Hyperhomocysteinemia as an Independent Risk Factor for Coronary Heart Disease. Comparison with Conventional Risk Factors / Hiper-homocisteinemia como fator de risco independente para doença coronariana: comparação com fatores de risco convencionais

Abstract The present study was designed to evaluate the strength of association of raised plasma homocysteine concentration as a risk factor for coronary heart disease independent of conventional risk factor. It was a case control study conducted at Punjab Institute of Cardiology Lahore. A total of 210 subjects aged 25 to 60 years comprising of 105 newly admitted patients of CHD as cases and 105 age and sex matched healthy individuals with no history of CHD as control were recruited for the study. Fasting blood samples were obtained from cases and controls. Plasma homocysteine was analyzed by fluorescence polarization immunoassay (FPIA) method on automated immunoassay analyzer (Abbott IMX). Total cholesterol, triglyceride and HDL cholesterol were analyzed using calorimetric kit methods. The concentration of LDL cholesterol was calculated using Friedewald formula. The patients were also assessed for traditional risk factors such as age, sex, family history of CVD, hypertension, smoking and physical activity, and were compared with control subjects. The collected data was entered in SPSS version 24 for analysis and interpretation.The mean age in controls and experimental groups were 43.00± 8.42 years and 44.72± 8.59 years with statistically same distribution (p- value= 0.144). The mean plasma homocysteine for cases was 22.33± 9.22 µmol/L where as it was 12.59±3.73 µmol/L in control group. Highly significant difference was seen between the mean plasma level of homocysteine in cases and controls (p˂0.001).Simple logistic regression indicates a strong association of coronary heart disease with hyperhomocysteinemia (OR 7.45), which remained significantly associated with coronary heart disease by multivariate logistic regression (OR 7.10, 95%C1 3.12-12.83, p=0.000). The present study concludes that elevated levels of Plasma homocysteine is an independent risk factor for coronary heart disease independent of conventional risk factors and can be used as an indicator for predicting the future possibility for the onset of CVD.

Resumo O presente estudo foi desenhado para avaliar a força da associação da concentração elevada de homocisteína no plasma como um fator de risco para doença cardíaca coronária independente do fator de risco convencional. Foi um estudo de caso-controle realizado no Punjab Institute of Cardiology Lahore. Um total de 210 indivíduos com idade entre 25 e 60 anos, compreendendo 105 pacientes recém-admitidos de CHD como casos e 105 indivíduos saudáveis ​​pareados por idade e sexo sem histórico de CHD como controle, foi recrutado para o estudo. Amostras de sangue em jejum foram obtidas de casos e controles. A homocisteína plasmática foi analisada pelo método de imunoensaio de polarização de fluorescência (FPIA) em analisador de imunoensaio automatizado (Abbott IMX). Colesterol total, triglicerídeos e colesterol HDL foram analisados ​​usando métodos de kit calorimétrico. A concentração de colesterol LDL foi calculada pela fórmula de Friedewald. Os pacientes também foram avaliados para fatores de risco tradicionais, como idade, sexo, história familiar de DCV, hipertensão, tabagismo e atividade física, e foram comparados com indivíduos de controle. Os dados coletados foram inseridos no SPSS versão 24 para análise e interpretação. A média de idade nos grupos controles e experimentais foi de 43,00 ± 8,42 anos e 44,72 ± 8,59 anos com distribuição estatisticamente igual (p-valor = 0,144). A homocisteína plasmática média para os casos foi de 22,33 ± 9,22 µmol / L, enquanto no grupo controle foi de 12,59 ± 3,73 µmol / L. Diferença altamente significativa foi observada entre o nível plasmático médio de homocisteína em casos e controles (p ˂ 0,001). A regressão logística simples indica uma forte associação de doença cardíaca coronária com hiper-homocisteinemia (OR 7,45), que permaneceu significativamente associada com doença cardíaca coronária por multivariada regressão logística (OR 7,10, 95% C1 3,12-12,83, p = 0,000). O presente estudo conclui que níveis elevados de homocisteína plasmática são fator de risco independente para doença cardíaca coronária, independentemente dos fatores de risco convencionais, e pode ser usado como um indicador para prever a possibilidade futura de aparecimento de DCV.

The obstetric origins of health for a lifetime.

There is a new "developmental" model for the origins of a wide range of chronic diseases. Under this model the causes to be identified are linked to normal variations in fetoplacental development. These variations are thought to lead to variations in the supply of nutrients to the baby that permanently alter gene expression, a process known as "programming." According to the developmental model variations in the processes of development program the function of a few key systems that are linked to disease, including the immune system, antioxidant defenses, inflammatory responses, and the number and quality of stem cells.

Mother's body size and placental size predict coronary heart disease in men.

