Association study of lipoprotein(a) genetic markers, traditional risk factors, and coronary heart disease in HIV-1-infected patients.

Objectives: General population studies have shown associations between copy number variation (CNV) of the LPA gene Kringle-IV type-2 (KIV-2) coding region, single-nucleotide polymorphism (SNP) rs6415084 in LPA and coronary heart disease (CHD). Because risk factors for HIV-infected patients may differ from the general population, we aimed to assess whether these potential associations also occur in HIV-infected patients. Methods: A unicenter, retrospective, case-control (1:3) study. Eighteen HIV-patients with confirmed diagnosis of acute myocardial infarction (AMI) were adjusted for age, gender, and time since HIV diagnosis to 54 HIV-patients without CHD. After gDNA extraction from frozen blood, both CNV and SNP genotyping were performed using real-time quantitative PCR. All genetic and non-genetic variables for AMI were assessed in a logistic regression analysis. Results: Our results did not confirm any association in terms of lipoprotein(a) LPA structural genetic variants when comparing KIV-2 CNV (p = 0.67) and SNP genotypes (p = 0.44) between AMI cases and controls. However, traditional risk factors such as diabetes mellitus, hypertension, and CD4(+) T cell count showed association (p < 0.05) with CHD. Conclusion: Although significant associations of AMI with diabetes, hypertension and CD4(+) T cell count in HIV-patients were found, this study could not confirm the feasibility neither of KIV-2 CNV nor rs6415084 in LPA as genetic markers of CHD in HIV-infected patients.Highlights:● Individuals with HIV infection are at higher risk of coronary heart disease (CHD) than the non-infected population.● Our results showed no evidence of LPA structural genetic variants associated with CHD in HIV-1-infected patients.● Associations were found between diabetes mellitus, arterial hypertension, CD4(+) T cell count, and CHD.● The clinical usefulness of these biomarkers to predict CHD in HIV-1-infected population remains unproven.● Further studies are needed to assess the contribution of common genetic variations to CHD in HIV-infected individuals.

Multislice CT for assessing in-stent dimensions after left main coronary artery stenting: a comparison with three dimensional intravascular ultrasound

Objective: To evaluate the agreement between multislice CT (MSCT) and intravascular ultrasound (IVUS) to assess the in-stent lumen diameters and lumen areas of left main coronary artery (LMCA) stents. Design: Prospective, observational single centre study. Setting: A single tertiary referral centre. Patients: Consecutive patients with LMCA stenting excluding patients with atrial fibrillation and chronic renal failure. Interventions: MSCT and IVUS imaging at 9-12 months follow-up were performed for all patients. Main outcome measures: Agreement between MSCT and IVUS minimum luminal area (MLA) and minimum luminal diameter (MLD). A receiver operating characteristic (ROC) curve was plotted to find the MSCT cut-off point to diagnose binary restenosis equivalent to 6 mm2 by IVUS. Results: 52 patients were analysed. Passing-Bablok regression analysis obtained a β coefficient of 0.786 (0.586 to 1.071) for MLA and 1.250 (0.936 to 1.667) for MLD, ruling out proportional bias. The α coefficient was −3.588 (−8.686 to −0.178) for MLA and −1.713 (−3.583 to −0.257) for MLD, indicating an underestimation trend of MSCT. The ROC curve identified an MLA ≤4.7 mm2 as the best threshold to assess in-stent restenosis by MSCT. Conclusions: Agreement between MSCT and IVUS to assess in-stent MLA and MLD for LMCA stenting is good. An MLA of 4.7 mm2 by MSCT is the best threshold to assess binary restenosis. MSCT imaging can be considered in selected patients to assess LMCA in-stent restenosis

Coronary vasomotor responses to isometric handgrip exercise are primarily mediated by nitric oxide: a noninvasive MRI test of coronary endothelial function.

