that were chosen with CAD parents and their descendants to examine conventional as well as novel risk factors like sd LDLc of CAD and the genetic predisposition of CAD in the descendants. Thus, we examined for any link between risk factors of parents and descendants. Since ATP III (2001) recommends that subjects greater than 40 yrs must undergo screening for various risk factors, proven cases were taken for the purpose of comparison of various risk factors in the descendants. The majority of CVDs are caused by risk factors that can be controlled, treated or modified, such as high blood pressure, cholesterol, overweight/obesity, tobacco chewing, lack of physical activity and diabetes. In terms of attributable deaths, the leading CVD risk factor is raised blood pressure (to which 13% of global deaths is attributed), followed by tobacco use (9%), raised blood glucose (6%), physical inactivity (6%) and overweight and obesity (5%). Subjects of current study were observed to have the conventional risk factors of CAD i.e. smoking, tobacco chewing, alcoholism, hypertension and obesity, with higher incidence in descendants with CAD than parents with CAD (Table 1). Evidences support that people with MetS are at relatively greater risk of developing diabetes and CVD because components of MetS are the established risk factors for diabetes and CVD and have a high predictive value for diabetes and coronary heart disease (CHD) risk 12. It represents a constellation of risk factors for CHD and diabetes comprising of abdominal obesity, hypertriglyceridemia, hypertension, hyperglycaemia, IR without or with glucose intolerance, pro-thrombotic and pro-inflammatory states 13. The incidence of MetS was an important factor observed with higher incidence in the descendants (83%) as compared to the parents (54.6%) with CAD and 55% fulfilling >3 conditions for MetS (Table 2). Similar reports of high prevalence of MetS in patients with CAD have been reported The frequency of metabolic risk factors of CAD in the various study groups showed a higher prevalence of hypertension (89% diastolic and 92% systolic), hypertriglyceridemia (93%), low HDL (84.3%) and hyperglycemia (57.2%) in the descendants with CAD, as compared to lower frequencies of incidence in the Table 1 Demographic, anthropometric and biochemical characteristics of subjects With CAD (n = 97) Parents (n = 142) Descendants (n = 209) Descendants spouses (n = 109) Without CAD (n = 45) With CAD (n = 95) Without CAD (n = 114) With CAD (n=8) Without CAD (n = 101) Age yrs yrs >61 yrs Smoking 7% 5% 18% 12% 7% 0% Tobacco 16% 10% 28% 23% 8% 2% Alcohol 12% 15% 57% 41% 7% 1% SBP 74.2% 79% 92% 39.2% 70% 31% >130 mm Hg DBP>85 mm Hg 86% 63% 89% 47% 62% 33% WHR* 88% 80% 82% 62% 86% 59% BMI 87% 40% 86.8% 34.1% 88% 15% (>25 kg/m 2 ) HyperTG (>150 mg/dl) 69% 39.4% 93% 30.5% 76% 20.2% Low HDL**(mg/dl) 56.1% 35.2% 84.3% 41.2% 70.4% 38.1% Hyperglycemia (>110 mg/dl) 52.3% 36.7% 57.2% 13.8% 42.2% 5.1% *WHR>0.9 in males and>0.85 in females; **HDL<40 mg/dl in males and<50 mg/dl in females

4 456 INDIAN J. BIOCHEM. BIOPHYS., VOL. 50, OCTOBER 2013 parents with CAD (Table 1). The increased prevalence in descendants clearly indicated that besides genetic predisposition life-habits also contributed for the increase prevalence of risk factors in younger generation. Higher BMI and hypertension are considered as important factors contributing to development of CAD in the Asian Indians 6. Obesity has also been considered as one of the important risk factor for the development of hypertension and CAD, due to associated abnormalities in lipid metabolism 17. Abdominal obesity as reflected by increased WC has been found to be associated with hyperinsulinemia, IR and this increases cardiovascular events 13,18. A higher WC and WHR in subjects with CAD and CAD + DM as compared to those without CAD suggested the importance of abdominal obesity (Tables 3 and 4). Table 2 Incidence of components of metabolic syndrome on the basis of ATP III criteria Subjects 3 or 3+ risk factors 2 risk factors 0-1 risk factor Parents (142) 78 (54.9%) 55 (38.7%) 9 (7%) With CAD (97) 53 (54.6%) 44 (45.3%) 0 (0%) Without CAD (45) 22 (48.8%) 15 (33.33%) 8 (17.7%) Descendants (209) 115 (55%) 30 (14.35%) 64 (30.6%) With CAD (95) 76 (83%) 16 (17%) 0 (0%) Without CAD (114) 27 (26%) 16 (16%) 60 (58%) Hyperinsulinemia and IR denoted by HOMA-IR on statistical analysis showed that those subjects with CAD and CAD + DM had higher SI and HOMA-IR (Tables 3 and 4). IR of glucose metabolism is strongly related to several classic CVD risk factors like hyperglycemia, obesity, high triglycerides, low HDL cholesterol, hypertension and microalbuminuria 19. There are reports of a strong association between hypertension, diabetes and IR in diabetics 20. Furthermore, when the general population is stratified according to the number of abnormalities clustering in the same individual, i.e. the features of the MetS, IR increases across categories and subjects with 4 to 5 abnormalities have the most severe IR. IR seems to be a gateway to several physiological derangements which ultimately impact on the arterial wall 21. A deranged lipid metabolism has an important consequence of IR, is recognised as a hallmark of CAD risk. High serum TC, TG and low HDLc increases the risk for CAD 22. Prospective epidemiologic studies associate low levels of HDLc as a significant independent risk factor for the development of CHD 23. It has been suggested that any benefit underlying elevated HDLc could be attributed to the HDL2c subfraction 24. From a functional perspective, the HDL2c subfraction particles are generally considered potent anti-atherosclerotic molecules, whereas the smaller, denser HDL3c subfraction particles are considered less athero-protective. Most HDLc resides in the large Table 3a Anthropometric and biochemical characteristics of parents without and with CAD Mean difference p value 95% CI With CAD (79) Without CAD (36) Age (yrs) 66.4 ± ± to 1.78 SBP (mm of Hg) ± ± to 4.01 DBP (mm of Hg) ± ± to 4.01 BMI (kg/m 2 ) ± ± to 3.93 WHR 0.94 ± ± to 0.04 TC (mg/dl) ± ± to TG (mg/dl) ± ± to HDLc (mg/dl) ± ± to 1.03 HDL-2c (mg/dl) ± ± to HDL3c (mg/dl) ± ± to 3.24 LDLc (mg/dl) ± ± to sdldlc (mg/dl) 53.4 ± ± to LbLDLc (mg/dl) ± ± to 3.83 PL (mg/dl) ± ± to Insulin (µiu/ml) ± ± to HOMA IR 7.97 ± ± to 4.69 HOMA β ± ± to

5 SHARMA et al.: CARDIAC RISK FACTORS IN DESCENDANTS OF PARENTS 457 Table 3b ANOVA of anthropometric and biochemical characteristics of parents with only CAD and with CAD + DM Mean p value 95% CI F value CAD (68) CAD + DM (29) difference Age (yrs) ± ± to SBP (mm of Hg) ± ± to DBP (mm of Hg) ± ± to * BMI (kg/m 2 ) ± ± to * WHR 0.94 ± ± to TC (mg/dl) ± ± to * TG (mg/dl) ± ± to * HDLc (mg/dl) ± ± to * HDL2c (mg/dl) ± ± to ** HDL3c (mg/dl) ± ± to ** LDLc (mg/dl) ± ± to sdldlc (mg/dl) ± ± to * LbLDLc (mg/dl) ± ± to PL (mg/dl) ± ± to Insulin (µiu/ml) ± ± to ** HOMA IR 5.99 ± ± to ** HOMA β ± ± to F above 3 is significant; * denotes significance spherical lipid-rich particles of the HDL2a and HDL2b sub-fractions 25. The Asian Indian group has been also reported as having significantly low levels of HDL2c, which may help explain the high prevalence of CAD in this ethnic population 26. In the present study results were observed in groups regarding the traditional risk factors like high TC and low HDLc, with significantly higher levels of TC in parents with CAD as compared to those without CAD (Table 3a). Similarly, the levels of HDLc, HDL2c and HDL3c were observed to be significantly reduced in the parents with CAD as compared to parents without CAD (Tables 3a and b). The group of parents with both CAD and DM had further decline in their HDL subfraction levels (Table 3b). ANOVA for the parents with CAD, with CAD + DM and without CAD showed significant decrease in HDL2c and HDL3c in parents with CAD and CAD + DM, as compared to those without CAD (Table 3b). Similar observations were also seen in the present study descendants group ANOVA, as is shown in Table 4b and Figs. 1 & 2. High serum TG levels are independently associated with the risk of developing CVD. Earlier studies have shown that the association between TG and CVD risk diminishes after adjustment for TC and more importantly HDLc 19. However, in