Classification of subtype of acute ischemic stroke. Definitions for use in a multicenter clinical trial. TOAST. Trial of Org 10172 in Acute Stroke Treatment

BACKGROUND AND PURPOSE

The etiology of ischemic stroke affects prognosis, outcome, and management. Trials of therapies for patients with acute stroke should include measurements of responses as influenced by subtype of ischemic stroke. A system for categorization of subtypes of ischemic stroke mainly based on etiology has been developed for the Trial of Org 10172 in Acute Stroke Treatment (TOAST).

METHODS

A classification of subtypes was prepared using clinical features and the results of ancillary diagnostic studies. "Possible" and "probable" diagnoses can be made based on the physician's certainty of diagnosis. The usefulness and interrater agreement of the classification were tested by two neurologists who had not participated in the writing of the criteria. The neurologists independently used the TOAST classification system in their bedside evaluation of 20 patients, first based only on clinical features and then after reviewing the results of diagnostic tests.

RESULTS

The TOAST classification denotes five subtypes of ischemic stroke: 1) large-artery atherosclerosis, 2) cardioembolism, 3) small-vessel occlusion, 4) stroke of other determined etiology, and 5) stroke of undetermined etiology. Using this rating system, interphysician agreement was very high. The two physicians disagreed in only one patient. They were both able to reach a specific etiologic diagnosis in 11 patients, whereas the cause of stroke was not determined in nine.

CONCLUSIONS

The TOAST stroke subtype classification system is easy to use and has good interobserver agreement. This system should allow investigators to report responses to treatment among important subgroups of patients with ischemic stroke. Clinical trials testing treatments for acute ischemic stroke should include similar methods to diagnose subtypes of stroke.

Transfemoral intraluminal graft implantation for abdominal aortic aneurysms

This study reports on animal experimentation and initial clinical trials exploring the feasibility of exclusion of an abdominal aortic aneurysm by placement of an intraluminal, stent-anchored, Dacron prosthetic graft using retrograde cannulation of the common femoral artery under local or regional anesthesia. Experiments showed that when a balloon-expandable stent was sutured to the partially overlapping ends of a tubular, knitted Dacron graft, friction seals were created which fixed the ends of the graft to the vessel wall. This excludes the aneurysm from circulation and allows normal flow through the graft lumen. Initial treatment in five patients with serious co-morbidities is described. Each patient had an individually tailored balloon diameter and diameter and length of their Dacron graft. Standard stents were used and the diameter of the stent-graft was determined by sonography, computed tomography, and arteriography. In three of them a cephalic stent was used without a distal stent. In two other patients both ends of the Dacron tubular stent were attached to stents using a one-third stent overlap. In these latter two, once the proximal neck of the aneurysm was reached, the sheath was withdrawn and the cephalic balloon inflated with a saline/contrast solution. The catheter was gently removed caudally towards the arterial entry site in the groin to keep tension on the graft, and the second balloon inflated so as to deploy the second stent. Four of the five patients had heparin reversal at the end of the procedure. We are encouraged by this early experience, but believe that further developments and more clinical trials are needed before this technique becomes widely used.

From vulnerable plaque to vulnerable patient: a call for new definitions and risk assessment strategies: Part I

