Collateral function in chronic total coronary occlusions is related to regional myocardial function and duration of occlusion

miR-34a/SIRT1/HIF-1α axis is involved in cardiac angiogenesis of type 2 diabetic rats: The protective effect of sodium butyrate combined with treadmill exercise

Type 2 diabetes mellitus (T2DM) is one of the most common metabolic disorders worldwide. Recent research has indicated that sodium butyrate (NaB) affects glucose metabolism and exercise has an anti-hyperglycemic effect in diabetes. This study aimed to evaluate the effects of NaB and treadmill exercise on heart angiogenesis through the miR-34a/SIRT1/FOXO1-HIF-1α pathway. Diabetic animals received NaB (400 mg/kg daily, orally) and treadmill exercise for 6 weeks. The effect of NaB and treadmill exercise, alone or combined, on miR-34a expression, SIRT1, FOXO1, HIF-1α levels, and angiogenesis in diabetic heart tissue was measured. Diabetes caused increased miR-34a (p < 0.01) and FOXO1 (p < 0.001) expression levels. Also, SIRT1 (p < 0.001) and HIF-1α (not significant) expression levels were reduced in diabetic rats. NaB and treadmill exercise decreased miR-34a (respectively p < 0.05 and not significant) and FOXO1 (both p < 0.001) expression levels and improved SIRT1 (both not significant) and HIF-1α (respectively p < 0.01 and p < 0.001) levels. Also, NaB combined with treadmill exercise decreased miR-34a (p < 0.001) and FOXO1 (p < 0.001) expression levels, and elevated SIRT1 (p < 0.05) and HIF-1α (p < 0.001) levels in comparison with the diabetic group. NaB and treadmill exercises modulate the expression of miR-34a and the levels of SIRT1, FOXO1, and HIF-1α proteins, thus increasing angiogenesis in the heart tissue of diabetic rats. It can be concluded that NaB and treadmill exercise, alone or combined, may be useful in the treatment of diabetes through the miR-34a/SIRT1/FOXO1-HIF-1α pathway.

The Relationship Between Coronary Collateral Circulation and Serum Adropin Levels

Objective Coronary collateral circulation (CCC) are vascular structures that limit the infarct area, protect left ventricular function, and reduce the frequency of arrhythmia and mortality during myocardial ischemia and infarction. In this study, we examined the relationship between the development of CCC and serum adropin levels, which has been shown in previous studies to regulate endothelial functions and increase endothelial nitric oxide synthesis, in patients with acute myocardial infarction. Methods This study included 41 patients with insufficient CCC and 43 patients with well-developed CCC who were hospitalized for acute myocardial infarction and underwent coronary angiography. The Cohen-Rentrop classification was used to grade the CCC. The patients were divided into two groups according to Rentrop grades: those with a 0-1 stage were considered as insufficient and those with grades of 2-3 were considered as well-developed CCC. We took blood samples to measure the adropin levels within the first 24 hours of hospitalization. Results The mean age was 59.1±11.9 years and 62 (73.8%) were male. The right coronary artery was the most frequently target vessel (n: 51, 60.7%), and the majority of the patients presented with ST-segment elevation myocardial infarction (STEMI) (n:58, 69%). The median interval between the severe chest pain and the intervention was significantly higher in patients with well-developed CCC (p=0.042). The serum adropin levels in patients with insufficient CCC were significantly lower than in those with well-developed CCC (196.3 [131.5 - 837.0] pg/mL vs. 235.5 [171.9 - 1124.2] pg/mL, p<0.001). Logistic regression analysis revealed that the circumflex artery as the target vessel, NSTEMI (non-STEMI) as the type of myocardial infarction, and serum adropin level were the independent risk factors for the prediction of poor coronary collateral vessel formation (p<0.05). Conclusions In this study, we found that in patients with acute myocardial infarction, those with well-developed CCC had higher adropin levels.

Cytokine storm: behind the scenes of the collateral circulation after acute myocardial infarction

At least 17 million people die from acute myocardial infarction (AMI) every year, ranking it first among causes of death of human beings, and its incidence is gradually increasing. Typical characteristics of AMI include acute onset and poor prognosis. At present, there is no satisfactory treatment, but development of coronary collateral circulation (CCC) can be key to improving prognosis. Recent research indicates that the levels of cytokines, including those related to promoting inflammatory responses and angiogenesis, increase after the onset of AMI. In the early phase of AMI, cytokines play a vital role in inducing development of collateral circulation. However, when myocardial infarction is decompensated, cytokine secretion increases greatly, which may induce a cytokine storm and worsen prognosis. Cytokines can regulate the activation of a variety of signal pathways and form a complex network, which may promote or inhibit the establishment of collateral circulation. We searched for published articles in PubMed and Google Scholar, employing the keyword "acute myocardial infarction", "coronary collateral circulation" and "cytokine storm", to clarify the relationship between AMI and a cytokine storm, and how a cytokine storm affects the growth of collateral circulation after AMI, so as to explore treatment methods based on cytokine agents or inhibitors used to improve prognosis of AMI.

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.