Endothelial cell release of nitric oxide (NO) is a defining characteristic of nondiseased arteries, and abnormal endothelial NO release is both a marker of early atherosclerosis and a predictor of its progression and future events. Healthy coronaries respond to endothelial-dependent stressors with vasodilatation and increased coronary blood flow (CBF), but those with endothelial dysfunction respond with paradoxical vasoconstriction and reduced CBF. Recently, coronary MRI and isometric handgrip exercise (IHE) were reported to noninvasively quantify coronary endothelial function (CEF). However, it is not known whether the coronary response to IHE is actually mediated by NO and/or whether it is reproducible over weeks. To determine the contribution of NO, we studied the coronary response to IHE before and during infusion of N(G)-monomethyl-l-arginine (l-NMMA, 0.3 mg·kg(-1)·min(-1)), a NO-synthase inhibitor, in healthy volunteers. For reproducibility, we performed two MRI-IHE studies ∼8 wk apart in healthy subjects and patients with coronary artery disease (CAD). Changes from rest to IHE in coronary cross-sectional area (%CSA) and diastolic CBF (%CBF) were quantified. l-NMMA completely blocked normal coronary vasodilation during IHE [%CSA, 12.9 ± 2.5 (mean ± SE, placebo) vs. -0.3 ± 1.6% (l-NMMA); P < 0.001] and significantly blunted the increase in flow [%CBF, 47.7 ± 6.4 (placebo) vs. 10.6 ± 4.6% (l-NMMA); P < 0.001]. MRI-IHE measures obtained weeks apart strongly correlated for CSA (P < 0.0001) and CBF (P < 0.01). In conclusion, the normal human coronary vasoactive response to IHE is primarily mediated by NO. This noninvasive, reproducible MRI-IHE exam of NO-mediated CEF promises to be useful for studying CAD pathogenesis in low-risk populations and for evaluating translational strategies designed to alter CAD in patients.

Circulating FABP4 Is a prognostic biomarker in patients with acute coronary syndrome but not in asymptomatic individuals.

OBJECTIVE: Blood-borne biomarkers reflecting atherosclerotic plaque burden have great potential to improve clinical management of atherosclerotic coronary artery disease and acute coronary syndrome (ACS). APPROACH AND RESULTS: Using data integration from gene expression profiling of coronary thrombi versus peripheral blood mononuclear cells and proteomic analysis of atherosclerotic plaque-derived secretomes versus healthy tissue secretomes, we identified fatty acid-binding protein 4 (FABP4) as a biomarker candidate for coronary artery disease. Its diagnostic and prognostic performance was validated in 3 different clinical settings: (1) in a cross-sectional cohort of patients with stable coronary artery disease, ACS, and healthy individuals (n=820), (2) in a nested case-control cohort of patients with ACS with 30-day follow-up (n=200), and (3) in a population-based nested case-control cohort of asymptomatic individuals with 5-year follow-up (n=414). Circulating FABP4 was marginally higher in patients with ST-segment-elevation myocardial infarction (24.9 ng/mL) compared with controls (23.4 ng/mL; P=0.01). However, elevated FABP4 was associated with adverse secondary cerebrovascular or cardiovascular events during 30-day follow-up after index ACS, independent of age, sex, renal function, and body mass index (odds ratio, 1.7; 95% confidence interval, 1.1-2.5; P=0.02). Circulating FABP4 predicted adverse events with similar prognostic performance as the GRACE in-hospital risk score or N-terminal pro-brain natriuretic peptide. Finally, no significant difference between baseline FABP4 was found in asymptomatic individuals with or without coronary events during 5-year follow-up. CONCLUSIONS: Circulating FABP4 may prove useful as a prognostic biomarker in risk stratification of patients with ACS.

Pathomorphological and CT-angiographical characteristics of coronary atherosclerotic plaques in cases of sudden cardiac death.

