Scintigraphic results in asymptomatic myocardial infarction patients with exercise-induced ST segment elevation

BACKGROUND

The mechanism responsible for exercise-induced ST segment elevation is debated, but heterogeneous patients were likely included in previous studies. This study was specifically aimed at investigating the clinical meaning of isolated exercise-induced ST segment elevation in asymptomatic patients with a recent acute myocardial infarction (MI).

METHODS

We studied 30 patients (28 males, 2 females, mean age 62 +/- 9 years) with a recent MI who developed ST segment elevation in leads with a Q/QS wave pattern, and who did not develop angina or ST segment depression during exercise testing and did not have any history of post-infarction angina. Patients underwent bicycle 99m-Tc-sestamibi (MIBI) myocardial scintigraphy for the assessment of myocardial perfusion and of left ventricular function.

RESULTS

Only 7 patients (23.3%) showed reversible perfusion defects on stress MIBI myocardial scintigraphy, which were mild and of limited extension in all. There were no statistically significant differences in the main exercise variables between groups with or without stress-related perfusion defects. Signs of exercise-related left ventricular dysfunction were detected in 6 patients (20%), 3 of whom also showed reversible perfusion defects. Again, no significant differences in the main exercise variables were found between patients with or without stress-induced scintigraphic abnormalities.

CONCLUSIONS

In asymptomatic MI patients, isolated exercise-induced ST segment elevation in leads with a Q/QS wave pattern is unlikely to represent clinically relevant residual myocardial ischemia during exercise, thus suggesting that further diagnostic investigations are not necessary in these patients.

Inflammation and atherosclerosis

Atherosclerosis, formerly considered a bland lipid storage disease, actually involves an ongoing inflammatory response. Recent advances in basic science have established a fundamental role for inflammation in mediating all stages of this disease from initiation through progression and, ultimately, the thrombotic complications of atherosclerosis. These new findings provide important links between risk factors and the mechanisms of atherogenesis. Clinical studies have shown that this emerging biology of inflammation in atherosclerosis applies directly to human patients. Elevation in markers of inflammation predicts outcomes of patients with acute coronary syndromes, independently of myocardial damage. In addition, low-grade chronic inflammation, as indicated by levels of the inflammatory marker C-reactive protein, prospectively defines risk of atherosclerotic complications, thus adding to prognostic information provided by traditional risk factors. Moreover, certain treatments that reduce coronary risk also limit inflammation. In the case of lipid lowering with statins, this anti-inflammatory effect does not appear to correlate with reduction in low-density lipoprotein levels. These new insights into inflammation in atherosclerosis not only increase our understanding of this disease, but also have practical clinical applications in risk stratification and targeting of therapy for this scourge of growing worldwide importance.

Risk of myocardial infarction and angina in patients with severe peripheral vascular disease: predictive role of C-reactive protein

BACKGROUND

Patients undergoing revascularization procedures for peripheral vascular disease (PVD) have a greatly increased risk for coronary artery disease (CAD) that is predicted only partly by clinical data and cardiovascular risk factors. We investigated whether the prognostic assessment in PVD patients could be improved by preoperative measurements of C-reactive protein (CRP).

METHODS AND RESULTS

We assessed clinical and risk factors profiles, Eagle clinical scores, and preoperative CRP serum levels in 51 patients with PVD at Fontaine-Leriche stages II to IV without severe rest ventricular dysfunction or ischemia. During 24 months of follow-up, 17 patients (34%) had fatal (11) or nonfatal (6) myocardial infarction (MI). With univariate logistic regression analysis, only previous history of CAD, Eagle score, and CRP were independently related to MI. At multivariate logistic regression analysis, only CRP values in the upper tertile (<9 mg/L) were significantly associated with MI (P<0.05) and identified 65% of cases.

CONCLUSIONS

The high incidence of MI in patients with PVD severe enough to require revascularization is strongly predicted by preprocedural measurements of serum CRP, independent of previous CAD, Eagle score index, and traditional cardiovascular risk factors. These patients may benefit from therapy modulating the inflammatory response.

[Role of clopidogrel in acute coronary syndromes without ST-segment elevation]

Unstable angina and no ST-segment elevation myocardial infarction are acute coronary syndromes (ACS) typically characterized by minimal or little myocardial damage, but often heralding "classical" infarction or coronary death in the short or medium term. Coronary thrombi, mainly composed by platelets, are the major pathogenetic component of ACS and an effective therapeutic target. The hemostatic balance can be shifted towards an antithrombotic state in the clinical setting. Although the thrombogenic stimuli acting in each individual patient, their intensity as well as the prothrombotic factors that may contribute to an inappropriate thrombus growth, remain largely unknown. To this purpose the modulation of platelet aggregation is a particularly effective and practical therapeutic target. The availability of a new antiplatelet agent, clopidogrel, with a proven efficacy in the prevention of cardiovascular events, suggests the opportunity of reviewing the mechanisms of instability and the therapeutic strategies in patients with ACS. In this review we analyze: 1) the composition of coronary thrombi in patients with ACS, 2) the mechanisms of thrombus development and growth, 3) the mechanisms of platelet adhesion and aggregation, 4) the characteristics of clopidogrel, 5) the efficacy of the various therapeutic strategies, 6) the possible implications of the adjunctive therapy with clopidogrel for the treatment and prevention of cardiovascular events in ACS with no ST-segment elevation.

Inflammatory gene polymorphisms and ischaemic heart disease: review of population association studies

Inflammation and genetics are both prominent mechanisms in the pathogenesis of atherosclerosis and arterial thrombosis. Accordingly, a number of population studies have explored the association of ischaemic heart disease with gene polymorphisms of the inflammatory molecules tumour necrosis factors (TNF) alpha and beta, transforming growth factors (TGF) beta1 and 2, interleukin (IL) 1 and its receptor antagonist (IL 1ra), CD14 (the receptor for lipopolysaccharide), P and E selectins, and platelet endothelial cell adhesion molecule (PECAM) 1. Although they are very preliminary and partly conflicting, the data provide some evidence that alterations in the genetics of the inflammatory system may modify the risk of ischaemic heart disease.