Biological aspects in controlling angiogenesis: current progress

All living beings continue their life by receiving energy and by excreting waste products. In animals, the arteries are the pathways of these transfers to the cells. Angiogenesis, the formation of the arteries by the development of pre-existed parental blood vessels, is a phenomenon that occurs naturally during puberty due to certain physiological processes such as menstruation, wound healing, or the adaptation of athletes' bodies during exercise. Nonetheless, the same life-giving process also occurs frequently in some patients and, conversely, occurs slowly in some physiological problems, such as cancer and diabetes, so inhibiting angiogenesis has been considered to be one of the important strategies to fight these diseases. Accordingly, in tissue engineering and regenerative medicine, the highly controlled process of angiogenesis is very important in tissue repairing. Excessive angiogenesis can promote tumor progression and lack of enough angiogensis can hinder tissue repair. Thereby, both excessive and deficient angiogenesis can be problematic, this review article introduces and describes the types of factors involved in controlling angiogenesis. Considering all of the existing strategies, we will try to lay out the latest knowledge that deals with stimulating/inhibiting the angiogenesis. At the end of the article, owing to the early-reviewed mechanical aspects that overshadow angiogenesis, the strategies of angiogenesis in tissue engineering will be discussed.

Correlation of serum Vascular Endothelial growth factor (VEGF) and cardiovascular risk factors on collateral formation in patients with acute coronary artery syndrome

Coronary collaterals serve as an alternative source of blood flow in obstructive coronary heart disease. Coronary collateral development by releasing various angiogenic growth factors, including vascular endothelial growth factor-A (VEGF-A). Cardiovascular risk factors strongly associated with coronary artery disease include age, sex, elevated serum cholesterol, disturbed carbohydrate metabolism, and elevated blood pressure. A better understanding of the effects of these cardiovascular risk factors and serum VEGF-A level on collateral recruitment is necessary for a better prognosis in coronary artery diseases and new insight for further therapeutic promotion of coronary collaterals.220 consecutive patients undergoing coronary angiography with a mean age of 61 ± 9.83 were selected for the analysis. Two millilitres of blood were taken from the patients for analysis. The blood serum VEGF concentration was quantified via the ELISA method. Angiograms and other clinical reports were collected. Significant coronary artery disease was diagnosed in those with ≥ 70% of stenosis in at least one of the coronary arteries. The angiographic and clinical data were documented. The collateral grading was done according to the Rentrop Scoring system. The serum vascular endothelial growth factor level was correlated with the collateral score and cardiovascular risk factors like age, sex, type ll diabetes, blood pressure, and cholesterol level. An increase in the level of the collateral score was noted with an increase in the level of VEGF in blood serum. A significant association was founded between serum VEGF level and cardiovascular risk factors on collateral formation in patients with diabetes and hypertension. This article is protected by copyright. All rights reserved.

Ischemic Burden Assessment Using Single Photon Emission Computed Tomography in Single Vessel Chronic Total Occlusion of Coronary Artery

BACKGROUND AND OBJECTIVES

Studies evaluating the nature of ischemic burden of chronic total occlusion (CTO) vessels are still lacking.

METHODS

A total of 165 patients with single vessel CTO >2.5 mm in an epicardial coronary artery who underwent single photon emission computed tomography (SPECT) were enrolled in the study. Ischemic burden was calculated with the use of semi-quantitative SPECT analysis, and was defined as the summed difference score (SDS) divided by the maximal limit of the score (=SDS/68).

RESULTS

The mean age of the participants was 59.5 years and the CTO of the left anterior descending coronary artery (LAD), left circumplex coronary artery (LCX), and right coronary artery (RCA) accounted for 93 (56.4%), 18 (10.9%), and 54 (32.7%) patients, respectively. The median ischemic burden of the total population was 8.8%, and it was highest in the LAD CTO (10.3%) compared with the LCX (5.9%) and RCA CTO (5.9%, p<0.001). High-ischemic burden (ischemic burden >10%) was observed in 66 patients (40.0%), and in 47 patients (50.5%) of the LAD CTO. Ischemic burden was different according to the CTO location only in LAD CTO. The statistically significant predictors for high-ischemic burden were hypertension, baseline ejection fraction >45%, LAD CTO, proximal CTO location, and de novo CTO. Japanese-CTO score and Rentrop scale collateral grade were not associated with high-ischemic burden.

CONCLUSIONS

Only 40% of patients with single vessel CTO had ischemic burden >10%. For CTO vessels, measurement of ischemic burden using SPECT prior to revascularization may be helpful in identifying beneficial subjects.

The effect of aerobic exercise on the expression of mir-126 and related target genes in the endothelial tissue of the cardiac muscle of diabetic rats

BACKGROUND

The aim of this study was to investigate the effect of 8 weeks of aerobic exercise on the expression of mir-126 and some angiogenesis factors in the endothelial tissue of the cardiac muscle of type 2 diabetic rats.

METHODS

Sixteen male Wistar rats were divided into two groups: diabetic control and diabetic training. Nicotinamide and streptozotocin injections were used to induce type 2 diabetes. After familiarization, the training group participated in an 8-week exercise protocol on a treadmill with an intensity of 25 m per minute, a slope of 5% and 30 min per session. RT-PCR was used to evaluate the expression of mir-126 and PI3K genes. Expression of raf1, VEGF, blood glucose and insulin was determined by ELISA and insulin resistance was assessed by HOMA-IR homeostasis model. Immunohistochemistry was used to measure the capillary density of the cardiac muscle. Data were analyzed by t-test for independent groups with a significance level of p < 0.05.