The goal of this study was to assess the localization and types of thrombosed plaques in cases of sudden cardiac death attributed to coronary artery disease and to evaluate possible correlations with body mass index (BMI) and increased heart weight. This retrospective study was performed on forensic cases for which the cause of death was attributed to coronary artery disease. A complete autopsy and a multi-phase postmortem computed tomography (CT) angiography (MPMCTA) were performed in all cases. Eighty-five cases were selected (mean age, 55.18 ± 11.04 years; 72 men and 13 women). MPMCTA performed prior to autopsy enabled an evaluation of coronary artery perfusion before dissection of the body and helped therefore to guide sampling for histology. An acute coronary thrombosis was found in 57 cases, which included plaque erosion in 26 cases (mean age, 46.73 ± 8.33 years) and rupture or intra-plaque hemorrhage in 31 cases (mean age, 58.23 ± 10.62 years). Erosions were most frequently found in the left anterior descending artery (61.5 %), while only 35.48 % of ruptures were observed in this artery. Chronic coronary pathology was considered as the main cause of death in 28 cases (mean age, 59.64 ± 9.47 years). Sixty-two of the cases (72.94 %) had a BMI in the overweight category (BMI ≥25), with the highest mean BMI in patients with chronic coronary pathology without acute thrombosis found at autopsy. The heart weight was above the predicted reference values in 52 cases (61.18 %). Our results are in accordance with previously published studies on the spatial distribution of vulnerable plaques. We observed a higher percentage of eroded plaques than previously reported. Patients with coronary erosions were significantly younger than those with plaque rupture or those without an acute coronary thrombosis (p values <0.0001). BMI and heart weight were significantly higher for cases without thrombosis in comparison with those with plaque rupture (p values 0.028 and 0.003, respectively). Our results indicating that increased BMI and overweight hearts are associated with chronic ischemic heart disease are compatible with clinical studies. Performing more postmortem studies on forensic autopsies, including modern radiological examinations with MPMCTA, can enhance the detection of vulnerable plaques in living patients and prevent sudden cardiac death.

CT attenuation values of blood and myocardium: rationale for accurate coronary artery calcifications detection with multi-detector CT.

OBJECTIVES: To determine inter-session and intra/inter-individual variations of the attenuations of aortic blood/myocardium with MDCT in the context of calcium scoring. To evaluate whether these variations are dependent on patients' characteristics. METHODS: Fifty-four volunteers were evaluated with calcium scoring non-enhanced CT. We measured attenuations (inter-individual variation) and standard deviations (SD, intra-individual variation) of the blood in the ascending aorta and of the myocardium of left ventricle. Every volunteer was examined twice to study the inter-session variation. The fat pad thickness at the sternum and noise (SD of air) were measured too. These values were correlated with the measured aortic/ventricular attenuations and their SDs (Pearson). Historically fixed thresholds (90 and 130 HU) were tested against different models based on attenuations of blood/ventricle. RESULTS: The mean attenuation was 46 HU (range, 17-84 HU) with mean SD 23 HU for the blood, and 39 HU (10-82 HU) with mean SD 18 HU for the myocardium. The attenuation/SD of the blood were significantly higher than those of the myocardium (p < 0.01). The inter-session variation was not significant. There was a poor correlation between SD of aortic blood/ventricle with fat thickness/noise. Based on existing models, 90 HU threshold offers a confidence interval of approximately 95% and 130 HU more than 99%. CONCLUSIONS: Historical thresholds offer high confidence intervals for exclusion of aortic blood/myocardium and by the way for detecting calcifications. Nevertheless, considering the large variations of blood/myocardium CT values and the influence of patient's characteristics, a better approach might be an adaptive threshold.

Association between parental history and genetic risk scores for coronary heart disease prediction: The population-based CoLaus study.

BACKGROUND AND AIMS: Parental history (PH) and genetic risk scores (GRSs) are separately associated with coronary heart disease (CHD), but evidence regarding their combined effects is lacking. We aimed to evaluate the joint associations and predictive ability of PH and GRSs for incident CHD. METHODS: Data for 4283 Caucasians were obtained from the population-based CoLaus Study, over median follow-up time of 5.6 years. CHD was defined as incident myocardial infarction, angina, percutaneous coronary revascularization or bypass grafting. Single nucleotide polymorphisms for CHD identified by genome-wide association studies were used to construct unweighted and weighted versions of three GRSs, comprising of 38, 53 and 153 SNPs respectively. RESULTS: PH was associated with higher values of all weighted GRSs. After adjustment for age, sex, smoking, diabetes, systolic blood pressure, low and high density lipoprotein cholesterol, PH was significantly associated with CHD [HR 2.61, 95% CI (1.47-4.66)] and further adjustment for GRSs did not change this estimate. Similarly, one standard deviation change of the weighted 153-SNPs GRS was significantly associated with CHD [HR 1.50, 95% CI (1.26-1.80)] and remained so, after further adjustment for PH. The weighted, 153-SNPs GRS, but not PH, modestly improved discrimination [(C-index improvement, 0.016), p = 0.048] and reclassification [(NRI improvement, 8.6%), p = 0.027] beyond cardiovascular risk factors. After including both the GRS and PH, model performance improved further [(C-index improvement, 0.022), p = 0.006]. CONCLUSION: After adjustment for cardiovascular risk factors, PH and a weighted, polygenic GRS were jointly associated with CHD and provided additive information for coronary events prediction.

