Epidemiological characteristics of platelet aggregability

Sensitivity of thrombin-induced platelet aggregation to inhibition by ethanol

BACKGROUND

The purpose of this study was to determine the concentration of ethanol required for inhibition of thrombin-induced aggregation of human platelets in vitro.

METHODS

Three methods, light transmission method, particle counting method using light scattering and screen filtration pressure method using whole blood, were used for evaluation of platelet aggregation.

RESULTS

Thrombin (0.2 U/ml)-induced platelet aggregation was significantly inhibited by ethanol, and the threshold ethanol concentrations for inhibition determined by measurements using the light transmission method, particle counting method and screen filtration pressure method were 0.5%, 0.125% and 2%, respectively. Platelet aggregation induced by a lower concentration (0.05 U/ml) of thrombin was detected by the screen filtration pressure method but not by the light transmission method or particle counting method. The threshold ethanol concentration for the inhibition of thrombin (0.05 U/ml)-induced platelet aggregation was 0.125% according to results obtained by using the screen filtration pressure method.

CONCLUSIONS

Sensitivities for detection of thrombin-induced platelet aggregation and for detection of inhibition of platelet aggregation by ethanol were high in the screen filtration pressure method and the particle counting method, respectively. The threshold concentration of ethanol to inhibit thrombin-induced platelet aggregation is about 0.125% (approximately 21 mmol/l), which is easily attainable after drinking alcohol.

The prevalence of the platelet glycoprotein IIIa Pl(A1/A2) polymorphism in three South African ethnic groups and its effect on platelet function

INTRODUCTION

In South Africa coronary artery disease (CAD) is less common in African than Indian or white subjects. Although the association between CAD and metabolic factors have been well documented, the role of genetic factors is as yet poorly understood. Specific polymorphisms in the platelet membrane glycoprotein (GP) IIIa gene Pl(A1/A2), have been implicated in the development of CAD.

METHODS

The prevalence of platelet GPIIIa (Pl(A1/A2)) polymorphisms and their effect on platelet function was determined in 313 Indian, 267 white and 227 African subjects with and without a history of CAD.

RESULTS

In subjects without a history of CAD the frequency of the unfavourable Pl(A2) allele was 8.0%, 14.8% and 8.7% in the Indian, white and African populations respectively, with the frequency being significantly higher (p<0.05) in the white than both other groups. The frequency of the Pl(A2) allele was higher in subjects with (23.0%) than without (10.0%; p<0.0001) a history of CAD. Aggregation studies showed that platelets carrying the Pl(A2) allele were hypersensitive to the platelet aggregating agonists ADP and collagen and produced a higher amount of TXA(2) when stimulated with low concentrations of both these agonists.

CONCLUSIONS

The positive association observed between the platelet GPIIIa Pl(A1/A2) polymorphism and platelet function suggests that the GPIIIa Pl(A2) allele may be a genetic factor that contributes to the risk of sudden death from myocardial infarction in the absence of known risk factors but it does not explain ethnic differences in the prevalence of CAD.

Platelet counts and platelet activation markers in obese subjects

OBJECTIVE

In this work we studied the correlation between platelet count, platelet activation, and systemic inflammation in overweight, obese, and morbidly obese individuals.

METHODS AND SUBJECTS

A total of 6319 individuals participated in the study. Complete blood counts, high sensitivity C-reactive protein (hs-CRP) serum levels, and body mass index (BMI) were measured during routine checkups. Platelet activation markers were studied among 30 obese (BMI = 41 +/- 8 kg/m(2)) and 35 nonobese (BMI = 24 +/- 3 kg/m(2)) individuals. Platelet activation status was evaluated by flow cytometry using specific antibodies against the activated platelet membrane glycoprotein IIb/IIIa, p-selectin (CD-62 p), and binding of Annexin-V to platelet anionic phospholipids.

RESULTS

Overweight, obese, and morbidly obese females had significantly elevated platelet counts ( P < .0001) compared with normal-weight females. No significant elevation of platelet counts was observed in the male subgroups. A significant age adjusted correlation between BMI and platelet counts ( P < .0001) was found among females. This correlation was attenuated (P = .001) after adjustment for hs-CRP concentrations. The flow cytometry analysis of platelets showed no significant differences in activation marker expression between nonobese and obese individuals.

DISCUSSION

Obesity may be associated with elevated platelet counts in females with chronic inflammation. Obesity is not associated with increased platelet activation.

The interaction of vasoactive substances during exercise modulates platelet aggregation in hypertension and coronary artery disease

Background

Acute vigorous exercise, associated with increased release of plasma catecholamines, transiently increases the risk of primary cardiac arrest. We tested the effect of acute submaximal exercise on vasoactive substances and their combined result on platelet function.

Methods

Healthy volunteers, hypertensive patients and patients with coronary artery disease (CAD) performed a modified treadmill exercise test. We determined plasma catecholamines, thromboxane A₂, prostacyclin, endothelin-1 and platelet aggregation induced by adenosine diphosphate (ADP) and collagen at rest and during exercise.

Results

Our results during exercise showed a) platelet activation (increased thromboxane B₂, TXB₂), b) increased prostacyclin release from endothelium and c) decreased platelet aggregation in all groups, significantly more in healthy volunteers than in patients with CAD (with hypertensives lying in between these two groups).

Conclusion

Despite the pronounced activation of Sympathetic Nervous System (SNS) and increased TXB₂ levels during acute exercise platelet aggregation decreases, possibly to counterbalance the prothrombotic state. Since this effect seems to be mediated by the normal endothelium (through prostacyclin and nitric oxide), in conditions characterized by endothelial dysfunction (hypertension, CAD) reduced platelet aggregation is attenuated, thus posing such patients in increased risk for thrombotic complications.

Effects of platelet glycoprotein IIb-IIIa number and glycoprotein IIIa Leu33Pro polymorphism on platelet aggregation and sensitivity to glycoprotein IIb-IIIa antagonists