RESULTS

Diabetes reduces angiogenesis in cardiac tissue, which is associated with a significant reduction in the expression of mir-126, raf1, VEGF and PI3K; while aerobic exercise increased the expression of mir-126, raf1, PI3K, VEGF. Exercise also decreased blood glucose levels and insulin resistance.

CONCLUSION

It seems that aerobic exercise can prevent the destructive effects of diabetes by activating the angiogenic pathway of cardiac tissue. Therefore, regulatory processes through mir-126, which are influenced by aerobic exercise, can be a valuable strategy in developing new treatments for diabetes.

Association between the triglyceride glucose index and coronary collateralization in coronary artery disease patients with chronic total occlusion lesions

Background

Recent studies have substantiated the role of the triglyceride glucose (TyG) index in predicting the prognosis of coronary artery disease (CAD) patients, while no relevant studies have revealed the association between the TyG index and coronary collateralization in the event of coronary chronic total occlusion (CTO). The current study intends to explore whether, or to what extent, the TyG index is associated with impaired collateralization in CAD patients with CTO lesions.

Methods

The study enrolled 1093 CAD patients undergoing cardiac catheterization for at least one CTO lesion. Data were collected from the Beijing Anzhen Hospital record system. The degree of collaterals was determined according to the Rentrop classification system. The correlation between the TyG index and coronary collateralization was assessed.

Results

Overall, 318 patients were included in a less developed collateralization (Rentrop classification 0-1) group. The TyG index was significantly higher in patients with impaired collateralization (9.3±0.65 vs. 8.8±0.53, P<0.001). After adjusting for various confounding factors, the TyG index remained correlated with the occurrence of impaired collateralization, with odds ratios (ORs) of 1.59 and 5.72 in the T2 and T3 group compared with the first tertile group (P<0.001). In addition, subgroup analysis showed that higher TyG index values remained strongly associated with increased risk of less developed collateralization. To compare the risk assessment efficacy for the formation of collateralization between the TyG index and other metabolic abnormality indicators, an area under the receiver-operating characteristic (ROC) curve (AUC) was obtained. A significant improvement in the risk assessment performance for impaired collateralization emerged when adding the TyG index into a baseline model.

Conclusions

The increased TyG index is strongly associated with less developed collateralization in CAD patients with CTO lesions and its risk assessment performance is better than single metabolic abnormality indicators.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12944-021-01574-x.

Coronary Microvascular Dysfunction

Many patients with chest pain undergoing coronary angiography do not show significant obstructive coronary lesions. A substantial proportion of these patients have abnormalities in the function and structure of coronary microcirculation due to endothelial and smooth muscle cell dysfunction. The coronary microcirculation has a fundamental role in the regulation of coronary blood flow in response to cardiac oxygen requirements. Impairment of this mechanism, defined as coronary microvascular dysfunction (CMD), carries an increased risk of adverse cardiovascular clinical outcomes. Coronary endothelial dysfunction accounts for approximately two-thirds of clinical conditions presenting with symptoms and signs of myocardial ischemia without obstructive coronary disease, termed "ischemia with non-obstructive coronary artery disease" (INOCA) and for a small proportion of "myocardial infarction with non-obstructive coronary artery disease" (MINOCA). More frequently, the clinical presentation of INOCA is microvascular angina due to CMD, while some patients present vasospastic angina due to epicardial spasm, and mixed epicardial and microvascular forms. CMD may be associated with focal and diffuse epicardial coronary atherosclerosis, which may reinforce each other. Both INOCA and MINOCA are more common in females. Clinical classification of CMD includes the association with conditions in which atherosclerosis has limited relevance, with non-obstructive atherosclerosis, and with obstructive atherosclerosis. Several studies already exist which support the evidence that CMD is part of systemic microvascular disease involving multiple organs, such as brain and kidney. Moreover, CMD is strongly associated with the development of heart failure with preserved ejection fraction (HFpEF), diabetes, hypertensive heart disease, and also chronic inflammatory and autoimmune diseases. Since coronary microcirculation is not visible on invasive angiography or computed tomographic coronary angiography (CTCA), the diagnosis of CMD is usually based on functional assessment of microcirculation, which can be performed by both invasive and non-invasive methods, including the assessment of delayed flow of contrast during angiography, measurement of coronary flow reserve (CFR) and index of microvascular resistance (IMR), evaluation of angina induced by intracoronary acetylcholine infusion, and assessment of myocardial perfusion by positron emission tomography (PET) and magnetic resonance (CMR).

Collaterals in STEMI patients: An uncommon but critical lifeline

Angiographically visible collaterals are seen in a minority of STEMI patients, predominantly to the RCA and in patients with delays to reperfusion. Patients with visible collaterals were less likely to have cardiogenic shock and tended to have a longer survival. Further studies will determine the mechanisms of collateral formation and their protective associations.