AIMS: People whose birthweights were towards the lower end of the normal range are at increased risk of coronary heart disease. This is attributed to foetal programming through malnutrition, but the cause of the malnutrition is unknown. METHODS AND RESULTS: We studied 6975 men born in Helsinki during 1934-44. Their size at birth was recorded. Babies who later developed coronary heart disease tended to have a low ponderal index (birthweight/length(3)). Three different placental phenotypes predicted the disease. In primiparous mothers who were short, having below median height, the hazard ratio for the disease was 1.14 (95% confidence interval 1.08-1.21, P< 0.0001) for each centimetre increase in the difference between the length and breadth of the placental surface. In tall mothers whose body mass index was above the median, the hazard ratio was 1.25 (1.10-1.42, P= 0.0007) per 40 cm(2) decrease in the surface area. In tall mothers whose body mass index was below the median, the hazard ratio was 1.07 (1.02-1.13, P= 0.01) per 1% increase in the placental weight/birthweight ratio. CONCLUSIONS: Three different combinations of maternal and placental size predicted coronary heart disease. The mother's body size determines the availability of nutrients and is linked to the development and function of the placenta, reflected in its shape and size. We speculate that variations in three processes of normal placental development lead to foetal malnutrition. The processes are (i) implantation and spiral artery invasion, (ii) growth of the chorionic surface, and (iii) compensatory expansion of the chorionic surface.

Head size at birth and long-term mortality from coronary heart disease.

BACKGROUND: Many studies have shown that low birthweight is associated with increased risk of heart disease in adulthood. It is controversial whether this association is caused by genetic or non-genetic factors, and whether life course exposures, such as adult overweight, could modify the association. We have studied the association of head circumference at birth with later deaths from coronary heart disease (CHD), and assessed whether maternal height and adult body mass could modify the association. METHODS: Population-based cohort study of 35,846 men and women born between 1920 and 1959 with mortality follow-up from 1961 to 2005. RESULTS: During follow-up, 630 people died from CHD and there was an inverse association of head circumference with deaths from CHD (Ptrend = 0.010). The association was modified by maternal height (Pinteraction = 0.01) and by adult body mass (Pinteraction = 0.05). People in the lowest third of head circumference, who had a tall mother or a high body mass index in adulthood, were at the highest risk of death from CHD. CONCLUSIONS: Head circumference at birth was inversely associated with deaths from CHD, and the combination of small head and tall mother, or small head and high adult body mass, was associated with the highest risk. These findings suggest that combined effects of genetic factors (growth potential and intrauterine growth) and non-genetic factors acting throughout the life course (intrauterine growth restriction and later weight gain) could mediate the effects of birth size on adult heart disease.

[From the newborn infant to the child, to the adult: historia magistra vitae]. / Dal neonato all'adolescente, all'uomo adulto: historia magistra vitae.

The hypothesis of the prenatal programming of adult diseases took on increasing interest from the moment that, in the 60s, an epidemiological association was proposed between low birth weight and cardiovascular diseases. In the last 20 years it has been demonstrated that individuals with low weight, low stature and thinness at birth have a higher risk of developing cardiovascular diseases and type 2 diabetes. Animal and clinical studies are casting light on the biological mechanisms underlying the association between modified development in the uterus and diseases, and on how growth in adolescence and in adult life can modulate this initial proneness to disease. One of the mechanisms that has aroused most interest among researchers is the reduced number of nephrons, associated with low birth weight, which predisposes to glomerulosclerosis and increased systemic arterial pressure in adult life. A correlation has also been found between low weight at birth and peripheral resistance to insulin. Nevertheless, it is thought that modified prenatal development is only a predisposing factor, open to profound influences in the course of postnatal development. It has in fact been demonstrated that accelerated development in the period of infancy and adolescence can extend the initial condition of neonatal suffering. Indirectly these studies renew and at the same time extend the concept of prevention, a priority aim of the physician of the third millennium.

[Evidence and mechanisms of fetal origins of adult diseases].

This review focuses on the fetal origins of adult disease hypothesis put forward by David Barker and his colleagues, recent advances in epidemiological studies and experimental research in this field. Barker Hypothesis states that environmental factors, particularly intrauterine nutrition, as indicated by birth weight, operate in early life to program the risks for adverse health outcomes in adult life. A large growing body of reports described the association between the early development and adult diseases, such as diabetes, hypertension, coronary heart disease, abnormal lipids metabolism, obesity and cancer, etc. Experimental studies show that the changes of some key genes' expression, caused by epigenetic modifications, lead to a permanent alteration of cellular proliferation and differentiation and finally the genesis in key tissues and organs. These results bring about the impairment in structures and functions and the increased susceptibility to chronic diseases in adult life. The hypothesis provides a new perspective for the prevention and therapy of chronic diseases.

Adult consequences of fetal growth restriction.

Low birthweight in relation to the length of gestation, is now known to be associated with increased rates of coronary heart disease and the related disorders stroke, hypertension and type 2 diabetes. These associations extend across the whole range of birthweight, which implies that normal variations in nutrient delivery to the fetus have profound long-term effects. The associations are thought to reflect the body's plasticity during development, by which its structure and function can be permanently changed by the intra uterine and early post natal environment. Slow growth during infancy and rapid weight gain after the age of two years exacerbate the effect of slow fetal growth. Cardiovascular disease and type 2 diabetes arise through a series of interactions between environmental influences and the pathways of development that precede them.