We investigated the influence of glycoprotein (GP) IIIa Leu33Pro polymorphism, platelet GP IIb-IIIa number, and plasma fibrinogen concentration on platelet aggregation and antiaggregatory action of GP IIb-IIIa antagonists. Healthy volunteers with GP IIIa Pro33(-) (Leu33Leu33, n = 20) and Pro33(+) (Leu33Pro33, n = 13, and Pro33Pro33, n = 2) genotypes were included into the study. GP IIIa Leu33Pro substitution was associated with the increase of the level and rate of platelet microaggregate formation induced by GP IIb-IIIa activating antibody CRC54 (100, 200, 400 microg/ml) against the epitope within 1-100 residues of GP IIIa N-terminal part (p from 0.001 to 0.047). No significant differences were detected between parameters of platelet aggregation induced by ADP (1.25, 2.5, 5.0, 20 microM) in GP IIIa Pro33(+) and Pro33(-) donors. GP IIb-IIIa antagonist Monafram (F(ab')(2) fragment of GP-IIb-IIIa blocking antibody CRC64) (1, 2, 3 microg/ml), but not eptifibatide (50, 100, 150 ng/ml) inhibited ADP-induced aggregation slightly less efficiently in GP IIIa Pro33(+) group (p < 0.05 at 1 and 2 microg/ml Monafram). GP IIb-IIIa number (evaluated as maximal binding of (125)I-labelled antibody CRC64) varied from 40.5 to 80.8 x 10(3) per platelet with no significant influence of GP IIIa genotype. Consistent correlations were revealed between GP IIb-IIIa quantity and the level and rate of ADP-induced aggregation (r from 0.353 to 0.583, p from <0.001 to 0.037) as well as resistance (level of residual aggregation) to both GP IIb-IIIa antagonists (r from 0.345 to 0.602, p from <0.001 to 0.042). ADP-induced aggregation was considerably increased and efficiency of GP IIb-IIIa antagonists decreased in donors with high in comparison with low GP IIb-IIIa quantity (>60 and 40-50 x 10(3) per platelet respectively, p < 0.01 for most tests). No correlations were observed between all tested parameters and plasma fibrinogen concentration. Our results indicate that inter-individual variability of platelet GP IIb-IIIa number significantly affects platelet aggregation and antiaggregatory effects of GP IIb-IIIa antagonists. Contribution of this factor is higher than that of GP IIIa Leu33Pro polymorphism and variations of fibrinogen concentration.

Blood HDL Cholesterol Levels Influence Association of Alcohol Intake With Blood Pressure in Young Men But Not in Middle-Aged Men

BACKGROUND

Both blood pressure and HDL cholesterol are affected by alcohol drinking. However, it has not been determined whether association of alcohol drinking with blood pressure varies depending on blood HDL level.

METHODS

The subjects were male workers aged 20 to 29 year and 50 to 59 year (n = 21,301), representing young and middle ages, respectively, who had received periodic health checkup examinations. The subjects were divided into tertile groups by serum HDL level, and they were further divided into 3 subgroups based on the average daily alcohol intake [nondrinkers, light drinkers (<30 g of ethanol per day) and heavy drinkers (30 g or more of ethanol per day)]. Blood pressure and incidence of high blood pressure were compared among the 3 alcohol subgroups in each age and HDL group.

RESULTS

In the lowest HDL tertile of 20 to 29-year-old subjects, systolic and diastolic blood pressure and incidences of high systolic and diastolic blood pressure were not significantly different among the 3 alcohol subgroups. In the middle and highest HDL tertiles of the twenties age group, systolic and diastolic blood pressure was significantly higher in heavy drinkers than in nondrinkers, and incidences of high systolic and diastolic blood pressure were significantly higher in drinkers than in nondrinkers. On the other hand, in all HDL tertile groups of 50 to 59-year-old subjects, blood pressure was significantly higher in light drinkers and heavy drinkers than in nondrinkers, and incidences of high systolic and diastolic blood pressure were significantly higher in drinkers than in nondrinkers.

CONCLUSIONS

The results suggest that blood pressure of middle-aged men is elevated by alcohol drinking independently of blood HDL level and is more sensitive to drinking than is blood pressure of young men.

Effects of dietaryn-3 polyunsaturated fatty acids from plant and marine origin on platelet aggregation in healthy elderly subjects

In the present intervention study we compared the effects of α-linolenic acid with those of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on platelet aggregationin vitroandex vivoin healthy non-institutionalized elderly subjects. We also compared the effects of α-linolenic acid on platelet aggregation in elderly subjects with those in younger volunteers. During a run-in period of 3 weeks all subjects (thirty-eight elderly (> 60 years) and twelve younger volunteers (< 35 years)) received a diet rich in oleic acid. For the next 6 weeks the elderly subjects received a diet rich in oleic acid (n11), α-linolenic acid (n14) (6·8 g/d) or EPA/DHA (n13) (1·05 g EPA plus 0·55 g DHA). The younger subjects were given a diet rich in α-linolenic acid. The diets did not affect ADP- or collagen-induced platelet aggregationin vitroin either platelet-rich plasma or whole blood. Theex vivoplatelet aggregation as measured with filtragometry was significantly decreased in the elderly group that received EPA/DHA compared with the α-linolenic acid (P= 0·006) and the oleic acid (P= 0·005) diet groups. Effects of α-linolenic acid were not age-dependent. Our results suggest that α-linolenic acid and EPA/DHA do not changein vitroplatelet aggregation. Compared with oleic acid, EPA/DHA, but not α-linolenic acid, favourably affectsex vivoplatelet aggregation in healthy elderly subjects.

Long-term effects of hemostatic variables on fatal coronary heart disease: 30-year results from the first prospective Northwick Park Heart Study (NPHS-I)

BACKGROUND

The long-term associations of established risk factors for coronary heart disease (CHD), for example cholesterol, are well known, but not for the less familiar hemostatic variables.

OBJECTIVES

To establish whether associations between hemostatic variables and CHD first identified nearly three decades ago have persisted long-term.

METHODS

The first Northwick Park Heart Study (NPHS-I) recruited 2167 white men and 941 white women, average age at entry 48 years, on whom measures of factor (F) VII activity (VIIc) and plasma fibrinogen were carried out, both at entry and at follow-up approximately 6 years later.

RESULTS

During a median follow-up of 29 years, 231 male and 36 female CHD deaths were recorded from notifications by the Office for National Statistics. VIIc at recruitment was significantly related to CHD mortality, corrected rate ratio, RR, per 1 SD increase 1.56 (95% CI 1.29, 1.88) in men and RR 1.78 (95% CI 1.17, 2.72) in women. Recruitment fibrinogen was also strongly related to CHD mortality in men, RR 1.63 (95% CI 1.33, 1.99) but not in women, RR 0.75 (95% CI 0.40, 1.43). The associations persisted after controlling for confounders and were confirmed using 6-year follow-up measurements and in analyses omitting deaths within 10 years of recruitment.

CONCLUSIONS

The hemostatic system contributes to CHD mortality, and its effect is stable over time. For VIIc, the effect was similar in men and women, while for fibrinogen it appeared to be present only in men.

Associations of plasma fibrinogen and factor VII clotting activity with coronary heart disease and stroke: prospective cohort study from the screening phase of the Thrombosis Prevention Trial

BACKGROUND

As with 'conventional' risk factors such as cholesterol and smoking, there is a need for large, long-term prospective studies on hemostatic factors.

OBJECTIVES

To investigate the prospective relationship of fibrinogen and factor VII clotting activity (FVIIc) with risk of coronary heart disease (CHD) and stroke in a study with a large number of outcomes over a period of 15 years.

PATIENTS/METHODS

A cohort of 22 715 men aged 45-69 years was screened for participation in the Thrombosis Prevention Trial. Men were followed up for fatal and non-fatal CHD and stroke events. There were 1515 CHD events (933 CHD deaths) and 391 strokes (180 stroke deaths). Hazard ratios (HRs) and 95% confidence intervals are expressed per standardized increase in log fibrinogen and log FVIIc, adjusting for age, trial treatment group, conventional CHD risk factors and regression dilution bias.

