CD14 and toll-like receptor 4: a link between infection and acute coronary events?

The CD14 receptor is a pattern recognition molecule in the innate immune response against microorganisms and other exogenous and endogenous stress factors. The most important CD14 signalling co-receptor is toll-like receptor 4 (TLR4), which activates, among others, the nuclear factor kappaB (NF-kappaB) inflammatory pathway. Besides its role in innate immunity and host defence, the proinflammatory cytokines expressed upon TLR4/NF-kappaB pathway activation exert proatherogenic effects. The CD14 C(-260)T promoter and TLR4 Asp299Gly functional polymorphisms have been recently implicated in the development of cardiovascular events, suggesting that the genetically determined inflammatory response against pathogens or their antigens may have a major role in atherogenesis and subsequent acute events. Is the association of these polymorphisms with cardiovascular disease more evidence for the implication of infection, especially by Gram negative bacteria, in the development of acute coronary events? This article reviews the molecular basis, biological functions, and clinical implications of the CD14/TLR4 polymorphisms in the development of cardiovascular events.

Increased plasma endothelin levels in angina patients with rapid coronary artery disease progression

AIMS

To investigate the association between plasma endothelin levels and rapid coronary artery disease progression, as assessed by quantitative angiography.

METHODS AND RESULTS

Changes in diameter were assessed in 224 coronary stenoses of 92 consecutive patients (62 men) with chronic stable angina pectoris who were on a waiting list for routine coronary angioplasty and underwent coronary angiography on two occasions: the first (diagnostic) angiogram was carried out at study entry and the second 5.5+/-3.0 months later, immediately prior to coronary angioplasty. A digital quantitative angiographic analysis system was used to assess differences in stenosis diameter between the first and second angiogram. Plasma immunoreactive endothelin levels were estimated by radioimmunoassay at study entry. Rapid coronary artery disease progression occurred in 29 (31.5%) patients according to pre-established criteria: 12 (41%) had a > or =10% diameter reduction of at least one pre-existing stenosis > or =50%, 10 (34%) had a > or =30% diameter reduction of a pre-existing stenosis <50%, 5 (17%) patients developed a new stenosis and 2 (7%) had progression of a lesion to total occlusion by the second angiogram. Baseline demographic, clinical and angiographic data were similar in patients with and without stenosis progression. Plasma endothelin levels were significantly higher in patients with rapid disease progression than in those without (5.7+/-2.0 pg. ml(-1)vs 3.9+/-1.6 pg. ml(-1), P<0.001). Multiple logistic regression analysis revealed that endothelin was an independent predictor of disease progression (P=0.001). Moreover, endothelin levels above 4.26 pg. ml(-1)(the median of the total endothelin concentrations) were associated with a sixfold increase in the risk of developing rapid stenosis progression.

CONCLUSIONS

Plasma endothelin is raised in patients with coronary artery disease progression and may be a marker of risk of rapid stenosis progression. Endothelin may also play a pathogenic role in this process.

Serum levels of the antiinflammatory cytokine interleukin-10 are decreased in patients with unstable angina

BACKGROUND

Proinflammatory cytokines play a role in acute coronary events. However, the potential role of antiinflammatory cytokines in the modulation of the atherosclerotic process remains unknown. Interleukin (IL)-10, which is expressed in human atherosclerotic plaques, has potent deactivating properties in macrophages and T cells. The aim of this study was to assess whether serum concentrations of IL-10 differed between patients with unstable and stable angina pectoris.

METHODS AND RESULTS

A total of 95 patients with angina pectoris and angiographically documented coronary artery disease were studied. Of these, 50 patients had chronic stable angina (with stable symptoms over 3 months), and 45 patients had Braunwald class IIIB unstable angina with ST-segment changes. Serum IL-10 and IL-6 concentrations were measured on admission using commercially available immunoassays. Serum IL-10 concentrations were lower in unstable angina patients compared with those who had chronic stable angina (28.4 versus 14.0 pg/mL; 95% CI, 9.8 to 19.0; P<0.0001), even after adjustment for variables that were significantly different on univariate analysis. IL-6 concentrations were higher in the unstable angina group (20.9 versus 11.4 pg/mL; 95% CI, 1.0 to 12.6; P=0.04).

CONCLUSIONS

Patients with unstable angina had significantly lower serum IL-10 concentrations than did patients with chronic stable angina. This important finding is in keeping with previous data from animal model studies that suggest that IL-10 has a protective role in atherosclerosis.

Rarefaction of skin capillaries in patients with anginal chest pain and normal coronary arteriograms

AIMS

Patients with arterial hypertension often have a reduction in capillary density (rarefaction) and a reduction in coronary flow reserve because of functional and structural alterations of the coronary microcirculation. Patients with chest pain and normal coronary arteriograms may have coronary microvascular dysfunction, but it is not known whether capillary rarefaction plays a role in the pathogenesis of this syndrome. The aim of this study was to compare capillary density in hypertensive and normotensive subjects with anginal chest pain and normal coronary arteriograms vs asymptomatic hypertensives and healthy controls.

METHODS AND RESULTS

We studied 49 patients with typical anginal chest pain, positive exercise testing and normal coronary arteriograms; 22 were hypertensive and 27 were normotensive. We used intra-vital video-microscopy to examine the skin of the dorsum of the middle finger of the non-dominant hand before and after maximization of perfused capillaries with venous congestion. Mean capillary density was significantly lower in patients with chest pain and normal coronary arteriograms independent of their blood pressure level, compared to normotensive healthy controls. Differences were found both at baseline [51+/-2 (hypertensive) and 52+/-2 (normotensive) vs 65+/-2 (controls) per 0.56 mm(2) respectively], (P<0.0001) and after maximization [57+/-3 (hypertensive) and 59+/-2 (normotensive) versus 75+/-3 (controls) respectively] (P<0.0001).

CONCLUSIONS

Skin capillary density is significantly lower in patients with chest pain and normal coronary arteriograms compared to normotensive controls. The pathophysiological importance of capillary rarefaction in patients with chest pain and normal coronary arteriograms remains unknown. Further studies are needed to determine whether the abnormality is associated with myocardial flow disturbances such that the findings can be extended to the heart.