Antibodies to 60-kilodalton heat shock protein and outer membrane protein 2 of Chlamydia pneumoniae in patients with coronary heart disease

Evidence linking Chlamydia pneumoniae infection to atherosclerosis and to atherothrombotic events has recently emerged. A primary candidate implicated in these pathogenetic events is the 60-kDa chlamydial heat shock protein (HSP60). Another putative candidate to activate a potential proinflammatory mechanism is the chlamydial outer membrane protein 2 (OMP2). We have generated both HSP60 and OMP2 recombinant antigens in a nondenatured form and shown that (i) the two antigens were highly immunogenic in mice and (ii) murine antisera thus generated recognized the native C. pneumoniae proteins. We measured by enzyme linked immunosorbent assay (ELISA) and immunoblot assay antibody titers to the recombinant antigens in samples from 219 patients with coronary heart disease (CHD), 179 patients with unstable angina (UA), 40 patients with acute myocardial infarction (AMI), and 100 age-, sex-, and risk factor-matched healthy controls. We also examined whether anti-HSP60 and/or anti-OMP2 antibodies correlated with anti-C. pneumoniae antibodies assessed by a commercial microimmunofluorescence (MIF) assay. Immunoglobulin G (IgG), but neither IgA nor IgM, antibodies against the two recombinant proteins were detected by ELISA. In particular, anti-HSP60 antibodies were detected in >99% of CHD patients versus 0% of the controls, whereas the proportions of anti-OMP2 positive subjects were >70 and 27%, respectively. Nonetheless, among CHD patients, similar frequencies of positive subjects and titers of anti-HSP60 or anti-OMP2 antibodies were present in UA and AMI subjects. The anti-OMP2, but not the anti-HSP60, antibodies showed high specificity. Consistently, high serological correlation was observed between IgG MIF titers and IgG ELISA reactivity to OMP2 but not to HSP60. Overall, the results of this study demonstrate a strong correlation between CHD and anti-HSP60 IgG levels, as measured by our in-house ELISA. They also suggest that recombinant OMP2 ELISA, because of its high specificity and strong correlation with MIF assay, could be a candidate diagnostic marker for C. pneumoniae infection, which would be of potential usefulness for its specificity and nonsubjective nature.

Increased prevalence of the G20210A prothrombin gene variant in acute coronary syndromes without metabolic or acquired risk factors or with limited extent of disease

AIMS

To investigate the prevalence of the G20210A prothrombin and G1691A factor V gene variants in patients with acute coronary syndrome stratified according to risk factor profile and to extent of coronary disease, in comparison with matched healthy controls.

METHODS AND RESULTS

The 20210 prothrombin and the 1691 factor V loci were genotyped in 247 patients < or =65 years of age (190 myocardial infarction and 57 unstable angina as first presentation of disease) and in 247 healthy age- and sex-matched controls. The prevalence of the 1691A factor V allele was similar in cases and controls. The frequency of heterozygotes for the 20210A prothrombin allele was 6.5% among patients and 2.8% among controls (OR 2.4, 95% CI 1.0-5.9), increasing to 8.7% in patients with a family history of myocardial infarction (OR 3.3, 95% CI 1.2-9.1), to 9.9% in patients (n=81) with < or =1 vessel disease (OR 3.8, 95% CI 1.3-10.8), and to 13.0% in patients who were normocholesterolaemic, non-diabetic, normotensive and non-smokers (OR 5.1, 95% CI 1.2-21.4).

CONCLUSIONS

These findings suggest that the 20210A prothrombin allele represents an inherited risk factor for acute coronary syndrome among patients who have limited extent of coronary disease at angiography or who lack major metabolic and acquired risk factors.

Relation of the -174 G/C polymorphism of interleukin-6 to interleukin-6 plasma levels and to length of hospitalization after surgical coronary revascularization

Interleukin (IL)-6 plasma levels are predictive of major cardiovascular events. The -174 G/C promoter polymorphism of the IL-6 gene affects basal levels in vivo and transcription rates in vitro, but its association with IL-6 acute phase levels among patients with coronary artery disease has not been investigated. In 111 patients with multivessel coronary artery disease undergoing elective coronary artery bypass graft surgery, we prospectively assessed genotype at position -174 and serial blood levels of IL-6 and other inflammatory indexes. Clinical and surgical characteristics did not differ among genotypic groups. IL-6 levels--measured daily up to 72 hours before surgery, after surgery, and at discharge--showed a mean 17-fold increase, peaking at 24 hours (p <0.0001). IL-6 levels (but not fibrinogen, white-blood cell count, and C-reactive protein values) differed significantly according to the -174 genotype (p = 0.042 for difference between areas under the curve), the 62 GG homozygotes exhibiting higher concentrations than the 49 carriers of the C allele (widest difference at 48 hours, p = 0.015 in multivariate analysis). GG homozygosity was associated with longer stays in the intensive care unit (2.5 +/- 3.4 vs 1.4 +/- 0.9 days, p = 0.02) and in the hospital (6.7 +/- 4.0 vs 5.3 +/- 1.4 days, p = 0.02) than C carriership. Rates of postoperative death, myocardial infarction, and stroke were 8% in GG homozygotes and 2% in C-carriers (p = 0.16). The IL-6-174 GG genotype is associated with higher acute phase levels of IL-6 and with longer stays in the hospital and in the intensive care unit than C allele carriership after surgical coronary revascularization.

Platelet aggregability in cardiac syndrome X

AIMS

To assess platelet aggregability at rest and in response to exercise in patients with cardiac syndrome X (anginal chest pain, ST-segment depression on exercise, angiographically normal coronary arteries).

METHODS AND RESULTS

We performed a symptom/sign-limited exercise test in 31 patients with syndrome X, 25 patients with coronary artery disease and 29 healthy subjects. Platelet aggregability was measured in flowing whole blood at baseline, at peak exercise, and after 30 and 120 min, as the time to occlude a collagen/adenosine diphosphate coated ring (aggregation time). Resting aggregation time was shorter in syndrome X patients (83.2+/-12 s), compared to patients with coronary disease (94.0+/-18 s, P<0.01) and to healthy subjects (96.4+/-21 s, P<0.01). With exercise, aggregation time did not change in healthy controls, decreased in patients with coronary disease (-13.8 s at peak; 95% CI, -10.2, -17.3 s;P<0.001), but increased in syndrome X (+17.4 s 30 min after exercise; 95% CI, +10.4, +24.4 s;P<0.0001). The intravenous administration of an adenosine antagonist (theophylline) prevented the exercise-induced prolongation of aggregation time in syndrome X patients (n=11), but had no effect in healthy controls (n=11).

CONCLUSION

Platelet aggregability at rest was increased in syndrome X patients, compared to patients with coronary artery disease and healthy subjects. In contrast to patients with coronary disease, however, platelet aggregability was reduced by exercise. This response was prevented by theophylline, strongly suggesting the involvement of adenosine.

