Determinants of collateral development in patients with acute myocardial infarction

Study of blood rheological parameters and NO in coronary artery disease patients with and without collaterals

BACKGROUND

In coronary artery disease (CAD), an alternative way of improvement of blood circulation in the ischemic area of the myocardium is coronary collateral circulation. Our study aimed to investigate the rheological parameters of blood and nitric oxide (NO) content in patients with various degrees of collateral development and the likelihood of the influence of blood fluidity on collateral angiogenesis.

METHODS

We studied patients with stable CAD who underwent elective coronary angiography and a control group with the same mean age. We investigated patients with different degrees of developing collaterals and those without them. In studied patients, the blood plasma viscosity, aggregability, and deformability of erythrocytes, as the main indicators of blood rheology. We recorded content of stable metabolic end products of nitric oxide (NOx).

RESULTS

Results of the studies showed that in the blood of studied patients with CAD erythrocyte aggregation was increased and NO content decreased compared to the control level; NO content was as lower, as less was the number of developed collaterals was recorded.

CONCLUSION

In this work, the role of the aggregation ability of erythrocytes and the endothelial origin of NO in the direct and feedback regulatory mechanism of angiogenesis in patients with CAD are discussed.

Opportunities and challenges of pain-related myocardial ischemia-reperfusion injury

Pain is one of the most serious problems plaguing human health today. Pain is not an independent pathophysiological condition and is associated with a high impact on elevated disability and organ dysfunction. Several lines of evidence suggested the associations of pain with cardiovascular diseases, especially myocardial ischemia-reperfusion (I/R) injury, while the role of pain in I/R injury and related mechanisms are not yet comprehensively assessed. In this review, we attempted to explore the role of pain in myocardial I/R injury, and we concluded that acute pain protects myocardial ischemia-reperfusion injury and chronic pain aggravates cardiac ischemia-reperfusion injury. In addition, the construction of different pain models and animal models commonly used to study the role of pain in myocardial I/R injury were discussed in detail, and the potential mechanism of pain-related myocardial I/R injury was summarized. Finally, the future research direction was prospected. That is, the remote regulation of pain to cardiac function requires peripheral pain signals to be transmitted from the peripheral to the cardiac autonomic nervous system, which then affects autonomic innervation during cardiac ischemia-reperfusion injury and finally affects the cardiac function.

Collateral Development in Patients Undergoing Coronary Angiography in a Tertiary Care Centre: A Descriptive Cross-sectional Study

Introduction

Coronary artery disease is one of the major cardiovascular diseases affecting the global human population. When the primary stenotic or blocked channel fails to deliver enough blood to the myocardium, the coronary collateral circulation serves as a backup source of blood supply. The aim of this study was to find out the prevalence of collateral development in patients undergoing coronary angiography in a tertiary care centre.

Methods

This descriptive cross-sectional study was conducted among patients with peripheral vascular injuries that underwent operative management in a tertiary care centre from November 2021 to April 2022. Ethical approval was taken from the Institutional Review Committee (Registration number: CMC-IRC/078/079-027). Convenience sampling technique was used. Data for the study was retrieved from operation records of the patients along with their treatment summaries. Point estimate and 95% Confidence Interval were calculated.

Results

Among 170 patients undergoing coronary angiography, 84 (49.41%) (41.6-56.6, 95% Confidence Interval) had developed collateral circulation. The mean age was 62.8±11.7 years.

Conclusions

The prevalence of collateral development in the coronary artery was similar to other published literature.

Keywords

angiography; artery; blood circulation; prevalence.

The impact of myocardial compressibility on organ-level simulations of the normal and infarcted heart

Myocardial infarction (MI) rapidly impairs cardiac contractile function and instigates maladaptive remodeling leading to heart failure. Patient-specific models are a maturing technology for developing and determining therapeutic modalities for MI that require accurate descriptions of myocardial mechanics. While substantial tissue volume reductions of 15-20% during systole have been reported, myocardium is commonly modeled as incompressible. We developed a myocardial model to simulate experimentally-observed systolic volume reductions in an ovine model of MI. Sheep-specific simulations of the cardiac cycle were performed using both incompressible and compressible tissue material models, and with synchronous or measurement-guided contraction. The compressible tissue model with measurement-guided contraction gave best agreement with experimentally measured reductions in tissue volume at peak systole, ventricular kinematics, and wall thickness changes. The incompressible model predicted myofiber peak contractile stresses approximately double the compressible model (182.8 kPa, 107.4 kPa respectively). Compensatory changes in remaining normal myocardium with MI present required less increase of contractile stress in the compressible model than the incompressible model (32.1%, 53.5%, respectively). The compressible model therefore provided more accurate representation of ventricular kinematics and potentially more realistic computed active contraction levels in the simulated infarcted heart. Our findings suggest that myocardial compressibility should be incorporated into future cardiac models for improved accuracy.

Association between Hemogram Parameters and Coronary Collateral Development in Subjects with Non-ST-Elevation Myocardial Infarction

OBJECTIVE

Coronary collateral development (CCD) predicts the severity of coronary heart disease. Hemogram parameters, such as mean platelet volume (MPV), eosinophil, red cell distribution width, and platelet distribution width (PDW), are supposed novel inflammatory markers. We aimed to compare hemogram parameter values in patients presenting with non-ST-elevation myocardial infarction (NSTEMI) with adequate or inadequate CCD.

METHODS

A total of 177 patients with NSTEMI undergoing coronary arteriography were enrolled and divided into two groups based on the development of CCD: one group with adequate CCD (n=88) and the other with impaired CCD (n=89).

RESULTS

Baseline demographics and clinical risk factors were similar between the groups. Hemogram parameters were not significantly different between the two groups. However, compared to the inadequate CCD group, the median PDW was significantly higher in the adequate CCD group, 17.6 (1.4) vs. 17.8 (1.6) p=0.004. In a multivariate analysis, PDW (p=0.001, 95% CI for OR: 0.489(0,319-0,750) was found to be significantly different in the adequate CCD group compared to the inadequate CCD group. Pearson's correlation analysis revealed that PDW was significantly correlated with the Rentrop score (r=0.26, p<0.001).

CONCLUSIONS

We suggest that since PDW is an index that is inexpensive and easy to assess, it could serve as a marker of CCD in patients with NSTEMI.

Effect of Recruitment of Acute Coronary Collaterals on In-Hospital Mortality and on Left Ventricular Function in Patients Presenting With ST Elevation Myocardial Infarction

Recruitment of the coronary collateral circulation is frequently observed during ST elevation myocardial infarction (STEMI) and is of uncertain significance. The aim of this study was to identify and determine the predictors and prognostic implications of the presence of robust collaterals during STEMI. All patients presenting to a large tertiary centre with a STEMI undergoing percutaneous coronary intervention from 2010 to 2018 were reviewed. Patients with poor collateral recruitment were defined as those with Rentrop grade 0 or 1 collaterals, whilst patients with robust collateral recruitment were defined as Rentrop grade 2 or 3. A total of 1,625 patients were included in the study, with 1,280 (78.8%) patients having poor collateral recruitment and 345 patients (21.2%) having robust collateral recruitment. Patients with robust collaterals were younger (63.1 vs 65.1 years, p < 0.05), had a longer ischemic time (628.5 minutes vs 433.1 minutes, p < 0.0001), and more likely to have a chronic total occlusion of a noninfarct related artery (10.4% vs 5.3%, p < 0.001). The presence of robust collaterals was associated with higher rates of normal or mildly impaired left ventricular function (83.5% vs 63.2%, p < 0.0001) and lower in-hospital mortality (2.1% vs 7.6%, p < 0.0001). After correcting for left ventricular function, collateral recruitment was not an independent predictor of mortality. In conclusion, in patients presenting with STEMI, the presence of robust coronary collaterals appears to be associated with improved left ventricular function. Further research is required to identify mechanisms of collateral maturation and recruitment.