Increased QT dispersion in patients with Prinzmetal's variant angina and cardiac arrest

OBJECTIVES

We sought to compare QT dispersion in patients presenting with Prinzmetal's variant angina complicated by cardiac arrest or syncope and patients with uncomplicated variant angina.

BACKGROUND

Despite the usually benign course of treated Prinzmetal's variant angina, a proportion of vasospastic angina patients develop ventricular arrhythmias and sudden death in association with coronary spasm. Increased QT dispersion has been suggested to increase susceptibility to ventricular arrhythmias in patients with coronary artery spasm.

METHODS

We studied 25 consecutive patients (mean age 58 years; 14 men) with classical Prinzmetal's variant angina and documented coronary artery spasm. None of the patients had coronary artery stenoses < or =40%. Five patients had suffered a documented cardiac arrest, two had recurrent syncope and 18 had no arrhythmic events or syncopal episodes. In all patients QT dispersion (QT maximum-QT minimum in every ECG lead) was measured on the baseline 12-lead electrocardiogram at study entry using a digitising board.

RESULTS

Mean (+/-S.D.) QT dispersion of study patients was 62.3+/-19.5 ms. QT dispersion in patients with cardiac arrest and syncope (79.4+/-17.3 ms) was significantly higher compared to patients with no such events (56.3+/-16.9 ms), (95% CI 7.5-38.8, P=0.005). No significant clinical, biochemical or angiographic differences were found between patients with and those without cardiac arrest or syncope.

CONCLUSION

QT dispersion is increased in patients with Prinzmetal's variant angina complicated by cardiac arrest and syncope compared to patients without such events. Increased QT dispersion may be both a substrate for sudden cardiac death and a marker of risk in patients with Prinzmetal's variant angina.

Microvascular angina in patients with syndrome X

Syndrome X (SX) is usually diagnosed in the presence of angina and normal coronary arteriograms. It is an heterogeneous syndrome which encompasses different pathogenic mechanisms. Whether myocardial ischaemia is responsible for the condition remains controversial. The term "microvascular angina" has been used to define the syndrome of chest pain and normal coronary arteries with heightened sensitivity of the coronary microcirculation to vasoconstrictor stimuli. It has been suggested that the abnormal vasodilator response of the coronary circulation in patients with SX is due to impaired endothelial function. Plasma levels of endothelin in patients with chest pain and normal coronary arteries were found to be significantly raised compared to normal controls. Endothelial dysfunction in SX is likely to be multifactorial and many cardiac risk factors, such as hypertension, hypercholesterolemia, oestrogen deficiency and smoking, can contribute to its development. As the majority of SX patients are women and most are post-menopausal, oestrogen deficiency has been proposed as a pathogenic factor. A large proportion of patients satisfying the stated criteria for SX have one or more coronary risk factors. Additional factors, such as abnormal pain perception, may contribute to the evolution of chest pain in patients with normal coronaries and endothelial dysfunction. Combined alteration of pain perception and microvascular dysfunction are likely to explain a proportion of all cases of SX. The treatment of this syndrome represents a major challenge for the cardiologist. Beta-blockers and calcium channel blockers are effective in controlling chest pain in SX patients. A very important therapeutic intervention in microvascular angina is the control of risk factors that can lead to endothelial dysfunction. Different approaches, including spinal cord stimulation and psychological treatment, have been proposed especially for those patients in whom a cardiac origin of pain is unlikely.

[Progress in the knowledge on endothelial dysfunction and its application in clinical practice]

The endothelium plays a crucial role in the maintenance of vascular homeostasis; endothelial cells produce a series of molecules that determine vascular tone and modulate the interactions between the arterial wall components and the circulating blood. Endothelial dysfunction (ED) thus results in significantly impaired physiological responses that often lead to atheroma formation. Recent studies suggest that endothelial dysfunction as assessed invasively during coronary angiography is a prognostic marker. Recently, a non-invasive ultrasound technique has been developed which may allow screening of ED in both patients and healthy subjects. This article reviews current knowledge regarding non-invasive assessment of endothelial dysfunction and proposes potential uses of a promising ultrasound technique.

[Inflammation, infection and coronary artery disease: myths and realities. Special XXXV Conference of the National Congress of the Spanish Society of Cardiology]

In the past decades it has become apparent that inflammation plays a role in atherogenesis and rapid coronary artery disease progression. Active, or vulnerable, atheromatous plaques are responsible for acute coronary events and contain high concentrations of inflammatory cells as well as molecules involved in the inflammatory process, such as cytokines, adhesion molecules and growth factors. From a clinical perspective, early detection of these plaques may prevent the occurrence of serious coronary events. Unfortunately, current diagnostic techniques -i.e. angiography- do not allow the characterization of events taking place in the arterial wall. Therefore, these diagnostic tools cannot identify vulnerable plaques. Recent studies have suggested that markers of systemic inflammation may help in the detection of high risk patients. Although the role of inflammation in the pathogenesis of atherosclerosis is established, it is not known what triggers inflammation in this context. Infectious agents such as viruses and Gram negative bacteria -i.e. Chlamydia pneumoniae- have been postulated to play a role. Several mechanisms, involving inflammation and immunological processes, have been suggested to explain how chronic infections may cause atherosclerosis. Small pilot studies have also been carried out which suggest a causal role of infection in coronary artery disease. These results, however, await confirmation by other large, currently ongoing, studies. The infectious hypothesis of atherosclerosis is still a matter of debate; however, this theory has contributed to the rapid advance of our knowledge regarding the pathogenesis of coronary artery disease in the past few years. Moreover, the notion that coronary artery disease can be considered to be an inflammatory condition in its own right has opened new and challenging avenues for research.