Thoracic fat volume is independently associated with coronary vasomotion.

PURPOSE: Thoracic fat has been associated with an increased risk of coronary artery disease (CAD). As endothelium-dependent vasoreactivity is a surrogate of cardiovascular events and is impaired early in atherosclerosis, we aimed at assessing the possible relationship between thoracic fat volume (TFV) and endothelium-dependent coronary vasomotion. METHODS: Fifty healthy volunteers without known CAD or major cardiovascular risk factors (CRFs) prospectively underwent a (82)Rb cardiac PET/CT to quantify myocardial blood flow (MBF) at rest, and MBF response to cold pressor testing (CPT-MBF) and adenosine (i.e., stress-MBF). TFV was measured by a 2D volumetric CT method and common laboratory blood tests (glucose and insulin levels, HOMA-IR, cholesterol, triglyceride, hsCRP) were performed. Relationships between CPT-MBF, TFV and other CRFs were assessed using non-parametric Spearman rank correlation testing and multivariate linear regression analysis. RESULTS: All of the 50 participants (58 ± 10y) had normal stress-MBF (2.7 ± 0.6 mL/min/g; 95 % CI: 2.6-2.9) and myocardial flow reserve (2.8 ± 0.8; 95 % CI: 2.6-3.0) excluding underlying CAD. Univariate analysis revealed a significant inverse relation between absolute CPT-MBF and sex (ρ = -0.47, p = 0.0006), triglyceride (ρ = -0.32, p = 0.024) and insulin levels (ρ = -0.43, p = 0.0024), HOMA-IR (ρ = -0.39, p = 0.007), BMI (ρ = -0.51, p = 0.0002) and TFV (ρ = -0.52, p = 0.0001). MBF response to adenosine was also correlated with TFV (ρ = -0.32, p = 0.026). On multivariate analysis, TFV emerged as the only significant predictor of MBF response to CPT (p = 0.014). CONCLUSIONS: TFV is significantly correlated with endothelium-dependent and -independent coronary vasomotion. High TF burden might negatively influence MBF response to CPT and to adenosine stress, even in persons without CAD, suggesting a link between thoracic fat and future cardiovascular events.

Combining T2-preparation with spectral and spatial selectivity for improved coronary MRA