Angiogenic Abnormalities in Diabetes Mellitus: Mechanistic and Clinical Aspects

CONTEXT

Diabetes causes severe pathological changes to the microvasculature in many organs and tissues and is at the same time associated with an increased risk of coronary and peripheral macrovascular events. We herein review alterations in angiogenesis observed in human and experimental diabetes and how they contribute to diabetes onset and development of vascular complications.

EVIDENCE ACQUISITION

The English language medical literature was searched for articles reporting on angiogenesis/vasculogenesis abnormalities in diabetes and their clinical manifestations, mechanistic aspects, and possible therapeutic implications.

EVIDENCE SYNTHESIS

Angiogenesis is a complex process, driven by a multiplicity of molecular mechanisms and involved in several physiological and pathological conditions. Incompetent angiogenesis is pervasive in diabetic vascular complications, with both excessive and defective angiogenesis observed in various tissues. A striking different angiogenic response typically occurs in the retina vs the myocardium and peripheral circulation, but some commonalities in abnormal angiogenesis can explain the well-known association between microangiopathy and macroangiopathy. Impaired angiogenesis can also affect endocrine islet and adipose tissue function, providing a link to diabetes onset. Exposure to high glucose itself directly affects angiogenic/vasculogenic processes, and the mechanisms include defective responses to hypoxia and proangiogenic factors, impaired nitric oxide bioavailability, shortage of proangiogenic cells, and loss of pericytes.

CONCLUSIONS

Dissecting the molecular drivers of tissue-specific alterations of angiogenesis/vasculogenesis is an important challenge to devise new therapeutic approaches. Angiogenesis-modulating therapies should be carefully evaluated in view of their potential off-target effects. At present, glycemic control remains the most reasonable therapeutic strategy to normalize angiogenesis in diabetes.

Association between Vascular Endothelial Growth Factor Plasma Levels and rs699947 Polymorphism and Coronary Collateral Vessel Formation

Background: The vascular endothelial growth factor (VEGF), as an angiogenic cytokine, binds endothelial cell receptors and stimulates angiogenesis and collateral formation. We evaluated the association between VEGF plasma levels and the gene polymorphism rs699947 and the formation of coronary collaterals in patients with coronary artery disease. Methods: A total of 195 patients with ≥70% narrowing in at least 1 coronary vessel (according to coronary angiography) were included in the study. The presence of the rs699947 polymorphism within the promoter of the VEGF gene was investigated using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The plasma VEGF concentration was quantified via the ELISA method. The Rentrop method was used to grade the extent of collateral development. Results: There was no significant difference in VEGF levels between the groups with good and poor collaterals. The frequency of the A allele of rs699947 was found to be higher in the patients with good collaterals than in those with poor collaterals (P=0.014). The odds ratio of good collaterals for AA was 2.67 (P=0.025) when compared with the CC genotype. Further, our additive model revealed an association between the rs699947 polymorphism and collateral formation (OR: 1.96, 95% CI: 1.05-3.65, P=0.033). Conclusion: The rs699947 polymorphism might be a novel genetic factor affecting collateral development in Iranian patients with coronary artery disease.

Macrophage migration inhibitory factor (MIF) is associated with degree of collateralization in patients with totally occluded coronary arteries

BACKGROUND

Collaterals in patients with coronary artery disease (CAD) limit myocardial infarction and improve survival. Macrophage migration inhibitory factor (MIF) might play a role in collateral development. We aimed this study to evaluate the association of Macrophage migration Inhibitory Factor (MIF) with the extent of collateralization in patients with coronary occlusion.

METHODS AND RESULTS

We consecutively enrolled: a) 40 patients undergoing PCI of a chronic coronary total occlusion (CTO); b) 26 patients with ST-elevation myocardial infarction (STEMI) undergoing primary PCI (pPCI) of the infarct-related artery (IRA); c) 12 control patients undergoing angiography without significant coronary artery disease (CTRL). CTO patients were grouped in high (HCG) or low collateralization group (LCG). STEMI patients were grouped in COLL+ or COLL- group depending on the presence of collaterals to the IRA. Blood sampling was performed from the arterial sheath (SYSTEMIC), and distal to the occlusion (LOCAL). SYSTEMIC and LOCAL levels were significantly different between the 3 groups. A progressive increase in MIF ratio (defined as: % (LOCAL-SYSTEMIC)/SYSTEMIC) was observed (CTRL: -0.5[-23;28] vs. CTO: 4[-19;32] vs. STEMI: 55[37;87], p < 0.01). In CTO, MIF ratio was significantly higher in HCG vs. LCG (68 [45;120] vs. 46 [29;66], p = 0.02). In STEMI, MIF ratio was not different between COLL+ and COLL- patients; however, in COLL+, LOCAL was significantly higher as compared with SYSTEMIC (83 ng/ml [63;100] vs. 67 ng/ml [40;79], p = 0.04).

CONCLUSIONS

Local MIF is significantly associated with the extent of collateralization in both acute and chronic total coronary occlusions.

Infarct characterization using CT

Myocardial infarction (MI) is a major cause of death and disability worldwide. The incidence is not expected to diminish, despite better prevention, diagnosis and treatment, because of the ageing population in industrialized countries and unhealthy lifestyles in developing countries. Nowadays it is highly requested an imaging tool able to evaluate MI and viability. Technology improvements determined an expansion of clinical indications from coronary plaque evaluation to functional applications (perfusion, ischemia and viability after MI) integrating additional phases and information in the mainstream examination. Cardiac computed tomography (CCT) and cardiac MR (CMR) employ different contrast media, but may characterize MI with overlapping imaging findings due to the similar kinetics and tissue distribution of gadolinium and iodinated contrast media. CCT may detect first-pass perfusion defects, dynamic perfusion after pharmacological stress, and delayed enhancement (DE) of non-viable territories.

Vascular endothelial growth factor and hypoxia-inducible factor-1α gene polymorphisms and coronary collateral formation in patients with coronary chronic total occlusions

Introduction:

We evaluated the association between two single nucleotide polymorphisms of the vascular endothelial growth factor gene and one of the hypoxia-inducible factor-1α gene and the degree of coronary collateral formation in patients with a coronary chronic total occlusion.

Methods:

Totally, 98 patients with symptomatic coronary artery disease and a chronic total occlusion observed during coronary angiography were recruited. Genotyping of two vascular endothelial growth factor promoter single nucleotide polymorphisms (−152G>A and −165C>T) and the C1772T single nucleotide polymorphism of hypoxia-inducible factor-1α were performed using polymerase chain reaction and restriction fragment length polymorphism analysis. The presence and extent of collateral vessel filling was scored by blinded observers using the Rentrop grade.

