Determinants of collateral filling observed during sudden controlled coronary artery occlusion in human subjects

Effect of Fibroblast Growth Factor-21 Molecule on Coronary CollateralDevelopment

BACKGROUND

Collateral arteries provide an alternative source to the myocardium resulting from ischemia due to occlusive coronary artery disease and may help preserve myocardial function in the case of coronary artery disease (CAD). Although collateral development is so important, its pathophysiology has not been fully elucidated. Till now, no study has investigated the relationship between Fibroblast growth factor-21(FGF-21) and coronary collateral.

OBJECTIVE

This study aims to investigate the pathophysiology of coronary collateral development.

METHODS

In our study, which we planned as a case-control, 60 consecutive patients with ≥90 stenosis in at least one large coronary artery as a result of coronary angiography (CAG) and 30 patients with normal coronary angiography were included in the study cross-sectional. Demographic, echocardiographic and laboratory data were recorded. Coronary collateral circulation was evaluated using the Rentrop-Cohen method. FGF-21 levels were measured in all individuals.

RESULTS

In the analysis, no significant difference was observed between the two groups in basic biochemical parameters other than HDL (p>0.05 for all). FGF-21 level was statistically significantly higher in the patient group compared to the control group (p: 0.003). Also, the FGF-21 level was found to be statistically significantly higher in the good collateral circulation group than the poor (p:0.006). Univariate and multivariate logistic regression analysis was performed to predict the presence of collateral. We found that FGF-21(p=0.006), and C-reactive protein (p=0.020) predicted the presence of collateral independently.

CONCLUSION

Collateral formation and cardiac prognosis are closely related. Our study is the first to investigate the relationship between collateral formation and FGF-21. Our study showed that the FGF-21 level is an independent predictor of collateral formation. In addition, there was a significant difference between bad and good collateral formation regarding FGF-21 levels.

Triglyceride-glucose index in the prediction of clinical outcomes after successful recanalization for coronary chronic total occlusions

BACKGROUND

Triglyceride-glucose index (TyG) has been widely used to predict cardiovascular outcomes. However, it remains unclear whether TyG holds prognostic significance for patients with coronary chronic total occlusions (CTO). Thus, our study aimed to evaluate the predictive accuracy and prognostic value of TyG in individuals who underwent successful percutaneous coronary intervention (PCI) for CTO.

METHODS

A total of 331 consecutive patients with ≥ 1 successful CTO-PCI were included. The baseline and angiographic data were acquired. The duration of follow-up ranged from 32 to 79 months, with a median of 44 months and an interquartile range of 39 to 67 months. The primary outcome measured was the occurrence of major adverse cardiac and cerebrovascular events (MACCE), including mortality, target vessel revascularization, recurrent myocardial infarction, and stroke.

RESULTS

After controlling for confounders, multivariate Cox regression analysis revealed that TyG remained statistically significant, regardless of being a continuous or categorical variable. In the partially adjusted regression model, the Hazard ratio (95%CI) for MACCE was 2.54 (1.12-5.79) in tertile 3 and 1.61 (1.22-2.12) per SD increase in the TyG.Kaplan-Meier survival analysis demonstrated significant differences in MACCE-free survival rates across tertiles of the TyG, as indicated by the log-rank test (p = 0.001). ROC analysis was conducted to evaluate the predictive ability of TyG for MACCE, resulting in an AUC of 0.677.

CONCLUSION

The TyG index demonstrates independent predictive capabilities for MACCE in patients who have undergone successful CTO-PCI. These findings suggest that TyG holds the potential as a valuable tool in risk stratification and the identification of patients who may benefit from early intervention in the management of CTO.

iFR uncovers profound but mostly reversible ischemia in CTOs and helps to optimize PCI results

OBJECTIVES

The study aimed to demonstrate through instant wave-free ratio (iFR) measurements that myocardium distal to a chronic total occlusion (CTO) is ischemic, that ischemia is reversible by PCI, and that iFR assessment after PCI can be used to optimize PCI results.

BACKGROUND

The greatest benefit of revascularization is found in patients with low fractional flow reserve. In patients with CTOs, iFR measurement may be more appropriate to evaluate ischemia as it does not require maximal microvascular vasodilation, which may be hampered by microvascular dysfunction.

METHODS

The iFR was measured in 81 CTO patients, both pre- and post-PCI in 63 patients, and only post-PCI in the following 18 patients. A pressure wire pullback was performed post-PCI if iFR ≤0.89.

RESULTS

The first 63 patients all had significant ischemia distal to the CTO with a median iFR of 0.33 [0.22; 0.44], improving significantly post-PCI to a median iFR of 0.93 [0.89;0.96] (p < .001). In the complete cohort, the median iFR post-PCI was 0.93 [0.86;0.96] but still ≤0.89 in 23 patients (30%). 12 of these patients had further PCI optimization because of a residual focal pressure gradient on pullback, after which only two had a final iFR ≤0.89.

CONCLUSIONS

In CTO patients with an indication for PCI, iFR consistently demonstrated profound myocardial ischemia. Successful PCI immediately relieved ischemia in 70% of patients. In the remaining 30% of cases, a manual iFR pullback proved helpful in guiding further optimization of the PCI result.

In Vivo Validation of Patient-Specific Pressure Gradient Calculations for Iliac Artery Stenosis Severity Assessment

Background

Currently, the decision to treat iliac artery stenoses is mainly based on visual inspection of digital subtraction angiographies. Intra‐arterial pressure measurements can provide clinicians with accurate hemodynamic information. However, pressure measurements are rarely performed because of their invasiveness and the time required. Therefore, the aim of the study was to test the feasibility of a computational model that can predict translesional pressure gradients across iliac artery stenoses on the basis of imaging data only.

Methods and Results

Patients (N=21) with symptomatic peripheral arterial disease and a peak systolic velocity ratio between 2.5 and 5.0 were included in the study. Patients underwent per‐procedural 3‐dimensional rotational angiography and hyperemic intra‐arterial translesional pressure measurements. Vascular anatomical features were reconstructed from the 3‐dimensional rotational angiography data into an axisymmetrical 2‐dimensional computational mesh, and flow was estimated on the basis of the stenosis geometry. Computational fluid dynamics were performed to predict the pressure gradient and were compared with the measured pressure gradients. A good agreement by overlapping error bars of the predicted and measured pressure gradients was found in 21 of 25 lesions. Stratification of the stenosis on the basis of the predicted pressure gradient into hemodynamic not significant (<10 mm Hg) and hemodynamic significant (≥10 mm Hg) resulted in sensitivity, specificity, and overall predictive values of 95%, 60%, and 88%, respectively.

Conclusions

The feasibility of the patient‐specific computational model to predict the hyperemic translesional pressure gradient over iliac artery stenosis was successfully tested. Presented results suggest that, with further optimization and corroboration, the model can become a valuable aid to the diagnosis of equivocal iliac artery stenosis.

Clinical Trial Registration

URL: http://www.trialregister.nl. Unique identifier: NTR5085.