RESULTS

Hazard ratios for fibrinogen were 1.52 (1.37-1.70) for all CHD events, and 1.36 (1.09-1.69) for all strokes. Exclusion of events within the first 10 years showed a persistent association between CHD and fibrinogen, with an adjusted HR of 1.93 (1.42-2.64). The HRs for FVIIc, adjusting for age and trial treatment, were 1.07 (1.01-1.12) for all CHD events and 1.07 (0.97-1.20) for all strokes, and the fully adjusted HRs were, respectively, 0.97 (0.84-1.05) and 1.07 (0.85-1.33).

CONCLUSIONS

The persisting association between fibrinogen and CHD beyond 10 years may imply a causal effect. There is a small effect of FVIIc on CHD, after adjustment for age and trial treatment, but no association independent of other risk factors.

INFLUENCE OF DRINKING ALCOHOL ON ATHEROSCLEROTIC RISK IN ALCOHOL FLUSHERS AND NON-FLUSHERS OF ORIENTAL PATIENTS WITH TYPE 2 DIABETES MELLITUS

AIMS

Facial flushing caused by alcohol drinking is a typical symptom of high sensitivity to alcohol in orientals. We investigated whether drinking alcohol influences atherosclerotic risk factors in alcohol flushers and non-flushers in patients with diabetes mellitus.

METHODS

A cross-sectional study was performed using 225 subjects with type 2 diabetes. Sensitivity to alcohol was surveyed by a questionnaire on facial flushing. Subjects were divided into three groups by average amount of alcohol drinking (non-drinkers; light drinkers: <140 g/week; heavy drinkers: 140 g/week or more).

RESULTS

Systolic blood pressure and blood HDL cholesterol were significantly higher in heavy drinkers than in non-drinkers. There were no significant differences in body mass index, blood pressure, blood total cholesterol, HDL cholesterol, uric acid, fibrinogen and sialic acid levels in flushers and non-flushers. In alcohol flushers, diastolic blood pressure and HDL cholesterol in heavy drinkers were significantly higher than those in non-drinkers, and systolic blood pressure was significantly higher in heavy drinkers than in non-drinkers and light drinkers. On the other hand, blood pressure and HDL cholesterol in non-flushers were not significantly different among non-, light and heavy drinkers. Serum total cholesterol was not significantly different among the three drinking groups both in flushers and non-flushers.

CONCLUSIONS

Blood pressure and HDL cholesterol are more prone to be affected by drinking in flushers than in non-flushers, suggesting that alcohol sensitivity evaluated by flushing response due to drinking alcohol should be taken into account when the effects of alcohol drinking on atherosclerotic risk factors are considered in oriental patients with type 2 diabetes mellitus.

Planned versus provisional use of glycoprotein IIb/IIIa inhibitors in smokers undergoing percutaneous coronary intervention

Postmortem and angiographic studies have demonstrated that thrombosis is the primary cause of coronary artery occlusion in smokers. Further, smokers have high levels of fibrinogen, increased platelet aggregation, and more platelet-dependent thrombin generation than do nonsmokers, suggesting that glycoprotein (GP) IIb/IIIa inhibitor use during percutaneous coronary intervention (PCI) may be especially useful among smokers. We evaluated a subpopulation of active smokers in the REPLACE-2 trial to assess the effect of treating smokers with bivalirudin and provisional GP IIb/IIIa blockade compared with heparin and planned GP IIb/IIIa blockade. The REPLACE-2 trial enrolled 1,558 smokers and 4,305 nonsmokers. Smokers who were treated with bivalirudin had an absolute 3.2% increase in the composite end point of death and myocardial infarction at 48 hours compared with smokers who were treated with heparin and GP IIb/IIIa inhibitors (7.7% vs 4.5%, p=0.008, interaction p=0.016). This difference was ameliorated when GP IIb/IIIa inhibitors were used consistently in a previous trial that compared bivalirudin with heparin during PCI (4.6% vs 6.7%, p=0.322). In conclusion, these results suggest that smokers may derive particular benefit with GP IIb/IIIa inhibitors for decreasing myocardial infarction and death after PCI. These findings require further validation from other large, randomized trials.

Coagulation and atherothrombotic disease

Atherothrombotic disease arises secondary to a complex gene-environment interaction. In the initial stages, the condition is clinically silent but with more advanced disease, an occlusive thrombus is formed resulting in the classical clinical manifestations. Both environmental factors and genetic variations in elements of the clotting cascade influence thrombosis risk by inducing quantitative and qualitative changes in the mature protein, which may affect the final structure of the clot and determine its resistance to lysis. Understanding the fine details of gene-environment interactions in relation to thrombus formation will help to shed more light on disease pathogenesis. Consequently, this will allow the development of more efficacious treatment strategies and will also help to identify subjects at risk, thereby enabling the introduction of early preventative measures.

Factors influencing the relation between alcohol and cardiovascular disease

PURPOSE OF REVIEW

Light-to-moderate alcohol intake is known to have cardioprotective properties in some subsets of the population. This review focuses on factors that modify the relation between alcohol and cardiovascular disease.

RECENT FINDINGS

Several large American studies have shown that the J-shaped relation is influenced by age and coronary heart disease risk-factor status since only middle-aged and elderly and those already at risk of developing coronary heart disease seem protected by drinking alcohol. It has also been suggested that only those who have a steady - in contrast to a binge - intake of alcohol have benefits with regard to cardiovascular disease. Prospective studies from the UK, Sweden and Denmark have further suggested that wine drinkers have a lower mortality than beer and spirits drinkers.

SUMMARY

The J-shaped relation between alcohol intake and cardiovascular disease seems to be influenced by age, gender, drinking pattern and type of alcohol.

New risk factors for atherosclerosis in hypertension: focus on the prothrombotic state and lipoprotein(a)

Although adequate control of blood pressure is of basic importance in cardiovascular prevention in hypertensive patients, correction of additional risk factors is an integral part of their management. In addition to classical risk factors, epidemiological research has identified a number of other conditions that might significantly contribute to cardiovascular risk in the general population and might achieve specific relevance in patients with high blood pressure. In fact, more than 20% of patients with premature cardiovascular events do not have any of the traditional risk factors and, although effective intervention on blood pressure and additional risk factors has significantly reduced cardiovascular morbidity and mortality, the contribution to stroke, coronary artery disease and renal failure is still unacceptably high. Evaluation of new risk factors may further expand our capacity to predict atherothrombotic events when these factors are included along with the traditional ones in the assessment of global cardiovascular risk in hypertensive patients. Because it could be anticipated that the role of these novel factors will become increasingly evident in the future, researchers with an interest in hypertension and physicians dealing with problems related to cardiovascular prevention should give them appropriate consideration. This review summarizes the basic biology and clinical evidence of two emerging risk factors that are reciprocally related and contribute to the development and progression of organ damage in hypertension: the prothrombotic state and lipoprotein(a).