Cardioprotection during ischemia by coronary collateral growth

Ischemic heart diseases (IHD) cause millions of deaths around the world annually. While surgical and pharmacological interventions are commonly used to treat patients with IHD, their efficacy varies from patient to patient and is limited by the severity of the disease. One promising, at least theoretically, approach for treating IHD is induction of coronary collateral growth (CCG). Coronary collaterals are arteriole-to-arteriole anastomoses that can undergo expansion and remodeling in the setting of coronary disease when the disease elicits myocardial ischemia and creates a pressure difference across the collateral vessel that creates unidirectional flow. Well-developed collaterals can restore blood flow in the ischemic area of the myocardium and protect the myocardium at risk. Moreover, such collaterals are correlated to reduced mortality and infarct size and better cardiac function during occlusion of coronary arteries. Therefore, understanding the process of CCG is highly important as a potentially viable treatment of IHD. While there are several excellent review articles on this topic, this review will provide a unified overview of the various aspects related to CCG as well as an update of the advancements in the field. We also call for more detailed studies with an interdisciplinary approach to advance our knowledge of CCG. In this review, we will describe growth of coronary collaterals, the various factors that contribute to CCG, animal models used to study CCG, and the cardioprotective effects of coronary collaterals during ischemia. We will also discuss the impairment of CCG in metabolic syndrome and the therapeutic potentials of CCG in IHD.

Five-Year Outcomes of Successful Percutaneous Coronary Intervention with Drug-Eluting Stents versus Medical Therapy for Chronic Total Occlusions

PURPOSE

Many recent studies have reported that successful percutaneous coronary intervention (PCI) with drug-eluting stents (DESs) for chronic total occlusion (CTO) has more beneficial effects than failed CTO-PCI; however, there are only limited data available from comparisons of successful CTO-PCI with medical therapy (MT) in the Korean population.

MATERIALS AND METHODS

A total of 840 consecutive CTO patients who underwent diagnostic coronary angiography, receiving either PCI with DESs or MT, were enrolled. Patients were divided into two groups according to the treatment assigned. To adjust for potential confounders, propensity score matching (PSM) analysis was performed using logistic regression. Individual major clinical outcomes and major adverse cardiac events, a composite of total death, myocardial infarction (MI), stroke, and revascularization, were compared between the two groups up to 5 years.

RESULTS

After PSM, two propensity-matched groups (265 pairs, n=530) were generated, and the baseline characteristics were balanced. Although the PCI group showed a higher incidence of target lesion and vessel revascularization on CTO, the incidence of MI tended to be lower [hazard ratio (HR): 0.339, 95% confidence interval (CI): 0.110 to 1.043, p=0.059] and the composite of total death or MI was lower (HR: 0.454, 95% CI: 0.224 to 0.919, p=0.028), compared with the MT group up to 5 years.

CONCLUSION

In this study, successful CTO PCI with DESs was associated with a higher risk of repeat PCI for the target vessel, but showed a reduced incidence of death or MI.

Defining the prognosis of chronic total occlusions during primary percutaneous coronary intervention

BACKGROUND

The influence of coexisting collateral circulation between chronic total occlusion (CTO) and infarct-related artery (IRA) in patients with acute ST segment elevation myocardial infarction (STEMI) remains unclear. We aimed to investigate the impact of coexisting collateral circulation between CTO and IRA on early clinical outcomes in patients with acute STEMI.

METHODS

A total of 1488 consecutive acute STEMI patients who underwent primary percutaneous coronary intervention were prospectively included in the study. After restoration of antegrade flow, the patients who had coexisting CTO and collateral supply from IRA were defined as the CTO-IRA-related (CIR) group (n=56). Patients with coexisting CTO but with no collateral supply from IRA were defined as the CTO-IRA-unrelated (CIUR) group (n=104). Patients without coexisting CTO were defined as the non-CTO group (n=1328).

RESULTS

Compared with the CIUR and non-CTO groups, the CIR group was significantly associated with higher Killip class of at least 2 (P<0.001) at presentation, a lower rate of postprocedural thrombolysis in myocardial infarction 2/3 flow (P<0.001), and myocardial perfusion grade 3 (P<0.001). Moreover, the CIR group had significantly higher in-hospital (P<0.001) and 30-day mortality (P<0.001). On multivariate regression analysis, the CIR group (odds ratio=15.96, 95% confidence interval=4.94-51.54; P<0.001) as well as age, post-PCI TIMI, Killip and NT-proBNP levels were independently associated with 30-day mortality. However, the CIUR group was not an independent predictor of early clinical outcomes.

CONCLUSION

After restoration of antegrade flow, coexisting CTO supplied by IRA collaterals has unfavourable effects on procedural success, enzymatic infarct size and postprocedural haemodynamic conditions. These collaterals are also independent predictors of 30-day mortality in acute STEMI patients.

Which Coronary Lesions Are More Prone to Cause Acute Myocardial Infarction?

Background

According to common belief, most myocardial infarctions (MIs) are due to the rupture of nonsevere, vulnerable plaques with < 70% obstruction. Data from recent trials challenge this belief, suggesting that the risk of coronary occlusion is, in fact, much higher after severe stenosis. The aim of this study was to investigate whether or not acute ST-elevation MIs result from high-grade stenoses by evaluating the presence of coronary collateral circulation (CCC).