Lipoprotein(a) as a predictor of poor collateral circulation in patients with chronic stable coronary heart disease

As a mechanism compensating for obstructive coronary artery disease, coronary collateral circulation (CCC) has attracted cardiologists for a long time to explore its potential impact. In the present study, Chinese patients suffering from ≥95% coronary stenosis, as diagnosed by angiography, have been investigated for the correlation between CCC and lipoprotein(a) [Lp(a)] levels. A cohort of 654 patients was divided into four categories according to Rentrop grades 0, 1, 2, and 3. Lp(a) levels were divided into model 1, discretized with critical values of 33 and 66%, and model 2, discretized with a cutoff value of 30.0 mg/dL. Furthermore, we evaluated the correlation between CCC and serum Lp(a) levels. The four groups had significantly different Lp(a) levels (25.80±24.72, 18.99±17.83, 15.39±15.80, and 8.40±7.75 mg/dL; P<0.001). In model 1, concerning R0, the risk in the third Lp (a) tertile (OR=3.34, 95%CI=2.32-4.83) was greater than that in the first tertile. In model 2, concerning R0, the risk in Lp(a) >30.0 group (OR=6.77, 95%CI=4.44-10.4) was greater than that of Lp(a) <30.0 mg/dL. The worst condition of CCC can be predicted independently by Lp(a) levels. In addition to clinical usage, Lp(a) levels can also be utilized as biological markers.

The correlation between lymphocyte/monocyte ratio and coronary collateral circulation in stable coronary artery disease patients

AIM

Coronary collateral circulation (CCC) has an important impact on cardiovascular prognosis and well-developed CCC is associated with better clinical outcomes. We investigated whether lymphocyte/monocyte ratio (LMR) has an association with CCC in patients with stable coronary artery disease (SCAD).

METHODS

The study population consisted of 245 patients with SCAD. Patients were classified into a poor CCC group (Rentrop grades 0/1, n = 87), or good CCC group (Rentrop grades 2/3, n = 158).

RESULTS

LMR values were significantly higher in patients with good CCC than in those with poor CCC (4.41 ± 1.58 vs 2.76 ± 1.10; p < 0.001). In receiver operating characteristic analysis, optimal cutoff of LMR for predicting well-developed CCC was 3.38. In multivariate analysis, LMR >3.38 (OR 4.637; p = 0.004), high sensitivity C-reactive protein (OR 0.810, p < 0.001), dyslipidemia (OR 2.485; p = 0.039), and presence of chronic total occlusion (OR 16.836; p < 0.001) were independent predictors of well-developed CCC.

CONCLUSION

Increased LMR predicts well-developed CCC in SCAD patients.

Therapy of unstable angina with the low molecular weight heparins

Unstable angina is in most cases caused by partial or complete coronary artery occlusion due to the disruption of an atherosclerotic plaque and to thrombus formation. An immediate antithrombotic approach is essential to prevent fatal and non-fatal myocardial infarction, and the combination of aspirin and unfractionated heparin has played a pivotal role in the past years. Low molecular weight heparins have improved pharmacokinetic and pharmaco-dynamic properties over unfractionated heparin that have resulted in greater efficacy and safety in the field of venous thromboembolism. Low molecular weight heparins can be administered by once or twice daily subcutaneous injections at fixed, weight-adjusted doses without the need for monitoring. Because of their potential, many recent clinical trials have evaluated their efficacy and safety in the management of patients with unstable angina. Three low molecular weight heparins have so far been tested: nadroparin, dalteparin and enoxaparin. The results of the published trials confirm that the newer compounds are at least as safe and effective as unfractionated heparin, and offer considerable therapeutic advantages. Nevertheless, the different properties of the three compounds and perhaps the different designs of the clinical trials have led to not entirely comparable findings.

Determinants of human coronary collaterals

The human coronary collateral circulation is prognostically relevant. The understanding of collateral formation and its determinants may guide future therapeutic strategies aiming at promoting collateral growth and functionality, and hence reducing the global burden of coronary artery disease (CAD).

Epicardial adipose tissue is related to coronary collateral vessel formation in patients with acute coronary syndrome

OBJECTIVES

Epicardial adipose tissue (EAT) is the ectopic fat surrounding the heart, and it may contribute to coronary collateral vessel (CCV) formation. We aimed to evaluate the association of EAT with the presence of CCV in patients with acute coronary syndrome (ACS).

DESIGN

A total of 230 patients with ACS were included. The CCVs were graded according to the Rentrop scoring system, and a Rentrop grade 0-1 was accepted as low-grade CCV group, Rentrop grade 2-3 was accepted as high-grade CCV group.

RESULTS

According to angiography, 70 (30%) patients constituted the high-grade CCV group and 160 (70%) constituted the low-grade CCV group. The high-grade CCV group had thicker EAT than the low-grade CCV group (6.1 ± 1.4 vs. 5.3 ± 1.4 mm; p = 0.001). Multivariate logistic regression analysis showed that presence of CCV was independently associated with EAT thickness, ejection fraction, presenting with ST-segment elevation myocardial infarction, and presence of angina on admission. EAT thickness of > 5.7 mm can independently predict high-grade CCV with 73% sensitivity and 69% specificity (area under the curve or AUC: 0.65; 95% confidence interval or CI: 0.57-0.72).

CONCLUSIONS

EAT thickness on admission was associated with the presence of CCVs in patients with ACS.

The association of plasma vitamin A and E levels with coronary collateral circulation

OBJECTIVE

To investigate if plasma levels of vitamin A and E have an association with coronary collateral development.

METHODS

A total of 189 patients who underwent coronary angiography and had total occlusion in at least one major epicardial coronary artery were enrolled in the study. To classify coronary collateral circulation (CCC), the Rentrop scoring system was used. Patients were classified as having poor CCC (Rentrop grades 0-1) or good CCC (Rentrop grades 2-3), and all patients were also screened for hypertension, hypercholesterolemia, diabetes, and smoking history.

RESULTS

There were no differences in plasma vitamin A and E levels between the two groups (vitamin A: 2.37 ± 0.65 vs. 2.35 ± 0.78, p = 0.253; vitamin E: 47.1 ± 12.8 vs. 44.6 ± 15.1, p = 0.082), and plasma vitamin A and E levels were not associated with CCC. Serum high-sensitivity C-reactive protein (hs-CRP) levels were significantly higher in patients with poor CCC (4.68 ± 2.52 vs. 3.89 ± 1.78, p = 0.001). The higher frequency of diabetes and higher serum hs-CRP levels were found to be an independent predictor for poor CCC (odds ratio = 2.44, p = 0.006; odds ratio = 1.24, p = 0.007, respectively). And a higher frequency of total occluded RCA was found to be a positive predictor for good CCC (odds ratio = 2.36, p = 0.06) in a multivariate logistic regression analysis.

CONCLUSIONS

We found that serum hs-CRP levels, presence of diabetes, and total occlusion of RCA have an effect on coronary collateral development. We found no correlation between plasma vitamin A and E levels and CCC.

Absence of a 'smoker's paradox' in field triaged ST-elevation myocardial infarction patients undergoing percutaneous coronary intervention

PURPOSE

The 'smoker's paradox' refers to the observation of favorable prognosis in current smokers following an acute myocardial infarction (AMI). Initial positive findings were in the era of fibrinolysis, with more contemporary studies finding conflicting results. We sought to determine the presence of a 'smoker's paradox' in a cohort of ST Elevation Myocardial Infarction (STEMI) patients identified via field triage, treated with primary percutaneous coronary intervention (pPCI).

METHODS

This was a single center retrospective cohort study identifying consecutive STEMI patients presenting for pPCI via field triage. The primary end points were all cause mortality, major adverse cardiac events (MACE), major bleeding, in-hospital cardiac arrest and length of stay (LOS).