Cardiovascular disease is the leading cause of death worldwide. Within this subset, coronary artery disease (CAD) is the most prevalent. Magnetic resonance angiography (MRA) is an emerging technique that provides a safe, non-invasive way of assessing CAD progression. To generate contrast between tissues, MR images are weighted according to the magnetic properties of those tissues. In cardiac MRI, T2 contrast, which is governed by the rate of transverse signal loss, is often created through the use of a T2-Preparation module. T2-Preparation, or T2-Prep, is a magnetization preparation scheme used to improve blood/myocardium contrast in cardiac MRI. T2-Prep methods generally use a non-selective +90°, 180°, 180°, -90° train of radiofrequency (RF) pulses (or variant thereof), to tip magnetization into the transverse plane, allow it to evolve, and then to restore it to the longitudinal plane. A key feature in this process is the combination of a +90° and -90° RF pulse. By changing either one of these, a mismatch occurs between signal excitation and restoration. This feature can be exploited to provide additional spectral or spatial selectivity. In this work, both of these possibilities are explored. The first - spectral selectivity - has been examined as a method of improving fat saturation in coronary MRA. The second - spatial selectivity - has been examined as a means of reducing imaging time by decreasing the field of view, and as a method of reducing artefacts originating from the tissues surrounding the heart. Two additional applications, parallel imaging and self-navigation, are also presented. This thesis is thus composed of four sections. The first, "A Fat Signal Suppression for Coronary MRA at 3T using a Water-Selective Adiabatic T2-Preparation Technique", was originally published in the journal Magnetic Resonance in Medicine (MRM) with co-authors Ruud B. van Heeswijk and Matthias Stuber. The second, "Combined T2-Preparation and 2D Pencil Beam Inner Volume Selection", again with co-authors Ruud van Heeswijk and Matthias Stuber, was also published in the journal MRM. The third, "A cylindrical, inner volume selecting 2D-T2-Prep improves GRAPPA-accelerated image quality in MRA of the right coronary artery", written with co-authors Jerome Yerly and Matthias Stuber, has been submitted to the "Journal of Cardiovascular Magnetic Resonance", and the fourth, "Combined respiratory self-navigation and 'pencil-beam' 2D-T2 -Prep for free-breathing, whole-heart coronary MRA", with co¬authors Jerome Chaptinel, Giulia Ginami, Gabriele Bonanno, Simone Coppo, Ruud van Heeswijk, Davide Piccini, and Matthias Stuber, is undergoing internal review prior to submission to the journal MRM. -- Les maladies cardiovasculaires sont la cause principale de décès dans le monde : parmi celles-ci, les maladies coronariennes sont les plus répandues. L'angiographie par résonance magnétique (ARM) est une technique émergente qui fournit une manière sûre, non invasive d'évaluer la progression de la coronaropathie. Pour obtenir un contraste entre les tissus, les images d'IRM sont pondérées en fonction des propriétés magnétiques de ces tissus. En IRM cardiaque, le contraste en T2, qui est lié à la décroissance du signal transversal, est souvent créé grâce à l'utilisàtion d'un module de préparation T2. La préparation T2, ou T2-Prep, est un système de préparation de l'aimantation qui est utilisé pour améliorer le contraste entre le sang et le myocarde lors d'une IRM cardiaque. Les méthodes de T2-Prep utilisent généralement une série non-sélective d'impulsions de radiofréquence (RF), typiquement [+ 90°, 180°, 180°, -90°] ou une variante, qui bascule l'aimantation dans le plan transversal, lui permet d'évoluer, puis la restaure dans le plan longitudinal. Un élément clé de ce processus est la combinaison des impulsions RF de +90° et -90°. En changeant l'une ou l'autre des impulsions, un décalage se produit entre l'excitation du signal et de la restauration. Cette fonction peut être exploitée pour fournir une sélectivité spectrale ou spatiale. Dans cette thèse, les deux possibilités sont explorées. La première - la sélectivité spectrale - a été examinée comme une méthode d'améliorer la saturation de la graisse dans l'IRM coronarienne. La deuxième - la sélectivité spatiale - a été étudiée comme un moyen de réduire le temps d'imagerie en diminuant le champ de vue, et comme une méthode de réduction des artefacts provenant des tissus entourant le coeur. Deux applications supplémentaires, l'imagerie parallèle et la self-navigation, sont également présentées. Cette thèse est ainsi composée de quatre sections. La première, "A Fat Signal Suppression for Coronary MRA at 3T using a Water-Selective Adiabatic T2-Preparation Technique", a été publiée dans la revue médicale Magnetic Resonance .in Medicine (MRM) avec les co-auteurs Ruud B. van Heeswijk et Matthias Stuber. La deuxième, Combined T2-Preparation and 2D Pencil Beam Inner Volume Selection", encore une fois avec les co-auteurs Ruud van Heeswijk et Matthias Stuber, a également été publiée dans le journal MRM. La troisième, "A cylindrical, inner volume selecting 2D-T2-Prep improves GRAPPA- accelerated image quality in MRA of the right coronary artery", écrite avec les co-auteurs Jérôme Yerly et Matthias Stuber, a été présentée au "Journal of Cardiovascular Magnetic Resonance", et la quatrième, "Combined respiratory self-navigation and 'pencil-beam' 2D-T2 -Prep for free-breathing, whole-heart coronary MRA", avec les co-auteurs Jérôme Chaptinel, Giulia Ginami, Gabriele Bonanno , Simone Coppo, Ruud van Heeswijk, Davide Piccini, et Matthias Stuber, subit un examen interne avant la soumission à la revue MRM.