Coronary artero-venous gradient of endogenous urokinase

Experimental data indicate that urokinase-type plasminogen activator (u-PA) contributes significantly to endogenous fibrinolysis and vascular remodeling in proportion to its local concentrations. In humans, however, it is not known whether u-PA levels vary at different sites and across specific vascular beds. We investigated possible regional and artero-venous differences in plasma u-PA concentrations in 15 patients undergoing cardiac catheterization. Three pairs of simultaneous samples were taken from: (1) the ascending aorta and coronary sinus; (2) left ventricle and right atrium; (3) femoral artery and femoral vein. Single-chain urokinase-type plasminogen activator (scu-PA) was measured by bioimmunoassay, and total u-PA antigen (including scu-Pa and two-chain urokinase-type plasminogen activator complexed with inhibitors (tcu-PA)) by enzyme-linked immunosorbent assay. Scu-PA represented, on average, 51+/-15% of total u-PA concentrations. Scu-PA and total u-PA levels were correlated (r=.72, P<.0001) and did not differ significantly among the arterial or venous locations. There was a small but consistent increase in mean (+/-standard deviation (S.D.)) scu-PA concentrations from all arterial to all venous samples (1.5+/-0.6 vs. 1.6+/-0.5 ng/ml, P=.038) and from ascending aorta to coronary sinus (1.6+/-0.5 vs. 1.7+/-0.6 ng/ml, P=.046). Similarly, total u-PA levels increased from femoral artery to femoral vein (2.9+/-0.7 vs. 3.0+/-0.8 ng/ml, P<.001). In contrast, across the lungs, no significant concentration-gradient was seen in either scu-PA or total u-PA. The changes in total u-PA roughly followed those of scu-PA. These data identify an artero-venous gradient in human plasma u-PA across the coronary and peripheral beds, but not across the lungs, suggesting differences in u-PA kinetics according to vascular location.

Autoantibodies against oxidized low density lipoproteins in patients with stable angina, unstable angina or peripheral vascular disease; pathophysiological implications

BACKGROUND

Antibody antioxidized low density lipoproteins (oxLDL) might play a role both in atherogenesis and in the pathogenesis of acute coronary syndromes.

METHODS AND RESULTS

Antibody titres to oxLDL and levels of C-reactive protein were compared in unstable angina, stable angina or peripheral artery disease. Antibody titres to LDL oxidated by CuSO(4)for 2, 4 and 18 h (Cu-oxLDL-Ab(2-4-18)) or by peroxidase (HRP-oxLDL-Ab) were assessed by ELISA. Cu-oxLDL-Ab(2-4-18)were consistently higher in peripheral artery disease than in unstable angina (P<0.001, P<0.001, P=0.01, respectively) or in stable angina (P<0.001, P=0.01, P=ns) but similar in unstable and stable angina. Accordingly, HRP-oxLDL-Ab were higher in peripheral artery disease than in unstable angina (P<0.001) or stable angina (P=0.04) but similar in unstable and stable angina. The number of arterial stenoses was higher in peripheral artery disease than unstable and stable angina (P<0.01). Cu-oxLDL-Ab and HRP-oxLDL-Ab correlated with the severity of atherosclerosis (P<0.01, R=0.4;P=0.02, R=0.3 respectively). Conversely, C-reactive protein levels were higher in unstable than in stable angina (P<0.001) or in peripheral artery disease (P<0.03) but similar in stable angina and peripheral artery disease and did not correlate with the severity of atherosclerosis.

CONCLUSION

The autoimmune response to oxLDL is likely to play an important role in atherogenesis but not in precipitating acute coronary syndromes.

Inflammatory left ventricular microaneurysms as a cause of apparently idiopathic ventricular tachyarrhythmias

BACKGROUND

We sought to investigate the arrhythmogenic role, incidence, treatment, and prognosis of inflammatory left ventricular (LV) microaneurysms in patients with apparently idiopathic ventricular tachyarrhythmias. Methods and Results-- We studied 156 consecutive patients (71 men, 85 women; mean age, 44.1+/-11.8 years) with severe ventricular arrhythmias and normal 2D echo cardiac parameters by coronary and ventricular angiography, biventricular endomyocardial biopsy, and electrophysiological study. Polymerase chain reaction was used to detect genomic sequences of enterovirus, adenovirus, Epstein Barr virus, cytomegalovirus, herpes simplex viruses, influenza A and B viruses, and hepatitis C virus in frozen endomyocardial samples. Of these patients, 15 (9.6%) showed angiographic evidence of single or multiple LV microaneurysms. All 15 patients had recurrent episodes of ventricular tachycardia with right bundle-branch block morphology, and the arrhythmias originated within or close to the aneurysms in those patients (n=6) undergoing ventricular mapping. A lymphocytic myocarditis was observed in LV biopsies of all patients and in the right ventricles of 3 patients. Polymerase chain reaction analysis was performed in 12 and viral genomes were found in 5 (42%): hepatitis C virus in 2, enterovirus in 2, and influenza virus A in 1. The patients were treated with antiarrhythmics, and cardiac function was preserved for the next 47+/-39.5 months of follow-up. No major clinical event was registered, and arrhythmias were successfully treated by antiarrhythmics.

CONCLUSIONS

Inflammatory LV microaneurysms, often of viral origin, are a consistent cause of apparently idiopathic ventricular arrhythmias. Their prognosis so far has been benign, and aggressive therapeutic strategies have been unnecessary.

The C807T/G873A polymorphism in the platelet glycoprotein Ia gene and the risk of acute coronary syndrome in the Italian population

Membrane glycoprotein (GP) Ia/IIa mediates platelet adhesion to collagen. The linked C807T/G873A polymorphisms in the GP Ia gene are correlated with a variable expression of the platelet surface receptor, the 807 TT/873 AA genotype being associated with a higher receptor density. Our study aimed to evaluate the possible role of the GP Ia C807T/G873A polymorphism as a risk factor for acute coronary syndrome in the Italian population. We investigated 157 patients with acute coronary syndrome (117 with myocardial infarction and 40 with severe unstable angina) as the first manifestation of coronary disease occurring before 65 years of age, compared with 312 healthy controls. All individuals were of Italian ancestry and were genotyped for the GP Ia C807T/G873A polymorphism. Complete linkage between the 807 and 873 sites was found in all samples. The 807 TT genotype was present in 12.7% of cases and in 4.8% of controls; the odds ratio for acute coronary syndrome was 2.9 (95% CI 1.4--5.8) for the 807 TT genotype compared with C-allele carriers and 0.6 (95% CI 0.4--0.9) for the 807 CC genotype compared with T-allele carriers. For the TT genotype, compared with CC homozygotes, the increase in risk was 3.4-fold in patients with at least one risk factor (smoking, hypercholesterolaemia, diabetes, systemic hypertension) and 4.1-fold in patients with angiographically diagnosed two- or three-vessel disease. We conclude that the GP Ia 807 TT (873 AA) genotype is associated with an increased risk of acute coronary syndrome in the Italian population; conversely, the GP Ia 807 CC (873 GG) genotype seems to represent a protective factor.