RESULTS

A total of 382 patients were included in the study. Current smokers were more likely to be younger (p<0.00001), male (p<0.001) and have fewer comorbidities, including renal impairment (p<0.01) and a history of AMI (p<0.05). Current smokers also had a shorter ischemic time (p<0.05), were less likely to have collateral circulation (p<0.05), and more likely to have signs of pulmonary edema at presentation (p<0.05). There was no difference between smoking groups and all cause mortality (p=0.67), MACE (p=0.49), major bleeding (p=0.49) or in-hospital cardiac arrest (p=0.43). Current smokers had a shorter LOS (p<0.05). In multivariate analysis smoking status did not correlate with primary outcomes.

CONCLUSION

The 'smoker's paradox' does not appear to be relevant among STEMI patients undergoing pPCI, identified via field triage. The previously documented 'smoker's paradox' may have been an indication of patient characteristics and the historical treatment of STEMI with thrombolysis. Further studies with larger numbers may be warranted.

Cardioprotection by placenta-derived stromal cells in a murine myocardial infarction model

BACKGROUND

Autologous cells for cell therapy of ischemic cardiomyopathy often display age- and disease-related functional impairment, whereas an allogenic immunotolerant cell product would allow off-the-shelf application of uncompromised donor cells. We investigated the cardiac regeneration potential of a novel, clinical-grade placenta-derived human stromal cell product (PLX-PAD).

METHODS

PLX-PAD cells derived from human donor placentas and expanded in a three-dimensional bioreactor system were tested for surface marker expression, proangiogenic, anti-inflammatory, and immunomodulatory properties in vitro. In BALB/C mice, the left anterior descending artery was ligated and PLX-PAD cells (n = 10) or vehicle (n = 10) were injected in the infarct border zone. Four weeks later, heart function was analyzed by two-dimensional and M-mode echocardiography. Scar size, microvessel density, extracellular matrix composition, myocyte apoptosis, and PLX-PAD cell retention were studied by histology.

RESULTS

In vitro, PLX-PAD cells displayed both proangiogenesis and anti-inflammatory properties, represented by the secretion of both vascular endothelial growth factor and angiopoietin-1 that was upregulated by hypoxia, as well as by the capacity to suppress T-cell proliferation and augment IL-10 secretion when co-cultured with peripheral blood mononuclear cells. Compared with control mice, PLX-PAD-treated hearts had better contractile function, smaller infarct size, greater regional left ventricular wall thickness, and less apoptosis after 4 wk. PLX-PAD stimulated both angiogenesis and arteriogenesis in the infarct border zone, and periostin expression was upregulated in PLX-PAD-treated hearts.

CONCLUSIONS

Clinical-grade PLX-PAD cells exert beneficial effects on ischemic myocardium that are associated with improved contractile function, and may be suitable for further evaluation aiming at clinical pilot trials of cardiac cell therapy.

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.

The association between impaired collateral circulation and non-alcoholic fatty liver in patients with severe coronary artery disease

BACKGROUND AND PURPOSE

Coronary collateral circulation (CCC) has been demonstrated to be impaired in patients with type 2 diabetes mellitus which is characterized by insulin resistance. In this study, our purpose was to find out a possible relationship between CCC and non-alcoholic fatty liver disease (NAFLD), which is also characterized by insulin resistance, in non-diabetic patients with severe coronary artery disease.

METHODS

One hundred and fifty-one consecutive non-diabetic patients with stable angina pectoris who were found to have >95% stenosis of at least one major coronary artery were enrolled. Abdominal ultrasonography (USG) was performed after coronary angiography to determine the presence or absence of NAFLD.

RESULTS

According to Cohen-Rentrop method, 81 (53.7%) patients had good and 70 (46.3%) patients had poor collateral development. NAFLD was present in 98 patients (64.9% of study population) and more prevalent in patients with poor collateral development [58 of 70 patients (82.9%) vs. 40 of 81 patients (49.4%), p<0.001]. Mean Rentrop collateral score was significantly lower in patients with NAFLD (1.2±1.2 vs. 2.1±0.9, p<0.001). Shorter angina time, metabolic syndrome, presence of insulin resistance, less severe coronary artery disease, and female sex were also associated with poor collateral development. When the logistic regression analysis was performed using these factors, NAFLD was still significantly related to poor collateral development.

CONCLUSIONS

Presence of NAFLD is associated with poor coronary collateral development in non-diabetic patients with severe coronary artery disease independent from other variables, especially metabolic syndrome and insulin resistance. Which mechanisms play role in this association is needed to be cleared with further studies.

Plasma chemokine levels are associated with the presence and extent of angiographic coronary collaterals in chronic ischemic heart disease

BACKGROUND

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.

METHODOLOGY/PRINCIPAL FINDINGS

We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).

CONCLUSIONS/SIGNIFICANCE

Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment.

Manual versus nonmanual thrombectomy in primary and rescue percutaneous coronary angioplasty

Although many thrombectomy devices have been tested in ST-segment elevation acute myocardial infarction (STEMI), there are no comparative data on safety or effectiveness in thrombectomy or ST-segment resolution. This study compares manual versus nonmanual thrombectomy devices in patients undergoing primary or rescue percutaneous coronary intervention in a tertiary care center. We identified 232 consecutive patients with STEMI and time from symptom onset to emergency room contact of < or = 12 h undergoing percutaneous coronary intervention with coronary thrombectomy devices. Primary end point was ST-segment resolution of > or = 70%. Several angiographic, procedural and clinical secondary end points were also evaluated. The manual thrombectomy group included 110 patients and the nonmanual group 122 patients. Both groups were similar in their clinical characteristics. The primary end point occurred with similar frequency in patients treated with manual versus nonmanual thrombectomy (67.9% vs 60.0%, P = 0.216). No significant differences were found in the two groups with regard to procedural complications, angiographic reperfusion parameters, in-hospital major adverse cardiac events, or infarct size, whereas manual thrombectomy was associated with a better left ventricle ejection fraction at discharge. Furthermore, treatment with a manual thrombectomy device was associated with significantly shorter procedural times (69 min vs 95 min, P < 0.001) and lower procedural costs (2981 euros vs 7505 euros, P < 0.001). The use of manual thrombus-aspiration catheters appeared equivalent to nonmanual thrombectomy devices in the setting of primary or rescue percutaneous intervention in terms of clinical efficacy, and led to shorter procedures and cost savings.

Role of endothelial progenitor cells during ischemia-induced vasculogenesis and collateral formation

Cell-based therapy has emerged as a promising therapeutic tool for treatment of ischemic cardiovascular disease. Both unselected bone marrow-derived mononuclear cells (BMNCs), which include stem/progenitor cells and several other cell types, and endothelial progenitor cells (EPCs), a subpopulation of BMNCs, display regenerative potential in ischemic tissue. Abundant evidence supports the involvement of EPCs in capillary growth, and EPCs also appear to participate in the formation of collateral vessels. Collectively, these effects have led to improved perfusion and functional recovery in animal models of myocardial and peripheral ischemia, and in early clinical trials, the therapeutic administration of EPCs to patients with myocardial infarction or chronic angina has been associated with positive trends in perfusion. EPCs also contribute to endothelial repair and may, consequently, impede the development or progression of arteriosclerosis. This review provides a brief summary of the preclinical and clinical evidence for the role of EPCs in blood-vessel formation and repair during ischemic cardiovascular 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.