Mean platelet volume and exercise stress test

BACKGROUND

Long-term moderate or strenuous physical activity is associated with a considerable reduction in cardiovascular morbidity and mortality. However acute exercise leads to a transient activation of the thrombotic system. Healthy individuals can react this by increasing their fibrinolytic capacity acutely. However, patients with ischemic heart disease, lacking fibrinolytic potential, may be at considerable risk for acute ischemic events if exposed to heavy physical exertion. Platelet size has been shown to reflect platelet activity. The mean platelet volume (MPV) can reflect changes in either the level of platelet stimulation or rate of platelet production.

DESIGN AND METHODS

We evaluated Treadmill exercise test (TMET) and compared MPV values (fl) before and after TMET in 63 consecutive patients who, then, underwent coronary angiography and found to have significant coronary artery disease in more than one coronary artery (>70% diameter stenosis in left anterior descending, right coronary or circumflex artery and >50% diameter stenosis in left main coronary artery). Sixty-three male patients were enrolled as a patient group with a mean age of 52.43 +/- 4.08 years and with strongly positive exercise test (> or =2 mm ST segment depression, horizontal or down-sloping). Thirty-five patients without significant coronary artery disease were selected as a control group with a mean age of 52.66 +/- 4.39 years having undergone TMET.

RESULTS AND DISCUSSION

In the patient and control groups, mean MPV values before TMET were the same, 8.52 +/- 0.63 and 8.45 +/- 0.58 respectively. Following TMET within 30 minutes, mean MPV were 10.03 +/- 0.96 and 8.50 +/- 0.45 respectively ( p < 0.001). When pre and post-TMET MPV values were evaluated together, the patient group had a significant increase in the MPV ( p < 0.001), whereas, the control group had no significant increase in the MPV ( p = 0.379). It was concluded that exercise possibly makes patients with significant coronary artery disease, more susceptible to a thrombotic event through various routes, one of that is platelet activation that could be measured indirectly via MPV. Healthy subjects react this thrombotic process by increasing their fibrinolytic capacity acutely. Patients with ischemic heart disease, particularly those with significantly narrowed coronary arteries, known to lack fibrinolytic capacity and have high shear stress, on the other hand, might face ischemic events, including sudden death following acute exercise.

Aspirin Withdrawal and Acute Lower Limb Ischemia

Aspirin is used mainly to prevent arterial events in patients with arteriopathy. Myocardial infarction and cerebrovascular events have been described after recent aspirin withdrawal. Experimental data suggest rebound platelet activity after aspirin discontinuation. Among a retrospective cohort of 181 patients admitted for acute lower limb ischemia for 4 yr, we studied 11 patients who had recently stopped taking aspirin. Aspirin was administered for vascular event prevention. The median duration of aspirin treatment without vascular events was 12 mo (range, 6-60 mo). The median time between aspirin withdrawal and lower limb ischemia was 23 days (range, 7-60 days). Four of the 11 patients stopped aspirin before a surgical procedure, without any substitution. In five patients, a recent diagnosis of neoplasia was observed. This study should alert clinicians to the risk of discontinuing chronic aspirin therapy in patients with severe peripheral vascular disease.

Role of thrombotic and fibrinolytic factors in acute coronary syndromes

There is a growing body of literature concerning the contribution of hemostatic factors to the development of cardiovascular disease. The mechanisms of the coagulation/fibrinolytic system are complicated and one factor is intimately interrelated with another; thus the contribution of each factor cannot be clearly understood, unless hemostatic factors are considered in accordance with endothelial function and vessel morphology. Although there are many clinical studies about the correlation between hemostatic factors and cardiovascular risk, the results are inconsistent and conflicting at times. Fibrinogen and D-dimer are associated with atherosclerosis or coronary events across multiple studies, even after multivariate adjustment. But the hemostatic factors are intimately correlated, so it can be said that focusing on one to the exclusion of others is inappropriate. The clinical trials with statins or angiotensin converting enzyme inhibitors have shown favorable effects on the prognosis of cardiovascular disease. The study of hemostatic factors in relation to these drugs has provided insights into understanding how these drugs produce beneficial effects.

Epidemiologic evidence for the cardioprotective effects associated with consumption of alcoholic beverages

The impact of alcohol intake on mortality from all causes has been described in a large number of prospective population studies from many countries. Most have shown a J-shaped relation between alcohol intake and subsequent mortality, indicating that there are both beneficial and harmful effects of ethanol on health. The risk of death from ischemic heart disease is seen to be significantly increased, and highest among abstainers, but not significantly increased among heavy drinkers. Some studies have found plausible mechanisms for the beneficial effect of light to moderate drinking. Subjects with a moderate alcohol intake have a higher level of high density lipoprotein than abstainers. Further, moderate drinkers are seen to have a lower low density lipoprotein. Also, alcohol has a beneficial effect on platelet aggregation, and thrombin level in blood is higher among drinkers than among non-drinkers. In the other end of the range of intake, the ascending leg of the U-shaped curve has been explained by the increased risk of cirrhosis, pancreatitis, and development oropharynx, oesophagus, and breast cancer. In exploring the French paradox, it has been suggested that wine may have beneficial effects additional to that of ethanol. Recently, several prospective population studies have supported this idea. It is, however, also likely that the apparent additional beneficial effect of wine on health in addition to the effect of ethanol itself is a consequence of confounding.

Platelet cGMP inversely correlates with age in healthy subjects

Biochemical modifications associated with the increase in platelet activity with age are not well defined. Furthermore it is well known that the nitric oxide/cyclic 3', 5'-guanosine monophosphate (cGMP) pathway regulates platelet aggregation. The aim of the present study was to examine the relationship between platelet content of cGMP and age. 120 normal subjects, evaluating the cGMP platelet concentration, 17betaE2, IGF-I, dehydroepiandrosterone sulphate (DHEAS), insulin, plasma glucose, lipid pattern, homocysteine and PAI-I antigen, were studied. The multivariate analysis in a model with cGMP as dependent variable and with age, LDL, apolipoprotein B (ApoB), DHEAS, E2 and insulin-like growth factor (IGF)-I as independent variables shows a negative correlation between cGMP and age (p<0.01, beta=-0.388). In conclusion our data suggest that the reduced efficiency of the system constitutive nitric oxide synthase (cNOS)/guanylate cyclase represents at least one of the reasons of the increased platelet aggregability with age.

Effects of exercise on platelet and aortic functions in aged rats

AIM AND METHODS

To assess age- and exercise-related changes in platelet aggregation, we measured the magnitude of platelet aggregation with a four-channel aggregometer, plasma and aortic polyunsaturated fatty acids by gas chromatography and related prostanoids with a reagent kit in young and aged non-exercised and in aged exercised rats.

RESULTS

Platelet aggregation in platelet-rich plasma induced by ADP (5 microm) in the primary wave increased with age. In the non-exercised groups, the basal levels of thromboxane B2 in platelet-rich plasma increased in aged rats compared with young rats. In aged exercised rats, the basal levels of 6-keto-prostaglandin F1alpha in platelet-rich plasma were stimulated and those of thromboxane B2 were depressed, compared with non-exercised aged rats. The plasma levels of eicosapentaenoic acid and docosahexaenoic acid increased with age. Only aortic eicosapentaenoic acid in the aged group increased by exercise. In the aged non-exercised and exercised groups, the aortic, but not the plasma, levels of eicosapentaenoic acid correlated inversely with the basal levels of thromboxane B2 in platelet-rich plasma (r = -0.53, P < 0.05) and associated negatively with the magnitudes of platelet aggregation induced by ADP (5 microm) (r = -0.47, P < 0.05).