Atherosclerotic cardiovascular disease results in >19 million deaths annually, and coronary heart disease accounts for the majority of this toll. Despite major advances in treatment of coronary heart disease patients, a large number of victims of the disease who are apparently healthy die suddenly without prior symptoms. Available screening and diagnostic methods are insufficient to identify the victims before the event occurs. The recognition of the role of the vulnerable plaque has opened new avenues of opportunity in the field of cardiovascular medicine. This consensus document concludes the following. (1) Rupture-prone plaques are not the only vulnerable plaques. All types of atherosclerotic plaques with high likelihood of thrombotic complications and rapid progression should be considered as vulnerable plaques. We propose a classification for clinical as well as pathological evaluation of vulnerable plaques. (2) Vulnerable plaques are not the only culprit factors for the development of acute coronary syndromes, myocardial infarction, and sudden cardiac death. Vulnerable blood (prone to thrombosis) and vulnerable myocardium (prone to fatal arrhythmia) play an important role in the outcome. Therefore, the term "vulnerable patient" may be more appropriate and is proposed now for the identification of subjects with high likelihood of developing cardiac events in the near future. (3) A quantitative method for cumulative risk assessment of vulnerable patients needs to be developed that may include variables based on plaque, blood, and myocardial vulnerability. In Part I of this consensus document, we cover the new definition of vulnerable plaque and its relationship with vulnerable patients. Part II of this consensus document focuses on vulnerable blood and vulnerable myocardium and provide an outline of overall risk assessment of vulnerable patients. Parts I and II are meant to provide a general consensus and overviews the new field of vulnerable patient. Recently developed assays (eg, C-reactive protein), imaging techniques (eg, CT and MRI), noninvasive electrophysiological tests (for vulnerable myocardium), and emerging catheters (to localize and characterize vulnerable plaque) in combination with future genomic and proteomic techniques will guide us in the search for vulnerable patients. It will also lead to the development and deployment of new therapies and ultimately to reduce the incidence of acute coronary syndromes and sudden cardiac death. We encourage healthcare policy makers to promote translational research for screening and treatment of vulnerable patients.

Impact of aortic stiffness on survival in end-stage renal disease

BACKGROUND

Damage to large arteries is a major factor in the high cardiovascular morbidity and mortality of patients with end-stage renal disease (ESRD). Increased arterial stiffness and intima-media thickness, together with increased pulse pressure, are the principal arterial alterations. Whether increased aortic pulse-wave velocity (PWV), a classic marker of increased arterial stiffness, may predict all-cause and/or cardiovascular mortality has never been investigated.

METHODS AND RESULTS

A cohort of 241 patients with ESRD undergoing hemodialysis was studied between April 1987 and April 1998. The mean duration of follow-up was 72+/-41 months (mean+/-SD). Mean age at entry was 51.5+/-16.3 years. Seventy-three deaths occurred, including 48 cardiovascular and 25 noncardiovascular fatal events. At entry, together with standard clinical and biochemical analyses, patients underwent echocardiography and aortic PWV measured by Doppler ultrasonography. On the basis of Cox analyses, 2 factors emerged as predictors of all-cause and cardiovascular mortality: age and aortic PWV. Hemoglobin and low diastolic pressure interfered to a smaller extent. After adjustment for all the confounding factors, an OR for PWV >12. 0 versus <9.4 m/s was 5.4 (95% CI, 2.4 to 11.9) for all-cause mortality and 5.9 (95% CI, 2.3 to 15.5) for cardiovascular mortality. For each PWV increase of 1 m/s in our study population, all-cause mortality-adjusted OR was 1.39 (95% CI, 1.19 to 1.62).

CONCLUSIONS

These results provide the first direct evidence that in patients with ESRD, increased aortic stiffness determined by measurement of aortic PWV is a strong independent predictor of all-cause and mainly cardiovascular mortality.

Association of coronary heart disease incidence with carotid arterial wall thickness and major risk factors: the Atherosclerosis Risk in Communities (ARIC) Study, 1987-1993

Few studies have determined whether greater carotid artery intima-media thickness (IMT) in asymptomatic individuals is associated prospectively with increased risk of coronary heart disease (CHD). In the Atherosclerosis Risk in Communities Study, carotid IMT, an index of generalized atherosclerosis, was defined as the mean of IMT measurements at six sites of the carotid arteries using B-mode ultrasound. The authors assessed its relation to CHD incidence over 4-7 years of follow-up (1987-1993) in four US communities (Forsyth County, North Carolina; Jackson, Mississippi; Minneapolis, Minnesota; and Washington County, Maryland) from samples of 7,289 women and 5,552 men aged 45-64 years who were free of clinical CHD at baseline. There were 96 incident events for women and 194 for men. In sex-specific Cox proportional hazards models adjusted only for age, race, and center, the hazard rate ratio comparing extreme mean IMT (> or = 1 mm) to not extreme (< 1 mm) was 5.07 for women (95% confidence interval 3.08-8.36) and 1.85 for men (95% confidence interval 1.28-2.69). The relation was graded (monotonic), and models with cubic splines indicated significant nonlinearity. The strength of the association was reduced by including major CHD risk factors, but remained elevated at higher IMT. Up to 1 mm mean IMT, women had lower adjusted annual event rates than did men, but above 1 mm their event rate was closer to that of men. Thus, mean carotid IMT is a noninvasive predictor of future CHD incidence.