Results:

We found no association between the vascular endothelial growth factor −152G>A, −165C>T and hypoxia-inducible factor-1α −1772C>T with the presence and filling of coronary collateral vessels. A history of percutaneous coronary intervention and transient ischaemic attack/cerebrovascular accident were associated with the presence of enhanced collateral vessel formation following binary logistic regression analysis.

Conclusion:

The study findings suggest that coronary collateral formation is not associated with the tested polymorphic variants of vascular endothelial growth factor and hypoxia-inducible factor-1α in patients with symptomatic coronary artery disease and the presence of a chronic total occlusion.

A protective role of early collateral blood flow in patients with ST-segment elevation myocardial infarction

Conflict persists regarding whether the presence of early collateral blood flow to the infarct-related artery has an effective role in reducing infarct size and improving myocardial salvage in patients with ST-segment elevation myocardial infarction (STEMI). We sought to investigate the impact of the collateral circulation on myocardial salvage and infarct size in STEMI patients.

METHODS

In 306 patients who were diagnosed with STEMI and underwent cardiac magnetic resonance within 1 week after revascularization, initial collateral flow to the infarct-related artery was assessed by coronary angiography. Using cardiac magnetic resonance imaging, myocardial infarct size and salvage were measured.

RESULTS

Among 247 patients with preprocedural Thrombolysis in Myocardial Infarction flow 0/1, 54 (22%) patients had good collaterals (Rentrop grade ≥ 2, Collateral Connection Score ≥ 2). Infarct size and area at risk were significantly smaller in patients with good collaterals than those with poor collaterals (infarct size: 17.1 ± 10.1 %LV vs 21.8 ± 10.5 %LV, P = .003, area at risk: 33.8 ± 16.8 %LV vs 38.8 ± 15.5 %LV, P = .039). There was a significant difference of myocardial salvage index between 2 groups (50.9% ± 15.0% vs 43.8% ± 18.5%, P = .005). Poor collateralization was an independent predictor for large infarct size (odd ratio 2.48 [1.28-4.80], P = .007).

CONCLUSIONS

In patients with STEMI, the presence of well-developed collaterals to occluded coronary artery from the noninfarct vessel and its extent were independently associated with reduced infarct burden and improved myocardial salvage. Our results help explain why MI patients with well-developed collateralization have reduced mortality and morbidity.

Coronary collateral circulation in patients with chronic coronary total occlusion; its relationship with cardiac risk markers and SYNTAX score

BACKGROUND

Compared to patients without a collateral supply, long-term cardiac mortality is reduced in patients with well-developed coronary collateral circulation (CCC). Cardiovascular risk markers, such as N-terminal pro-brain natriuretic peptide (NT-proBNP), high-sensitive C-reactive protein (hs-CRP) and high-sensitive cardiac troponin T (hs-cTnT) are independent predictors for cardiovascular mortality.

OBJECTIVES

The main goal of this study was to examine the relationship between CCC and cardiovascular risk markers.

METHODS

We prospectively enrolled 427 stable coronary artery disease patients with chronic total occlusion (mean age: 57.5±11.1 years). The patients were divided into two groups, according to their Rentrop scores: (a) poorly developed CCC group (Rentrop 0 and 1) and (b) well-developed CCC group (Rentrop 2 and 3). NT-proBNP, hs-CRP, hs-cTnT, uric acid and other biochemical markers were also measured. The SYNTAX score was calculated for all patients.

RESULTS

The patients in the poorly developed CCC group had higher frequencies of diabetes and hypertension (p<0.05 for both). Compared to the well-developed CCC group, the SYNTAX score, Hs-cTnT, hs-CRP, NT-proBNP, uric acid, neutrophil count and mean platelet volume (MPV) values were higher in patients with poorly developed CCC (p<0.05 for all). On multivariate logistic regression analysis, hs-cTnT (β=0.658, 95% CI=0.589-0.735, p<0.001) and NT-proBNP (β=0.991, 95% CI=0.987-0.995, p<0.001) as well as hs-CRP and diabetes were independent predictors of CCC.

CONCLUSION

Cardiac risk markers, such as NT-proBNP, hs-cTnT and hs-CRP are independently associated with CCC in stable coronary artery disease with chronic total occlusion.

Coronary Collateral Circulation and Cardiovascular Risk Factors: Is There a Paradox?

We sought to determine the association of major cardiovascular risk factors and other comorbidities with the presence or absence of coronary collateral (CC) circulation. All electronic medical records from 2010 to 2011 were retrospectively reviewed. A total of 563 patients were divided into 2 groups: CC present (180) and CC absent (383). Smoking (P = .012, odds ratio [OR] 1.58), hypercholesterolemia (P = .001, OR 2.21), and hypertension (P = .034, OR 1.75) were associated with the presence of CC. Increasing body mass index (BMI, P = .001) and decreasing estimated glomerular filtration rate (eGFR, P = .042) were associated with the absence of CC. On multivariable linear regression analysis, hypercholesterolemia (P = .001, OR 2.28), BMI (P = .012, OR 0.77), and eGFR (P = .001, OR 0.70) were found to be independently associated with CC. Our findings will help predict patient populations more likely to have presence or absence of CC circulation.

Association between clinical presentations before myocardial infarction and coronary mortality: a prospective population-based study using linked electronic records

Background

Ischaemia in different arterial territories before acute myocardial infarction (AMI) may influence post-AMI outcomes. No studies have evaluated prospectively collected information on ischaemia and its effect on short- and long-term coronary mortality. The objective of this study was to compare patients with and without prospectively measured ischaemic presentations before AMI in terms of infarct characteristics and coronary mortality.

Methods and results

As part of the CALIBER programme, we linked data from primary care, hospital admissions, the national acute coronary syndrome registry and cause-specific mortality to identify patients with first AMI (n = 16,439). We analysed time from AMI to coronary mortality (n = 5283 deaths) using Cox regression (median 2.6 years follow-up), comparing patients with and without recent ischaemic presentations. Patients with ischaemic presentations in the 90 days before AMI experienced lower coronary mortality in the first 7 days after AMI compared with those with no prior ischaemic presentations, after adjusting for age, sex, smoking, diabetes, blood pressure and cardiovascular medications [HR: 0.64 (95% CI: 0.57–0.73) P < 0.001], but subsequent mortality was higher [HR: 1.42 (1.13–1.77) P = 0.001]. Patients with ischaemic presentations closer in time to AMI had the lowest seven day mortality (P-trend = 0.001).

Conclusion

In the first large prospective study of ischaemic presentations prior to AMI, we have shown that those occurring closest to AMI are associated with lower short-term coronary mortality following AMI, which could represent a natural ischaemic preconditioning effect, observed in a clinical setting.

Clinical trials registration

Clinicaltrials.gov identifier NCT01604486.

Smoking status and severity of ischemic stroke. A population-based study

We aimed to investigate the impact of smoking status on clinical severity in patients with ischemic stroke event (IS). Patients were prospectively identified among residents of the city of Dijon, France (ca. 151,000 inhabitants), using a population-based registry, between 2006 and 2011. Demographic and clinical data were recorded. The initial clinical severity was quantified by the means of the National Institutes of Health Stroke Scale (NIHSS). Multivariable ordinal logistic regression was used to assess the effect of smoking status on severity. Among the 1,056 recorded patients with IS, data about smoking status were available for 973 (92.1%), of whom 658 (67.3%) were non-smokers, 187 (19.2%) were current smokers, and 128 (13.2%) were former smokers. Compared with non-smoking, former smoking was associated with less severe IS (OR 0.55; 95% CI 0.38-0.82, p = 0.003), whereas this association was not found for current smokers (OR 0.97; 95% CI 0.69-1.36, p = 0.856). Further work is needed to understand the underlying mechanisms of this finding.