Methods

We retrospectively included 207 consecutive patients who had undergone primary percutaneous coronary intervention for acute ST-elevation MI. Collateral blood flow distal to the culprit lesion was assessed by two investigators using the Rentrop scoring system.

Results

Out of the 207 patients included in the study, 153 (73.9%) had coronary collateral vessels (Rentrop 1-3). The Rentrop scores were 0, 1, 2, and 3 in 54 (26.1%), 50 (24.2%), 51 (24.6%), and 52 (25.1%) patients, respectively. Triglycerides, mean platelet volume (MPV), white cell (WBC) count, and neutrophil count were significantly lower in the group with good collateral vessels (p = 0.013, p = 0.002, p = 0.003, and p = 0.021, respectively).

Conclusion

More than 70% of the patients with acute MI had CCC with Rentrop scores of 1-3 during primary coronary angiography. This shows that most cases of acute MI in our study originated from underlying high-grade stenoses, challenging the common believe. Higher serum triglycerides levels, greater MPV, and increased WBC and neutrophil counts were independently associated with impaired development of collateral vessels.

Collateral Circulation in Chronic Total Occlusions – an interventional perspective

Human coronary collaterals are inter-coronary communications that are believed to be present from birth. In the presence of chronic total occlusions, recruitment of flow via these collateral anastomoses to the arterial segment distal to occlusion provide an alternative source of blood flow to the myocardial segment at risk. This mitigates the ischemic injury. Clinical outcome of coronary occlusion ie. severity of myocardial infarction/ischemia, impairment of cardiac function and possibly survival depends not only on the acuity of the occlusion, extent of jeopardized myocardium, duration of ischemia but also to the adequacy of collateral circulation. Adequacy of collateral circulation can be assessed by various methods. These coronary collateral channels have been used successfully as a retrograde access route for percutaneous recanalization of chronic total occlusions. Factors that promote angiogenesis and further collateral remodeling ie. arteriogenesis have been identified. Promotion of collateral growth as a therapeutic target in patients with no suitable revascularization option is an exciting proposal.

Correlation of Angina Pectoris and Perfusion Decrease by Collateral Circulation in Single-Vessel Coronary Chronic Total Occlusion Using Myocardial Perfusion Single-Photon Emission Computed Tomography

PURPOSE

To evaluate the perfusion decrease in donor myocardium by collateral circulation and its correlation with angina pectoris in patients with chronic total occlusion (CTO) using myocardial perfusion single-photon emission computed tomography (MPS).

MATERIALS AND METHODS

Thirty-six patients with single-vessel CTO without any other stenosis were included. All patients underwent MPS and coronary angiography (CAG) within 2 months. Total 72 donor arteries were evaluated for the grades of collaterals to the CTO artery using the Rentrop grading system on CAG. Perfusion defects and perfusion scores in donor and CTO territories were analyzed on MPS. Myocardial perfusion of donor and CTO territories were evaluated according to the presence of angina pectoris and the grades of collateral circulation.

RESULTS

When the CTO territory was ischemic, symptomatic patients showed higher summed difference scores in the CTO territory compared to asymptomatic patients (3.5 ± 2.4 vs. 1.5 ± 0.8 for symptomatic and asymptomatic groups respectively; p = 0.034). However, when the CTO territory was nonischemic, symptomatic patients showed higher summed stress scores (SSS, 4.3 ± 2.9 vs. 1.6 ± 1.2; p = 0.032) and summed rest scores (SRS, 4.2 ± 2.5 vs. 1.5 ± 1.1; p = 0.003) in the donor territories. On the per-vessel analysis, perfusion defects in donor territories were more frequent (0 % vs. 53 % vs. 86 % for Rentrop 0, Rentrop 1-2 and Rentrop 3, respectively; p < 0.001) and showed higher SSS (0.0 ± 0.0, 1.3 ± 1.6 and 2.1 ± 1.1 for Rentrop 0, Rentrop 1-2 and Rentrop 3, respectively; p = 0.001) and SRS (0.0 ± 0.0, 1.0 ± 1.4 and 1.7 ± 1.2; p = 0.003) at higher Rentrop grades, but their patterns were variable.

CONCLUSION

Angina pectoris was related to either ischemia of the myocardium beyond CTO or a perfusion decrease in the donor myocardium. The perfusion decrease in donor myocardium positively correlated with the collateral grades.

The role of coronary collaterals in chronic total occlusions

A chronic total occlusion (CTO) describes a completely occluded coronary artery. This type of lesion is found in about 18% of all significant lesions in patients with coronary artery disease. A system of collateral connections are observed in almost all of these lesions, which have the capacity to prevent myocardial necrosis and may even uphold metabolic supply to the territory distal to an occlusion to maintain full contractile capacity. During exercise these collaterals are limited in their functional reserve, and more than 90% of patients with a well collateralized occlusion will experience ischemia. in the absence of ideal animal models that mimic the human collateral circulation, we need to rely on studies in man. The knowledge of collateral physiology in man has increased considerably over the past two decades with the advent of intracoronary sensors of coronary pressure and flow velocity. A number of basic physiologic questions have been answered by these studies. The blood supply through coronary arteries depends on a complex array of in general serial resistance systems, with an additional array of multiple parallel resistances on the collateral level. There seems to be a great interindividual variability in the ability to recruit preformed collateral connections in the case of an epicardial occlusion. Collateral function can develop to a similar functional level in patients post myocardial infarction with large akinetic territories as it does in patients with normal preserved regional function. The presence of viability is thus not a prerequisite for collateral development. The question of practical relevance in the era of interventional therapy of chronic occlusions is also, whether a patient with coronary artery disease will remain protected by collaterals after removing the obstruction in the collateralized artery, or whether collaterals regress and lose their functional capacity. Both developments are observed again mainly depending of individual predisposition.