CONCLUSION

These findings suggest that exercise in aged rats increases aortic eicosapentaenoic acid concentrations, which in turn depress the basal levels of thromboxane, B2 in platelet-rich plasma to modulate platelet aggregation.

The effect of vegetarian diet, plant foods, and phytochemicals on hemostasis and thrombosis

Ischemic heart disease (IHD) is multifactorial with a complex etiology. Conventional risk factors including serum lipids account for less than one half of future IHD events. In the past few years, novel risk factors such as hemostatic and thrombotic factors contributing to the development and progression of IHD have been explored. Typically, diet is the first line of consideration in the prevention of IHD, but very little is known about the effect of diet and nutrients on hemostasis and thrombosis. Cross-sectional studies indicate that vegetarians may have a lower concentration of certain markers of hemostasis compared with nonvegetarians. Platelet aggregation, an index of thrombosis, appears to be higher among vegetarians than nonvegetarians, perhaps because of the lower intake of long-chain n-3 fatty acids among vegetarians. Monounsaturated-fat-rich plant foods may have a protective role in hemostasis and may explain in part the lower incidence of IHD in Mediterranean countries where residents consume a diet high in monounsaturated fatty acid. Finally, certain fruits and vegetables such as soy, garlic, and purple grapes may have antithrombotic effects, which may in part be due to the phytochemicals in these foods. Although this review suggests that a plant-based diet with sufficient n-3 fatty acids and certain fruits and vegetables may have a favorable impact on hemostasis and thrombosis, the evidence is neither sufficient nor conclusive at this time to warrant specific recommendations for the public. Clearly, much remains to be done in this area of investigation.

Oxidative stress and smoking-induced vascular injury

The relative importance of mechanisms relevant to smoking-induced vascular injury is poorly understood. Cigarette smoke is a source of free radicals but also results in cellular activation and consequent generation of free radicals in vivo. Here we consider several approaches to estimating the consequences of free radical generation in vivo, using measurements of modified lipids, proteins, and DNA. Smoking appears to result in elevation of several biomarkers of oxidant stress, some in a dose-related fashion. There is also some evidence that disordered endothelial function in smokers may be partly attributable to oxidant stress. Other effects of smoking on hemostatic activation, sympathoadrenal function, and lipoprotein structure and function may also be modulated by smoking-induced oxidant stress. The emergence and application of rational quantitatively reliable indexes of oxidant stress in vivo is likely to elucidate the relative contribution of oxidant stress to smoking-induced vascular injury.

Alcohol, type of alcohol, and all-cause and coronary heart disease mortality

Many studies from a variety of countries have shown a U- or J-shaped relation between alcohol intake and mortality from all causes. It is now quite well documented from epidemiologic as well as clinical and experimental studies that the descending leg of the curve results from a decreased risk of cardiovascular disease among those with light-to-moderate alcohol consumption. The findings that wine drinkers are at a decreased risk of mortality from cardiovascular disease compared to non-wine drinkers suggest that substances present in wine are responsible for a beneficial effect on the outcome, in addition to that from a light intake of ethanol. Several potential confounding factors still remain to be excluded, however.

Factors influencing the relation between alcohol and mortality--with focus on wine

The impact of alcohol intake on mortality has been described in a large number of prospective population studies from many countries. Most have shown a J-shaped relation between alcohol intake and subsequent mortality, indicating that there are both beneficial and harmful effects of ethanol on health. In exploring the French paradox, it has been suggested that wine may have beneficial effects additional to that of ethanol. Recently, several prospective population studies have supported this idea. However, it is also likely that the apparent additional beneficial effect of wine on health is confounding.

Effects of smoking on myocardial injury in patients with conservatively treated acute myocardial infarction: a study with resting 123I-15-iodophenyl 3-methyl pentadecanoic acid/201Tl myocardial single photon emission computed tomography

Many reports have demonstrated that smokers who have suffered an acute myocardial infarction (AMI) have a better prognosis than nonsmokers. The present study investigated the effects of current smoking on myocardial injury with resting 123I-15-iodophenyl 3-methyl pentadecanoic acid (BMIPP)/201Tl myocardial single photon emission computed tomography in 103 patients with conservatively treated AMI. The left ventricular myocardium was divided into 9 segments and BMIPP and 201Tl defects were scored using a 5-point grading system (0 = normal and 4 = no uptake). The sum of the defect scores was defined as the total defect score. There was no significant difference in either the baseline severity of the coronary artery disease or the total defect scores for BMIPP and 201Tl between the current smoker and nonsmoker groups. The difference between the total defect scores for BMIPP and 201Tl tended to be larger in the current smoker group than in the nonsmoker group (2.0 +/- 1.9 vs 1.3 +/- 1.6, p = 0.056). Forty-one (53%) of 77 patients in the current smoker group exhibited a BMIPP/201Tl mismatch, whereas only 8 (31%) of 26 patients in the nonsmoker group did (p = 0.047). In conclusion, current smokers had more likelihood of salvageable myocardium in areas at risk, as demonstrated by BMIPP/201Tl mismatch, in AMI than nonsmokers.

Platelet glycoprotein IIIa Pl(a) polymorphism, fibrinogen, and platelet aggregability: The Framingham Heart Study

BACKGROUND

Recent data suggest that the Pl(A2) allele of the platelet glycoprotein IIIa receptor may be a genetic risk factor for cardiovascular disease. We previously reported that the Pl(A2) allele was associated with increased platelet aggregability, as indicated by lower epinephrine threshold concentrations. Paradoxically, however, it has been reported that Pl(A2)-positive platelets have reduced fibrinogen binding. Because fibrinogen mediates platelet aggregability, we hypothesized that plasma fibrinogen levels may interact with Pl(A) genotype in modulating platelet aggregability. Methods and Results-- Glycoprotein IIIa Pl(A) genotype, fibrinogen level, and platelet aggregability were ascertained in 1340 subjects enrolled into the Framingham Offspring Study. Platelet aggregability was evaluated by the Born method. Higher fibrinogen levels were associated with increased epinephrine-induced aggregation (P=0.002) and a trend for ADP-induced aggregation (P=0.07). The fibrinogen effect was genotype specific, however, in that the increase in platelet aggregability with higher fibrinogen was present for the Pl(A1/A1) genotype (P=0.0005 and P=0.03 for epinephrine- and ADP-induced aggregation, respectively) but not for the Pl(A2)-positive genotype (P>0.90).

CONCLUSION

Higher fibrinogen levels were associated with increased platelet aggregability. However, the association between fibrinogen and platelet aggregability was genotype specific. This interaction may be responsible for the conflicting findings regarding Pl(A) genotype and platelet aggregability. Further study of this gene-environment interaction may provide insight into cardiovascular disease risk.