The relationship between diastolic pressure and coronary collateral circulation in patients with stable angina pectoris and chronic total occlusion

BACKGROUND

The most important biomechanical source of activation of the coronary collateral circulation (CCC) is increased tangential fluid shear stress at the arterial endothelial surface. The coronary circulation is unique in that most coronary blood flow occurs in diastole. Consequently, the diastolic blood pressure (DBP) may influence the tangential fluid shear stress on the arterial endothelial surface in diastole, therebyaffecting development of the CCC.

METHODS

To investigate this, we conducted a study of 222 patients with stable angina pectoris and chronic total occlusion of coronary arteries. All of the patients had no history of coronary artery interventional therapy, coronary artery bypass surgery, cardiomyopathy, or congenital heart disease. The extent of the collateral vasculature of the area perfused by the artery affected by chronic total occlusion was graded as poor or well-developed according to Rentrop's classification.

RESULTS

Univariate analysis showed a significant difference between the study subgroup with poorly developed collaterals and that with well-developed collaterals in terms of high diastolic blood pressure (DBP) and mean DBP. Multivariate analysis revealed high DBP as the only independent positive predictor of a well-developed collateral circulation.

CONCLUSIONS

High DBP is positively related to a well-developed CCC. Differences in development of the CCC may be one of the pathophysiologic mechanisms responsible for the J-curve phenomenon in the relationship between DBP and cardiovascular risk.

Coronary and carotid atherosclerosis: similarities and differences

Although a relationship is commonly accepted between coronary and carotid arterial disease, suggesting that atherosclerosis is a systemic condition, the extent of this association and correspondence has not been fully elucidated. This review discusses recent research in this field and highlights areas for future study. The prevalence of severe carotid stenosis increases with prevalence of coronary stenosis, with the latter being found in a significant number of stroke patients, while those with carotid stenosis may be at higher risk of myocardial infarction than stroke. There also appear to be common risk factors (age, diabetes, hypertension, smoking and dyslipidemia), although the effects in both vascular systems may not be identical. Furthermore, while the degree of stenosis in the coronary artery has little ability to predict acute coronary syndrome, which is caused by local thrombosis from a ruptured or eroded plaque, severe carotid stenosis causing hypoperfusion is highly predictive of stroke, although this effect may be time-limited. This apparent difference in event mechanism in the two arteries is interesting as is the difference in the rate of development of collaterals. Overall, the evidence shows that a clear relationship exists between disease in the coronary and carotid arteries, since conventional risk factors and the extent of stenosis and/or previous events emanating from one artery have a strong bearing on the prevalence of events in the other artery. Nevertheless, the exact correspondence between the two arteries is unclear, with sometimes contradictory study results. More research is needed to identify the full extent of risk factors for severe stenosis and cardio- or cerebral vascular events, among which, inflammatory biomarkers such as hs-CRP and prior vascular events are likely to play a key role.

Severity of coronary atherosclerosis in patients with a first acute coronary event: a diabetes paradox

AIMS

We aimed to compare coronary artery disease (CAD) at the time of a first acute coronary syndrome (ACS) in type II diabetic and non-diabetic patients by coronary angiography and by optical coherence tomography (OCT).

METHODS AND RESULTS

Two different patient populations with a first ACS were enrolled for the angiographic (167 patients) and the OCT (72 patients) substudy. Angiographic CAD severity was assessed by Bogaty, Gensini, and Sullivan scores, whereas collateral development towards the culprit vessel was assessed by the Rentrop score. Optical coherence tomography plaque features were evaluated at the site of the minimum lumen area (MLA) and of culprit segment. In the angiographic substudy, at multivariate analysis, diabetes was associated with both the stenosis score and the extent index (P = 0.001). Furthermore, well-developed collateral circulation (Rentrop 2-3) towards the culprit vessel was more frequent in diabetic than in non-diabetic patients (73% vs. 16%, P = 0.001). In the OCT substudy, at MLA site lipid quadrants were less and the lipid arc was smaller in diabetic than in non-diabetic patients (2.3 ± 1.3 vs. 3.0 ± 1.2; P = 0.03 and 198° ± 121° vs. 260° ± 118°; P = 0.03). Furthermore, the most calcified cross-section along the culprit segment had a greater number of calcified quadrants and a wider calcified arc in diabetic than in non-diabetic patients (1.7 ± 1.0 vs. 1.2 ± 0.9; P = 0.03 and 126° ± 95° vs. 81° ± 80°; P = 0.03). Superficial calcified nodules were more frequently found in diabetic than in non-diabetic patients (79 vs. 54%, P = 0.04).

CONCLUSIONS

In spite of potent pro-inflammatory, pro-oxidant and pro-thrombotic stimuli operating in type II diabetes, diabetic patients exhibit substantially more severe coronary atherosclerosis than non-diabetic patients at the time of a first acute coronary event. Better collateral development towards the culprit vessel, a predominantly calcific plaque phenotype and, probably, yet unknown protective factors operating in diabetic patients may explain these intriguing paradoxical findings.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.

Coronary collateral growth--back to the future

The coronary collateral circulation is critically important as an adaptation of the heart to prevent the damage from ischemic insults. In their native state, collaterals in the heart would be classified as part of the microcirculation, existing as arterial-arterial anastomotic connections in the range of 30 to 100 μM in diameter. However, these vessels also show a propensity to remodel into components of the macrocirculation and can become arteries larger than 1000 μM in diameter. This process of outward remodeling is critically important in the adaptation of the heart to ischemia because the resistance to blood flow is inversely related to the fourth power of the diameter of the vessel. Thus, an expansion of a vessel from 100 to 1000 μM would reduce resistance (in this part of the circuit) to a negligible amount and enable delivery of flow to the region at risk. Our goal in this review is to highlight the voids in understanding this adaptation to ischemia-the growth of the coronary collateral circulation. In doing so we discuss the controversies and unknown aspects of the causal factors that stimulate growth of the collateral circulation, the role of genetics, and the role of endogenous stem and progenitor cells in the context of the normal, physiological situation and under more pathological conditions of ischemic heart disease or with some of the underlying risk factors, e.g., diabetes. The major conclusion of this review is that there are many gaps in our knowledge of coronary collateral growth and this knowledge is critical before the potential of stimulating collateralization in the hearts of patients can be realized. This article is part of a Special Issue entitled "Coronary Blood Flow".

Study on the role of environmental parameters and HIF-1A gene polymorphism in coronary collateral formation among patients with ischemic heart disease

OBJECTIVES

To evaluate the association between collateral formation and some environmental factors along with a polymorphism in HIF-1A gene in selected Iranian patients with CAD.

DESIGN AND METHODS

Patients with ≥ 70% narrowing in at least one coronary vessel according to coronary angiography were enrolled. The patients' demographic, clinical and biochemical data were collected. The presence of C1772T polymorphisms within HIF-1A was analyzed using the polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP).

RESULTS

There is no significant difference between the patients with and without collaterals according to the frequency of T allele or HIF-1A variants. The higher severity of coronary vessel obstruction was positive predictor of collateral formation (OR=1.026, 95%, CI: 1.02-0.04, p<0.001), whereas aging and cigarette smoking were negative predictors (OR=0.95, 95% CI: 0.91-0.99, p<0.05; OR=0.30, 95% CI: 0.11-0.79, p <0.05; respectively).