Significance of a fragmented QRS complex in patients with chronic total occlusion of coronary artery without prior myocardial infarction

Objective:

Fragmented QRS (fQRS) complexes that have numerous RSR´ patterns represent alteration of ventricular depolarization. We evaluated the relationship between fQRS and poor coronary collateral circulation and the diagnostic ability of fQRS for myocardial scar detection in patients with chronic total occlusion (CTO) without a history of myocardial infarction.

Methods:

The study population consisted of patients undergoing coronary angiography with a suspicion of CAD. Seventy-nine patients with one totally occluded major coronary artery were enrolled. Exclusion criteria were history of MI; recent acute coronary syndrome; pathologic Q wave on 12-lead ECG; cardiomyopathy or severe valvular disease; coronary artery bypass surgery or percutaneous coronary angioplasty. Collateral circulation was scored on the basis of Rentrop's classification. All patients were assessed by myocardial perfusion SPECT. Fragmented QRS was characterized as existence of an R´ or R wave or S wave notch in two adjacent leads related to the location of a major coronary artery region. Single and multiple logistic regression analyses were completed in the forward method.

Results:

Forty-nine patients had poor and 30 had well-developed collateral circulation. Fragmented QRS complexes were significantly higher in the poor collateral group (81% vs. 20%, p<0.001). Sensitivity, specificity, and the positive and negative predictive values of fQRS for myocardial scar identification were 89.4%, 87.5%, and 91.3% and 84.8%, respectively. The summed stress score and the summed rest score on SPECT were significantly higher in the poor collateral group than in the well-developed group (p<0.001) as well as in the fQRS group than the non-fQRS group (p<0.001). Logistic regression analysis revealed that the presence of fQRS was significantly and independently associated with poor collateral circulation and myocardial scar in patients with CTO.

Conclusion:

Fragmented QRS is independently related to poor coronary collateral circulation in patients with CTO without prior myocardial infarction. Notably, it can be a good predictor of myocardial scar rather than merely ischemia, with high diagnostic accuracy.

Aberrant phenotype in human endothelial cells of diabetic origin: implications for saphenous vein graft failure?

Type 2 diabetes (T2DM) confers increased risk of endothelial dysfunction, coronary heart disease, and vulnerability to vein graft failure after bypass grafting, despite glycaemic control. This study explored the concept that endothelial cells (EC) cultured from T2DM and nondiabetic (ND) patients are phenotypically and functionally distinct. Cultured human saphenous vein- (SV-) EC were compared between T2DM and ND patients in parallel. Proliferation, migration, and in vitro angiogenesis assays were performed; western blotting was used to quantify phosphorylation of Akt, ERK, and eNOS. The ability of diabetic stimuli (hyperglycaemia, TNF-α, and palmitate) to modulate angiogenic potential of ND-EC was also explored. T2DM-EC displayed reduced migration (~30%) and angiogenesis (~40%) compared with ND-EC and a modest, nonsignificant trend to reduced proliferation. Significant inhibition of Akt and eNOS, but not ERK phosphorylation, was observed in T2DM cells. Hyperglycaemia did not modify ND-EC function, but TNF-α and palmitate significantly reduced angiogenic capacity (by 27% and 43%, resp.), effects mimicked by Akt inhibition. Aberrancies of EC function may help to explain the increased risk of SV graft failure in T2DM patients. This study highlights the importance of other potentially contributing factors in addition to hyperglycaemia that may inflict injury and long-term dysfunction to the homeostatic capacity of the endothelium.

The collateral circulation of the heart in coronary total arterial occlusions in man: systematic review of assessment and pathophysiology

BACKGROUND

Anatomical and functional assessment of the collateral circulation of the heart in total arterial occlusions is challenging, and this is particularly true of the microcirculation. The pathophysiology of the collateral circulation has historically been and remains of considerable research focus but with diverging and sometimes conflicting results. Our purpose was to conduct a systematic review on the assessment and pathophysiology of the collateral circulation of the heart in total coronary arterial occlusions.

METHODS

We extracted data from Pubmed, Ovid, EMBASE, and Cochrane database from 1966 to December 2012. Two investigators independently reviewed the identified articles for eligibility and extracted the data.

RESULTS

Seventy-seven studies met inclusion criterion. An invasive assessment of the collateral circulation with pressure and/or Doppler wires is the gold standard in the assessment of collateral physiology and anatomy, although this can only be undertaken after successful passage of the sensor in the true lumen of the occluded vessel. A collateral circulation can provide resting metabolic requirements for the heart but invariably cannot meet demands on stress irrespective of the degree of collateralization as assessed by coronary angiography. In the case of myocardium subtending a totally occluded epicardial artery coronary collateral grading systems or physiological assessment of collateral flow is only moderately sensitive and poorly specific at predicting viability. Regression of collaterals seems more profound in totally occluded arteries versus nonoccluded lesions postrevascularization.