Metabolic syndrome and collateral vessel formation in patients with documented occluded coronary arteries: association with hyperglycaemia, insulin-resistance, adiponectin and plasminogen activator inhibitor-1

Aims

The metabolic syndrome (MS) is associated with an increased cardiovascular risk. Patients with the MS have endothelial dysfunction, decreased circulating adiponectin, and a high expression of angiogenic inhibitors such as plasminogen activator inhibitor-1 (PAI-1). We hypothesized that such patients, in the event of a coronary occlusion, might exhibit a less developed collateral circulation.

Methods and results

Three hundred and eighty-seven consecutive patients with at least one coronary occlusion of a major coronary vessel at diagnostic angiography were prospectively enrolled. Collateral development was graded with validated angiographic methods. The MS was defined according to the ATP-III definition. Fasting glucose, adiponectin, insulin concentrations, and PAI-1 were measured at the time of angiography. MS was associated with less developed collateral vessels (P = 0.005). In multivariable analysis adjusting for potential confounding factors including the duration of coronary occlusion (P = 0.0001), fasting glycaemia (P = 0.0007), low adiponectin concentration (P = 0.01), insulin-resistance (HOMA-IR; P = 0.01), high circulating PAI-1 concentration (P = 0.01), and hypertension (P = 0.008) were independently associated with poor coronary collateral vessel development.

Conclusion

This study shows that in patients with coronary occlusion, collateral circulation is impaired in patients with the MS. This association is partly related to fasting glycaemia and to key parameters linked to insulin resistance.

High serum levels of adiponectin improve coronary collateral development in patients with coronary artery disease

Adiponectin is a novel polypeptide that modulates endothelial function. Association between high serum adiponectin level and stimulation of new blood vessel formation have been reported in two experimental studies, however, data in humans are lacking. We sought to determine relationship between serum adiponectin and collateral vessel development in patients with coronary artery disease. We included 89 patients with stable angina pectoris and angiographically documented total occlusion in one of the major coronary arteries. Coronary collateral circulation was graded according to Rentrop scoring method in which collateralisation was graded between 0 and 3 from the poorest to the best. Adiponectin was determined by the ELISA method. High serum adiponectin level were significantly associated with increased new collateralisation (p = 0.001). With the increase of body mass index and waist circumference, the collateral development decreased (p = 0.001, p = 0.002; respectively). Presence of the diabetes mellitus (DM) was more frequent in those with poor collateral group than in those with good collateral group. DM was associated with poor collateral development (p = 0.002). In multiple stepwise logistic regression analysis, low level of serum adiponectin (p = 0.0001), waist circumference (p = 0.001), and presence of DM (p = 0.003) were found to be significant independent predictors of poor collateral formation. In conclusion, we have shown for the first time that elevated levels of serum adiponectin are associated with coronary collateral development in patients with coronary artery disease and additionally, the present study confirms many of the metabolic associations reported previously with adiponectin.

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.

Collateral blood flow between left coronary artery bypass grafts and chronically occluded right coronary circulation in patients with triple vessel disease. Observations during complete revascularisation of beating hearts

OBJECTIVE

Preoperative measurements of collateral blood flow in patients with triple vessel disease and chronic occlusions of the right coronary artery do not, currently, ascertain the need to revascularise an occluded right coronary artery. We performed direct measurements of flow across left coronary bypass grafts to determine their contributions to collateral blood flow.

METHODS

Collateral blood flow was scored preoperatively according to Rentrop in 13 patients with triple vessel disease and chronic occlusions of the right coronary artery who underwent complete, off-pump, surgical revascularisation. The transit-time flow through the left coronary grafts was measured before and after unclamping of the right coronary artery bypass graft.

RESULTS

Unclamping of the right coronary artery bypass graft was associated with a 5.9+/-6.9ml/min (mean+/-SD) decrease in flow across the left circumflex territory (P=0.009), which was proportional to the preoperative Rentrop score (P=0.007). No significant change was observed in flow across the graft to the left anterior descending artery.

CONCLUSIONS

Grafts to the left circumflex system are the only grafts that supply a significant, albeit modest amount of collateral blood flow to chronically occluded right coronary artery. These observations confirm that (1) most collateral flow after revascularisation is supplied by the native network, and (2) revascularisation of an occluded right coronary artery is fully justified.

High mortality after coronary bypass surgery in patients with high-grade left main coronary artery stenosis

OBJECTIVE

To determine mortality after coronary artery bypass grafting (CABG) in relation to degree of left main coronary artery (LMCA) obstruction.

DESIGN

All patients without LMCA stenosis (n=3370), with low-grade stenosis (n = 261), high-grade stenosis (n = 224) or total occlusion of the LMCA (n = 15) were followed for ten years after CABG performed during 1970-1989.

RESULTS

Early mortality was 1.9% and 2.3%, respectively, if there was no or a low-grade LMCA stenosis vs. 6.3% if the stenosis was high-grade. Ten-year survival was 76% if no LMCA obstruction, 74% if low-grade stenosis and 64% if the stenosis was high-grade. Risk of early death (odds ratio 2.6, 95% CI 1.4-4.8) and mortality at ten years (relative risk 1.5, 95% CI 1.1-2.0) was higher in patients with high-grade stenosis than in those without LMCA stenosis. There was no increased long-term mortality in patients with low-grade stenosis or among the few patients with occlusion of the LMCA.

CONCLUSIONS

High-grade LMCA stenosis was associated with a three-fold increased risk of early and fifty percent higher risk of late death than in patients without LMCA stenosis.

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.

Serum level of lipoprotein (a) is inversely associated with the development of coronary collateral circulation

BACKGROUND

This study sought to determine the relationship between serum lipoprotein (a) levels and angiographically visible coronary collateral circulation and to evaluate whether lipoprotein (a) exerts any effect on vascular endothelial cell growth factor.

METHODS

The study population included 60 patients (39 men, mean age 59+/-13 years) with angiographically documented total occlusion in one of the major coronary arteries. Development of collaterals was classified by Rentrop's method. Patients were defined as having poorly developed collaterals for grades 0 and 1 (group 1), or well-developed collaterals for grades 2 and 3 (group 2). Serum lipoprotein (a) and vascular endothelial cell growth factor levels were determined by enzyme-linked immunosorbent assay.

RESULTS

In group 1, lipoprotein (a) levels were significantly higher and vascular endothelial cell growth factor levels were significantly lower than in group 2 (34+/-19 vs. 20+/-12 mg/dl, P<0.001, and 2.5+/-0.7 vs. 3.4+/-0.8 ng/dl, P<0.001, respectively). Poorly developed collaterals were significantly more frequent in patients with lipoprotein (a) levels >or=30 mg/dl than in patients with levels <30 mg/dl (72 vs. 37%, P=0.008). A strong negative correlation was observed between lipoprotein (a) and vascular endothelial cell growth, factor (r=-0.708, P<0.0001). Multivariate analysis revealed that a high level of lipoprotein (a) negatively affected the development of collaterals, whereas the duration of angina had a positive effect.

CONCLUSION

This study demonstrated for the first time that the high level of lipoprotein (a) negatively affects the formation of coronary collateral vessels in human beings. Reduced production or bioactivity of vascular endothelial cell growth factor caused by high levels of lipoprotein (a) may be the possible responsible mechanisms of hyperlipoprotein (a)-related poor collateral formation.

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.