C-reactive protein in patients with chronic stable angina: differences in baseline serum concentration between women and men

AIMS

Serum C-reactive protein has prognostic significance in apparently healthy men and women and in men with coronary artery disease. Little is known regarding the predictive role of C-reactive protein in women with coronary heart disease. We assessed whether differences exist in C-reactive protein levels and their prognostic value in men compared with women. We also assessed whether C-reactive protein concentrations differed in women receiving hormone replacement therapy vs those on no hormone replacement therapy.

METHODS AND RESULTS

We prospectively studied 911 consecutive patients (327 women) with typical exertional angina. All patients underwent clinical, biochemical and angiographic characterization at study entry. Serum C-reactive protein was measured using a highly sensitive assay and correlated with clinical events during follow-up (from 1.0 to 3.7 years). C-reactive protein was significantly higher in women than men (3.0 mg. l(-1)[range 1.3-5.8] vs 2.1 mg. l(-1)[range 1.0-4.2], P<0.001), even after multiple regression adjustment for other risk factors. C-reactive protein was also significantly higher in women receiving hormone replacement therapy than in women not using hormone replacement therapy (P=0.001). C-reactive protein was an independent predictor of cardiovascular risk (logistic regression P=0.033) in the whole group but, despite higher C-reactive protein concentration, women had a similar rate of cardiac events compared to men.

CONCLUSIONS

Baseline C-reactive protein levels were higher in women than men but the event rate was similar in men and women. Women on hormone replacement therapy had significantly higher C-reactive protein than women not using hormone replacement therapy. In the group as a whole, increased C-reactive protein was associated with a higher cardiovascular risk.

Release of platelet activation markers during coronary angioplasty

BACKGROUND

Authors of several studies have reported that activation of platelets occurs during coronary angioplasty, but consistent results have not been obtained. Levels of serotonin in coronary circulation have been found to be elevated during percutaneous transluminal coronary angioplasty but greater than normal concentrations of beta-thromboglobulin and platelet factor 4 have not been detected.

OBJECTIVE

To perform a serial analysis of platelet-activation markers with simultaneous measurements of levels of serotonin, beta-thromboglobulin and platelet factor 4 in blood samples from the coronary artery and coronary sinus of patients undergoing coronary angioplasty.

METHODS

Twenty patients undergoing elective coronary angioplasty were studied. Measurements of levels of beta-thromboglobulin, platelet factor 4, and serotonin in samples from the ostium of the coronary artery and the coronary sinus were performed immediately before angioplasty and after the first balloon deflation.

RESULTS

Concentrations of beta-thromboglobulin and platelet factor 4 in coronary artery and coronary sinus were elevated in all patients before dilatation, whereas concentrations of serotonin were elevated in 85% of the patients. Concentrations of all markers in coronary sinus decreased after the first inflation. The coronary-sinus: coronary-artery concentration ratios before dilatation for beta-thromboglobulin, platelet factor 4, and serotonin were > 1 for the majority of patients, particularly for those with complex culprit lesions, indicating that coronary activation of platelets was occurring. Ratios remained unchanged or decreased after the first inflation, depending on initial values.

CONCLUSIONS

Both systemic and coronary activation occur in patients subjected to percutaneous transluminal coronary angioplasty before the onset of intervention. After balloon deflation the greater than normal baseline coronary-sinus:coronary-artery concentration ratios of all markers (beta-thromboglobulin, platelet factor 4 and serotonin) tend to decline or remain unchanged, depending on the level of activation.

Serum neopterin and complex stenosis morphology in patients with unstable angina

OBJECTIVES

We sought to assess the relation between serum neopterin concentration and complex coronary artery stenosis in patients with unstable angina.

BACKGROUND

Monocyte activation is associated with acute atheromatous plaque disruption and acute coronary syndromes. Angiographically demonstrated complex coronary stenosis is often an expression of plaque disruption. Increased serum concentration of neopterin, a pterydine derivative secreted by macrophages after stimulation by interferon-gamma, has been observed in patients with acute coronary syndromes as compared with control subjects and patients with stable angina pectoris.

METHODS

We studied 50 patients with unstable angina (32 men) who underwent coronary angiography after hospital admission. All coronary stenoses with > or =30% diameter reduction were assessed and classified as "complex" (irregular or scalloped borders, ulceration or filling defects suggesting thrombi) or "smooth" (absence of complex features). Serum neopterin levels were assessed within 24 h of hospital admission using a commercially available immunoassay (enzyme-linked immunosorbent assay kit, IBL, Hamburg, Germany).

RESULTS

Thirty-nine patients were classified in Braunwald class IIIb, four in class IIb and seven in class Ib. The number of complex lesions per patient was 2.6+/-1.8 (mean +/- SD). The mean neopterin concentration was 7.76+/-3.62 nmol/liter. A significant correlation was observed between neopterin serum concentration and the presence of complex coronary stenoses (r = 0.35, p = 0.015). Multiple regression analysis showed that serum neopterin (p < 0.0001) was independently associated with the number of complex lesions. Other variables associated with complex lesions were the number of vessels with > or =75% stenosis (p < 0.0001), plasma creatinine (p = 0.003), triglycerides (p = 0.014) and a history of unstable angina (p = 0.032).

CONCLUSIONS

Serum neopterin concentration is associated with the presence of angiographically demonstrated complex lesions in patients with unstable angina and may represent a marker of coronary disease activity.

Increased serum neopterin: a marker of coronary artery disease activity in women

OBJECTIVE

To assess whether neopterin concentrations in women with unstable angina differ from those in women with chronic stable angina.

DESIGN

Prospective cohort study.

SETTING

University hospital in south west London.

PATIENTS

114 consecutive women with angina were studied: 82 had chronic stable angina (typical exertional chest pain, positive exercise ECG testing, and/or abnormal myocardial scintigraphy; symptoms stable for at least three months), and 32 had unstable angina (Braunwald class III). All patients with chronic stable angina (100%) and 18 with unstable angina (56.3%) underwent digital coronary angiography; neopterin concentrations were determined using a commercially available immunoassay.

MAIN OUTCOME MEASURES

Major clinical events during one year follow up were readmission with Braunwald's class IIIb unstable angina, non-fatal myocardial infarction, and cardiac death.