Adverse cerebral outcomes after coronary bypass surgery. Multicenter Study of Perioperative Ischemia Research Group and the Ischemia Research and Education Foundation Investigators

BACKGROUND

Acute changes in cerebral function after elective coronary bypass surgery is a difficult clinical problem. We carried out a multicenter study to determine the incidence and predictors of -- and the use of resources associated with -- perioperative adverse neurologic events, including cerebral injury.

METHODS

In a prospective study, we evaluated 2108 patients from 24 U.S. institutions for two general categories of neurologic outcome: type I (focal injury, or stupor or coma at discharge) and type II (deterioration in intellectual function, memory deficit, or seizures).

RESULTS

Adverse cerebral outcomes occurred in 129 patients (6.1 percent). A total of 3.1 percent had type I neurologic outcomes (8 died of cerebral injury, 55 had nonfatal strokes, 2 had transient ischemic attacks, and 1 had stupor), and 3.0 percent had type II outcomes (55 had deterioration of intellectual function and 8 had seizures). Patients with adverse cerebral outcomes had higher in-hospital mortality (21 percent of patients with type I outcomes died, vs. 10 percent of those with type II and 2 percent of those with no adverse cerebral outcome; P<0.001 for all comparisons), longer hospitalization (25 days with type I outcomes, 21 days with type II, and 10 days with no adverse outcome; P<0.001), and a higher rate of discharge to facilities for intermediate- or long-term care (69 percent, 39 percent, and 10 percent ; P<0.001). Predictors of type I outcomes were proximal aortic atherosclerosis, a history of neurologic disease, and older age; predictors of type II outcomes were older age, systolic hypertension on admission, pulmonary disease, and excessive consumption of alcohol.

CONCLUSIONS

Adverse cerebral outcomes after coronary bypass surgery are relatively common and serious; they are associated with substantial increases in mortality, length of hospitalization, and use of intermediate- or long-term care facilities. New diagnostic and therapeutic strategies must be developed to lessen such injury.

Transluminal placement of endovascular stent-grafts for the treatment of descending thoracic aortic aneurysms

BACKGROUND

The usual treatment for thoracic aortic aneurysms is surgical replacement with a prosthetic graft, but the associated morbidity and mortality are considerable. We studied the use of transluminally placed endovascular stent-graft devices as an alternative to surgical repair.

METHODS

We evaluated the feasibility, safety, and effectiveness of transluminally placed stent-graft to treat descending thoracic aortic aneurysms in 13 patients over a 24-month period. Atherosclerotic, anastomotic, and post-traumatic true or false aneurysms and aortic dissections were treated. The mean diameter of the aneurysms was 6.1 cm (range, 5 to 8). The endovascular stent-grafts were custom-designed for each patient and were constructed of self-expanding stainless-steel stents covered with woven Dacron grafts.

RESULTS

Endovascular placement of the stent-graft prosthesis was successful in all patients. There was complete thrombosis of the thoracic aortic aneurysm surrounding the stent-graft in 12 patients, and partial thrombosis in 1. Two patients initially had small, residual patent proximal tracts into the aneurysm sac, but both tracts thrombosed within two months after the procedure. In four patients, two prostheses were required to bridge the aneurysm adequately. There have been no deaths or instances of paraplegia, stroke, distal embolization, or infection during an average follow-up of 11.6 months. One patient with an extensive chronic aortic dissection required open surgical graft replacement four months later because of progressive dilatation of the arch.

CONCLUSIONS

These preliminary results demonstrate that endovascular stent-graft repair is safe in highly selected patients with descending thoracic aortic aneurysms. This new method of treatment will, however, require careful long-term evaluation.