Early time course of myocardial electrical impedance during acute coronary artery occlusion in pigs, dogs, and humans

Changes in myocardial electrical impedance (MEI) and physiological end points have been correlated during acute ischemia. However, the importance of MEI's early time course is not clear. This study evaluates such significance, by comparing the temporal behavior of MEI during acute total occlusion of the left anterior descending coronary artery in anesthetized humans, dogs, and pigs. Here, interspecies differences in three MEI parameters (baseline, time to plateau onset, and plateau value normalized by baseline) were evaluated using Kruskal-Wallis ANOVA and post hoc tests ( P < 0.05). Noteworthy differences in the MEI time to plateau onset were observed: In dogs, MEI ischemic plateau was reached after 46.3 min (SD 12.9) min of occlusion, a significantly longer period compared with that of pigs and humans [4.7 (SD 1.2) and 4.1 min (SD 1.9), respectively]. However, no differences could be observed between both animal species regarding the normalized MEI ischemic plateau value (15.3% (SD 4.7) in pigs, vs. 19.6% (SD 2.6) in dogs). For all studied MEI parameters, only swine values resembled those of humans. The severity of myocardial supply ischemia, resulting from coronary artery occlusion, is known to be dependent on collateral flow. Thus, because dogs possess a well-developed collateral system (unlike humans or pigs), they have shown superior resistance to occlusion of a coronary artery. Here, the early MEI time course after left anterior descending coronary artery occlusion, represented by the time required to reach ischemic plateau, was proven to reflect such interspecies differences.

Novel index of coronary collateral development as a useful predictor of clinical outcome in type 2 diabetic patients with coronary artery disease

BACKGROUND

There is a paucity of information regarding the impact of the coronary collaterals on prognosis in type 2 diabetic (T2DM) patients. We developed a novel index, which considers not only the degree of collateral circulation but also the stimulus of collateral development, and investigated its prognostic value in T2DM patients with coronary artery disease (CAD).

METHODS AND RESULTS

One hundred and ninety four consecutive T2DM patients were analyzed and followed for an average of 30 months. We measured the diameter stenosis (DS; %), corrected TIMI frame count (CTFC) and Rentrop score at 3 major epicardial coronary arteries. The collateral development (CD) score was calculated by: (Sigma Rentrop score +1)/Sigma [DS (%) x CTFC] x1,000. During the follow-up, acute cardiovascular events occurred in 49 patients. By multivariate analysis, the CD score was an independent predictor of adverse events not only in the total population (p<0.001), but in all 3 subgroups (p=0.020 for coronary artery bypass grafting, p=0.030 for percutaneous transluminal coronary angioplasty (PTCA) and p=0.003 for the medical group). Furthermore, patients in the tertile with the highest CD score showed improved survival by Kaplan-Meier analysis in the total population, the PTCA and the medical group.

CONCLUSIONS

The CD score, a novel index of collateral development, may be a useful predictor of clinical outcome in T2DM patients with CAD.

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.

Recent insights into human coronary collateral development

Enhancement of coronary collateral function is an intriguing approach to the preservation of ischaemic myocardium. Coronary collateral development consists of collateral recruitment and collateral growth. Collateral growth encompasses proliferation of capillaries in the ischaemic area (angiogenesis) and maturation of pre-existing collateral vessels (arteriogenesis), with the latter being more relevant in humans. Therefore, treatment intended directly for arteriogenesis of collateral vessels appears to be more effective. Promotion of coronary collateral growth has many attractive features, particularly in patients with angina who are not indicated for percutaneous coronary intervention or coronary artery bypass grafting surgery. A complete elucidation of the remaining practical and mechanistic questions of arteriogenesis may lead to a new remedy capable of developing collateral vessels more effectively.

Assessment of left ventricular systolic and diastolic function by doppler tissue imaging in patients with preinfarction angina

BACKGROUND

The aim of this study was assessment of left ventricular (LV) systolic and diastolic function by pulsed wave Doppler tissue imaging (DTI) in patients with or without preinfarction angina in acute myocardial infarction.

METHODS

We prospectively evaluated 31 consecutive patients (4 women, 27 men; age 58 +/- 10 years) with a first acute myocardial infarction. LV systolic and diastolic function was assessed by classic methods and DTI on the third day during acute myocardial infarction. Patients were divided into 2 groups according to the presence (group 1; n = 10) or absence (group 2; n = 21) of preinfarction angina. Mitral inflow velocities and early diastolic mitral annular velocity (Em), late diastolic mitral annular velocity (Am), peak systolic mitral annular velocity, Em/Am, the ratio of early diastolic mitral inflow velocity (E) to Em, and myocardial performance index were calculated by DTI.

RESULTS

Group 1 had significantly higher Em and Em/Am than group 2 (11.3 +/- 3.34 cm/s vs 7.4 +/- 2.07 cm/s, P <.0001; 1.01 +/- 0.38 cm/s vs 0.6 +/- 0.2 cm/s, P =.001, respectively). The E/Em ratio and myocardial performance index were significantly lower in group 1 than in group 2 (5.1 +/- 2.92 vs 8.10 +/- 3.15, P=.018; 0.49 +/- 0.15 vs 0.65 +/- 0.24, P =.042, respectively). Wall-motion score index was lower in those with preinfarction angina than in those without (1.6 +/- 0.36 vs 1.9 +/- 0.39; P =.04, respectively). Peak systolic mitral annular velocity and Am were not statistically different between groups (9.4 +/- 1.84 vs 8.3 +/- 2.03, P =.172; 11.7 +/- 3.07 vs 12.1 +/- 3.34, P =.72, respectively). There were no significant differences between the 2 groups regarding transmitral E velocity, atrial contraction mitral inflow velocity (A), E/A ratio, isovolumetric relaxation time, and deceleration time of the mitral E wave (P =.91, P =.08, P =.58, P =.81, and P =.71, respectively).

CONCLUSION

LV diastolic function was better in patients with preinfarction angina than in patients without. This condition could not be detected by conventional mitral inflow Doppler velocities, but could be detected by DTI. This preliminary evidence shows that DTI is better than conventional mitral Doppler indices in the assessment of a favorable LV diastolic function in patients with preinfarction angina.

Do clinical and angiographic parameters predict failure of medical therapy in patients suitable for coronary angioplasty?

AIMS

Recent studies have suggested that patients with coronary disease suitable for angioplasty have an equally good outcome with medical therapy if clinically stable. Complex lesion morphology may predict acute events without intervention and stenosis severity influences the degree of collateralisation. This study was designed to assess the influence of these factors on clinical outcome.

METHODS AND RESULTS

A retrospective review of patients suitable for angioplasty who were randomised to initial medical therapy as part of a multicentre study. Angiograms were reviewed for lesion characteristics, TIMI flow grade, and degree of collateralisation. Angiograms were available on 79 patients (13 female, 66 male). Mean age was 54.8 years (range 43-68) in the group crossing-over to revascularisation, and 58.4 (range 37-78) in the group who did not (P=ns). Seventeen patients crossed-over (two to CABG, 15 to PTCA) at 5.4 months (range 0-10) after initial angiography. Disease progression had occurred in 10/17 patients (58.8%), three of whom developed a new occlusion. Collateralisation was more likely in smokers, independent of lesion severity (P<0.05). Time to cross-over was not influenced by progression of disease. Crossing-over was not affected by age, diabetic status, cholesterol level, vessel involved, lesion severity, TIMI flow, lesion morphology, collateralisation, or the number of vessels diseased, but was more likely in females (P<0.05).