Markedly reduced insulin-like growth factor-1 in the acute phase of myocardial infarction

OBJECTIVES

We investigated whether insulin-like growth factor-1 (IGF-1) is reduced in the early phase of acute myocardial infarction (AMI) and whether such a decrease might influence prognosis.

BACKGROUND

Insulin-like growth factor-1 protects against insulin resistance and apoptosis. Although insulin resistance has been reported in AMI, IGF-1 levels have not been investigated.

METHODS

We measured serum IGF-1 in 23 patients with AMI within 24 h of symptom onset and in 11 matched controls. In the first 12 patients and controls, we also measured fasting insulin, diurnal growth hormone (GH) and insulin sensitivity (assessed as glucose disappearance or T/2 after an insulin bolus), and repeated IGF-1, insulin and GH after one year. In all patients, 90-day cardiovascular death, recurrent ischemia, reinfarction, revascularization and late malignant arrhythmias were assessed.

RESULTS

The AMI patients versus controls showed markedly reduced IGF-1 (115 +/- 112 vs. 615 +/- 300 ng/ml, p < 0.0001) and slower T/2 (-0.98 +/- 1.5 vs. -2.57 +/- 1.0 mg/dl/min, p = 0.01). Low IGF-1 often preceded the rise of myocardial necrosis markers. Patients with 90-day events (n = 12) versus those without had lower IGF-1 (47 +/- 54 vs. 189 +/- 110 ng/ml, p < 0.0001). Acute phase GH and insulin concentrations did not differ significantly from controls. After one year, the patients' IGF-1 values had risen to 460 +/- 242 ng/ml (p = 0.1 vs. controls, p < 0.0005 vs. acute phase), whereas GH levels were lower (0.2 +/- 0.2 vs. 2.5 +/- 2.3 ng/ml, p = 0.01) and insulin levels higher (12.5 +/- 0.2 vs. 3.9 +/- 2.6 microU/ml, p < 0.0001) compared with controls.

CONCLUSIONS

In the early phase of AMI, serum IGF-1 levels are markedly reduced and may contribute to adverse outcomes. Reduced IGF-1 preceding the rise of myocardial necrosis markers suggests a possible pathogenetic role. A compensatory increase in IGF-1 appears to occur by one year.

Enhanced response of blood monocytes to in vitro lipopolysaccharide-challenge in patients with recurrent unstable angina

BACKGROUND

C-reactive protein (CRP) plasma levels have been associated with short- and long-term occurrence of coronary events. We investigated whether circulating inflammatory cell responsiveness to low-grade stimuli could contribute to the reported association between CRP and coronary events.

METHODS AND RESULTS

We studied 32 patients with unstable angina who were followed for 24 months and were free of symptoms for 6 months (group 1): 19 patients had persistently high CRP levels (>0.3 mg/dL) (group 1A); 13 patients had normal CRP levels (group 1B). During the follow-up, 12 (63%) group 1A but no group 1B patients developed an infarction or recurrence of unstable angina (P<0.001). Eighteen patients with chronic stable angina (group 2) and 18 healthy subjects (group 3) were studied as controls. Interleukin (IL)-6 production (median, range) by peripheral blood mononuclear cells after 4 hours of in vitro stimulation with 1 ng/mL lipopolysaccharide (LPS) was significantly higher in group 1A (4526 pg/mL, 3042 to 10 583 pg/mL) than in group 1B (1752 pg/mL, 75 to 3981 pg/mL), group 2 (707 pg/mL, 41 to 3275 pg/mL), and group 3 (488 pg/mL, 92 to 3503 pg/mL) (all P<0.001). No significant differences were observed among the other groups. IL-6 production after LPS-challenge was correlated with baseline CRP levels (r=0.42, P=0.005).

CONCLUSIONS

Mononuclear cells of patients with recurrent phases of instability exhibit an enhanced production of IL-6 in response to low-dose of LPS, correlated with baseline CRP levels, 6 months after the last acute event. This persisting enhanced acute-phase responsiveness may help explain the association between CRP and acute coronary events.

Dipyridamole-induced increased glucose uptake in patients with single-vessel coronary artery disease assessed with PET

BACKGROUND

The aim of this study was to determine the relationship between vasodilatation-induced ischemia and poststress glucose uptake. Coronary vasodilators may induce myocardial ischemia due to coronary steal through collateral circulation or transmural blood flow redistribution with diminished subendocardial perfusion. Myocardial ischemia can be demonstrated by increased glucose uptake as previously shown in patients with exercise-induced ischemia.

METHODS AND RESULTS

We studied 11 patients with single-vessel disease and no history of myocardial infarction. Five patients had no collateral circulation, and 6 had angiographic evidence of collateral vessels. We measured myocardial blood flow (MBF) and glucose uptake at baseline and after the administration of dipyridamole (0.56 mg/kg) with positron emission tomography, using O-15 water and fluorine 18 deoxyglucose (FDG) as perfusion and glucose tracers. MBF at baseline was 0.82 +/- 0.13 mL/g/min in normal areas and 0.80 +/- 0.15 mL/g/min in areas supplied by stenotic arteries. MBF during dipyridamole was 2.05 +/- 0.66 and 1.19 +/- 0.66 mL/g/min in normal areas and areas with stenotic arteries, respectively (P < or = .001). FDG uptake at baseline was 1.36 +/- 0.55 in normal areas and 1.57 +/- 0.62 in areas supplied by stenotic arteries. FDG uptake after dipyridamole infusion was 1.79 +/- 1.1 and 4.04 +/- 0.84 in normal areas and areas with stenotic arteries, respectively (P < or =.001). MBF and FDG uptake were not different between patients with collateral circulation and those without collateral circulation.