CONCLUSIONS

Key controversies in the assessment and pathophysiology of the collateral circulation of the heart in total coronary arterial occlusions are systematically evaluated.

The collateral circulation of the heart

The coronary arteries have been regarded as end arteries for decades. However, there are functionally relevant anastomotic vessels, known as collateral arteries, which interconnect epicardial coronary arteries. These vessels provide an alternative source of blood supply to the myocardium in cases of occlusive coronary artery disease. The relevance of these collateral arteries is a matter of ongoing debate, but increasing evidence indicates a relevant protective role in patients with coronary artery disease. The collateral circulation can be assessed by different methods; the gold standard involves intracoronary pressure measurements. While the first clinical trials to therapeutically induce growth of collateral arteries have been unavailing, recent pilot studies using external counterpulsation or growth factors such as granulocyte colony stimulating factor (G-CSF) have shown promising results.

Radial approach and single wiring as first intentional strategies in chronic total occlusions of the left anterior descending coronary artery

BACKGROUND

Percutaneous coronary intervention (PCI) for chronic total occlusion (CTO) of the left anterior descending coronary artery (LAD) specifically is associated with improved long-term 5 years survival as compared to PCI failure. Simpler PCI techniques may be successful and safer than complex techniques which are perceived to have high failure rates and technical complexity. We aimed to describe the safety and effectiveness of first intentional single wiring and radial approach in the treatment of patients with a CTO of the native LAD coronary artery at Toulouse Rangueil university hospitals.

PATIENTS AND METHODS

The study was a single center prospective registry. All patients showed evidence of myocardial viability in LAD territory. The operators' initial strategy was to start by a radial access as a first choice whenever feasible; if not, a femoral access was chosen. The initial strategy for lesion crossing in either antegrade or retrograde approaches was single wiring by lesion crossing using one guidewire (GW) as a simple technique.

RESULTS

A total of 30 patients with 30 LAD CTO lesions (100%) were recorded. Mean age was 71.6 + 15 years, 77% were males and 23% were females. The access route was radial 66% of the time and femoral 54% of the time and with double access for contralateral injection in 40% of the patients. Sheaths and catheters sizes 6F were used in 53% of the patients, and 7F in 73% of the patients. Overall lesion success rate was 83% of lesions. Single wiring was the prevailing technique used in 97% of successful lesions (83% of total cases), while only 3% were by multiple wiring techniques. Successful single antegrade wiring represented 63% of our total study cases with a GW success rate of 92% of cases. Successful single retrograde wiring represented 13% of our cases with a GW success rate of 67%. Q-wave myocardial infarction (MI), stent thrombosis, stroke, emergency coronary artery bypass graft (CABG), major bleeding, radiation dermatitis, cardiac tamponade or clinical perforation requiring any hemostatic maneuvers did not occur. There was a post-procedural Troponin rise of 3x normal levels in 30% of patients, and contrast induced nephropathy in 7%. Intra-aortic balloon counterpulsation (IABCP) was used in 3% of patients and cardiac death occurred in 3% of patients.

CONCLUSION

Single wiring and radial access as initial strategies in PCI for LAD-CTO lesions in either approaches antegrade or retrograde are associated with a high procedural success rate and an acceptable incidences of adverse events.

Endothelial and smooth muscle cells dysfunction distal to recanalized chronic total coronary occlusions and the relationship with the collateral connection grade

OBJECTIVES

This study sought to assess the vascular function in patients with chronic total coronary occlusions (CTO) immediately after successful percutaneous recanalization and its relation with the pre-existing collateral circulation.

BACKGROUND

CTOs represent a long-acting occlusion of a coronary vessel, in which the progressively developed collateral circulation may limit ischemia and symptoms. However, it is unknown if the coronary segment distal to the occlusion has a preserved vascular function.

METHODS

We prospectively enrolled 19 consecutive patients, after percutaneous coronary intervention of a CTO. Luminal diameter, measured by quantitative coronary angiography, and coronary blood flow at level of epicardial coronary artery distal to the treated CTO was assessed before and after administration of acetylcholine (Ach), adenosine, and nitroglycerin (NTG). Collaterals were assessed angiographically by grading of Rentrop and of collateral connections (CC1: threadlike continuous connection; CC2: side branch-like connection).

RESULTS

Overall, Ach and adenosine caused coronary artery vasoconstriction (p=0.001 and p=0.004, respectively), whereas NTG failed to induce vasodilation (p=0.084). Coronary blood flow significantly decreased with Ach (p=0.005), significantly increased with NTG (p=0.035), and did not change with adenosine (p=0.470). Patients with CC2 collaterals (n=8) had less vasoconstriction response and reduction in coronary blood flow after Ach (p=0.005 and p=0.008, respectively), and better vasomotor response to NTG (p=0.029) than patients with CC1 collaterals (n=11).