RESULTS

Major events occurred in 12 women with chronic stable angina (14.6%) and nine women with unstable angina (28.1%). Mean (range) neopterin concentrations were significantly higher in women with unstable angina than in those with chronic stable angina (7.6 (5.1-11.5) nmol/l v 5.9 (4.4-7.5) nmol/l; p = 0.003), even after adjustment for variables which were significantly different on univariate analysis. In women with chronic stable angina, baseline neopterin concentrations were higher in those with cardiac events than in those without events (7.1 (5.9-9.1) nmol/l v 5.7 (3.9-7.3 nmol/l); p = 0.010), even after adjustment for variables with significant differences between both groups on univariate analysis.

CONCLUSIONS

On average, women with unstable angina had significantly higher neopterin concentrations than women with chronic stable angina. Women with chronic stable angina with events during follow up had higher neopterin concentrations than those without events. Neopterin concentrations were similar in patients with unstable angina and women with chronic stable angina who developed events. Neopterin concentrations may therefore be a marker of risk in women with coronary artery disease.

Effects of transcendental meditation on symptoms and electrocardiographic changes in patients with cardiac syndrome X

Chest pain with normal coronary angiograms is often associated with chronic sympathetic activation, anxiety, and depression, and is resistant to conventional antianginal treatment. The practice of transcendental meditation, a standard relaxation method for 3 months twice daily, significantly improved exercise tolerance, angina episodes, and quality of life in 9 women; the positive findings in this study warrant further research.

Cardiac syndrome X: an overview

Not all patients with angina have myocardial ischemia. A sizable minority--up to 30% of angina patients studied at tertiary referral centers--have normal coronary angiograms. Such patients often undergo an expensive and extensive array of testing and treatment. Yet the prognosis is generally good, and symptomatic management may be effective.

Antianginal and anti-ischaemic efficacy of tedisamil, a potassium channel blocker

OBJECTIVE

To determine the efficacy and safety of the potassium channel blocker tedisamil versus placebo in the treatment of patients with stable angina.

DESIGN

Prospective, double blind, placebo controlled study. 203 patients first completed a seven day placebo run in. They were then randomised to receive 50 mg, 100 mg or 150 mg tedisamil twice daily, or placebo. Treadmill exercise testing was carried out at baseline and after 14 days of double blind treatment.

MAIN OUTCOME MEASURES

Primary efficacy parameters were an increase in total exercise duration and a reduction of the sum of ST segment depression using six ECG leads at maximum workload at trough (12 hours after last medication). Secondary aims included increase in exercise time to onset of 0.1 mV ST segment depression, increase in exercise time to onset of any anginal pain, and reduction in ST segment depression in any of the six specified leads at maximum workload. These were all at trough. The same parameters were also assessed at peak concentrations (two hours after administration). Overall attacks of angina and the use of short acting nitrates were assessed from patient diaries.

RESULTS

Tedisamil led to a dose dependent prolongation of exercise duration (significant at all concentrations), an effect that was greater at peak than at trough. Treatment also led to a significant dose dependent reduction in the sum of ST segment depression at both trough and peak concentrations. Tedisamil also decreased (in a dose dependent way) the frequency of anginal attacks and the consumption of short acting nitrates, an improvement that became significant for all doses in the second treatment week. Adverse events with tedisamil were few. There was a pronounced rise in the incidence of diarrhoea with the 150 mg twice daily regimen. Bradycardic effects and increases in QT interval were dose dependent, but were no more evident at exercise than at rest.

CONCLUSIONS

Tedisamil, at doses of 50-100 mg twice daily, was found to be an effective antianginal and anti-ischaemic agent. At doses above 100 mg twice daily its main side effect, diarrhoea, becomes pronounced; therefore the 50-100 mg twice daily regimen appears to be appropriate.

Negative stress echocardiographic responses in normotensive and hypertensive patients with angina pectoris, positive exercise stress testing, and normal coronary arteriograms

OBJECTIVES

To systematically compare the results of dobutamine stress echocardiography in matched groups of hypertensive and normotensive patients with anginal chest pain and normal coronary arteriograms (CPNA).

SETTING

University hospital.

SUBJECTS

33 patients with exertional anginal chest pain, a positive exercise stress ECG, and a completely normal coronary arteriogram; 17 had a history of systemic hypertension (14 women; mean (SD) age 57 (6) years), and 16 had no hypertensive history (12 women; age 54 (9) years).

METHODS

Ambulatory ECG monitoring, dobutamine stress echocardiography, and thallium-201 single photon emission computed tomography (SPECT) were performed in all subjects.

RESULTS

All patients had normal left ventricular systolic function at rest and none fulfilled the criteria for ventricular hypertrophy. Eight normotensive patients and 10 hypertensive patients had perfusion abnormalities on thallium SPECT (p = 0.61). Dobutamine infusion reproduced anginal pain in seven normotensive and seven hypertensive patients (p = 0.88). ST segment depression was also recorded in eight normotensive patients and seven hypertensive patients (p = 0. 61). No patient in either group developed regional wall motion abnormalities during dobutamine stress echocardiography.

CONCLUSIONS

Neither hypertensive nor normotensive CPNA patients developed regional wall motion abnormalities during dobutamine stress echocardiography, despite the high prevalence of scintigraphic perfusion defects in both groups and the presence of chest pain and ST segment depression. Thus myocardial ischaemia was not present in either group, or else dobutamine stress echocardiography is insensitive to ischaemia caused by microvascular dysfunction.