CONCLUSIONS

Increased myocardial glucose uptake was consistently observed after dipyridamole administration in those areas with diminished coronary vasodilatory capacity. The similar MBF and FDG findings in patients with and without collateral circulation may indicate that transmural blood flow redistribution appears to be a possible mechanism of dipyridamole-induced myocardial ischemia.

[Cellular mechanisms of regulation of the inflammatory response in atherosclerosis: the role of cell contact-mediated signaling]

The regulatory mechanisms of the inflammatory process in the atherosclerotic plaque are still not clearly understood. Stimulated T cells may have a key role in enhancing and perpetuating inflammation at the atherosclerotic site. They activate endothelial cells, macrophages and smooth muscle cells in the atherosclerotic plaque, not only via the production of soluble mediators, but also through cell-cell contact-mediated interactions (via membrane receptors and their ligands). Cell/cell contact between stimulated T lymphocytes and monocytes/macrophages and endothelial cells induces the production of pro-inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6) and chemokines (interleukin-8, monocyte chemotactic factor-1). Thus, these interactions could play a relevant role in the disregulation of the inflammatory process in the atherosclerotic plaque, representing a novel mechanism of progression and complication of the atherosclerotic disease. Understanding the key ligands and receptors involved may permit the definition of new therapeutic targets.

Low-grade exercise enhances platelet aggregability in patients with obstructive coronary disease independently of myocardial ischemia

Moderate and strenuous exercise is known to enhance platelet aggregability in patients with obstructive coronary artery disease (CAD), but the effect of low-grade exercise is not known. We assessed shear-induced platelet aggregability before and after mild exercise (less than or equal to stage III of the modified Bruce protocol) in 27 patients with documented CAD who were receiving aspirin and in 12 subjects without CAD (controls). Ex vivo platelet aggregability was assessed in flowing whole blood as the time to occlude a collagen and adenosine diphosphate-coated ring; shorter times indicated greater aggregability. Aggregability, plasma von Willebrand factor (vWF) antigen, platelet and white cell counts, and hematocrit were measured at baseline, immediately after exercise (peak), and at 30 and 180 minutes after exercise. Exercise of similar workloads induced myocardial ischemia in 14 patients (group 1), but not in the other 13 (group 2) nor in controls. Both patient groups showed a reduction in aggregation time at peak exercise compared with baseline (group 1: 84+/-17 seconds at peak vs 96+/-22 seconds at baseline; group 2: 84+/-20 seconds at peak vs 99+/-20 seconds at baseline; p <0.03 for both comparisons), with a return to baseline values within 180 minutes. No significant variation occurred in controls (89+/-18 seconds at peak vs 85+/-21 second at baseline). Changes in vWF antigen did not differ significantly among groups. Aggregation times did not correlate with hematocrit or platelet and white cell counts. Thus, even low-grade exercise transiently enhances whole blood platelet aggregability in patients with obstructive CAD, but not in controls. The effect is independent of myocardial ischemia, occurs despite aspirin, and is likely dependent on hemodynamic factors interacting with coronary obstructions or dysfunctional endothelium.

Spinal cord stimulation in patients with refractory anginal pain and normal coronary arteries

BACKGROUND

Spinal cord stimulation (SCS) has been shown to be effective in patients with refractory angina and coronary artery disease. No previous study assessed the clinical effects of SCS in patients with refractory angina who present angiographically normal coronary arteries.

METHODS

SCS was performed in 7 patients (4 men, 3 women, mean age 59.3 +/- 11 years) with refractory angina and normal coronary arteries. Clinical status was assessed 1 month after SCS device implantation and at a mean follow-up of 11 months (range 2-17 months) by: 1) an estimate of the number of anginal attacks and nitrate consumption in the 2 weeks prior to implantation and to follow-up visits; 2) a score of quality of life by a visual analogic scale; 3) a five-item questionnaire assessing effort angina and satisfaction with treatment; 4) treadmill exercise testing.

RESULTS

At the last follow-up the number of anginal episodes (p < 0.001) and nitrate consumption (p < 0.004) were both reduced by SCS. Visual analogic scale score improved from 2.1 +/- 0.98 to 9.0 +/- 0.9 (p < 0.001) at 1 month and to 6.4 +/- 2.3 (p < 0.01) at the last follow-up. Questionnaire analysis showed that mild (p = 0.006) and moderate (p = 0.000) physical activity, as well as patient satisfaction with anginal status (p = 0.000) and with current treatment (p = 0.000) all improved by SCS. Finally, time to 1 mm ST segment depression, time to angina, and exercise duration were all prolonged by SCS.

CONCLUSIONS

Our data point out that SCS may considerably improve anginal symptoms and exercise tolerance in a significant number of patients with refractory angina and normal coronary arteries and therefore it should be considered as a valuable treatment option in this group of patients.

Myocardial cell death in human diabetes

The renin-angiotensin system is upregulated with diabetes, and this may contribute to the development of a dilated myopathy. Angiotensin II (Ang II) locally may lead to oxidative damage, activating cardiac cell death. Moreover, diabetes and hypertension could synergistically impair myocardial structure and function. Therefore, apoptosis and necrosis were measured in ventricular myocardial biopsies obtained from diabetic and diabetic-hypertensive patients. Accumulation of a marker of oxidative stress, nitrotyrosine, and Ang II labeling were evaluated quantitatively. The diabetic heart showed cardiac hypertrophy, cavitary dilation, and depressed ventricular performance. These alterations were more severe with diabetes and hypertension. Diabetes was characterized by an 85-fold, 61-fold, and 26-fold increase in apoptosis of myocytes, endothelial cells, and fibroblasts, respectively. Apoptosis in cardiac cells did not increase additionally with diabetes and hypertension. Diabetes increased necrosis by 4-fold in myocytes, 9-fold in endothelial cells, and 6-fold in fibroblasts. However, diabetes and hypertension increased necrosis by 7-fold in myocytes and 18-fold in endothelial cells. Similarly, Ang II labeling in myocytes and endothelial cells increased more with diabetes and hypertension than with diabetes alone. Nitrotyrosine localization in cardiac cells followed a comparable pattern. In spite of the difference in the number of nitrotyrosine-positive cells with diabetes and with diabetes and hypertension, apoptosis and necrosis of myocytes, endothelial cells, and fibroblasts were detected only in cells containing this modified amino acid. In conclusion, local increases in Ang II with diabetes and with diabetes and hypertension may enhance oxidative damage, activating cardiac cell apoptosis and necrosis.