CONCLUSION

This group of patients generally does well with medical therapy. Whilst the numbers are relatively small, there does not appear to be any reliable prospective marker, including the presence of spontaneous collateral channels on diagnostic angiography, to indicate which patients will fail medical therapy and require revascularisation.

Shunt between the ventricular chamber and coronary arteries preserves left ventricular function in acute myocardial infarction

It is controversial whether newly created channels made by transmyocardial laser revascularization are functionally significant, so the present study evaluated the shunt flow from the left ventricular (LV) cavity to the ischemic myocardium in 51 patients with acute myocardial infarction (AMI) caused by complete occlusion of the proximal left anterior descending coronary artery. All patients underwent left heart catheterization within 24 h of onset and all underwent successful coronary reperfusion using primary coronary angioplasty with no angiographic restenosis on follow-up coronary angiography (CAG). The presence of the LV shunt flow was evaluated by selective left CAG after successful reperfusion. The LV global ejection fraction (EF) and regional function (centerline method) were analyzed by ventriculography in both the acute and chronic phases. The patients were divided into the 3 groups (Group A, no LV shunt without collaterals, n=20; Group B, no LV shunt with collaterals, n=24; Group C, LV shunt with collaterals, n=7). There was no difference in the grade of collateral circulation between Groups B and C. The improvements in LVEF and regional function from the acute phase to the chronic phase were significantly greater in Group C than in Groups A and B. Not only collateral circulation but also LV shunt contributes to the functional recovery of infarct myocardium in patients with AMI.

Coronary collateralization: determinants of adequate distal vessel filling after arterial occlusion

BACKGROUND

The protective effect of collateral vessels in coronary artery disease (CAD) is well established. Little is known, however, about factors that influence collateral formation.

METHODS

We studied the coronary angiograms of 200 consecutive patients with single-vessel coronary artery occlusion. Patients were excluded if obstructive stenoses were present in other vessels or if prior revascularization had been undertaken. Collateral circulation to the occluded artery was graded as 'poor' (no or incomplete filling) or 'rich' (complete filling). Patient characteristics, including mode of presentation, medications and CAD risk factors, were assessed.

RESULTS

Positive univariate correlates of rich collaterals included increasing age [odds ratio (OR) 1.03, P = 0.016], 'statin' use (OR 2.50, P = 0.005), nitrate use (OR 1.96, P = 0.034), calcium-channel blocker (CCB) use (OR 4.07, P < 0.001), presentation with stable angina (OR 2.34, P = 0.006), longer time since diagnosis of CAD (OR 1.12, P = 0.002) and history of hyperlipidemia (OR 3.55, P < 0.001). Significantly poorer collateralization was observed in the setting of acute myocardial infarction (MI) (OR 0.23, P < 0.001), diabetes mellitus (OR 0.33, P = 0.003), impaired left ventricular function (OR 0.64, P = 0.015) and occlusion of the left anterior descending coronary artery (LAD) (OR 0.28, P < 0.001). On multivariate analysis, rich collateralization was associated with hyperlipidemia (P = 0.003) and CCB use (P = 0.028). Independent predictors of poor collaterals were presence of diabetes (P < 0.001), LAD occlusion (P = 0.001) and presentation with acute MI (P = 0.017).

CONCLUSION

Diabetes mellitus, occlusion of the LAD and presentation with acute MI are independently associated with poor distal vessel collateralization, whereas hyperlipidemia and use of CCBs are associated with rich collateralization. Factors determining coronary collateral formation may in turn influence outcomes after coronary artery occlusion.

Plasma level of homocysteine is inversely-associated with the development of collateral circulation in patients with single-vessel coronary artery disease

Homocysteine induces endothelial injury and inhibits endothelial cell proliferation, which is a key role in angiogenesis. The purpose of this study was to investigate whether the plasma level of homocysteine is associated with the development of collaterals in patients with single-vessel coronary artery disease (CAD). Among a series of 105 male patients with angiographic estimation, 49 with single-vessel CAD were intensively investigated. Development of collaterals was classified by Rentrop's method. Univariate and multivariate analyses revealed that hyperhomocysteinemia negatively affected the development of collaterals (p=0.0015 and 0.0011, odds ratio 0.69, 95% confidence interval 0.52-0.90), whereas the duration of angina and percent stenosis evaluated by quantitative coronary angiography had a positive affect. Moreover, the level of homocysteine in the group with poorly developed collaterals (n=7, Rentrop class 0 and 1) was significantly higher than that in the group with well-developed collaterals (n=12, Rentrop class 2 and 3) of the patients with single-vessel disease showing total occlusion (p=0.034). This study clearly demonstrates that the plasma level of homocysteine is independently and inversely associated with the development of collateral circulation in CAD patients. Homocysteine might be a new undesirable aspect of ischemic heart disease through its inhibition of collateral development.

Time course and extent of collateral channel recruitment during coronary angioplasty

OBJECTIVES

To assess the extent and timing of recruitment of collateral channels during coronary angioplasty in patients without spontaneous collaterals at diagnostic angiography.

SETTING

The extent of collateral channel recruitment during coronary angioplasty is variable and its contribution to myocardial protection is not well established. The functional significance of collaterals recruited during balloon occlusion remains in question.

PATIENTS

Collateral channels were assessed in 16 patients by contralateral injection at 30, 60 and 90 s into each of four 90 s inflations and by a 0.014 " Doppler guide wire distal to the lesion.

RESULTS

Angiographic collateral recruitment was evident in 11 out of 16 patients (71%), but in only four (24%) by intracoronary Doppler. Grade I collaterals were present in seven patients, grade II in three and grade III in two. Collaterals were evident angiographically by 30 s in 10 out of 11 patients, with no progressive recruitment during subsequent inflations. In the four patients with Doppler evidence of collateral flow there were no differences in any flow velocity parameters with successive inflations. There was no difference in either maximum ST segment shift or time to 2 mm ST segment elevation between successive inflations.

CONCLUSIONS

Collateral channel recruitment is variable between patients and appears maximal early in the first inflation. The lack of incremental recruitment of collaterals together with low or absent evidence of flow by Doppler wire suggests that these channels do not make a major contribution to myocardial protection in this setting.

Frequency distribution of collateral flow and factors influencing collateral channel development. Functional collateral channel measurement in 450 patients with coronary artery disease

OBJECTIVES

We sought to determine the pathogenetic predictors of collateral channels in a large cohort of patients with coronary artery disease (CAD).

BACKGROUND

The frequency distribution of collateral flow in patients with CAD is unknown. Only small qualitative studies have investigated which factors influence the development of collateral channels.

METHODS

In 450 patients with one- to three-vessel CAD undergoing percutaneous transluminal coronary angioplasty (PTCA), collateral flow was measured. A collateral flow index (CFI; no unit) expressing collateral flow relative to normal anterograde flow was determined using coronary wedge pressure or Doppler measurements through sensor-tipped PTCA guide wires. Frequency distribution analysis of CFI and univariate and multivariate analyses of 32 factors, including gender, age, patient history, cardiovascular risk factors, medication and coronary angiographic data, were performed.