Vascular Function in Chronic Kidney Disease and in Renovascular Disease

Cardiovascular mortality is 15 to 30 times higher in patients with chronic kidney disease than in the age-adjusted general population. Even minor renal dysfunction predicts cardiovascular events and death in the general population. In patients with atherosclerotic renovascular disease the annual cardiovascular event and death rate is even higher. The abnormalities in coronary and peripheral artery function in the different stages of chronic kidney disease and in renovascular disease are still poorly understood, nor have the cardiac effects of renal artery revascularization been well characterized, although considered to be beneficial. This study was conducted to characterize myocardial perfusion and peripheral endothelial function in patients with chronic kidney disease and in patients with atherosclerotic renovascular disease. Myocardial perfusion was measured with positron emission tomography (PET) and peripheral endothelial function with brachial artery flow-mediated dilatation. It has been suggested that the poor renal outcomes after the renal artery revascularization could be due to damage in the stenotic kidney parenchyma; especially the reduction in the microvascular density, changes mainly evident at the cortical level which controls almost 80% of the total renal blood flow. This study was also performed to measure the effect of renal artery stenosis revascularization on renal perfusion in patients with renovascular disease. In order to do that a PET-based method for quantification of renal perfusion was developed. The coronary flow reserve of patients with chronic kidney disease was similar to the coronary flow reserve of healthy controls. In renovascular disease the coronary flow reserve was, however, markedly reduced. Flow-mediated dilatation of brachial artery was decreased in patients with chronic kidney disease compared to healthy controls, and even more so in patients with renovascular disease. After renal artery stenosis revascularization, coronary vascular function and renal perfusion did not improve in patients with atherosclerotic renovascular disease, but in patients with bilateral renal artery stenosis, flow-mediated dilatation improved. Chronic kidney disease does not significantly affect coronary vascular function. On the contrary, coronary vascular function was severely deteriorated in patients with atherosclerotic renovascular disease, possibly because of diffuse coronary artery disease and/or diffuse microvascular disease. The peripheral endothelial function was disturbed in patients with chronic kidney disease and even more so in patient with atherosclerotic renovascular disease. Renal artery stenosis dilatation does not seem to offer any benefits over medical treatment in patients with renovascular disease, since revascularization does not improve coronary vascular function or renal perfusion.

Periprocedural prognostic factors in coronary interventions – retrospective studies

Background: Approximately 11,000 revascularization procedures, either percutaneous coronary interventions (PCI) or coronary artery bypass grafting surgery (CABG), are performed yearly in Finland for coronary artery disease. Periprocedural risk factors for mortality and morbidity as well as long-term outcome have been extensively studied in general populations undergoing revascularization. Treatment choice between PCI and CABG in many high risk groups and risk-stratification, however, needs clarification and there is still room for improvement in periprocedural outcomes. Materials and methods: Cohorts of patients from Finnish hospitals revascularized between 2001 and 2011 were retrospectively analyzed. Patient records were reviewed for baseline variables and postprocedural outcomes (stroke, myocardial infarction, quality of life measured by the EQ-5D –questionnaire, repeat revascularization, bleeding episodes). Data on date and mode of death was acquired from Statistics Finland. Statistical analysis was performed to identify predictors of adverse events and compare procedures. Results: Postoperative administration of blood products (red blood cells, fresh frozen plasma, platelets) after isolated CABG independently and dose-dependently increases the risk of stroke. Patients 80 years or older who underwent CABG had better survival at 5 years compared to those who underwent PCI. After adjusting for baseline differences survival was similar. Patients on oral anticoagulation (OAC) for atrial fibrillation (AF) treated with CABG had better survival and overall outcome at 3 years compared to PCI patients. There was no difference in incidence of stroke or bleeding episodes. Differences in outcome remained significant after adjusting for propensity score. Lower health-related quality of life (HRQOL) scores as measured by the visual analogue scale (VAS) of the EQ-5D questionnaire at 6 months after CABG predicted later major adverse cardiac and cerebrovascular events (MACCE). Deteriorating function and VAS scores between 0 and 6 months on the EQ-5D also independently predicted later MACCE. Conclusions: Administration of blood products can increase the risk of stroke after CABG and liberal use of transfusions should be avoided. In the frail subpopulations of patients on OAC and octogenarians CABG appears to offer superior long-term outcome as compared to PCI. Deteriorating HRQOL scores predict later adverse events after CABG. Keywords: percutaneous coronary intervention, coronary artery bypass grafting, age over 80, transfusion, anticoagulants, coronary artery disease, health-related quality of life, outcome.