Rapid coronary artery disease progression and angiographic stenosis morphology

It is established that the progression of coronary artery disease is neither linear nor predictable. The unpredictable and often episodic nature of coronary disease progression can be explained by rapid increase of stenosis severity due to thrombosis, which occurs as a complication of the atherogenic process. Rapid coronary stenosis progression is most often responsible for the acute clinical manifestations of coronary artery disease, i.e. sudden cardiac death, acute myocardial infarction and unstable coronary syndromes. Recently, it has been shown that stenosis progression, whether clinically "silent" or associated with acute coronary events, is a strong predictor of cardiovascular risk. Atheromatous plaques associated with rapid coronary artery disease progression have well defined anatomo-pathological characteristics and are usually termed "vulnerable" or "unstable", terms which indicate both their propensity to acute disruption and increased thrombogenicity that may lead to the development of acute coronary events. Plaques have been regarded, in the past, as being inert and staying almost unchanged for years. However, they are very active entities. The fibrous cap is in a balance between smooth muscle cells producing collagen and the macrophages degrading collagen. The thickness of the cap depends on the relative activity of those two components and there is, therefore, a danger of the fibrous cap rupturing. Although only a relatively small proportion of all coronary artery lesions in patients with angina pectoris undergo complications that lead to fibrous cap disruption and acute coronary events, these stenoses are responsible for the majority of cases of serious coronary events. Thus the identification of vulnerable plaques that may lead to increased risk of coronary events will most certainly help in the rational management of patients with coronary artery disease. Angiographic studies have indicated that "complex" lesion morphology is associated with increased risk of myocardial infarction and "ulcerated" plaques identify vulnerable lesions. We therefore reasoned that the identification of angiographically complex coronary stenoses could provide a valuable marker of cardiovascular risk in relation to rapid disease progression. Our group sought to investigate the role of angiographically complex lesions as a marker of rapid disease progression in different clinical settings. We took advantage of the fact that patients with stable angina pectoris requiring routine myocardial revascularisation in our institution are put on waiting lists. We observed that complex lesions progressed more than smooth stenoses of similar severity both in patients presenting with stable angina and in patients presenting with unstable angina. Why complex plaques should be particularly vulnerable to rapid stenosis progression is speculative. In this paper we discuss the possible mechanisms that may explain an association between complex stenosis and acute coronary events.

Effect of alpha1-adrenoceptor blockade on coronary vasodilator reserve in cardiac syndrome X

We sought to test the response of the coronary microcirculation to alpha-adrenoceptor blockade in patients with syndrome X (angina, ischemia-like stress electrocardiogram, and a normal coronary arteriogram). The response of the microcirculation was assessed by quantification of coronary vasodilator reserve (the ratio of hyperemic to resting myocardial blood flow). We investigated 28 patients with syndrome X [18 women, age 54.4 (7.6) years]. Myocardial blood flow was measured at rest and after dipyridamole by using positron emission tomography with H(2)15O. The measurements were made before and after treatment for 10 days with doxazosin (1 mg o.d. for 3 days, followed by 2 mg o.d. for 7 days) or a matched placebo, similarly administered. Patients were randomized to alpha1-blockade or to placebo in double-blind fashion. No significant differences were demonstrable between syndrome X patients treated with doxazosin and those receiving placebo, with respect to resting myocardial blood flow, myocardial blood flow after dipyridamole, or coronary vasodilator reserve (the ratio of the latter two). In addition, no relations were demonstrable among myocardial blood flow, coronary vasodilator reserve, development of chest pain after dipyridamole, or development of ischemia-like ECG changes. Doxazosin had no effect on the perception of chest pain after dipyridamole. No differences were found between the effects of alpha1-blockade with doxazosin or those of placebo with respect to myocardial blood flow in syndrome X. The values obtained for myocardial blood flow and coronary vasodilator reserve for the patients were within the normal range. The data do not support the case for alpha1-mediated vasoconstriction having an etiologic role in the chest pain of syndrome X.

Chronic infections and coronary heart disease

The rapidly changing patterns of coronary heart disease (CHD) prevalence and presentation fail to be explained by conventional cardiovascular risk factors alone. An infectious basis to atherosclerosis may, at least in part, be contributing to the variable rates of prevalence of CHD in different parts of the world. The evidence for such an association appears to be strongest for Chlamydia pneumoniae. Results of recent anti-chlamydia antibiotic intervention pilot studies have renewed interest in the role of C. pneumoniae, and corroborated the evidence from sero-epidemiological, pathological and animal-model studies. The results of larger, on-going, purpose-designed intervention studies should help to increase our understanding of the role of infection in atherogenesis and potentially lead to a novel and effective treatment strategy for patients with CHD--broad spectrum antibiotics.

Elevated endothelin concentrations are associated with reduced coronary vasomotor responses in patients with chest pain and normal coronary arteriograms

OBJECTIVES

The purpose of this study was to investigate the relationship between arterial and coronary sinus endothelin (ET) concentrations and coronary vasomotor responses during rapid atrial pacing in patients with chest pain and normal coronary arteriograms (CPNA).

BACKGROUND

Plasma ET concentrations are significantly higher in CPNA patients than in healthy control subjects.

METHODS

We investigated 19 carefully characterized CPNA patients (14 women; mean age 53 +/- 9 years) of whom 10 had positive electrocardiographic responses to exercise. The percentage fall in coronary vascular resistance (%d.CVR) after 10 min of rapid atrial pacing was determined using a thermodilution pacing catheter. Plasma ET concentrations were measured by radioimmunoassay on simultaneously drawn arterial and coronary sinus samples.

RESULTS

No significant differences in ET concentrations were observed between men and women, but a strong statistical trend suggested that %d.CVR was lower in women than men (27[23 to 31]% vs. 34[29 to 45]%--median[interquartile range]; p = 0.07). Simple regression analysis including only the women (n = 14) suggested a significant relationship between baseline arterial ET concentrations and %d.CVR (R2 = 0.34; p = 0.06). Furthermore, stepwise multivariate regression analysis of the group as a whole indicated that both gender (p = 0.03) and baseline arterial ET concentration (p = 0.02) were independently predictive of %d.CVR (R2 = 0.44; overall p = 0.02); this relationship predicts that women with high ET levels would have the lowest %d.CVR during pacing.

CONCLUSIONS

These data support the hypothesis that elevated ET activity may be associated with reduced coronary flow responses during rapid atrial pacing in CPNA patients.

Assessment of quality of life in patients with chest pain and normal coronary arteriogram (syndrome X) using a specific questionnaire

BACKGROUND

Prognosis in patients with syndrome X (chest pain and normal coronary arteriograms) is good; however, persistent chest pain and functional disability are common in these patients. Accurate assessment of quality of life may be useful for patient management.