Platelet tests in the prediction of myocardial infarction and ischaemic stroke: evidence from the Caerphilly Prospective Study

A platelet test that is predictive of myocardial infarction (MI) and/or stroke would enable the targeting of anti-platelet drugs towards high-risk patients. The predictive power of several platelet tests for MI and for stroke was examined in 2000 older men in the Caerphilly Cohort Study of Heart Disease, Stroke and Cognitive Decline. The tests were: aggregation to adenosine diphosphate (ADP) in platelet-rich plasma (PRP); aggregation to ADP in whole blood measured using an impedance method and a test of platelet aggregation induced in whole blood by high-shear flow. Around 200 MIs and 100 ischaemic strokes occurred during a 10-year follow-up. Neither primary nor secondary aggregation in PRP was predictive of MI. However, the fifth of men in whom the primary response to ADP was least, showed the highest risk of a subsequent stroke [relative odds (RO) 1.64; 95% confidence interval (CI) 1.12-2.43]. Aggregation in whole blood was not predictive of MI but, again, the fifth of men with the least platelet response showed the highest stroke incidence (RO 1.79; 95% CI 1.06-3.00). Retention of platelets in the high-shear test was not predictive of either event.

Dietary monounsaturated fatty acids and haemostasis

Diets high in monounsaturated fatty acids (MUFA) are increasingly being recommended as a highly-effective cholesterol-lowering strategy in populations at risk of CHD. However, the need for a re-appraisal of the benefits of diets rich in MUFA became apparent as a result of recent studies showing that meals high in olive oil cause greater postprandial activation of blood coagulation factor VII than meals rich in saturated fatty acids. The present review evaluates the evidence for the effects of MUFA-rich diets on fasting and postprandial measurements of haemostasis, and describes data from a recently-completed long-term controlled dietary intervention study. The data show that a background diet high in MUFA has no adverse effect on fasting haemostatic variables and decreases the postprandial activation of factor VII in response to a standard fat-containing meal. Since the same study also showed a significant reduction in the ex vivo activation of platelets in subjects on the high-MUFA diet, the overall findings suggest that there is no reason for concern regarding adverse haemostatic consequences of high-MUFA diets.

Experimental thrombosis I: relation with fibrinogen and other haemostatic parameters

Epidemiological studies have shown that the haemostatic parameters Fibrinogen (Fg), Factor VII (F VII), Factor VIII (F VIII), von Willebrand factor (vWF), Tissue Plasminogen Activator (t-PA), Plasminogen Activator Inhibitors (PAI) are risk factors/markers of ischemic cardiovascular disease. Ferritin (sFER) and Leukocytosis have also been implicated. In the present study we have followed the levels of fibrinogen, von Willebrand factor and thrombomodulin in relation to lipids, iron and the appearance of atherosclerotic lesions in New Zealand rabbits fed with a cholesterol enriched diet for a two-month period compared with a group of control rabbits. Hematocrit and white blood cell count (WBC) were measured in parallel. In hyperchlesterolemic rabbits the levels of fibrinogen and von Willebrand factor increased progressively, showing a positive correlation with the increasing cholesterol levels. There was an increase in soluble thrombomodulin beginning at the eighth week of study. In addition, these animals showed gross intimal atherosclerotic lesions in the whole extension of their aortas. Immunohistochemical studies showed the presence of fibrin(ogen) related antigen throughout the arterial wall and in the central portions of the atheromas. In the control group there was no formation of atherosclerotic plaques and all haemostatic, haematological and biochemical parameters were within the normal range. WBC and sFER levels were unaffected in both groups. Our results show that increased levels of fibrinogen and von Willebrand factor, known coronary risk factors, are strongly associated with the formation of atherosclerotic plaques in rabbits. The plaques contain a considerable amount of fibrinogen related antigen.

Lipoprotein (a) and stroke

Strokes are one of the most common causes of mortality and long term severe disability. There is evidence that lipoprotein (a) (Lp(a)) is a predictor of many forms of vascular disease, including premature coronary artery disease. Several studies have also evaluated the association between Lp(a) and ischaemic (thrombotic) stroke. Several cross sectional (and a few prospective) studies provide contradictory findings regarding Lp(a) as a predictor of ischaemic stroke. Several factors might contribute to the existing confusion--for example, small sample sizes, different ethnic groups, the influence of oestrogens in women participating in the studies, plasma storage before Lp(a) determination, statistical errors, and selection bias. This review focuses on the Lp(a) related mechanisms that might contribute to the pathogenesis of ischaemic stroke. The association between Lp(a) and other cardiovascular risk factors is discussed. Therapeutic interventions that can lower the circulating concentrations of Lp(a) and thus possibly reduce the risk of stroke are also considered.

Novel risk factors for atherosclerosis

In the past several years, evidence has accumulated that factors other than conventional risk factors may contribute to the development of atherosclerosis. Conventional risk factors predict less than one half of future cardiovascular events. Furthermore, conventional risk factors may not have the same causal effect in different ethnic groups in whom novel risk factors may have a role. These newer risk factors for atherosclerosis include homocysteine, fibrinogen, impaired fibrinolysis, increased platelet reactivity, hypercoagulability, lipoprotein(a), small dense low-density lipoprotein cholesterol, and inflammatory-infectious markers. Identification of other markers associated with an increased risk of atherosclerotic vascular disease may allow better insight into the pathobiology of atherosclerosis and facilitate the development of preventive and therapeutic measures. In this review, we discuss the evidence associating these factors in the pathogenesis of atherosclerosis, the mechanism of risk, and the clinical implications of this knowledge.

Beneficial effect of moderate alcohol consumption on vascular disease: myth or reality?

Moderate ethanol consumption (1-3 drinks/day on 5-6 days/week) has a favourable effect on vascular disease-related mortality and morbidity [especially ischaemic heart disease (IHD)]. This cardioprotective effect may be due to significant effects on cardiovascular risk factors such as high density cholesterol (HDL) concentration (HDL protects from IHD) and an inhibition of platelet aggregation (increased platelet aggregability predicts coronary events). In contrast, alcoholics and problem drinkers have an excess of IHD-related, and possibly stroke-related, mortality. Excessive alcohol intake may raise the blood pressure. Prolonged alcohol abuse can also result in alcoholic heart muscle disease. Alcohol is the major cause of non-ischaemic cardiomyopathy in Western society. Although there is a widespread belief that red wine protects more than other alcoholic beverages, several studies do not support this interpretation.

Influence of systemic factors on pre-existing intimal hyperplasia and their effect on the outcome of infrainguinal arterial reconstruction with vein

BACKGROUND

The association between raised levels of homocysteine, fibrinogen and lipoprotein (a), and the presence of pre-existing intimal hyperplasia (IH) in vein has not been assessed. The positive association between such hyperplasia and graft failure following infrainguinal arterial reconstruction, and between lipoprotein (a) and graft failure, is disputed. The influence of homocysteine on outcome has not been investigated prospectively.

METHODS

Fifty-seven patients (63 grafts) undergoing infrainguinal arterial reconstruction with saphenous vein were studied. Homocysteine, fibrinogen and lipoprotein (a) levels were measured, and a vein biopsy was taken at operation. Patients underwent graft surveillance and outcome at 12 months was determined.