HFE gene mutations in coronary atherothrombotic disease

Although iron can catalyze the production of free radicals involved in LDL lipid peroxidation, the contribution of iron overload to atherosclerosis remains controversial. The description of two mutations in the HFE gene (Cys282Tyr and His63Asp) related to hereditary hemochromatosis provides an opportunity to address the question of the association between iron overload and atherosclerosis. We investigated the prevalence of HFE mutations in 160 survivors of myocardial infarction with angiographically demonstrated severe coronary atherosclerotic disease, and in 160 age-, gender- and race-matched healthy control subjects. PCR amplification of genomic DNA followed by RsaI and BclI restriction enzyme digestion was used to determine the genotypes. The frequency of the mutant Cys282Tyr allele was identical among patients and controls (0.022; carrier frequency, 4.4%), whereas the mutant His63Asp allele had a frequency of 0.143 (carrier frequency, 27.5%) in controls and of 0.134 (carrier frequency, 24.5%) in patients. Compound heterozygotes were found in 2 of 160 (1.2%) controls and in 1 of 160 (0.6%) patients. The finding of a similar prevalence of Cys282Tyr and His63Asp mutations in the HFE gene among controls and patients with coronary atherothrombotic disease, indirectly questions the possibility of an association between hereditary hemochromatosis and atherosclerosis.

Protective effect of N-acetylcysteine against oxygen radical-mediated coronary artery injury

The present study investigated the protective effect of N-acetylcysteine (NAC) against oxygen radical-mediated coronary artery injury. Vascular contraction and relaxation were determined in canine coronary arteries immersed in Kreb's solution (95% O2-5% CO2), incubated or not with NAC (10 mM), and exposed to free radicals (FR) generated by xanthine oxidase (100 mU/ml) plus xanthine (0.1 mM). Rings not exposed to FR or NAC were used as controls. The arteries were contracted with 2.5 µM prostaglandin F2alpha. Subsequently, concentration-response curves for acetylcholine, calcium ionophore and sodium fluoride were obtained in the presence of 20 µM indomethacin. Concentration-response curves for bradykinin, calcium ionophore, sodium nitroprusside, and pinacidil were obtained in the presence of indomethacin plus Nomega-nitro-L-arginine (0.2 mM). The oxidative stress reduced the vascular contraction of arteries not exposed to NAC (3.93 ± 3.42 g), compared to control (8.56 ± 3.16 g) and to NAC group (9.07 ± 4.0 g). Additionally, in arteries not exposed to NAC the endothelium-dependent nitric oxide (NO)-dependent relaxation promoted by acetylcholine (1 nM to 10 µM) was also reduced (maximal relaxation of 52.1 ± 43.2%), compared to control (100%) and NAC group (97.0 ± 4.3%), as well as the NO/cyclooxygenase-independent receptor-dependent relaxation provoked by bradykinin (1 nM to 10 µM; maximal relaxation of 20.0 ± 21.2%), compared to control (100%) and NAC group (70.8 ± 20.0%). The endothelium-independent relaxation elicited by sodium nitroprusside (1 nM to 1 µM) and pinacidil (1 nM to 10 µM) was not affected. In conclusion, the vascular dysfunction caused by the oxidative stress, expressed as reduction of the endothelium-dependent relaxation and of the vascular smooth muscle contraction, was prevented by NAC.