AIM

The quality of life status in patients with syndrome X was assessed using a specific questionnaire. This questionnaire was developed and validated for the assessment of quality of life in patients with typical chest pain despite normal coronary arteriograms.

METHODS

Ninety consecutive patients were invited to complete both the questionnaire (on two occasions within 2 weeks) and a standardized angina dairy. Fully completed questionnaires were received from 66 (73%) patients (mean age 58 +/- 8 years, 55 women).

RESULTS

Answers were scored according to a grading system where higher scores indicate worse quality of life. We observed that total scores increased with severity of angina (Canadian Class I, 38 +/- 16, II: 93 +/- 29, III-IV, 119 +/- 23; p < 0.001) and correlated with both the number and the severity of chest pain episodes (r = 0.50-0.66: p < 0.001). In patients who remained clinically stable (n = 37) during the 2-week assessment, test-retest analysis showed no score differences (87 +/- 30 vs. 81 +/- 30; p = 0.1), while total score increased in patients (n = 24) whose symptoms worsened (108 +/- 31 vs. 116 +/- 31; p < 0.02) and was reduced in those (n = 5) whose symptoms improved (55 +/- 37 vs. 39 +/- 28; p < 0.04).

CONCLUSION

Our study shows that quality of life is significantly impaired in patients with syndrome X and that the specific questionnaire used for assessment is a reliable and sensitive tool for the evaluation of quality of life in patients with chest pain and normal coronary arteriograms.

Interleukin-1 receptor antagonist gene polymorphism and coronary artery disease

BACKGROUND

Cytokine gene variations are contributory factors in inflammatory pathology. Allele frequencies of interleukin (IL)-1 cluster genes [IL-1A(-889), IL-1B(-511), IL-1B(+3953), IL-1RN Intron 2 VNTR] and tissue necrosis factor (TNF)-alpha gene [TNFA(-308)] were measured in healthy blood donors (healthy control subjects), patients with angiographically normal coronary arteries (patient control subjects), single-vessel coronary disease (SVD), and those with multivessel coronary disease (MVD).

METHODS AND RESULTS

Five hundred fifty-six patients attending for coronary angiography in Sheffield were studied: 130 patient control subjects, 98 SVD, and 328 MVD. Significant associations were tested in an independent population (London) of 350: 57 SVD, 191 MVD, and 102 control subjects. IL-1RN*2 frequency in Sheffield patient control subjects was the same as in 827 healthy control subjects. IL-1RN*2 was significantly overrepresented in Sheffield SVD patients (34% vs 23% in patient control subjects); IL-1RN*2 homozygotes in the SVD population (chi2 carriage=8.490, 1 df, P=0.0036). This effect was present though not quite significant in the London population (P=0. 0603). A summary trend test of the IL-1RN SVD genotype data for Sheffield and London showed a significant association with *2 (P=0. 0024). No significant effect of genotype at IL-1RN was observed in the Sheffield or London MVD populations. Genotype distribution analysis comparing the SVD and MVD populations at IL-1RN showed a highly significant trend (P=0.0007) with the use of pooled data. No significant associations were seen for the other polymorphisms.

CONCLUSIONS

IL-1RN*2 was significantly associated with SVD. A difference in genetic association between SVD and MVD was also apparent.

Transforming growth factor-beta1 gene polymorphisms and coronary artery disease

1. Transforming growth factor-beta1 is a cytokine with a very wide spectrum of biological activities. Previous studies have shown that it is involved in a number of physiological and pathological processes including heart disease. In our study we aimed to scan the transforming growth factor-beta1 locus for polymorphisms and to identify haplotypes significantly associated with a predisposition to coronary atherosclerosis.2. Two patient groups comprising 244 angiographically normal individuals and 655 patients with coronary artery disease were recruited from London and Sheffield. DNA samples from these subjects were screened for mutations in the transforming growth factor-beta1 locus and all subjects were genotyped by a coupled polymerase chain reaction-restriction enzyme digestion method.3. Five polymorphisms have been identified in the transforming growth factor-beta1 gene at positions G-800A, C-509T in the promoter region, Leu10-->Pro, Arg25-->Pro in exon 1 and Thr263-->Ile in exon 5. No significant difference in frequencies for any of the five polymorphisms was found between controls and patients with coronary artery disease. Similarly, there was no correlation between these polymorphisms and hypertension.4. The genotypes of all the individuals participating in the study were assigned to seven main haplotypes of the transforming growth factor-beta1 locus. Based on species comparison data we propose that GCCGC is the ancestral haplotype in humans.5. Our data suggest that these transforming growth factor-beta1 polymorphisms are not associated with coronary artery disease and therefore their presence alone would not be a genetic risk factor for predisposition to coronary artery disease.

Regional variations in endothelin-1 and its receptor subtypes in human coronary vasculature: pathophysiological implications in coronary disease

Endothelin-1 is a potent vasoconstrictor peptide and mitogen for vascular smooth muscle cells. Increased plasma or tissue levels of endothelin-1 have been described after myocardial infarction and in atherosclerosis, suggesting that this peptide may play a pathophysiological role in various coronary syndromes. Here, we have studied regional variations in ET-1 and its receptors in control and atherosclerotic human coronary vasculature using standard immunohistochemistry and in vitro autoradiography. ET-1 immunoreactivity was associated with luminal endothelial cells and smooth muscle cells at regions of atherosclerosis. ET(A) receptors were present on smooth muscle cells of coronary arteries and on cardiac myocytes. Medial ET(B) receptor binding at the proximal region of coronary arteries was weak, but increased significantly towards distal regions of this vessel (p<0.005 in control and p<0.0005 in ischaemic heart disease). Microvascular endothelial cells in the adventitia of coronary arteries, myocardial microvessels and the endocardial endothelium expressed the ET(B) receptor exclusively. The receptor variations revealed in this study provide supporting evidence that ET-1 is associated with (1) vascular smooth muscle and endothelial cell proliferation, including areas of intimal hyperplasia and regions of neovascularization (2) increased ET-1-induced reactivity of distal portions of the human coronary artery, (3) ET-1-mediated constriction of myocardial microvessels. These results provide new insights into different potential roles for this peptide in healthy and diseased human coronary vasculature.