Aortic pulse wave velocity as a marker of cardiovascular risk in hypertensive patients

Large artery damage is a major contributory factor to cardiovascular morbidity and mortality of patients with hypertension. Pulse wave velocity (PWV), a classic evaluation of arterial distensibility, has never been ascertained as a cardiovascular risk marker. To determine the factors influencing aortic PWV and the potential predictor role of this measurement, we studied a cohort of 710 patients with essential hypertension. Atherosclerosis alterations (AA) were defined on the basis of clinical events. Calculation of cardiovascular risks, by use of Framingham equations, was performed in subjects without AA. PWV was higher in the presence of AA (14.9+/-4.0 versus 12.4+/-2.6 m/s, P<0.0001), even after adjustments on confounding factors and was the first determinant (P<0.0001) of the extent of atherosclerosis assessed as the sum of the atherosclerotic sites. In patients without AA, all cardiovascular risks increased constantly with PWV. Furthermore, at a given age, aortic PWV was the best predictor of cardiovascular mortality. The odds ratio of being in a high cardiovascular mortality risk group (>5% for 10 years) for patients in the upper quartile of PWV was 7.1 (95% confidence intervals 4.5 to 11.3). The presence of a PWV >13 m/s, taken alone, appeared as a strong predictor of cardiovascular mortality with high performance values. This study shows that aortic PWV is strongly associated with the presence and extent of atherosclerosis and constitutes a forceful marker and predictor of cardiovascular risk in hypertensive patients.

Atherosclerosis, apolipoprotein E, and prevalence of dementia and Alzheimer's disease in the Rotterdam Study

BACKGROUND

Vascular disorders have been implicated in dementia, but whether atherosclerosis is related to the most frequent type of dementia, Alzheimer's disease, is not known. The apolipoprotein-E genotype has been associated with Alzheimer's disease, and we postulate that it plays a part, together with atherosclerosis, in the aetiology of Alzheimer's disease. We investigated the frequency of dementia and its subtypes in relation to atherosclerosis and apolipoprotein E.

METHODS

We did a population-based study of 284 patients with dementia, 207 of whom had Alzheimer's disease, and 1698 individuals who were not demented. Indicators of atherosclerosis included vessel wall thickness and plaques of the carotid arteries, assessed by ultrasonography, and the ratio of ankle-to-brachial systolic blood pressure as a measure of generalised atherosclerosis. Based on these indicators participants were scored from 0 (no atherosclerosis) to 3 (severe atherosclerosis) for degree of atherosclerosis. Apolipoprotein-E polymorphisms were assessed in 246 patients and in 928 controls.

FINDINGS

All indicators of atherosclerosis were associated with dementia (odds ratios ranging from 1.3 to 1.9) and its major subtypes Alzheimer's disease (odds ratios 1.3-1.8) and vascular dementia (odds ratios 1.9-3.2). The frequencies of all dementia. Alzheimer's disease, and vascular dementia increased with the degree of atherosclerosis. The odds ratio for Alzheimer's disease in those with severe atherosclerosis compared with those without atherosclerosis was 3.0 (95% CI 1.5-6.0; p = 0.001). In participants with the apolipoprotein-E epsilon 4 genotype and an atherosclerosis score of 2 or 3 the odds ratio for all dementia was 4.5 (2.0-10.1; p < 0.001), for Alzheimer's disease was 3.9 (1.6-9.6; p = 0.002), and for vascular dementia was 19.8 (4.1-95.0; p < 0.001).

INTERPRETATION

These findings suggest that dementia and its two major subtypes Alzheimer's disease and vascular dementia are associated with atherosclerosis and that there is an interaction between apolipoprotein E and atherosclerosis in the aetiology of Alzheimer's disease.

Risk of thrombosis in human atherosclerotic plaques: role of extracellular lipid, macrophage, and smooth muscle cell content

OBJECTIVE

To assess the size of the lipid pool and the number of smooth muscle cells and monocyte/macrophages in human aortic plaques that were intact and to compare the results with those in aortic plaques undergoing ulceration and thrombosis.

DESIGN

The lipid pool was measured as a percentage of the total cross sectional area of the plaque. Immunohistochemistry was used to identify cell types (monocytes/macrophages (M phi) by EBM11 and HAM56, smooth muscle cells by alpha actin). The area of the tissue occupied by each cell type was measured by quantitative microscopy in the peripheral (shoulder) area of the plaque and the plaque cap. Absolute counts of each cell type were expressed as the ratio of SMC:M phi.