a study in the Asia-Pacific region, it has been shown that serum TG level is an independent determinant of CVD risk Table 4a Anthropometric and biochemical characteristics of descendantss without any disease (n = 114) Variables Age (yrs) ± 7.20 SBP (mm of Hg) ± 8.30 DBP(mm of Hg) ± 6.72 BMI (kg/m 2 ) ± 4.88 WC (cms) ± HC (cms) ± WHR 0.9 ± 0.09 TC (mg/dl) ± TG (mg/dl) ± HDLc (mg/dl) ± 5.08 HDL2c (mg/dl) ± 4.01 HDL3c (mg/dl) ± 4.22 LDLc (mg/dl) ± sd LDLc (mg/dl) ± Lb LDLc (mg/dl) ± PL (mg/dl) ± across a broad population group within this region and even a slight increase in TG level could lead to increased risk of CAD 27. Hypertriglyceridemia was observed in the present study groups, with large arithmetic mean differences in their values in parents as well as in descendants with CAD, with CAD + DM, as compared to that of without CAD (Tables 3, 4 and 5). Also, ANOVA done for both the groups-parents with CAD and CAD + DM and descendants with CAD and CAD + DM showed F

6 458 INDIAN J. BIOCHEM. BIOPHYS., VOL. 50, OCTOBER 2013 Fig. 1 Box plots of sd LDLc levels in descendants with CAD, with CAD + DM and without CAD or DM Fig. 2 Box plots of HDL-2C levels in descendants with CAD, with CAD + DM and without CAD or DM Table 4b ANOVA of anthropometric and biochemical characteristics of descendants with only CAD and with CAD + DM Mean difference p value 95% CI F value CAD (67) CAD + DM (25) Age (yrs) ± ± to ** SBP (mm of Hg) ± ± to ** DBP (mm of Hg) ± ± to ** BMI (kg/m 2 ) ± ± to ** WC (cm) ± ± to ** HC (cm) ± ± to ** WHR 0.95 ± ± to ** TC (mg/dl) ± ± to * TG (mg/dl) ± ± to ** HDLc (mg/dl) ± ± to ** HDL-2c (mg/dl) ± ± to ** HDL3c (mg/dl) ± ± to LDLc (mg/dl) ± ± to ** sdldlc (mg/dl) ± ± to ** LbLDLc (mg/dl) ± ± to * PL (mg/dl) ± ± to ** F above 3 is significant; * denotes significance ratio of >3 for anthropometric variables and blood lipids and lipoprotein subfractions (except LbLDLc) (Tables 3, 4 and 5), suggesting that hypertriglyceridemia indeed is strong risk factor for CAD. The intrinsic atherogenicity of TG was because high plasma TG levels drive core lipid exchange between lipoproteins, as observed in the present study. The presence of increased TG stimulates the assembly and secretion of apo-b and VLDL. The cholestryl ester transfer protein (CETP) exchanges TG for HDLc, leading to cholesterol-rich VLDL remnant (atherogenic) andtg-rich, cholesterol depleted HDLc. This TG rich HDLc particle dissociates from apo-ai that is cleared through kidneys and thus HDLc levels reduce owing to reduced number of apo-ai 19,28. This supported low HDL2c and HDL3c, as observed in our study groups. Table 5a Anthropometric and biochemical characteristics of descendants spouses without any disease (n = 101) Variables Age (yrs) 42.2 ± 6.19 SBP (mm of Hg) ± 8.13 DBP (mm of Hg) ± 5.02 BMI (kg/m 2 ) ± 3.16 WC (cm) ± HC (cm) ± 9.23 WHR 0.91 ± PL (mg/dl) ± TC (mg/dl) ± TG (mg/dl) ± HDLc (mg/dl) ± 6.22 HDL2c (mg/dl) ± 5.89 HDL3c (mg/dl) 31.6 ± 3.92 LDLc (mg/dl) ± sdldlc (mg/dl) ± LbLDLc (mg/dl) ± 20.75

7 SHARMA et al.: CARDIAC RISK FACTORS IN DESCENDANTS OF PARENTS 459 Table 5b ANOVA of anthropometric and biochemical characteristics of descendants with CAD having one parent with CAD and both parents with CAD Mean difference p value 95% CI F value Variables Both parents CAD+ (32) Single parent CAD+ (63) Age (yrs) ± ± to * SBP (mm of Hg) ± ± to ** DBP (mm of Hg) ± ± to * BMI (kg/m ± ± to ** WC (cm) ± ± to ** HC (cm) ± ± to ** WHR 0.92 ± ± to * TC (mg/dl) ± ± to * TG (mg/dl) ± ± to ** HDLc (mg/dl) ± ± to ** HDL2c (mg/dl) 9.81 ± ± to ** HDL3c (mg/dl) ± ± to ** LDLc (mg/dl) ± ± to ** sdldlc (mg/dl) ± ± to ** LbLDLc (mg/dl) ± ± to PL (mg/dl) ± ± to ** F above 3 is significant; * denotes significance Table 5c ANOVA of anthropometric and biochemical characteristics of descendants without CAD having one parent with CAD and both parents with CAD Both parents with CAD (41) Single parent with CAD (73) Mean difference p value 95%CI F value Age (yrs) ± ± to ** SBP (mm of Hg) ± ± to * DBP (mm of Hg) ± ± to BMI (kg/m ± ± to * WC (cm) ± ± to * HC (cm) ± ± to ** WHR 0.91 ± ± to TC (mg/dl) ± ± to TG (mg/dl) ± ± to * HDLc (mg/dl) ± ± to HDL2c (mg/dl) ± ± to * HDL3c (mg/dl) ± ± to LDLc (mg/dl) ± ± to sdldlc (mg/dl) ± ± to * LbLDLc (mg/dl) ± ± to PL (mg/dl) ± ± to F above 3 is significant; * denotes significance The TGs are transferred to LDLc particles which get hydrolyzed by lipoprotein lipase (LPL) to form sdldlc. These sdldlc particles have several characteristics that increase their atherogenic potential like increased residence time in plasma owing to reduced binding to LDLc receptors, more time for infiltrating into intima, binding to intimal proteoglycans with greater affinity and higher susceptibility to oxidation 29,30. Quebec cardiovascular study has shown that a predominance of sdldlc is a strong and independent predictor of CHD in the first seven years of follow-up and another report suggests that progression of CHD is closely linked not to the LDLc particle size, but to

8 460 INDIAN J. BIOCHEM. BIOPHYS., VOL. 50, OCTOBER 2013 the concentration of sdldlc 31. It has been clearly demonstrated that there exists a correlation of inheritance of sdldlc particle size from parents to descendants and even in siblings 1. Asian Indians risk of premature CAD might be due to the high levels of sdldlc, as was observed in the present study groups (Table 3, 4 and 5 and Fig. 3) A positive family history of premature CAD is a recognised important predictor for cardiovascular death in the first degree relatives 32. CHD risk factors, including lipids are known to aggregate within families and many studies have shown that the variation in lipid levels is determined by genetic as well as environmental factors 33. A strong positive association is reported between TC levels in parents and descendants cholesterol and LDLc 34. ANOVA of the descendants with CAD having both parents with CAD and having one parent with CAD as against their spouses without any CAD or family history of CAD, showed F ratio of great significance for serum lipids, including TC and TG and lipoprotein subfractions, including HDLc, HDL2c, HDL3c and sd LDLc (Table 6). Thus, there was a strong association between parental history of CHD and descendants anthropometric variables, lipids and lipoprotein subfractions. We observed that descendants in which both parents were suffering from CAD had a tendency of low HDLc and also lower HDL2c, in comparison to those in which single parent had CAD (Table 5b). ANOVA in three groups, namely descendants without CAD having both parents with CAD, descendants without CAD having single parent with CAD and descendant spouses without CAD showed a significant F ratio for SBP, BMI, lipids and sd LDLc, HDLc, HDL2c and HDL3c, indicating that the descendants although did not have CAD, but were obese, hypertensive and inherited deranged lipid and lipoprotein subfractions from parents (Table 5b and Figs 2, 3 and 4). To observe which of the risk factors among the many discussed was the most prominent and independently responsible for CAD, multiple analysis of variation (MANOVA) was performed (Table 6). The number of factors was reduced to 9 from 21, without much loss of information. MANOVA used for a direct comparison of these 9 factors regarding the presence or absence of CAD showed that LDLc particle size had the strongest association with presence or absence of CAD (p = 0.002), followed by WC (p = 0.004), while other factors like HOMA-IR (0.01), HDL2c (p = 0.01) and HDLc (p = 0.02) also showed significant association. The raised WC and evaluation of sdldlc might enhance our capability to predict cardiovascular events (Table 6). Table 6 MANOVA for converging on the most important factor responsible for presence or absence of CAD Variables CAD(+/-) MANOVA P sdldlc WC HOMA IR 0.01 HDL-2c 0.01 HDLc 0.02 LDLc 0.2 SBP 0.5 BMI 0.5 TG 0.9 AGE 0.9 Fig. 3 Box plots of sd LDLc levels in descendants without CAD, but with positive family history of CAD and spouses without CAD and with negative family history of CAD Fig. 4 Box plots of HDL-2 levels in offspring without CAD, but with positive history of CAD and spouses without CAD and with negative family history

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