CONCLUSIONS

The findings indicate not any significant association between collateral formation and polymorphic variants of HIF-1A and P582S substitution does not appear to influence the collateral formation in patients with myocardial ischemia.

Coronary collateral growth and its therapeutic application to coronary artery disease

There is a tremendous body of data concerning the coronary collateral circulation in both experimental animals and humans. The functional importance of a well-developed coronary collateral circulation has now been documented. The paradigm regarding the principal stimulus for coronary collateral growth has shifted from myocardial ischemia to increased shear stress at the site of pre-existing collateral arterioles. Numerous experimental and clinical studies have contributed to elucidation of the mechanisms of coronary collateral growth. Stimulation of coronary collateral growth is an alternative therapeutic approach to patients with intractable angina pectoris who are not indicated for percutaneous coronary intervention and/or coronary artery bypass grafting. Pharmacological and mechanical modulations accelerating coronary collateral growth have been challenged. Because it is conceivable that a well-developed coronary collateral circulation attenuates myocardial ischemia upon exercise, further research addressing coronary collateral growth is needed in both experimental models of myocardial ischemia and human coronary artery disease.

Cardiovascular risk factors and collateral artery formation

Arterial lumen narrowing and vascular occlusion is the actual cause of morbidity and mortality in atherosclerotic disease. Collateral artery formation (arteriogenesis) refers to an active remodelling of non-functional vascular anastomoses to functional collateral arteries, capable to bypass the site of obstruction and preserve the tissue that is jeopardized by ischaemia. Hemodynamic forces such as shear stress and wall stress play a pivotal role in collateral artery formation, accompanied by the expression of various cytokines and invasion of circulating leucocytes. Arteriogenesis hence represents an important compensatory mechanism for atherosclerotic vessel occlusion. As arteriogenesis mostly occurs when lumen narrowing by atherosclerotic plaques takes place, presence of cardiovascular risk factors (e.g. hypertension, hypercholesterolaemia and diabetes) is highly likely. Risk factors for atherosclerotic disease affect collateral artery growth directly and indirectly by altering hemodynamic forces or influencing cellular function and proliferation. Adequate collateralization varies significantly among atherosclerotic patients, some profit from the presence of extensive collateral networks, whereas others do not. Cardiovascular risk factors could increase the risk of adverse cardiovascular events in certain patients because of the reduced protection through an alternative vascular network. Likewise, drugs primarily thought to control cardiovascular risk factors might contribute or counteract collateral artery growth. This review summarizes current knowledge on the influence of cardiovascular risk factors and the effects of cardiovascular medication on the development of collateral vessels in experimental and clinical studies.

Relationship Between Aortic Stiffness and the Development of Coronary Collateral in Patients With Coronary Artery Disease

Large artery stiffness is an independent predictor of cardiovascular mortality and a major determinant of pulse pressure. The stiff aorta may result in greater systolic, lower diastolic, and wider pulse pressures, which may decrease coronary artery perfusion. Shear stress has been implicated in the development of coronary collateral. Decreased coronary perfusion may reduce shear stress and thus collateral formation. The goal of this study was to assess the relationship between the development of coronary collateral and aortic stiffness in patients with coronary artery disease. In 106 patients with at least one coronary artery stenosis of 90% or greater, collateral vessels were assessed angiographically by the Rentrop grading (grade 0—3), establishing two groups: 50 patients with poor collateral vessels (Rentrop grade 0 or 1), and 56 patients with good collateral vessels (Rentrop grade 2 or 3). Internal aortic root diameters were measured at 3 cm above the aortic valve by use of two-dimensional guided M-mode transthoracic echocardiography, and arterial pressure was measured simultaneously at the brachial artery by sphygmomanometry. Two indexes of the aortic elastic properties were measured: aortic distensibility index was calculated by use of the formula: 2 × (systolic diameter — diastolic diameter)/(diastolic diameter) × (pulse pressure) in cm— 2dyn—110—6. The aortic stiffness index was calculated by: (systolic blood pressure/diastolic blood pressure)/pulsatile change in diameter/diastolic diameter. The aortic distensibility index and the aortic stiffness index were not significantly different between the patients with poor collateral vessels and those with good collateral vessels (5.1 ±2.3 vs 5.7 ±3.3 cm—2dyn —110—6, p = 0.31; 4.02 ±2.3 vs 4.43 ±3.7, p = 0.49, respectively). There were no significant differences regarding the aortic elastic properties between the patients with poor collateral vessels and those with good collateral vessels, suggesting that collateral formation is a complex phenomenon consisting of several distinct processes.

Pathophysiology of acute myocardial infarction

More than 80% of acute myocardial infarcts are the result of coronary atherosclerosis with superimposed luminal thrombus. Uncommon causes of myocardial infarction include coronary spasm, coronary embolism, and thrombosis in nonatherosclerotic normal vessels. Additionally, concentric subendocardial necrosis may result from global ischemia and reperfusion in cases of prolonged cardiac arrest with resuscitation. Myocardial ischemia shares features with other types of myocyte necrosis, such as that caused by inflammation, but specific changes result from myocyte hypoxia that vary based on length of occlusion of the vessel, duration between occlusion and reperfusion, and presence of collateral circulation.

Influence of oxidative stress on the development of collateral circulation in total coronary occlusions

OBJECTIVES

The purpose of this study was to investigate whether the levels of total antioxidant capacity (TAC), total peroxide and oxidative stress index (OSI) are associated with the development of collaterals in total coronary occlusions.

DESIGN AND METHODS

Our study group contained 176 consecutive men patients with single-vessel TCO, 94 of whom had poorly developed coronary collateral, while 82 had well-developed coronary collateral. TAC and total peroxide concentration were measured of plasma. The ratio of TAC to total peroxide was accepted as an indicator of oxidative stress.

RESULTS

The values of total peroxide and OSI in the Group I were significantly lower than that in Group II (p<0.001, for both). TAC levels were significantly higher in patients with poorly developed collaterals than in well-developed collateral group (p<0.001). OSI values were also significantly different among the Rentrop class-0, -1, -2 and -3 (ANOVA p<0.001). We found significant correlations between collaterals score and TAC, total peroxide and OSI levels (p<0.001 for all). In multiple linear regression analysis, total peroxide and OSI were independent predictors of collaterals score (p=0.006 and p<0.001 respectively).

CONCLUSION

This study clearly demonstrates that the level of OSI is independently and positively associated with the presence of collateral circulation in total coronary occlusion patients.

Gender differences in in-hospital mortality and mechanisms of death after the first acute myocardial infarction

BACKGROUND

There are conflicting data about gender differences in short-term mortality after acute myocardial infarction (AMI) after adjusting for age and other prognostic factors. Therefore, we investigated the risk profile, clinical presentation, in-hospital mortality and mechanisms of death in women and men after the first AMI.

METHODS

The data were obtained from a chart review of 3382 consecutive patients, 1184 (35%) women (69.7+/-10.9 years) and 2198 (65%) men (63.5+/-11.8 years) with a first AMI. The effect of gender and its interaction with age, risk factors and thrombolytic therapy on overall mortality and mechanisms of death were examined using logistic regression.