MATERIAL

Aortas were obtained at necropsy from men aged less than 69 years who died suddenly (within 6 hours of the onset of symptoms) of ischaemic heart disease. 155 plaques from 13 aortas were studied. Four aortas showed intact plaques only (group A, n = 31). Nine aortas showed both intact plaques (group B, n = 79) and plaques that were undergoing thrombosis (group C, n = 45).

RESULTS

In 41 (91.1%) of the 45 plaques undergoing thrombosis (group C) lipid pools occupied more than 40% of the cross sectional area of the plaque. Only 12 (10.9%) of the 110 intact plaques (groups A + B) had lipid pools of this size. The mean size of the lipid pool in plaques of groups A, B, and C was 12.7%, 27.3% and 56.7% respectively. Compared with intact plaques those undergoing thrombosis contained a smaller volume of smooth muscle cells (2.8% v 11.8%) and a larger volume of monocyte/macrophages (13.7% v 2.9%) in the plaque cap. The ratio of the number of smooth muscle cells to monocytes/macrophages was 7.8 in group A plaques, 4.1 in group B plaques, and 1.0 in group C plaques. This gradient was the result of an absolute increase in monocyte/macrophages and an absolute decrease in smooth muscle cells.

CONCLUSIONS

In the aorta ulceration and thrombosis were characteristic of plaques with a high proportion of their volume occupied by extracellular lipid, and in which there was a shift toward a preponderance of monocyte/macrophages compared with smooth muscle cells in the cap.

Edinburgh Artery Study: prevalence of asymptomatic and symptomatic peripheral arterial disease in the general population

Intermittent claudication has been studied in cardiovascular surveys but limited information is available on asymptomatic peripheral arterial disease. The purpose of this paper is to describe the prevalence of both asymptomatic and symptomatic disease and relation to ischaemic heart disease in the Edinburgh Artery Study. A cross-sectional survey was conducted on an age-stratified sample of men and women aged 55 to 74 years selected from age-sex registers in ten general practices in the city. Arterial disease was assessed in 1592 participants by means of the WHO questionnaire on intermittent claudication and measurement of the ankle brachial systolic pressure index (ABPI) and change in ankle systolic pressure during reactive hyperaemia. The prevalence of intermittent claudication was 4.5% (95% confidence interval (CI): 3.5%-5.5%). Major asymptomatic disease causing a significant impairment of blood flow occurred in 8.0% (95% CI: 6.6%-9.4%). A further 16.6% (95% CI: 14.6%-18.5%) had criteria considered abnormal in clinical practice: 9.0% had ABPI less than 0.9 and 7.6% had reactive hyperaemia pressure reduction greater than 20%. Intermittent claudication was equally common in both sexes. The ABPI and reactive hyperaemia results suggested a slight preponderance of asymptomatic disease in males and were consistent with an increasing prevalence with age and lower social class. Mean ABPI was higher in normal men than women, and was lower in the left leg than the right suggesting a unilateral predisposition to disease. Subjects with major asymptomatic disease had more evidence of ischaemic heart disease than in the normal population (relative risk (RR) 1.6; 95% CI: 1.3-1.9).(ABSTRACT TRUNCATED AT 250 WORDS)

The bimodal mortality pattern of systemic lupus erythematosus

The changing pattern of mortality in systemic lupus erythematosus (SLE) led to an examination of the deaths in a long-term systematic analysis of 81 patients followed for five years at the University of Toronto Rheumatic Disease Unit. During the follow-up 11 patients died; six patients died within the first year after diagnosis (group I) and five patients died an average of 8.6 years (from 2.5 to 19.5 years) after diagnosis (group II). In those who died early, the SLE was active clinically and serologically, and nephritis was present in four. Their mean prednisone dose was 53.3 mg/day. In four patients a major septic episode contributed to their death. In those who died late in the course of the disease, only one patient had active lupus and none had active lupus nephritis. Their mean prednisone dose was 10.1 mg/day taken for a mean of 7.2 years. In none was sepsis a contributing factor to their death. All five of these patients had had a recent myocardial infarction at the time of death; in four, ti was the primary cause of death. Mortality in SLE follows a bimodal pattern. Patients who die early in the course of their disease, die with active lupus, receive large doses of steroids and have a remarkable incidence of infection. In those who die late in the course of the disease, death is associated with inactive lupus, long duration of steroid therapy and a striking incidence of myocardial infarction due to atherosclerotic heart disease.