RESULTS

Fifty-seven per cent of patients had hyperhomocysteinaemia. Patients with pre-existing IH had significantly higher homocysteine levels. There was no association between homocysteine and outcome, or between fibrinogen and pre-existing IH or outcome. Lipoprotein (a) levels were significantly lower in patients with pre-existing disease, and were lower, but not significantly, in those whose grafts failed. The correlation between pre-existing IH and vein graft failure was highly significant.

CONCLUSION

Hyperhomocysteinaemia is associated with peripheral vascular disease and the development of pre-existing IH in vein, which itself is associated with vein graft failure.

Rheological influences on thrombosis

Blood flow plays important roles in the localization and morphology of thrombosis within the circulation. Blood flow properties (rheological variables) are associated with thrombotic risk factors and thrombotic risk; conversely their modification may reduce thrombotic risk.

Differential alterations of spontaneous and stimulated 45Ca(2+) uptake by platelets from patients with type I and type II diabetes mellitus

Diabetes mellitus (DM) is associated with hyperaggregability of platelets. Although the mechanisms underlying this abnormality remain unknown, Ca(2+) imbalance has been implicated. Both activators (alpha-adrenoceptor agonists, collagen, and ADP) and inhibitors (beta-adrenoceptor agonists, iloprost and dibutyryl cAMP) of platelet function, respectively, elicit the uptake of [45Ca(2+)] in human platelets. It was determined that the [45Ca(2+)] uptake methods employed reflected signal transduction events at the plasma membrane rather than absolute changes of Ca(2+) fluxes or levels of cytosolic Ca(2+). In the present study, basal (unstimulated) [45Ca(2+)] uptake by platelets from both type I and type II diabetic patients was significantly enhanced when compared to age-matched controls. When basal values were subtracted from stimulated values, there were highly significant decreases in [45Ca(2+)] uptake in platelets from type I diabetic patients compared to controls when stimulated with adrenaline, isoprenaline, noradrenaline, collagen, A23187, or iloprost. In contrast, when basal values were subtracted from stimulated values there were significant increases in [45Ca(2+)] uptake by platelets from type II diabetic patients when stimulated with adrenaline, isoprenaline, noradrenaline, A23187, iloprost, and collagen. It is concluded that in type I and type II DM there are differential alterations in [45Ca(2+)] sequestration linked to inhibitors and stimulators of platelet activation. These data indicate that the hyperaggregability of platelets that is associated with both type I and type II DM may be due to an aetiology other than Ca(2+) mobilization linked to signal transduction.

Haemostatic function, arterial disease and the prevention of arterial thrombosis

Recent years have seen the expansion of information linking raised plasma levels of individual clotting factors and evidence of disturbances of fibrinolytic activity with the risk of thrombotic manifestations of arterial disease, both in community-based, apparently healthy populations and in patients with known atherosclerosis. Some of these prothrombotic changes in the haemostatic system may result partly from underlying chronic inflammation or acute infection and may, in turn, contribute substantially to the thrombotic risk which accompanies these underlying processes. The importance of the coagulation system in the pathogenesis of arterial thrombosis is further illustrated by the benefit in the Thrombosis Prevention Trial of low-intensity, dose-adjusted warfarin in the primary prevention of ischaemic heart disease. Clinical trials of bezafibrate, which is being used for its fibrinogen-lowering as well as lipid-modifying properties, are in progress.

A prospective study of fibrinogen and risk of myocardial infarction in the Physicians' Health Study

OBJECTIVES

We examined the association of baseline plasma fibrinogen with future risk of myocardial infarction (MI) in the Physicians' Health Study.

BACKGROUND

Elevated plasma fibrinogen increases and low dose aspirin decreases risk of MI. However, prospective data are limited about their interrelationships.

METHODS

Blood samples were prospectively collected at baseline from 14,916 men in the Physicians' Health Study, aged 40 to 84 years, who were randomly assigned to take aspirin (325 mg every other day) or placebo for 5 years. We measured baseline plasma fibrinogen among 199 incident cases of MI and 199 age- and smoking-matched control subjects free of cardiovascular disease at the time of the case's diagnosis.

RESULTS

Cases had significantly higher baseline fibrinogen levels (geometric mean: 262 mg/dl) than did control subjects (245 mg/dl, p = 0.02). Those with high fibrinogen levels (> or =343 mg/dl, the 90th percentile distribution of the control subjects) had a twofold increase in MI risk (age- and smoking-adjusted relative risk = 2.09, 95% confidence interval = 1.15 to 3.78) compared with those with fibrinogen below 343 mg/dl. Adjustment for lipids and other coronary risk factors as well as randomized aspirin assignment did not materially change the result. Furthermore, we observed no interaction between fibrinogen level and aspirin treatment.

CONCLUSIONS

Among these apparently healthy U.S. male physicians, fibrinogen is associated with increased risk of future MI independent of other coronary risk factors, atherogenic factors such as lipids and antithrombotics such as aspirin.

Alcohol, blood pressure and hypertension

In the last 30 years a large number of cross-sectional studies, a smaller number of prospective cohort studies and several intervention studies have addressed the alcohol-blood pressure relationship. Although a number of questions--such as the validity of measurement of alcohol intake, shape of the alcohol-blood pressure relationship, threshold dose for hypertension, and plausible pathophysiological mechanisms--have not yet been answered satisfactorily, it is clear that a causal association exists between chronic intake of > or = 30-60 g alcohol per day and blood pressure elevation in men and women. To call the alcohol-blood pressure relationship causal is justified because chance and, to a large degree, bias and confounding, have been ruled out as plausible explanations in most observational studies. More importantly, the intervention studies support the observational studies and show a remarkable consistency in demonstrating a potentially valuable decrease in blood pressure when heavy drinkers abstain or restrict their alcohol intake. From the different studies a rule of thumb can be derived: above 30 g of alcohol intake per day an increment of 10 g of alcohol per day increases on average systolic blood pressure by 1-2 mmHg and diastolic blood pressure by 1 mmHg.

Segregation analysis of plasminogen activator inhibitor-1 and fibrinogen levels in the NHLBI family heart study

Elevated plasminogen activator inhibitor-1 (PAI-1) and fibrinogen concentrations are risk factors for coronary heart disease. We investigated environmental, familial, and genetic influences on PAI-1 antigen and fibrinogen concentrations in 2029 adults from 512 randomly ascertained families in 4 US communities. We used maximum-likelihood segregation analysis to fit several genetic and nongenetic modes of inheritance to the data to determine whether mendelian inheritance of a major gene could best explain the familial distributions of these 2 hemostatic factors. Age- and gender-adjusted familial correlations for PAI-1 antigen level averaged 0.16 in first-degree relatives (95% CI=0.11 to 0.21); the spouse correlation was positive but not statistically significant (r=0.10, 95% CI=-0.02 to 0.23). Complex segregation analysis indicated a major gene associated with higher PAI-1 concentrations in 65% of individuals from these families. Demographic, anthropometric, lifestyle, and metabolic characteristics together explained 37% to 47% of the variation in PAI-1 antigen levels, and the inferred major gene explained an additional 17% of the variance. Positive and statistically significant age- and gender-adjusted familial correlations in first-degree relatives indicated a possible heritable component influencing plasma fibrinogen concentration (r=0. 17, 95% CI=0.13 to 0.22); however, segregation analysis did not provide statistical evidence of a major gene controlling fibrinogen level. These family data suggest that there are modest familial and genetic effects on the concentration of PAI-1.