Myocardial ischemia-reperfusion damage after pacing-induced tachycardia in patients with cardiac syndrome X

The presence of myocardial ischemia in syndrome X (chest pain, "ischemia-like" electrocardiogram changes, and normal coronary angiograms) is uncertain possibly because, when focally distributed, it may not cause contractile dysfunction or lactate production. We measured lipid hydroperoxides (ROOHs) and conjugated dienes (CDs), two sensitive, independent markers of ischemia-reperfusion oxidative stress, in paired aortic and great cardiac vein blood samples before and after pacing-induced tachycardia in nine patients with syndrome X. Diagnostic ischemic S-T segment changes during pacing were followed by a consistent increase in ROOH and CD levels in the great cardiac vein (from 4.83 +/- 1.18 micromol/l at baseline to 7.88 +/- 1.12 micromol/l and from 0.038 +/- 0.002 to 0.051 +/- 0.003 arbitrary units, respectively, P < 0.01). In controls, ROOH and CD levels did not change after pacing. The large postpacing cardiac release of lipid peroxidation products, consistently observed in all patients and similar to that previously observed after ischemia caused by percutaneous transluminal coronary angioplasty, is consistent with an ischemic origin of syndrome X.

Evidence for antigen-driven T-cell response in unstable angina

BACKGROUND

Activation of T cells and macrophages has been associated with unstable angina (UA), but whether this reflects specific immune responses remains unclear.

METHODS AND RESULTS

We analyzed the repertoire and the length of complementarity-determining region 3 of the T-cell receptor (TCR) beta-chain variable (BV) gene segments of activated lymphocytes in 23 patients with UA, 13 patients with chronic stable angina (CSA), and 6 normal control subjects. We also tested the proliferation of systemic T cells in response to autologous coronary plaque proteins, oxidized LDL, and Chlamydia pneumoniae as candidate antigens, in vitro. The activated T cell-TCRBV repertoire was perturbed in 13 (57%) of 23 UA patients versus 3 (23%) of 13 CSA patients (P=0.016) and was restricted to 6 (28%) of 21 expanded TCRBV families; all were significantly higher in UA than in CSA patients. At least one monotypic or oligotypic activated TCRBV population was found in 15 (65%) of 23 UA patients and in 3 (23%) of 13 CSA patients (P<0.001). Finally, T cells from UA patients, but not from CSA patients or normal control subjects, proliferated in response to autologous proteins from coronary culprit lesions and/or to oxidized LDL.

CONCLUSIONS

Our findings suggest that the T-cell response observed in UA patients is antigen-driven and directed to antigens contained in the culprit coronary atherosclerotic plaques.

Major racial differences in coronary constrictor response between japanese and caucasians with recent myocardial infarction

BACKGROUND

Enhanced coronary vasomotion may contribute to acute coronary occlusion during the acute phase of myocardial infarction (AMI). Japanese have a higher incidence of variant angina than Caucasian patients, but racial differences in vasomotor reactivity early after AMI are controversial.

METHODS AND RESULTS

The same team studied 15 Japanese and 19 Caucasian patients within 14 days of AMI by acetylcholine injection into non-infarct-related (NIRA) and infarct-related (IRA) coronary arteries followed by nitroglycerin. Incidence of vasodilation, vasoconstriction, spasm, and basal tone were assessed in proximal, middle, and distal segments after each drug bolus by quantitative angiography. Japanese patients had much lower cholesterol levels than Caucasians (183+/-59 versus 247+/-53 mg/dL, P<0.006) but showed a lower incidence of vasodilation (2% versus 9% of coronary segments) and a greater incidence of spasm after acetylcholine (47% versus 15% of arteries, P<0.00001). Incidence of spasm was higher in IRAs than in NIRAs in both populations (67% versus 39% and 23% versus 11%, respectively). Multivessel spasm was more common (64% versus 17%, P<0.02) and vasoconstriction of nonspastic segments was greater in Japanese patients (-23.4+/-14.9% versus -20.1+/-15.7%, P<0.02) in the presence of similar average basal coronary tone with respect to post-nitroglycerin dilation and of nonsignificant differences of coronary atherosclerotic score.

CONCLUSIONS

Soon after AMI, Japanese patients exhibited a 3-fold-greater incidence of spasm and greater vasoconstriction of nonspastic segments after acetylcholine than Caucasians. The causes of such differences warrant further investigation because they may have relevant pathophysiological and therapeutic implications.

Large, sustained cardiac lipid peroxidation and reduced antioxidant capacity in the coronary circulation after brief episodes of myocardial ischemia

OBJECTIVES

We sought to investigate whether a brief episode of myocardial ischemia produces a detectable cardiac oxidative stress in patients undergoing elective coronary angioplasty (PTCA).

BACKGROUND

Although cardiac oxidative stress has been clearly demonstrated in experimental models of ischemia-reperfusion, its presence in patients after transient myocardial ischemia is still unclear.

METHODS

In order to evaluate oxidative stress in ischemic cardiac regions, plasma conjugated dienes (CD), lipid hydroperoxides (ROOHs) and total antioxidant capacity (TRAP), independent indexes of oxidative stress, were measured in the aorta and great cardiac vein (GCV) before (t0), 1, (t1), 5 (t5) and 15 min (t15) after first balloon inflation in 15 patients undergoing PTCA on left anterior descending coronary artery (Group 1); six patients with right coronary artery stenosis (Group 2), which is not drained by the GCV, were studied as controls.

RESULTS

In Group 1 at baseline, CD and ROOHs levels were higher in GCV than in aorta (p < 0.01 for both), and TRAP levels were lower (p < 0.01). Aortic levels of CD, ROOHs and TRAP did not change at any time after to; venous levels of CD and ROOHs levels markedly increased at t1, at t5 and remained elevated at t15 (p < 0.01 for all comparisons vs. to); venous levels of TRAP decreased at t1 and t5 (p < 0.01 vs. t0) and returned to normal at t15. In Group 2, CD, ROOHs and TRAP levels were similar in the aorta and GCV and did not change throughout the study.

CONCLUSIONS

Short episodes of myocardial ischemia during PTCA induce a sustained oxidative stress, which is detectable in the venous effluent of reperfused myocardium.