Lack of evidence of association between MTHFR C677T polymorphism and congenital heart disease in a TDT study design.

INTRODUCTION: Hyperhomocysteinemia is frequently associated with congenital defects of the heart and neural tube. A common missense mutation in the MTHFR gene (C to T substitution at position 677 changing valine to alanine) produces a variant with reduced enzymatic action, resulting in higher plasma levels of homocysteine. The aim of this study is to investigate whether MTHFR C677T functional genetic variant is associated with an increased risk of congenital heart disease (CHD) development using a family-based case-control design and the Transmission Disequilibrium Test (TDT) approach. METHODS: We selected 91 consecutive patients with congenital heart disease for the study. From these patients we were able to obtain samples on 147 parents. The C677T polymorphism at the MTHFR gene was determined from each participant. RESULTS: A statistically significant association was disclosed in univariate analysis using a family-based case-control design (p<0.0001 assuming an additive genetic model, p<0.0001 assuming a dominant genetic model, and p=0.01 assuming a recessive genetic model). This association was explained by an increased frequency of the T allele in patients as compared to their fathers. However, by using a TDT approach a highly non-significant result was obtained and no association could be defined between this locus and congenital heart disease. CONCLUSIONS: We did not find sufficient evidence for an association between MTHFR C677T genotype and congenital heart disease in our study group. Previous reports on such association may be due to population genetic structure.

Fetal origins of coronary heart disease-implications for cardiothoracic surgery?

Over the last 15 years, there has been growing evidence that poor nutrition during gestation plays an important role in the development of coronary heart disease. This hypothesis, commonly known as the 'fetal origins of adult disease' has now gained widespread acceptance in the scientific community. In this review, we discuss the evidence for this theory and analyse the patho-physiological mechanisms underlying the relationship between altered fetal growth and coronary heart disease. Finally, the potential relevance of the theory to cardiac surgical practice will be evaluated.

Does maternal nutrition in pregnancy and birth weight influence levels of CHD risk factors in adult life?

The fetal-origins hypothesis suggests that maternal and fetal nutrition can have a profound and sustained impact on the health of the offspring in adult life. Although there is abundant literature reporting on the associations between birth weight and disease risk factors, only a handful of studies have been able to examine the relationship between maternal nutrition in pregnancy with the health of offspring in adult life directly. Between 1942 and 1944, nearly 400 pregnant women were recruited into a dietary study to determine whether the wartime dietary rations were sufficient to prevent nutritional deficiencies. Detailed biochemical and clinical assessments were conducted for each of the women, who were followed-up until after delivery. More than 50 years later, approximately one-quarter of the adult offspring were recruited into a study to explore the possible impact of maternal nutrition in pregnancy on CHD risk factors, including glucose tolerance, blood pressure and components of the lipid profile. Results from the present study provide no evidence to support the hypothesis that birth weight or maternal nutrition in pregnancy are associated with CHD risk factors in adult life.

Studies of twins: can they shed light on the fetal origins of adult disease hypothesis?

There has been much interest in evidence that people with lower birthweight have higher risk of adult cardiovascular disease, but the causal pathways underlying such observations are uncertain. Study of twins offers an opportunity to shed light on these pathways, in three different ways. First, in a twin pregnancy maternal nutritional resources and the "supply line" to the fetuses will be more "stretched". We hypothesise that study of twin pregnancies is a more efficient way to identify modifiable maternal factors that influence later health than studies of singleton pregnancies. Second, twins have lower birthweight than singletons. Comparison of cardiovascular disease risk in twins versus that in singletons will provide insight into whether birthweight per se is in the underlying causal pathway of interest, and whether factors constraining fetal growth of twins (versus singletons) affect later outcome. Third, twin cohorts provide an opportunity to investigate the role of "shared" factors versus factors affecting each individual fetus, by comparing results of within-cohort versus within-pair analyses. Generalisability of findings in twins is debated. We suggest that findings in monochorionic twins (or in the absence of chorionicity data, those from monozygotic twins) need to be interpreted with caution.

Fetal origins of adult disease: strength of effects and biological basis.

BACKGROUND: Low birthweight has been consistently shown to be associated with coronary heart disease (CHD) and its biological risk factors. The effects of low birthweight are increased by slow infant growth and rapid weight gain in childhood. To quantify the importance of developmental processes in the genesis of CHD it is necessary to establish the impact of fetal, infant and childhood growth on major pathological events in later life-death, hospital treatment and the need for medication. METHODS: Longitudinal study of 13 517 men and women who were born in Helsinki University Hospital during 1924-1944, whose body sizes at birth and during childhood were recorded, and in whom deaths, hospital admissions, and prescription of medication for chronic disease are documented. RESULTS: The combination of small size at birth and during infancy, followed by accelerated weight gain from age 3 to 11 years, predicts large differences in the cumulative incidence of CHD, type 2 diabetes and hypertension. CONCLUSIONS: Coronary heart disease and type 2 diabetes may originate through two widespread biological phenomena-developmental plasticity and compensatory growth.