RESULTS

Two-thirds of the patients had a CFI < 0.25 and approximately 40% of patients had a CFI < 0.15, but only approximately 10% of the patients had a recruitable CFI > or =0.4. By univariate analysis, the following were predictors of CFI > or =0.25: high levels of high-density lipoprotein cholesterol, the absence of previous non-Q-wave myocardial infarction, angina pectoris during an exercise test, angiographic indicators of severe CAD and the left circumflex or right coronary artery as the collateral-receiving vessel. Percent diameter stenosis of the lesion undergoing PTCA was the only independent predictor of a high CFI.

CONCLUSIONS

This large clinical study of patients with CAD in whom collateral flow was quantitatively assessed reveals that two-thirds of the patients do not have enough collateral flow to prevent myocardial ischemia during coronary occlusion, and that coronary lesion severity is the only independent pathogenetic variable related to collateral flow.

Washout collaterometry: a new method of assessing collaterals using angiographic contrast clearance during coronary occlusion

OBJECTIVE

To investigate the hypothesis that the time to washout of radiographic contrast medium trapped distal to an occluded collateral receiving vessel is inversely related to collateral flow, and that this provides an accurate method for characterising coronary collaterals.

METHODS

An intracoronary pressure derived collateral flow index was determined in 54 patients undergoing percutaneous transluminal coronary balloon angioplasty (PTCA). The study group was subdivided according to whether the collateral vessels were sufficient (n = 17) or insufficient (n = 37) to prevent ECG signs of myocardial ischaemia during PTCA. Washout collaterometry-an angiographic washout method-was carried out simultaneously; after injection of radiographic contrast medium into the collateral receiving vessel followed immediately by vascular occlusion, the number of heart beats was counted until approximately half the length of the epicardial vessel was cleared of contrast.

RESULTS

The collateral flow index was higher (0.28 (0.09) v 0.12 (0.07); p < 0.0001) and the contrast washout time shorter (8.0 (2.9) v 17.5 (6.7) heart beats; p < 0.0001) in patients with sufficient versus insufficient collaterals. There was an inverse correlation between contrast washout time and collateral flow index (r = 0.72, p < 0.0001). Washout of contrast distal to the occluded vessel within 11 heart beats correctly determined sufficient and insufficient collaterals with 88% sensitivity and 81% specificity.

CONCLUSIONS

Washout collaterometry is a new radiographic contrast washout method based on the inverse relation between collateral flow and the time to clearance of radiographic dye injected into the ipsilateral vessel during PTCA. It appears to be an accurate method of characterising coronary collateral vessels.

Influence on collateral flow of recanalising chronic total coronary occlusions: a case-control study

OBJECTIVE

To assess the effect of recanalisation on collateral flow in a case-control study in patients with and without chronic total coronary occlusions.

DESIGN

In 54 patients undergoing percutaneous transluminal coronary angioplasty (PTCA) (mean (SD) age 61 (6) years), coronary collateral flow was measured by intracoronary pressure or Doppler guide wires at the end of repeated balloon occlusions. Coronary collateral flow index (collateral flow relative to normal antegrade flow) during the first two balloon inflations in 27 patients with a chronic total occlusion (occlusion group) was compared with that of 27 patients matched for age, sex, and collateral flow index at the first occlusion and with a coronary artery diameter stenosis </= 80% (stenosis group).

RESULTS

Following revascularisation, collateral flow index decreased in 17 of the patients in the occlusion group (63%) and in eight of the patients in the stenosis group (30%) (p = 0.03 between groups). The overall change of collateral flow index between the first and the second balloon occlusion was -0.04 (0.01) in the occlusion group (p = 0.07 for paired comparison; from 0.29 (0.17) to 0.25 (0.14)), and +0.02 (0.06) in the stenosis group (p = 0.06 for paired comparison; from 0.27 (0.13) to 0.30 (0.15)). The trend to collateral enhancement in the stenosis group differed significantly from the occlusion group (p = 0.01).

CONCLUSIONS

While repeated coronary balloon occlusions induce collateral recruitment in the majority of patients with moderate stenoses, recanalisation of chronic total coronary occlusions is more often associated with collateral flow reduction. A later decrease in collateral flow by involution of collateral channels cannot be excluded by this study but has not been reported so far.

Angiotensin-converting enzyme inhibition is associated with reduced troponin release in non-ST-elevation acute coronary syndromes

OBJECTIVES

This study was done to determine the effects of angiotensin-converting enzyme (ACE) inhibition and other clinical factors on troponin release in non-ST-elevation acute coronary syndrome (ACS).

BACKGROUND

Troponin is now widely used as a marker of risk in ACS, but determinants of its release have not been defined.

METHODS

This was a prospective cohort study of 301 consecutive patients admitted with non-ST-elevation ACS. Baseline clinical data were recorded, ACE gene polymorphism was determined and serial blood samples were obtained for troponin-I assay.

RESULTS

Significant troponin-I release (>0.1 microg/l) was detected in 93 (31%) patients. Pretreatment with ACE inhibitors, recorded in 53 patients (17.6%), independently reduced the odds of troponin-I release (odds ratio 0.25; 95% confidence intervals 0.10 to 0.64) and was associated with lower maximum troponin-I concentrations (median [interquartile range]) compared with patients not pretreated with ACE inhibitors (0.44 microg/l [0.19 to 2.65 microg/l] vs. 4.18 microg/l [0.91 to 12.41 microg/l], p = 0.01). Pretreatment with aspirin, recorded in 173 patients (57.5%), did not significantly reduce the odds of troponin-I release after adjustment but was associated with lower maximum troponin-I concentrations compared with patients not pretreated with aspirin (2.31 microg/l [0.72 to 8.02 microg/l] vs. 5.85 microg/l [1.19 to 12.79 microg/l], p = 0.05). The ACE genotyping (n = 268) showed 81 patients (30%) DD homozygous and 77 (29%) II homozygous. There was no association between ACE genotype and troponin release.

CONCLUSIONS

We conclude that ACE inhibition reduces troponin release in non-ST-elevation ACS. This is likely to be mediated by the beneficial effects of treatment on vascular reactivity and the coagulation system.

Effect of preinfarction angina pectoris on outcome in patients with acute myocardial infarction treated with primary angioplasty (results from the Myocardial Infarction Registry

Preinfarction angina is associated with better clinical outcome in patients with acute myocardial infarction (AMI) who receive intravenous thrombolysis. This has not been proved in patients with AMI treated with primary angioplasty. We analyzed the data of the prospective multicenter Myocardial Infarction Registry (MIR). Of 14,440 patients with AMI, 774 with a prehospital delay of < or =12 hours were treated with primary angioplasty. Five hundred thirty-two patients (68.7%) had preinfarction angina. Patients with preinfarction angina were slightly older than patients without (63 vs 62 years, p = 0.042), prehospital delay was 1 hour longer (180 vs 120 minutes, p = 0.001), and arterial hypertension was more prevalent (47.6% vs 32.2%, odds ratio [OR] 1.91, 95% confidence intervals [CI] 1.39 to 2.62). There was no significant difference in hospital mortality (5.6% vs 3.3%, OR 1.75, 95% CI 0.79 to 3.87), reinfarction, stroke, or the combined end point of death, reinfarction, or stroke between the 2 groups. Logistic regression analysis showed no association of preinfarction angina with the occurrence of either death (OR 2.21, 95% CI 0.91 to 6.08) or the combined end points (OR 1.10, 95% CI 0.55 to 2.31). There was also no significant difference in mortality (6% vs 5.1%, OR 1.19, 95% CI 0.56 to 2.52), reinfarction, stroke, postinfarction angina, or the combined end points between patients with preinfarction angina within 48 hours compared with patients with preinfarction angina between 49 hours and 4 weeks before the AMI. Thus, the MIR data showed no protective effects of preinfarction angina in patients with AMI treated with primary angioplasty.