RESULTS

Unadjusted in-hospital mortality was higher in women (OR 1.77, 95% CI 1.47-2.15). Adjustment that included both age only and age and other baseline differences (hypertension, diabetes mellitus, hypercholesterolemia, smoking, AMI type, AMI site, mean peak CK value, thrombolytic therapy) decreased the magnitude of the relative risk of women to men but did not eliminate it (OR 1.26, 95% CI 1.03-1.54 and OR 1.31 95% CI 1.03-1.66, respectively). Multivariate analysis revealed that female gender was an independent predictor of in-hospital mortality after the first AMI. Women were dying more often because of mechanical complications - refractory pulmonary edema and cardiogenic shock (P=0.02) or electromechanical dissociation (P=0.03), and men were dying mostly by arrhythmic death, primary ventricular tachycardia/fibrillation (P=0.002). Female gender was independently associated with mechanical death (OR 1.56, 95% CI 1.35-2.58; P=0.01) and anterior AMI was independently associated with arrhythmic death (OR 0.54, 95% CI 0.34-0.86; P=0.01).

CONCLUSION

Our results demonstrate significant differences in mechanisms of in-hospital death after the first AMI in women and men, suggesting the possibility that higher in-hospital mortality in women exists primarily because of the postponing AMI death due to the gender-related differences in susceptibility to cardiac arrhythmias following acute coronary events.

Transcriptional profiling in coronary artery disease: indications for novel markers of coronary collateralization

BACKGROUND

The development of collateral circulation plays an important role in protecting tissues from ischemic damage, and its stimulation has emerged as one of principal approaches to therapeutic angiogenesis. Clinical observations have documented substantial differences in the extent of collateralization among patients with coronary artery disease (CAD), with some individuals demonstrating marked abundance and others showing nearly complete absence of these vessels. Recent studies have suggested that circulating monocytes play a major role in collateral growth. The present study was undertaken to determine transcriptional profiles of circulating monocytes in CAD patients with different extents of collateral growth.

METHODS AND RESULTS

Monocyte transcriptomes from CAD patients with and without collateral vessels were obtained by use of high-throughput expression profiling. Using a newly developed redundancy-based data mining method, we have identified a set of molecular markers characteristic of a "noncollateralgenic" phenotype. Moreover, we show that these transcriptional abnormalities are independent of the severity of CAD or any other known clinical parameter thought to affect collateral development and correlated with protein expression levels in monocytes and plasma.

CONCLUSIONS

Monocyte transcription profiling identifies sets of patients with extensive versus poorly developed collateral circulation. Thus, genetic factors may heavily influence coronary collateral vessel growth in CAD and affect prognosis and response to therapeutic interventions.

Association between the dosage and duration of statin treatment with coronary collateral development

BACKGROUND

The coronary collateral circulation is an alternative source of blood supply to myocardium in the presence of advanced coronary artery disease and the therapeutic promotion of collateral growth appears to be a valuable treatment strategy in these patients. Although it has been shown in in-vivo studies that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) promote vasculogenesis and accelerate coronary collateral development in ischemic tissues, there are discordant results in clinical studies. Our aim was to investigate the effect of statin therapy, including dosage and duration of treatment, on coronary collateral growth in patients with advanced coronary artery disease.

METHODS

Study population consisted of 400 (306 men, with the mean age of 62+/-10 years) consecutive patients who have undergone clinically indicated coronary angiography and had at least one major coronary artery stenosis of > or =95%. Coronary collaterals were graded from 0 to 3 according to the Cohen-Rentrop method and patients with grade 0-1 collateral development were regarded as having poor collateral and patients with grade 2-3 collateral development were regarded as having good collateral.

RESULTS

Among 400 patients, 196 (48%) were on statin therapy. Patients with good collateral score were more likely to have stable angina pectoris as clinical presentation (P<0.001), and were on statin therapy (P=0.001), and have multivessel disease (P=0.003). Statin therapy for less than 3 months had no effect on collateral development (P=0.19); however, patients who were on statin therapy for more than 3 months had significantly better collateral development (P=0.002). Statin therapy had no effect on coronary collateral development in patients having <10 mg atorvastatin-equivalent dose (P=0.13); however, patients having > or =10 mg atorvastatin-equivalent dose had better collateral development (P<0.001). Diabetes mellitus was the only negative predictor for coronary collateral formation (P=0.03). On multivariate analysis, stable angina pectoris [odds ratio 2.88, 95% confidence interval (1.8-4.7), P<0.001], statin therapy with > or =10 mg atorvastatin-equivalent dose [odds ratio 2.06, 95% confidence interval (1.3-2.6), P<0.001] and having multivessel disease [odds ratio 1.86, 95% confidence interval (1.16-3), P=0.01] were found to be associated with rich collateralization.

CONCLUSION

Statin therapy (> or =10 mg atorvastatin-equivalent dose), stable angina pectoris and having multivessel disease are associated with enhanced coronary collateral development in patients with advanced coronary artery disease.

Coronary collateral circulation: the effects of smoking and alcohol

OBJECTIVE

The presence or absence of coronary collaterals is of vital importance during acute ischemia. Smoking and alcohol have been suggested to play a role, but data are scarce. We examined the extent to which smoking and alcohol use affect the presence of coronary collateral circulation.

METHODS

Cross-sectional study in 242 patients, admitted for elective PTCA. Smoking was defined as past or current. Pack years were calculated and categorized into never-smokers (reference-category): <10, 10-19, 20-29, and >or=30 pack years. Alcohol consumption was defined as past or current, and categorized into never-users (reference-category): <1, 1-10, 11-20, and >or=21 units per week (UPW). Collaterals were graded with Rentrop's classification. Coronary collateral presence was defined as Rentrop-grade >or=1.

RESULTS

Current smoking (odds ratio (OR) 4.17; 95% confidence interval (CI) 1.79-9.71) was positively associated, while pack years of smoking was not related. Current alcohol intake showed a J-shaped tendency with coronary collateral presence, while past moderate alcohol consumption was inversely associated (OR 0.19; 95% CI 0.04-0.98).

CONCLUSIONS

Smoking and (to some extent) alcohol use are associated with collateral presence. The results support the view that life-style factors may affect the formation of coronary collaterals in patients with ischemic cardiac disease.

Cardiac ischemic score determines the presence of coronary collateral circulation

PURPOSE

The presence of coronary collaterals is of vital importance during acute ischemia, however, marked interindividual variability exists. We examined the extent to which the burden of cardiac ischemia, expressed as a cardiac ischemic score, affects coronary collateral presence.

METHODS

Cross-sectional study in 244 patients, admitted for elective coronary angioplasty. Collaterals were graded with Rentrop's classification. Coronary collateral presence was defined as Rentrop-grade > or =1. The cardiac ischemic score (range 0-4) was calculated by adding 1 point for each of the following four clinical factors present: angina pectoris on exertion, angina pectoris during emotions, previous myocardial infarction, and previous coronary intervention. These four clinical factors were chosen because they can be easily assessed in every patient. We used logistic regression with adjustment for gender, age, hypertension, diabetes mellitus, and hyperlipidemia.

RESULTS

The extent of the cardiac ischemic score (odds ratio 1.8 per score-point; 95% confidence interval 1.3-2.5) was strongly associated with coronary collateral presence. Additional adjustment for multivessel coronary disease left the relation essentially unchanged. Also, if the definition of collateral presence was limited to Rentrop-grade 2 and 3, results were effectively the same.