Inflammation and acute coronary syndromes

The presence of inflammatory infiltrates in unstable coronary plaques suggests that inflammatory processes may contribute to the pathogenesis of these syndromes. In patients with unstable angina, coronary atherosclerotic plaques are characterized by the presence of macrophages, and to a lesser extent, T-lymphocytes, at the immediate site of either plaque rupture or superficial erosion; moreover, the rupture-related inflammatory cells are activated, indicating ongoing inflammation at the site of plaque disruption. These observations are confirmed by clinical studies demonstrating activated circulating neutrophils, lymphocytes and monocytes, and increased concentrations of pro-inflammatory cytokines, such as interleukin (IL) 1 and 6, and of acute phase reactants in patients with unstable angina and myocardial infarction. In particular elevated levels of C-reactive protein are associated with an increased risk of in-hospital and 1 to 2 years new coronary events in patients with unstable angina, but are also associated with an increased long-term risk of death and myocardial infarction in apparently normal subjects. Thus, accumulating evidence suggests that inflammation may cause local endothelial activation and, possibly, plaque fissure, leading to unstable angina and infarction. Although no information is yet available on the causes of inflammation and on its localization, these novel lines of research may open the way to a different approach to the patient with acute coronary syndromes.

Coronary Artery Spasm

Attacks of variant angina usually respond promptly to sublingual administration of short-acting nitrates (nitroglycerin, 0.3 to 0.4 mg, or isosorbide dinitrate, 5 to 10 mg), which may be repeated after 3 to 5 minutes if pain persists. In the rare cases resistant to sublingual nitrates, sublingual nifedipine (5 to 10 mg) or, when readily available, intravenous nitrates (nitroglycerin or isosorbide dinitrate, 2 to 10 mg) or calcium antagonists (verapamil, 5 to 10 mg, or diltiazem, 0.15 mg/kg) can be given. All attempts to prevent ischemic attacks by means of specific receptor blockade in patients with vasospastic angina have been unsatisfactory. This may be either because the doses of the blockers used were insufficient or, more likely, because the blockade of a single receptor-agonist interaction leaves receptors for other vasoconstrictor stimuli unopposed and therefore capable of eliciting spasm. Thus, for instance, alpha-adrenergic, serotoninergic, and thromboxane A(2) antagonists all failed to reduce significantly the number of anginal attacks, although they appeared to be effective in some patients. Until the actual causes of the coronary smooth muscle hyperreactivity to constrictor stimuli are known, treatment of vasospastic angina is based on the use of nonspecific vasodilators. Indeed, the mainstay of pharmacologic treatment of coronary artery spasm is calcium channel blocking agents together with nitrates to cover the periods in which spasm is most likely to occur. These powerful vasodilating agents, at their usual doses, are able immediately and completely to control the recurrences of ischemic attacks in as many as 80% of patients. Moreover, some studies have shown that use of calcium antagonists significantly improves clinical outcome in patients with variant angina.

Oxidative stress in ischemia-reperfusion injury: assessment by three independent biochemical markers

BACKGROUND

Oxidative stress plays a key role in ischemia-reperfusion injury, causing peroxidation of tissue lipids and proteins. However, it is debated whether brief ischemic episodes are sufficient to cause detectable oxidative stress in humans, since biochemical markers used so far in the setting of percutaneous transluminal coronary angioplasty (PTCA) gave conflicting results.

METHODS

We determined lipid hydroperoxides (ROOHs), conjugated dienes (CD) and total radical-trapping antioxidant capacity (TRAP), three different independent markers of oxidative stress, in aortic and great cardiac vein blood of 5 patients undergoing PTCA before a single balloon inflation lasting 115 +/- 38 s (t0), and 1 min (t1), 5 min (t5), 15 min (t15) after balloon deflation (Group 1). ROOHs and CD were also determined in aortic and great cardiac vein blood of 5 patients with mitral valve disease (Group 2).

RESULTS

In Group 1, great cardiac vein levels of ROOHs and CD at t1 increased by 219% and 79%, respectively, compared to t0 (p < 0.01); this sharp and consistent increase persisted up to t15 (+189% and +63%, respectively, compared to t0; p < 0.01). Great cardiac vein levels of TRAP were significantly lower than aortic levels at t0, and exhibited a further decrease at tl. No significant differences in aortic and great cardiac vein levels of ROOHs and CD at t0 were observed between Group 1 and Group 2.

CONCLUSIONS

The three methods we used showed a remarkable sensitivity for the detection of post-ischemic reperfusion injury in cardiac venous blood and may be useful for detecting small foci of ischemia-reperfusion injury in microvascular angina.

Different Effects of Lipopolysaccharide on Plasminogen Activator Inhibitor-1 Production in Aortic Media in Vivo and in Culture

Background: Lipopolysaccharide (endotoxin) has been shown to increase the expression of plasminogen activator inhibitor type-1 (PAI-1) in the vessel wall. Endotoxin is known to increase PAI-1 production in endothelial cells, but its action on smooth muscle cells (SMCs) is presently not clear. In this study we determined the effect of endotoxin on PAI-1 and tissue plasminogen activator (t-PA) production by aortic SMCs in vivo in two animal species, and in culture. Methods: The aortas of Sprague Dawley rats and of New Zealand White rabbits were rapidly excised after parenteral administration of endotoxin. Total RNA was extracted from the aortic media, and PAI-1 and t-PA mRNA levels were quantified after Northern blotting. In addition, cultured rat aortic SMCs were treated with endotoxin. PAI activity in the conditioned medium was determined with a spectrophotometric assay, and total RNA was extracted from the cells and analyzed. Results: A rapid and strong induction in the aortic medi a of PAI-1 mRNA was observed by endotoxin in both rat (50 mg/kg) and rabbit (1 mg/kg). t-PA mRNA was barely detectable and was not increased by endotoxin. Studies in cultured SMCs showed low expression of PAI-1 mRNA under serum-free conditions and little PAI activity in the cell-conditioned medium. Endotoxin did not increase the levels of PAI-1 mRNA nor PAI activity under serum-free conditions. The effect of endotoxin (10 mg/ml) in the presence of 10% (v/v) newborn calf serum on PAI-1 mRNA was negligible; PAI activity, however, increased by 50.3 +/- 7.3% compared with controls. mRNA levels of t-PA and low-density lipoprotein/receptor-related protein/alpha2-macroglobulin receptor also increased after endotoxin administration. PAI activity was identified as PAI-1 by immunoblotting. Fibrin zymography showed that t-PA was present only in complex with PAI-1. Conclusions: A strong increase in PAI-1 gene expression by endotoxin was observed in aortic SMCs in vivo but not in culture. Th is suggests that the effect of endotoxin on SMCs is indirect. The fibrinolytic/proteolytic potential of the SMCs in the vessel wall is likely to have important implications for the migration of cells during vessel wall remodeling, such as neointima formation, during tumor cell metastasis, and for the fate of intramural thrombi.