Truncated human endothelin receptor A produced by alternative splicing and its expression in melanoma

In this study, reverse transcriptase polymerase chain reaction was used to amplify human endothelin receptor A (ETA) and ETB receptor mRNA. A truncated ETA receptor transcript with exons 3 and 4 skipped was found. The skipping of these two exons results in 109 amino acids being deleted from the receptor. The truncated receptor was expressed in all tissues and cells examined, but the level of expression varied. In melanoma cell lines and melanoma tissues, the truncated receptor gene was the major species, whereas the wild-type ETA was predominant in other tissues. A 1.9-kb ETA transcript was identified in melanoma cell lines by Northern blot, which was much smaller than the transcript in heart and in other tissues reported previously (4.3 kb). The cDNA coding regions of the truncated and wild-type ETA receptors were stably transfected into Chinese hamster ovary (CHO) cells. The truncated ETA receptor-transfected CHO cells did not show binding affinity to endothelin 1 (ET-1) or endothelin 3 (ET-3). The function and biological significance of this truncated ETA receptor is not clear, but it may have regulatory roles for cell responses to ETs.

Complex stenosis morphology predicts late reocclusion during follow-up after myocardial infarction in patients with patent infarct-related coronary arteries

BACKGROUND

Whether angiographic morphology of infarct-related residual stenoses continues to affect prognosis after discharge is not known.

METHODS

We studied 175 patients after their myocardial infarction who required nonurgent coronary angioplasty for residual myocardial ischemia. The findings at diagnostic coronary angiography were compared with those before angioplasty (mean of 7 months later). Infarct-related stenoses were classified as complex or smooth. Stenosis progression was defined as >0.5 mm diameter reduction.

RESULTS

One hundred twenty-one (69%) infarct-related stenoses were complex. At restudy, total occlusion was found in 41 (35%) of the infarct-related complex stenoses compared with 7 (13%) smooth stenoses (P = .001). Reocclusion occurred in 16 (55%) of 29 complex infarct-related stenoses with thrombus, compared with 25 (28%) of 88 without thrombus (P = .01). During follow-up, 46 patients (26%) had cardiac events. Of these, 70% had complex lesions at study entry compared with 30% smooth (P < .05).

CONCLUSIONS

Residual angiographically complex stenoses after an uncomplicated myocardial infarction are associated with a greater risk of reocclusion and may predispose to coronary events at follow-up.

Serum sialic acid concentration is not associated with the extent or severity of coronary artery disease in patients with stable angina pectoris

BACKGROUND

Total serum sialic acid concentration has been reported to predict death from cardiovascular disease. This study was performed to assess the relation between serum sialic acid concentration and the angiographic extent and severity of coronary atheroma in patients with stable angina.

METHODS

Quantitative coronary angiography was performed in 40 patients with stable angina with either triple-vessel disease (23 patients) or normal/nearly normal coronary arteries (17 patients). A colorimetric assay for the enzymatic determination of serum sialic acid was used.

RESULTS

Serum sialic acid concentration was not significantly different in patients with normal or nearly normal coronary angiograms compared with those with triple-vessel disease (68+/-10 mg/100 mL and 68+/-11 mg/100 mL, respectively). Neither was there any association between the extent or severity of coronary disease and serum sialic acid levels.

CONCLUSIONS

Serum sialic acid concentration does not appear to be associated with the extent or severity of coronary artery disease in patients with stable angina pectoris. Thus the previously described association between serum sialic acid and cardiovascular death may reflect the role of mechanisms other than the severity of coronary artery narrowings.

Differential plasma endothelin levels in subgroups of patients with angina and angiographically normal coronary arteries. Coronary Artery Disease Research Group

BACKGROUND

Raised plasma endothelin concentrations have previously been reported in patients with cardiac syndrome X, but it is not known whether these levels vary between clinically distinct subgroups in this heterogeneous condition.

METHODS AND RESULTS

We compared plasma immunoreactive endothelin levels in 54 patients with angina pectoris and normal coronary angiograms and 21 healthy control subjects. The patient group was divided into 4 clinically distinct subgroups: 7 with left bundle branch block (group A); 7 with previous myocardial infarction (group B); 24 with positive exercise electrocardiography (group C); and 16 with negative exercise electrocardiography (group D). The plasma endothelin concentration was significantly higher in patients compared with control subjects (3.7 [2.9 to 4.3] vs 2.96 [2.4 to 3.4] pg/mL, respectively, median [interquartile range]; P=0.002). Endothelin concentrations were most significantly elevated in group A and group B (4.5 [3.6 to 5.2] pg/mL; P=0.005 and 4.1 [3.9 to 4.5] pg/mL; P=0.001, respectively). Plasma endothelin concentrations were also significantly elevated in group C (3.7 [2.8 to 4.1] pg/mL; P=0.02) but not in group D (3.0 [2.5 to 3.8] pg/mL; P=0.3).

CONCLUSIONS

Plasma endothelin concentration is elevated in patients with angina pectoris and angiographically normal coronary arteries, particularly those with left bundle branch block or previous myocardial infarction.