CONCLUSION

The extent of the cardiac ischemic score determines the presence of coronary collaterals, and may provide a new index for simple assessment of collateral vascular development.

Ischemic preconditioning and preinfarction angina in the clinical arena

In animals, brief episodes of ischemia before a total coronary occlusion protect the heart and result in a smaller myocardial infarct size. In humans, episodes of angina before acute myocardial infarction might also confer a preconditioning or protective effect; numerous studies show that preinfarction angina is associated with smaller infarcts. Preinfarction angina is also associated with reductions in ventricular dysfunction, arrhythmias and incidence of no-reflow phenomena, and, in some cases, improved survival. The protective effect of preconditioning in humans is characterized by marked individual variations and seems to be attenuated in women, people with diabetes and the elderly. Exercise seems to be an important way to induce preconditioning in humans and preserves it in the elderly.

High blood pressure is inversely related with the presence and extent of coronary collaterals

Patients with hypertension have an increased case fatality during acute myocardial infarction (MI). Coronary collateral (CC) circulation has been proposed to reduce the risk of death during acute ischaemia. We determined whether and to which degree high blood pressure (BP) affects the presence and extent of CC circulation. A cross-sectional study in 237 patients (84% males), admitted for elective coronary angioplasty between January 1998 and July 2002, was conducted. Collaterals were graded with Rentrop's classification (grade 0-3). CC presence was defined as Rentrop-grade > or =1. BP was measured twice with an inflatable cuff manometer in seated position. Pulse pressure was calculated by systolic blood pressure (SBP)-diastolic blood pressure (DBP). Mean arterial pressure was calculated by DBP+1/3 x (SBP-DBP). Systolic hypertension was defined by a reading > or =140 mmHg. We used logistic regression with adjustment for putative confounders. SBP (odds ratio (OR) 0.86 per 10 mmHg; 95% confidence interval (CI) 0.73-1.00), DBP (OR 0.67 per 10 mmHg; 95% CI 0.49-0.93), mean arterial pressure (OR 0.73 per 10 mmHg; 95% CI 0.56-0.94), systolic hypertension (OR 0.49; 95% CI 0.26-0.94), and antihypertensive treatment (OR 0.53; 95% CI 0.27-1.02), each were inversely associated with the presence of CCs. Also, among patients with CCs, there was a graded, significant inverse relation between levels of SBP, levels of pulse pressure, and collateral extent. There is an inverse relationship between BP and the presence and extent of CC circulation in patients with ischaemic heart disease.

Collaterals that regressed after angioplasty can be recruited to protect the left ventricle in case of an acute occlusion

A considerable fraction of collaterals has been shown to regress immediately after percutaneous transluminal coronary angioplasty (PTCA), but the fate of these well-developed collaterals is unknown. The authors aimed to show the protective role of these recruitable collaterals in case of an acute myocardial infarction (MI). They identified 22 patients who underwent PTCA and then were rehospitalized owing to acute myocardial infarction. These patients were compared with a group consisting of 48 patients hospitalized owing to acute MI without a history of previous PTCA. Then, the patients with collaterals were compared with the patients without collaterals to define the factors affecting the collateral formation. All the patients with collaterals before PTCA were shown to have collaterals also after AMI, and collateral grades were greater after MI (1.67 +/-0.98) when compared with those before PTCA (0.73 +/-0.7) (p = 0.001). Coronary collaterals were more commonly seen in patients with a history of previous PTCA (p = 0.005), and the grades of collaterals were also higher in these patients when compared with those without PTCA. Left ventricle score indices were lower and left ventricular ejection fractions (LVEF) were higher in patients with a history of PTCA (p = 0.001). Logistic regression analysis revealed that smoking increased the development of collaterals after AMI 3.8 fold, aspirin use 4.1 fold. On the contrary, diabetes mellitus (DM) decreased this 6.67 fold. As a result, well-developed coronary collaterals are preserved even if they have regressed after restoration of flow, and they may become functional and protect the myocardium against acute ischemia.

Influence of diabetes mellitus on coronary collateral flow: an answer to an old controversy

OBJECTIVES

To determine the influence of diabetes mellitus on coronary collateral flow by accurate means of collateral flow measurement in a large population with variable degrees of coronary artery disease.

METHODS

200 patients (mean (SD) age 64 (9) years; 100 diabetic and 100 non-diabetic) were enrolled in the study. Coronary collateral flow was assessed in 174 stenotic and in 26 angiographically normal vessels with a pressure guidewire (n = 131), Doppler guidewire (n = 36), or both (n = 33) to calculate pressure or flow velocity derived collateral flow index (CFI). Diabetic patients were perfectly matched with a non-diabetic control group for clinical, haemodynamic, and angiographic parameters.

RESULTS

CFI did not differ between the diabetic and the non-diabetic patients (0.21 (0.12) v 0.19 (0.13), not significant). Likewise, CFI did not differ when only angiographically normal vessels (0.20 (0.09) v 0.15 (0.08), not significant) or chronic total coronary occlusions (0.30 (0.14) v 0.30 (0.17), not significant) were compared. Fewer patients in the diabetic group tended to have angina pectoris during the one minute vessel occlusion (60 diabetic v 69 non-diabetic patients, p = 0.15).

CONCLUSION

Quantitatively measured coronary CFI did not differ between diabetic and non-diabetic patients with stable coronary artery disease.

Predictors of type and site of first acute myocardial infarction in men and women

BACKGROUND

The importance of pathophysiological mechanisms involved in onset of acute myocardial infarction (AMI) differs with age, gender, and risk profiles. Diversity in the triggering of cardiovascular events has been observed, particularly between men and women. Therefore, we investigated the relationship between age, gender, and risk factors and location of AMI and the presence of Q waves in ECG.

PATIENTS AND METHODS

Data was obtained from a chart review of 2958 patients with first AMI: 770 (26%) patients with non-Q-wave AMI and 2188 (74%) patients with Q-wave AMI. Four clinical groups were formed by predetermined criteria (anterior Q-wave, anterior non-Q-wave, inferior Q-wave, inferior non-Q-wave). A logistic regression was performed to assess independent predictors of AMI type and site.

RESULTS

Key findings were: 1) inferior non-Q-wave AMI was more frequent in young women (P<0.001); 2) inferior Q-wave AMI was more common in young men (P<0.001); 3) anterior non-Q-wave AMI was more common in older men (P<0.001). Multivariate analysis revealed that independent predictors of anterior non-Q-wave AMI were age over 65 (P=0.002), male gender (P=0.04) and hypercholesterolemia (P=0.0003), and that predictors of inferior Q-wave AMI were male gender (P<0.0001), smoking (P=0.04) and diabetes (P=0.049). In the gender-subgroup analyses, age <45 years (P=0.04), hypecholesterolemia (P=0.02) and smoking (P=0.01) were independent predictors of inferior Q-wave AMI whereas age >65 years (P<0.0001) and smoking (P=0.0003) were predictors of anterior non-Q-wave AMI in men. In women, age <45 years (P<0.0001) and smoking (P=0.02) were independent predictors of non-Q-wave AMI and hypercholesterolemia (P=0.02) was a predictor of inferior Q-wave AMI.

CONCLUSION

The link between particular types and the site of AMI and age, gender and risk factors suggest that the importance of pathophysiological mechanisms for onset of AMI differs according to sex and age subgroup.