A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association

This report is the continuation of two earlier reports that defined human arterial intima and precursors of advanced atherosclerotic lesions in humans. This report describes the characteristic components and pathogenic mechanisms of the various advanced atherosclerotic lesions. These, with the earlier definitions of precursor lesions, led to the histological classification of human atherosclerotic lesions found in the second part of this report. The Committee on Vascular Lesions also attempted to correlate the appearance of lesions noted in clinical imaging studies with histological lesion types and corresponding clinical syndromes. In the histological classification, lesions are designated by Roman numerals, which indicate the usual sequence of lesion progression. The initial (type 1) lesion contains enough atherogenic lipoprotein to elicit an increase in macrophages and formation of scattered macrophage foam cells. As in subsequent lesion types, the changes are more marked in locations of arteries with adaptive intimal thickening. (Adaptive thickenings, which are present at constant locations in everyone from birth, do not obstruct the lumen and represent adaptations to local mechanical forces). Type II lesions consist primarily of layers of macrophage foam cells and lipid-laden smooth muscle cells and include lesions grossly designated as fatty streaks. Type III is the intermediate stage between type II and type IV (atheroma, a lesion that is potentially symptom-producing). In addition to the lipid-laden cells of type II, type III lesions contain scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. This extracellular lipid is the immediate precursor of the larger, confluent, and more disruptive core of extracellular lipid that characterizes type IV lesions. Beginning around the fourth decade of life, lesions that usually have a lipid core may also contain thick layers of fibrous connective tissue (type V lesion) and/or fissure, hematoma, and thrombus (type VI lesion). Some type V lesions are largely calcified (type Vb), and some consist mainly of fibrous connective tissue and little or no accumulated lipid or calcium (type Vc).

Atherosclerotic disease of the aortic arch and the risk of ischemic stroke

BACKGROUND

Atherosclerotic disease of the aortic arch has been suspected to be a potential source of cerebral emboli. We conducted a study to quantify the risk of ischemic stroke associated with atherosclerotic disease of the aortic arch.

METHODS

Using transesophageal echocardiography, we performed a prospective case-control study of the frequency and thickness of atherosclerotic plaques in the ascending aorta and proximal arch in 250 consecutive patients admitted to the hospital with ischemic stroke and 250 consecutive controls, all over the age of 60 years.

RESULTS

Atherosclerotic plaques > or = mm in thickness were found in 14.4 percent of the patients but in only 2 percent of the controls. After adjustment for atherosclerotic risk factors, the odds ratio for ischemic stroke among patients with such plaques was 9.1 (95 percent confidence interval, 3.3 to 25.2; P < 0.001). Among the 78 patients who had brain infarcts with no obvious cause, 28.2 percent had plaques > or = 4 mm in thickness, as compared with 8.1 percent of the 172 patients who had infarcts whose possible or likely causes were known (odds ratio, 4.7; 95 percent confidence interval, 2.2 to 10.1; P < 0.001). Plaques of > or = 4 mm in the aortic arch were not associated with the presence of atrial fibrillation or stenosis of the extracranial internal carotid artery. In contrast, plaques that were 1 to 3.9 mm thick were frequently associated with carotid stenosis of > or = 70 percent.

CONCLUSIONS

These results indicate a strong, independent association between atherosclerotic disease of the aortic arch and the risk of ischemic stroke. The association was particularly strong with thick plaques. Atherosclerotic disease of the aortic arch should be regarded as a risk factor for ischemic stroke and as a possible source of cerebral emboli.

Plaque rupture with severe pre-existing stenosis precipitating coronary thrombosis. Characteristics of coronary atherosclerotic plaques underlying fatal occlusive thrombi

Ruptured atheromatous plaques were identified by step-sectioning technique as responsible for 40 of 51 recent coronary artery thrombi and 63 larger intimal haemorrhages. The degree of pre-existing luminal narrowing at the site of rupture was decisive for whether plaque rupture caused occlusive thrombosis or just intimal haemorrhage. If the pre-existing stenosis was greater than 90% (histologically determined) then plaque rupture nearly always caused occlusive thrombosis. Clearly indicating the primary role of plaque rupture in thrombus formation were the frequent finding of plaque fragments deeply buried in the centre of the thrombus and the nature of the thrombus at the site of rupture where it consisted predominantly of platelets. Thus, a severe chronic stenosis seems to be a prerequisite for occlusive thrombus formation, but the thrombotic process itself is triggered by an acute intimal lesion.