Circadianicity of hemostatic function and coronary vasomotion

Acute myocardial infarction, sudden cardiac death and ischemic stroke show a circadian periodicity, occurring more frequently in the morning. Because arterial thrombosis is common to these disorders, a circadianicity of prothrombotic and antithrombotic processes may contribute to explain the 24 h rhythms of these acute events. Available data indeed indicate that coronary vasomotor tone, platelet aggregability, plasma inhibition of fibrinolysis, coagulant activity and blood viscosity are all greater in the morning than at other times of day, producting a relative prothrombotic state in the early morning.

Acute coronary syndromes in women: pathophysiology and therapeutic options

Patients presenting with acute coronary syndromes disclose a number of gender-related differences. Women are more likely than men to have unstable angina and less likely to present with myocardial infarction. Women have a better prognosis than men among patients with unstable angina. Among patients with myocardial infarction without ST-segment elevation, men and women show similar outcomes. In contrast, among patients with myocardial infarction and ST-segment elevation, women consistently show a worse prognosis than men. This difference is not fully explained by age, comorbidities, extent of epicardial artery disease, or baseline left ventricular function, and may reflect gender differences in pathophysiological, functional and anatomical variables. Moreover, revascularization procedures and several anti-ischemic drugs appear underutilized in women.

Perturbation of the T-cell repertoire in patients with unstable angina

BACKGROUND

Monocytes are constitutively activated in unstable angina (UA), resulting in the production of IL-6 and the upregulation of acute phase proteins. Underlying mechanisms are not understood. To explore whether the production of the potent monocyte activator IFN-gamma is altered in UA, we compared cytokine production by T lymphocytes in patients with UA (Braunwald's class IIIB) and with stable angina (SA).

METHODS AND RESULTS

Peripheral blood lymphocytes were collected at the time of hospitalization and after 2 and 12 weeks. Cytokine-producing CD4(+) and CD8(+) T cells were quantified by 3-color flow cytometry after stimulation with phorbol myristate acetate and ionomycin. UA was associated with an increased number of CD4(+) and CD8(+) T cells producing IFN-gamma, whereas patients with SA had higher frequencies of IL-2(+) and IL-4(+) CD4(+) T cells. Expansion of the IFN-gamma( +) T-cell population in UA persisted for at least 3 months. Increased production of IFN-gamma in UA could be attributed to the expansion of an unusual subset of T cells, CD4(+)CD28(null) T cells.

CONCLUSIONS

Patients with UA are characterized by a perturbation of the functional T-cell repertoire with a bias toward IFN-gamma production, suggesting that monocyte activation and acute phase responses are consequences of T-cell activation. IFN-gamma is produced by CD4(+)CD28(null) T cells, which are expanded in UA and distinctly low in SA and controls. The emergence of CD4(+)CD28(null) T cells may result from persistent antigenic stimulation.

Effects of atrial pacing on arterial and coronary sinus endothelin-1 levels in syndrome X

Syndrome X may be caused by a coronary microvascular dysfunction, possibly due to abnormalities in coronary endothelial function. Previous studies suggested that endothelin-1 (ET-1) might be involved in the pathogenesis of syndrome X. Baseline arterial and coronary sinus ET-1 levels were measured in 13 patients with syndrome X (10 women, 52+/-7 years) and in 8 control patients (5 women, 46+/-11 years). ET-1 was also measured after atrial pacing in 12 patients with syndrome X and all controls. To simultaneously assess the activity of nitric oxide, guanosine 3'-5'-cyclic monophosphate (cGMP) was also measured in 11 patients with syndrome X and 7 controls. Baseline arterial (2.27+/-0.46 vs. 1.90+/-0.22 pg/ml, p<0.05) and coronary sinus (2.03+/-0.43 vs. 1.68+/-0.28 pg/ml, p = 0.06) ET-1 plasma levels were higher in patients than in controls. After pacing, arterial ET-1 levels did not change in either group and coronary sinus ET-1 levels were also unchanged in controls. In contrast, coronary sinus ET-increased significantly in response to atrial pacing in patients with syndrome X (p = 0.023), and differences between coronary sinus ET-1 levels of patients with syndrome X and controls after pacing became highly significant (2.22+/-0.45 vs. 1.69+/-0.20 pg/ml, respectively, p = 0.006). No significant differences in arterial and coronary sinus cGMP concentrations were found between the 2 groups, both at baseline and after pacing. Our findings suggest that an increased vasoconstrictor activity of microvascular endothelium is present in at least some patients with syndrome X and may be involved in the pathogenesis of the syndrome.

Enhanced inflammatory response in patients with preinfarction unstable angina

OBJECTIVES

We assessed the extent and the time course of the acute phase response following myocardial cell necrosis and its relationship with the presence of preinfarction unstable angina (UA).

BACKGROUND

Elevated levels of acute phase proteins have been reported in patients with UA and in patients with acute myocardial infarction (MI).

METHODS

C-Reactive Protein (CRP), serum amyloid A protein (SAA) and interleukin-6 (IL-6) were measured in 36 patients with MI admitted within 3 h from symptoms onset. All patients had normal levels of creatine kinase and of troponin T on admission, rising above diagnostic levels within 6 to 12 h. Blood samples for CRP, SAA and IL-6 measurements were taken on admission, at 6, 24, 48, 72 h and at discharge.

RESULTS

Twenty of the 36 patients studied presented an unheralded MI (Group 1); the remaining 16 patients had symptoms of unstable angina in the preceding 7 days (Group 2). Group 2 patients have much higher levels of CRP and SAA on admission (median values 8.8 vs. 3 mg/L and 28 vs. 3.4 mg/L, respectively, all p<0.001). Following the necrotic insult, despite similar infarct size and clinical signs of reperfusion, Group 2 patients had strikingly higher peaks of IL-6 (median values 85.2 vs. 19 pg/ml, p<0.05), CRP (50 vs. 31.4 mg/L, p<0.05) and SAA (228 vs. 45 mg/L, p<0.001).

CONCLUSIONS

Our data demonstrated that the acute phase response is greatly enhanced in patients with preinfarction UA compared with those presenting with an unheralded MI. The significant differences in acute phase response observed in these two clinical presentations of MI indicate a major difference in their underlying pathogenetic components.