Methylenetetrahydrofolate reductase polymorphism (C-677T) and coronary artery disease

1. Many studies have shown that hyperhomocysteinaemia is a risk factor for atherosclerotic vascular disease. A mutation (C-677T) in the gene coding for the methylenetetrahydrofolate reductase (MTHFR) enzyme has been shown to produce a thermolabile form of the enzyme. Homozygosity for this mutation has been correlated with an elevated plasma homocysteine concentration. The present study aimed to determine whether this mutation was a risk factor for coronary artery disease (CAD). This was achieved by comparing the frequency of the C-677T mutation in patients with angiographically proven CAD against angiographically normal patients in two separate U.K. samples. The analysis was repeated with CAD patients split into those with >=99% stenosis of arteries and those without, to establish whether the C-677T mutation could be correlated with severity of CAD.2. Two patient groups were selected from London and Sheffield. The London group comprised 174 cases and 148 controls. The Sheffield group comprised 93 cases and 85 controls. The DNA samples of the patients were genotyped by polymerase chain reaction and restriction enzyme digestion.3. For London the homozygous C-677T frequencies were: 0.07 (controls), 0.09 (CAD without >=99% stenosis) and 0.10 (CAD with >=99% stenosis). For Sheffield the homozygous C-677T frequencies were: 0.08 (controls), 0.10 (CAD without >=99% stenosis) and 0.11 (CAD with >=99% stenosis). No association was found between the C-677T mutation and CAD in our sample geographical groups. Statistical comparison by genotype distribution for 0 VD (no vessel disease, i.e. 0% diameter reduction in all epicardial arteries) versus CAD without >=99% stenosis: London, P=0.19; Sheffield, P=0.53; 0 VD versus CAD with >=99% stenosis: London, P=0. 23; Sheffield, P=0.55.

Histological patterns of atherosclerotic plaques in unstable angina patients vary according to clinical presentation

BACKGROUND

Unstable angina is a heterogeneous clinical syndrome. The diverse clinical presentations of unstable angina may reflect different pathogenic mechanisms within the plaque.

OBJECTIVE

To investigate the cellular constituents of culprit coronary atheromatous plaques in patients with stable angina pectoris and patients with diverse clinical presentations of unstable angina.

METHODS

48 patients who underwent coronary atherectomy for management of ischaemic heart disease: 23 had stable angina and 25 had unstable angina. Of the latter, 11 patients were classified as Braunwald's IIB and 14 as Braunwald's IIIB unstable angina. The presence of thrombus, cholesterol clefts, and smooth muscle cell proliferation was assessed in atherectomy samples using standard histological techniques. Monoclonal antibodies were used to identify smooth muscle cells and macrophages within atherosclerotic plaque fragments.

RESULTS

Fresh thrombus was more frequently found in patients with Braunwald's IIIB unstable angina (64%) than in patients with stable angina (22%) or IIB unstable angina (27%) (p < 0.0006). A pattern of smooth muscle cell proliferation ("accelerated progression pattern") was observed which was also associated with coronary thrombus. This pattern was present in 30% of patients with stable angina, 64% of patients with IIIB unstable angina, and in all patients (100%) with IIB unstable angina. Atherosclerotic plaques with thrombus, cholesterol clefts, and macrophages were more common in patients with unstable angina than in stable angina patients.

CONCLUSION

The presence of a specific smooth muscle cell proliferation (accelerated progression) pattern in patients with unstable angina, particularly in those with Braunwald's IIB unstable angina, suggests that episodic plaque disruption and subsequent healing may be an important mechanism underlying angina symptoms in these patients.

Angiographic progression in patients with angina pectoris and normal or near normal coronary angiograms who are restudied due to unstable symptoms

BACKGROUND

Syndrome X patients commonly remain symptomatic during follow-up and may be readmitted with unstable anginal symptoms. Angiographic disease progression must be considered as a possible mechanism for instability, particularly where multiple coronary risk factors are present and an interval of several years has elapsed since previous angiography.

METHODS AND RESULTS

We reviewed data from 139 consecutive patients with chest pain and normal or near normal coronary angiograms (101 patients with completely normal angiograms and 38 patients with minimal lumenal irregularities). During a 5-year period, 24 patients (19 women, median age 56 years) underwent repeat angiography due to primary unstable angina (median interval between angiograms 58 months (range 8-130 months)). This group included three patients with minimal lumenal irregularities and four patients with left bundle branch block. Only two patients had progression to significant angiographic stenosis (> 30% diameter reduction); both were male patients with minimal irregularities at baseline angiography, left bundle branch block and multiple coronary risk factors. However, overall only two of 18 (11%) patients with one or more conventional coronary risk factors had angiographic progression.

CONCLUSIONS

Unstable symptoms in patients with chest pain and previously normal or near normal coronary arteriograms are rarely due to angiographic disease progression. However, the presence of minimal lumenal irregularities at baseline angiography and LBBB may identify a sub-group at increased risk.

Elevated plasma lipoprotein(a) is associated with coronary artery disease in patients with chronic stable angina pectoris

OBJECTIVES

We sought to assess the relation between plasma lipoprotein(a) [Lp(a)] levels, clinical variables and angiographic coronary artery disease (CAD) in patients with chronic stable angina.

BACKGROUND

The relation between plasma Lp(a) levels and the severity and extent of angiographic CAD has not been studied in well characterized patients with stable angina pectoris.

METHODS

We investigated clinical variables, lipid variables and angiographic scores in 129 consecutive white patients (43 women) undergoing coronary angiography for chronic stable angina.

RESULTS

Plasma Lp(a) levels were significantly higher in patients with than in those without significant angiographic stenoses (> or =70%) (372 mg/liter [interquartile range 87 to 884] vs. 105 mg/liter [interquartile range 56 to 366], respectively, p=0.002). This difference remained significant when patients with mild or severe angiographic disease were compared with those with completely normal coronary arteries (312 mg/liter [interquartile range 64 to 864] vs. 116 mg/liter [interquartile range 63 to 366], respectively, p=0.02). However, subset analysis indicated that this difference achieved statistical significance only in women. Multiple logistic regression analysis indicated that Lp(a) concentration was independently predictive of significant angiographic stenoses (adjusted odds ratio [OR] 9.1, 95% confidence interval [CI] 2.0 to 42.1, p=0.006) and remained true even after exclusion of patients receiving lipid-lowering treatment (n=27) (OR 10.4, 95% CI 1.1 to 102.9, p=0.05). Lp(a) also had independent predictive value in a similar analysis using mild or severe angiographic disease as the outcome variable (OR 11.8, 95% CI 1.5 to 90.8, p=0.02).

CONCLUSIONS

Our results indicate that elevated plasma Lp(a) is an independent risk factor for angiographic CAD in chronic stable angina and may have particular significance in women.