Nicotine stimulates angiogenesis and promotes tumor growth and atherosclerosis

We provide anatomic and functional evidence that nicotine induces angiogenesis. We also show that nicotine accelerates the growth of tumor and atheroma in association with increased neovascularization. Nicotine increased endothelial-cell growth and tube formation in vitro, and accelerated fibrovascular growth in vivo. In a mouse model of hind-limb ischemia, nicotine increased capillary and collateral growth, and enhanced tissue perfusion. In mouse models of lung cancer and atherosclerosis, we found that nicotine enhanced lesion growth in association with an increase in lesion vascularity. These effects of nicotine were mediated through nicotinic acetylcholine receptors at nicotine concentrations that are pathophysiologically relevant. The endothelial production of nitric oxide, prostacyclin and vascular endothelial growth factor might have a role in these effects.

Diabetes and atherosclerosis: an epidemiologic view

Diabetes is associated with changes in plasma lipids and lipoproteins into atherogenic direction. In IDDM these changes are small or absent if good metabolic control can be maintained. Diabetic nephropathy is, however, associated with the appearance of dyslipoproteinemia. In NIDDM plasma total and VLDL triglyceride levels are elevated, and HDL-cholesterol level is decreased, and this pattern of dyslipoproteinemia does not always respond to improved control of hyperglycemia. Abnormalities of lipoprotein metabolism, not reflected in conventional plasma lipid and lipoprotein level measurements, and glucosylation of lipoproteins and resulting alterations in lipoprotein catabolism may be of importance in the enhanced atherogenesis in diabetes. Both IDDM and NIDDM are associated with an increased frequency of hypertension, but the underlying mechanisms appear to be different. In IDDM hypertension is usually associated with the development of diabetic nephropathy and thus with a long duration of the disease. In NIDDM hypertension is often present already at the time of diagnosis, and also in IGT, the precursor stage of NIDDM, the prevalence of hypertension is already increased. Obesity explains only in part the high prevalence of hypertension in patients with NIDDM. Diabetes is known to be associated with multiple abnormalities in hemostatic factors and, although these abnormalities may contribute importantly to the increased risk of ASVD in diabetic patients, information about their real role is scanty and conflicting. The impact of general major risk factors for ASVD, elevated plasma cholesterol, elevated blood pressure, and smoking, on the risk of ASVD appears to be similar in diabetics and nondiabetics. Only a relatively small proportion of the excessive occurrence of ASVD in diabetics can, however, be explained by the effects of diabetes on the levels of general risk factors for ASVD. This proportion mediated through the effects of diabetes on risk factors is larger in female diabetics than in male diabetics. The major proportion of the excess of ASVD in diabetics remains, however, unexplained and must be due to effects of diabetes itself through mechanisms that are incompletely understood.

Carotid atherosclerosis measured by B-mode ultrasound in populations: associations with cardiovascular risk factors in the ARIC study

To assess whether carotid atherosclerosis measured by B-mode ultrasound is related to cardiovascular risk factors, 386 cases with carotid artery wall thickening and an equal number of controls free of arterial intima-media thickening were drawn from the cohort of the Atherosclerosis Risk in Communities (ARIC) Study examined in four communities in the United States between 1988 and 1990. Cases and controls were individually matched on sex, race, age group, study center, and date of examination. The mean values of total cholesterol, low density lipoprotein (LDL) cholesterol, total triglyceride, blood pressure, and pack-years of cigarette smoking were higher in cases than controls. Mean high density lipoprotein (HDL) cholesterol was lower in cases than controls. Case-control differences were all statistically significant. Multivariable-adjusted odds ratios point to differences of considerable magnitude in the risk of carotid atherosclerosis between groups defined by clinical and public health-oriented risk factor cut-points.