Influence of clinical and angiographic factors on development of collateral channels

BACKGROUND

The degree of coronary collateralization is believed to be related to several clinical and angiographic factors. The duration and frequency of angina may be important factors in determining development of collateral channels.

OBJECTIVE

To assess these factors for a consecutive series of patients suspected to have coronary artery disease.

METHODS

Patients without at least one stenosis of < 50% and patients who had previously undergone bypass surgery were excluded from our study. Severity of stenosis was quantified by digital analysis, antegrade flow in terms of TIMI grade, and collaterals using the Rentrop classification.

RESULTS

We reviewed 106 patients [mean age 61 years (range 35-84), 77.6% men]. Of these, 22 (21%) had presented with an acute coronary syndrome on this admission, whilst 46 patients (43%) had previously had an acute coronary syndrome. Collaterals were more likely in patients with stenoses of > 90% (Spearman correlation 0.65, P < 0.001) in patients with lower than normal TIMI flow grade (Spearman correlation 0.86, P < 0.01) and were related to regions of hypokinesis (Spearman correlation 0.35, P < 0.01). Significant collaterals were present in 14 patients (13%) despite their having TIMI grade II/III flow. Two of these patients had grade 2/3 collaterals with TIMI grade II/III antegrade flow. Degree of collateralization was not related to chronicity and frequency of symptoms, age, risk factors for atherosclerosis and nature of presentation (i.e. acute or stable symptoms).

CONCLUSION

The likelihood of coronary collateralization cannot be prospectively predicted from clinical history alone, but appears to be largely a function of severity of stenosis and level of antegrade flow. A few patients develop high-grade collateral channels despite the presence of good antegrade flow.

Effects of metabolically ischemic, but viable, myocardium on QT dispersion in patients with acute myocardial infarction: a study with resting I-123-BMIPP/thallium-201 myocardial single-photon emission computed tomography

In chronic Q-wave myocardial infarction, QT dispersion is closely correlated with infarct size, but this correlation has not been evaluated for acute myocardial infarction (AMI). The effects of abnormal fatty acid metabolism on QT dispersion were examined in 123 patients with AMI who underwent resting iodine-123-15-iodophenyl 3-methyl pentadecanoic acid (BMIPP)/thallium-201(201Tl) myocardial single photon emission computed tomography (SPECT) and electrocardiographic analysis in the subacute phase. The relationship between BMIPP and 201Tl was defined as match when the total defect score for BMIPP was equal to or smaller than that for 201Tl, and as mismatch when the total defect score for BMIPP was larger than that for 201Tl. Twenty-six patients (21%) demonstrated BMIPP-201Tl match and 97 (79%) demonstrated mismatch. Infarct size was closely correlated with QT dispersion (r=0.67, p<0.001) in patients with BMIPP-201Tl match, but weakly correlated (r=0.30, p<0.005) in patients with BMIPP-201Tl mismatch. For small infarctions, QT dispersion was significantly larger in patients with BMIPP-201Tl mismatch than in those with BMIPP-201Tl match (62+/-24 ms vs 41+/-18 ms, p=0.03), but did not differ between the 2 groups for large infarctions. This study shows that QT dispersion is influenced by infarct size and by the presence of metabolically ischemic but viable myocardium in patients with AMI.

Degree of residual stenosis in the culprit coronary artery after thrombolytic administration (Thrombolysis In Myocardial Infarction [TIMI] trials)

This study was undertaken to characterize residual stenosis after thrombolytic administration and to evaluate clinical and angiographic features and early outcomes of patients with mild residual obstruction after thrombolytic administration. Patients who underwent angiography at 90 minutes after thrombolytic administration in the Thrombolysis In Myocardial Infarction 4, 10A, 10B, and 14 trials were divided into 3 groups according to the degree of residual stenosis measured by quantitative coronary angiography: patients with a patent culprit artery with <50% stenosis, patients with patent arteries and residual stenosis > or =50%, and patients with occluded arteries. Only 8.9% of the patients (188 of 2,119) had an infarct-related artery luminal diameter stenosis of <50% 90 minutes after thrombolysis. Compared with patients with patent arteries and > or =50% stenosis, patients with mild residual obstruction were younger (56.8 vs 58.6 years; p = 0.03), had fewer prior myocardial infarctions (6.9% vs 13.3%; p = 0.01), fewer eccentric (19.8% vs 42.1%; p <0.0001), ulcerated (7.5% vs 13.2%; p = 0.03), and collateralized (6.6% vs 13.2%, p = 0.01) lesions, but a greater thrombus burden (29.7% vs 18.3%, p = 0.0002). Among patients with patent arteries, a residual stenosis of <50% was associated with a significantly lower composite of in-hospital death, myocardial infarction, and congestive heart failure (2.8% vs 7.1%, p = 0.03). Thus, a minority of patients have a mild residual obstruction at 90 minutes after thrombolytic administration. These patients have less complex lesions with greater thrombus burdens and better clinical outcomes.

Functional significance of recruitable collaterals during temporary coronary occlusion evaluated by 99mTc-sestamibi single-photon emission computerized tomography

OBJECTIVES

The present study evaluated the impact of recruitable collaterals on regional myocardial perfusion measured by 99mtechnetium (Tc)-sestamibi single-photon emission computerized tomography (SPECT) during temporary coronary occlusion and related these estimates to the coronary wedge pressure and electrocardiographic (ECG) ST-segment changes.

BACKGROUND

Clinical variables (angina and ECG changes) and intracoronary flow and pressure recordings have indicated a protective role of recruitable collaterals on myocardial perfusion during percutaneous transluminal coronary angioplasty (PTCA).

METHODS

Thirty patients (mean age 55 years, SD 9; 20 men) with stable angina pectoris and proximal nonocluding single-vessel left anterior descending coronary artery (LAD)-stenosis scheduled for PTCA were included. Visualization of recruitable collaterals by ipsilateral and contralateral contrast injection, registration of coronary wedge pressure and injection of 99mTc-sestamibi during 90-s LAD occlusions were undertaken. A rest perfusion study was performed within four days before PTCA. As an estimate of the severity of regional hypoperfusion during occlusion, an occlusion/rest count ratio was calculated (mean defect pixel count during occlusion divided by mean pixel count in identical regions at rest).

RESULTS

The scintigraphic occlusion/rest count ratio was higher in patients with recruitable collaterals (n = 16), 67 +/- 11%, compared to patients without collaterals (n = 14), 60 +/- 6% (p < 0.05). The occlusion/rest count ratio correlated with the coronary wedge pressure (R2 = 0.34; p < 0.001). The occlusion/rest count ratio was lower, 61 +/- 6%, in patients with ST-segment elevation (n = 23) versus 74 +/- 9% in patients without ST-segment elevation (n = 7) (p < 0.0001).

CONCLUSIONS

Using 99mTc-sestamibi SPECT imaging during brief episodes of coronary occlusion, the severity of regional myocardial hypoperfusion was reduced by the presence of recruitable collaterals in a selected patient population with proximal LAD stenoses. Our results demonstrate a protective effect of recruitable collaterals on myocardial perfusion during temporary coronary occlusion.