Presence of the metabolic syndrome does not impair coronary collateral vessel formation in patients with documented coronary artery disease

OBJECTIVE

The metabolic syndrome confers an increased risk for cardiovascular morbidity and mortality. The presence of coronary collaterals may have beneficial effects during myocardial ischemia and may improve cardiovascular outcome in patients with coronary artery disease. Impaired collateral formation could be one of the reasons for the increased cardiovascular risk in patients with the metabolic syndrome. The aim of the present study was to determine the influence of the metabolic syndrome and insulin resistance on the presence of coronary collaterals.

RESEARCH DESIGNS AND METHODS

We conducted a cross-sectional study in 227 patients referred for elective percutaneous transluminal coronary angioplasty to the University Medical Centre Utrecht. The metabolic syndrome was diagnosed according to Adult Treatment Panel III, and homeostasis model assessment of insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) were used to quantify insulin resistance. Coronary collaterals were graded with Rentrop's classification. Rentrop grade >/=1 indicated the presence of collaterals. Results were adjusted for age, sex, and severity of coronary artery disease.

RESULTS

A total of 103 patients (45%) were diagnosed with the metabolic syndrome. There was no association between the metabolic syndrome and the presence of coronary collateral formation (odds ratio [OR] 1.2 [95% CI 0.7-2.0]). Also, the degree of insulin resistance was not related to the presence of coronary collaterals. The OR for HOMA-IR (highest versus lowest tertile) was 0.7 (0.3-1.5) and for QUICKI (lowest versus highest tertile) 0.8 (0.4-1.6).

CONCLUSIONS

The metabolic syndrome and insulin resistance are not related to the presence of coronary collaterals in patients with documented coronary artery disease.

Reactive oxygen species are critical mediators of coronary collateral development in a canine model

Recent evidence suggests that reactive oxygen species (ROS) promote proliferation and migration of vascular smooth muscle (VSMC) and endothelial cells (EC). We tested the hypothesis that ROS serve as crucial messengers during coronary collateral development. Dogs were subjected to brief (2 min), repetitive coronary artery occlusions (1/h, 8/day, 21 day duration) in the absence (occlusion, n = 8) or presence of N-acetylcysteine (NAC) (occlusion + NAC, n = 8). A sham group (n = 8) was instrumented identically but received no occlusions. In separate experiments, ROS generation after a single 2-min coronary artery occlusion was assessed with dihydroethidium fluorescence. Coronary collateral blood flow (expressed as a percentage of normal zone flow) was significantly increased (71 +/- 7%) in occlusion dogs after 21 days but remained unchanged (13 +/- 3%) in sham dogs. Treatment with NAC attenuated increases in collateral blood flow (28 +/- 8%). Brief coronary artery occlusion and reperfusion caused ROS production (256 +/- 33% of baseline values), which was abolished with NAC (104 +/- 12%). Myocardial interstitial fluid produced tube formation and proliferation of VSMC and EC in occlusion but not in NAC-treated or sham dogs. The results indicate that ROS are critical for the development of the coronary collateral circulation.

Correlates of coronary blood flow before and after percutaneous coronary intervention and their relationship to angiographic and clinical outcomes in the RESTORE trial. Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis

BACKGROUND AND OBJECTIVES

Slower blood flow in the setting of acute myocardial infarction (MI) has been related to adverse outcomes, but the relationship of coronary blood flow after percutaneous transluminal coronary angioplasty (PTCA) in the setting of acute coronary syndromes to adverse outcomes and restenosis has not been well described. We sought to evaluate the correlates of pre- and post-PTCA coronary blood flow to shed light on potential modifiable determinants.

METHODS

The RESTORE trial (Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis) was a randomized, double-blind, placebo-controlled trial of tirofiban in patients undergoing balloon angioplasty or directional atherectomy within 72 hours of occurrence of either unstable angina pectoris or acute MI. Coronary blood flow was assessed with the corrected TIMI frame count (CTFC), and clinical outcomes were assessed at 30 days.

RESULTS

In addition to tighter and longer minimum lumen diameters (MLDs), the multivariate correlates of slower flow before PTCA also included the presence of thrombus, collaterals, left coronary artery lesion location, acute MI, and >8F catheter size. As well as the above variables, type C and D dissection grades were related to slower post-PTCA CTFC. Death, or the composite of death/MI/coronary artery bypass graft at 30 days, was more frequent among patients with slower post-PTCA CTFCs and those with post-PTCA thrombus. In a multivariate model correcting for reference segment diameter and MLD, the post-PTCA CTFC was an independent predictor of late lumen loss and the follow-up MLD at 6 months. As a single index that integrates functional and anatomical aspects of the post-PTCA results, the ratio of CTFC/MLD was associated with death/MI by 30 days.

CONCLUSIONS

In addition to MLD, variables such as the presence of thrombus, left coronary artery lesion location, and dissection grade also are associated with slower coronary blood flow after PTCA. In turn, post-PTCA CTFCs were an independent predictor of late lumen loss and follow-up MLDs. Furthermore, patients who die or who sustain other adverse cardiac events have slower coronary blood flow and greater thrombus burden after PTCA.

Can thrombolytic therapy provide beneficial effects additional to epicardial coronary artery recanalization? A study based on coronary pressure measurement

BACKGROUND

Collaterals provide significant blood supply to the myocardium at risk and the presence of a preserved and adequate collateral network may limit microvascular damage during the occlusion of an epicardial coronary artery. The aim of this study was to evaluate whether thrombolytic therapy (TT) may produce beneficial effects at the level of microvascular circulation in addition to epicardial coronary artery recanalization by using quantitative intracoronary pressure measurement techniques in patients with recent acute myocardial infarction (AMI).

MATERIALS AND METHODS

Thirty-six patients who presented with AMI and had preinfarction angina pectoris, more than 60% stenosis and thrombolysis in myocardial infarction (TIMI) grade II flow in the infarct-related artery and who underwent a stent implantation procedure within 10 days of AMI were included in this study. Seventeen of 36 patients had received TT (group 1) and 19 had not received TT due to presence of contraindications or late admission (group 2). Quantitative coronary angiography, TIMI frame count (TFC) assessment and intracoronary pressure measurements were performed before and after stent implantation for all patients. Myocardial fractional flow reserve (FFRmyo) was calculated as the ratio of mean distal coronary pressure to mean aortic pressure. During total occlusion with balloon inflation, distal pressure was recorded as coronary wedge pressure (CWP). Collateral flow index (CFI) was determined by the ratio of simultaneously measured CWP to mean aortic pressure.

RESULTS

There were no differences between the two groups with respect to mean per cent stenosis and mean FFRmyo both before and after stent implantation. The mean CWP (25.1 +/- 8.6 mmHg compared with 17.2 +/- 6.2 mmHg, P < 0.01) and CFI (0.24 +/- 0.10 compared with 0.16 +/- 0.11, P < 0.01) were significantly higher and mean post-stent corrected TFC (18.8 +/- 3.7 compared with 22.4 +/- 3.1, P < 0.01) was significantly faster in the group of patients who had received TT compared to those who had not.

CONCLUSIONS

We concluded that destruction degree of collateral circulation and distal microvasculature is lower in patients who had received TT, compared to patients who could not be treated with TT. Besides protective effect on collateral vessels, TT provides even more reperfusion and less destruction of the microvasculature.