Ultrasonographically assessed carotid morphology and the risk of coronary heart disease

As ultrasonographically assessed carotid arteriosclerosis is being used as a surrogate measure for coronary arteriosclerosis, we performed a prospective longitudinal study of the association of our high-resolution ultrasound assessment of extracranial carotid morphology with the risk of acute coronary events in 1,288 eastern Finnish men. The presence of any structural changes in the common carotid arteries or carotid bulbs was associated with a 3.29-fold (95% confidence interval, 1.31-8.29; p = 0.0074), intimal-medial thickening with a 2.17-fold (95% confidence interval, 0.70-6.74; p = NS), small carotid plaques with a 4.15-fold (95% confidence interval, 1.51-11.47; p less than 0.01), and large ("stenotic") plaques with a 6.71-fold (95% confidence interval, 1.33-33.91; p less than 0.01) risk of acute myocardial infarction compared with men free of any structural changes in the carotid artery wall at baseline. These data confirm the close relation between carotid artery wall morphology and coronary heart disease.

Angiographic morphology and the pathogenesis of unstable angina pectoris

In 110 patients with either stable or unstable angina, the morphology of coronary artery lesions was qualitatively assessed at angiography. Each obstruction reducing the luminal diameter of the vessel by 50% or greater was categorized into one of the following morphologic groups: concentric (symmetric narrowing); type I eccentric (asymmetric narrowing with smooth borders and a broad neck); type II eccentric (asymmetric with a narrow neck or irregular borders, or both); and multiple irregular coronary narrowings in series. For the entire group, type II eccentric lesions were significantly more frequent in the 63 patients with unstable angina (p less than 0.001), whereas concentric and type I eccentric lesions were seen more frequently in the 47 patients with stable angina (p less than 0.05). Type II eccentric lesions were also present in 29 of 41 arteries in patients with unstable angina compared with 4 of 25 arteries in those with stable angina (p less than 0.0001) in whom an "angina-producing" artery could be identified. Therefore, type II eccentric lesions are frequent in patients with unstable angina and probably represent ruptured atherosclerotic plaques or partially occlusive thrombi, or both. A temporary decrease in coronary perfusion secondary to these plaques with or without superimposed transient platelet thrombi or altered vasomotor tone may be responsible for chest pain in some of these patients with unstable angina.

Race-ethnicity and determinants of intracranial atherosclerotic cerebral infarction. The Northern Manhattan Stroke Study

BACKGROUND AND PURPOSE

The aim of this investigation was to determine the importance of race as a determinant of intracranial atherosclerotic stroke in a community-based stroke sample.

METHODS

Residents from northern Manhattan over age 39 years hospitalized for acute ischemic stroke (n = 438, black 35%, Hispanic 46%, white 19%) were prospectively evaluated. Index ischemic strokes were classified as atherosclerotic (17%), lacunar (30%), cardioembolic (21%), cryptogenic (31%), and other (1%). Atherosclerotic infarcts were subdivided into extracranial (9%) and intracranial (8%) atherosclerosis.

RESULTS

The proportion of extracranial atherosclerotic stroke was similar among the three race-ethnic groups, while intracranial atherosclerosis was more frequent in blacks and Hispanics. The unadjusted odds ratio for nonwhites (blacks and Hispanics combined) was 0.8 (confidence interval [CI], 0.4 to 1.8) for extracranial and 7.8 (CI, 1.04 to 57.7) for intracranial atherosclerosis. Patients with intracranial disease were significantly younger and had an increased frequency of hypercholesterolemia and insulin-dependent diabetes compared with those with nonatherosclerotic disease. The odds ratio for the association of nonwhite race-ethnicity and intracranial atherosclerosis was reduced to 5.2 (CI, 0.7 to 40) after controlling for age and to 4.4 (CI, 0.6 to 35) after controlling for age, education, insulin-dependent diabetes, and hypercholesterolemia.

CONCLUSIONS

The greater prevalence of diabetes and hypercholesterolemia among blacks and Hispanics from northern Manhattan accounted for much of the increased frequency of intracranial atherosclerotic stroke. Further control of these risk factors could reduce the frequency of this stroke subtype and minimize the disparities among different race-ethnic groups.