The positive relationship between alcohol and heart disease in eastern Europe: potential physiological mechanisms

Research into the effect of alcohol on cardiovascular disease has indicated protective effects from moderate consumption. These observations, made in industrialized countries, have influenced policies on alcohol in countries where the situation may be quite different--specifically, where consumption is substantially higher or patterns of drinking are different. In central and eastern Europe and the former Soviet Union, a growing body of epidemiological research indicates a positive rather than negative association between alcohol consumption and cardiovascular deaths, especially sudden cardiac deaths. By means of a systematic review of published work, we examine whether there is a physiological basis for the observed association between alcohol and heart disease seen in eastern Europe, focusing on the effects of high levels of consumption and of irregular or binge drinking. In binge drinkers, cardioprotective changes in high-density lipoproteins are not seen, and adverse changes in low-density lipoproteins are acquired. Irregular drinking is associated with an increased risk of thrombosis, occurring after cessation of drinking. It predisposes both to histological changes in the myocardium and conducting system and to a reduction in the threshold for ventricular fibrillation. Measures of frequency as well as quantity of consumption should be included in epidemiological studies. Taken with the epidemiological evidence emerging from eastern Europe, these observations have important implications for estimates of the burden of disease attributable to alcohol.

Effects of long-term smoking on myocardial blood flow, coronary vasomotion, and vasodilator capacity

BACKGROUND

The effect of long-term smoking on coronary vasomotion and vasodilator capacity in healthy smokers is unknown.

METHODS AND RESULTS

Myocardial blood flow (MBF) was quantified with [13N]ammonia and positron emission tomography (PET) at rest, during cold pressor testing (endothelium-dependent vasomotion), and during dipyridamole-induced hyperemia in 16 long-term smokers and 17 nonsmokers. MBF at rest did not differ between the 2 groups. Cold induced similar increases in rate-pressure product (RPP) in smokers and nonsmokers. However, MBF increased only in nonsmokers and was, during cold, higher than in smokers (0.91+/-0.18 versus 0.78+/-0.14 mL x g(-1) x min(-1), P<0.05). MBF normalized to the RPP (derived from the ratio of MBF ([milliliters per gram per minute] to RPP [beats per minute times millimeters of mercury] times 10000) declined in smokers but remained unchanged in nonsmokers (0.86+/-0.10 versus 0.72+/-0.11, P=0.0006, and 0.99+/-0.25 versus 0.96+/-0.27, P=NS). The hyperemic response to dipyridamole and the myocardial flow reserve did not differ between the 2 groups. In a multiple regression model adjusted for age, sex, serum lipid levels, years of smoking, and pack-years, years of smoking was the strongest predictor of the normalized blood flow response to cold (P<0.001), followed by the HDL/LDL ratio.

CONCLUSIONS

The normal hyperemic response to dipyridamole in long-term smokers indicates a preserved endothelium-independent coronary vascular smooth muscle relaxation, whereas the abnormal response to cold suggests a defect in coronary vasomotion likely located at the level of the coronary endothelium. Its severity depends on the total exposure time to smoking.

Smoking and lipoprotein abnormalities on platelet aggregation in coronary heart disease

This study aimed to clarify whether smoking had any influence on platelet aggregability in coronary patients with different lipoprotein abnormalities. We studied 297 non-diabetic patients with coronary heart disease, 40 to 85 years of age, 223 (75%) male, 167 smokers and 130 never smokers. After 3 months on Step-One diet, without any regular medication, patients had fasting plasma total cholesterol levels > or = 6.2 mmol/L; low-density lipoprotein > or = 4.14 mmol/L; and different levels of high-density lipoprotein and triglycerides. Platelet aggregation was analyzed by turbidometric method of Born. Patients were classified in groups of smokers and non-smokers. Results showed that platelet hyperaggregability was more prevalent in smokers with lower levels of high-density lipoprotein (47% vs. 20%; P=0.004 for spontaneous platelet aggregation, 56% vs. 33%; P=0.02 for adenosine diphosphate induced platelet aggregation), and in smokers with hypertrygliceridemia (64% vs. 29%; P=0.004 for spontaneous, 81% vs. 43%; P<0.0001 for adenosine diphosphate induced, and 87% vs. 46%; P<0.0001 for adrenaline induced platelet aggregation). Platelet hypoaggregability was greater in non-smokers with normal high-density lipoprotein and triglycerides plasma levels when compared to non-smokers with the same lipid profile (39% vs. 12%; P=0.004). In conclusion, smoking increased platelet reactivity in hypercholesterolemic patients with low high-density lipoprotein levels or high triglycerides levels.

Hemostatic/fibrinolytic predictors of allograft coronary artery disease after cardiac transplantation

Allograft coronary artery disease (CAD) remains the leading cause of morbidity and mortality affecting the long-term survival of patients after cardiac transplantation. Because there is increasing evidence that imbalances in hemostatic and fibrinolytic pathways are associated with graft failure, we hypothesized that atherothrombotic risk factors may contribute to allograft CAD. This study sought to determine if plasma hemostatic and fibrinolytic parameters are associated with the severity of allograft CAD. The extent of allograft CAD was investigated by angiography and intravascular ultrasound (IVUS) in 16 cardiac transplant recipients. Intimal thickening was quantified using IVUS by measuring the intimal index (li = intimal area/[intimal area + luminal area]) in two to five segments of the left anterior descending (LAD) coronary artery. The maximal li per patient was calculated and index to the time post-transplant (Mxli/Yr). Plasma fibrinogen (FGN), tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), lipoprotein(a) (Lp(a)), and net fibrinolytic activity of plasma were assayed 6-24 months after transplant as indicators of the fibrinolytic system and then correlated with the IVUS measurements. The FGN level correlated with the severity of intimal thickening, Mxli/Yr (r2 = 0.41, p = 0.008), and was inversely correlated with angiographic tertiary vessel filling (r2 = 0.25, p = 0.051). In patients with lower plasma fibrinolytic activity (lytic zone less than 100 mm2), Mxli/Yr was increased eightfold (0.218 +/- 0.137 versus 0.025 +/- 0.021, p = 0.001). t-PA (r2 = 0.0004, p = 0.94), PAI-1 (r2 = 0.008, p = 0.75) and Lp(a) levels (r2 = 0.11, p = 0.21) did not predict Mxli/Yr. Thus, we demonstrate that plasma FGN and net fibrinolytic activity correlate with the degree of intimal thickening measured by IVUS after cardiac transplantation. These data suggest that fibrin deposition may play a role in allograft CAD after cardiac transplantation.