CONCLUSIONS

Significant endothelial and smooth muscle dysfunction is present in the distal segments of successfully recanalized CTOs, and that seems to be more pronounced in the presence of a low grading of collateral circulation.

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.

Assessment of recanalization of chronic total occlusions on left ventricular function in patients with or without previous myocardial infarction by real-time three-dimensional echocardiography

The changes of left ventricular ejection fraction (LVEF) were assessed after successful recanalization of chronic total occlusions (CTO) with or without previous myocardial infarction (MI) by real-time three-dimensional echocardiography (RT3DE). 32 patients with a successfully recanalyzed CTO were included in the present prospective study. The patients were divided into group 1 without previous MI and group 2 with previous MI in the territories of total occlusion vessel that was recanalized. In addition, there was a subgroup composed of 14 patients with collateral flow or retrograde flow in group 2. In all patients, LVEF was determined by RT3DE at baseline and after 6 weeks. In group 1, the evolution of LVEF increased significantly from 59.9 ± 7.2-67.5 ± 8.7% (P < 0.05). In group 2, the evolution of LVEF increased from 48.6 ± 6.1-50.1 ± 6.4%, however, it was without statistic significance (P > 0.05). The evolution of LVEF increased from 46.8 ± 7.1-53.0 ± 7.2% (P < 0.05) in the subgroup of group 2. Left ventricular function in patients with CTO can be feasibility and actually evaluated by RT3DE. The influence of recanalization of CTO on the improvement of left ventricular function was different between MI and non-MI patients. The left ventricular function did not improve in MI patients, but improved significantly in the patients having rich collateral circulation.

The relationship of serum erythropoietin level with coronary collateral grade

BACKGROUND

Erythropoietin has been shown to induce neovascularization and protect against ischemic vascular injury. We investigated whether a higher serum erythropoietin (EPO) level is related to better coronary collateral vessel grade.

METHODS

Ninety-nine patients with stable angina pectoris who have at least 1 coronary stenosis of equal to or greater than 70% at coronary angiography were prospectively enrolled. Serum EPO and vascular endothelial growth factor (VEGF) levels were studied. Coronary collateral degree was graded according to the Rentrop method. Patients with grade 2-3 collateral degree were included in the good collateral group and formed Group I. The patients with grade 0-1 collateral degree were included in the poor collateral group and formed Group II.

RESULTS

The serum EPO level was significantly higher in the good collateral group (17.3 ± 9.3 mU/mL vs 11.7 ± 5.0 mU/mL; P < 0.001). There was also a positive correlation between serum EPO level and Rentrop score (r = 0.39; P < 0.001). In multivariate analysis, serum EPO level (odds ratio [OR] 1.336; 95% confidence interval [CI], 1.120-1.593; P = 0.001), oxygen saturation (OR 0.638; 95% CI, 0.422-0.963; P = 0.033) and presence of chronic total occlusion (CTO) (OR 26.7; 95% CI, 3.874-184.6; P = 0.001) were independently related to well-developed coronary collaterals.

CONCLUSIONS

Higher serum EPO level is related to better coronary collateral development. Erythropoietin may have a positive effect on the development of collaterals and may provide a new agent for the treatment strategies to enhance coronary collateral vessel development.

Coronary physiology in the cath lab: beyond the basics

The adoption of invasive coronary physiologic lesion assessment before percutaneous coronary intervention has become routine in many catheterization laboratories. In the last decade, numerous studies have demonstrated favorable outcomes for revascularization decisions based on in-lab coronary physiology in many patients. The use of coronary physiology in the laboratory has been identified as a class IIa recommendation for patients in whom the clinical presentation and supporting data are too inconclusive to make an objective decision regarding treatment. This article reviews pertinent concepts and studies of the more complex applications of translesional pressure measurements for optimal patient outcomes.

Poor coronary collateral vessel development in patients with mild to moderate renal insufficiency

BACKGROUND

The development of coronary collaterals is crucial to survival through acute ischemia. Mild to moderate loss of renal function has been suggested to play a role in this event, but evidential data are scarce. The aim of this study was to investigate the relationship between mild to moderate renal insufficiency and coronary collateral development in patients with chronic total coronary artery occlusion.

METHODS AND RESULTS

A total of 83 patients with mild to moderate loss of renal function (30 mL/min/1.73 m(2) ≤ eGFR < 90 mL/min/1.73 m(2)) with chronic total coronary artery occlusion were included in our study. The collateral circulation was graded according to Rentrop classification and the function of collateral circulation was graded according to Werner collateral connection (CC) grades. Compared to patients with good collateral circulation (Rentrop = 2,3), eGFR was found to be lower in those patients with poor coronary collateral circulation (Rentrop = 0,1) (63.30 ± 10.51 vs. 54.13 ± 10.56, P = 0.02). eGFR was also found to be lower in poorly functioning coronary collateral circulation (CC = 0,1) than in efficiently functioning coronary collateral circulation (CC = 2) (55.22 ± 9.98 vs. 66.28 ± 9.16, P = 0.03). Multiple logistic regression analysis showed that low eGFR was independently associated with poor coronary collateral circulation (Rentrop = 0,1, 95% CI, 0.09-1.09, P = 0.044) and poor function of coronary collateral circulation (CC = 0,1, 95% CI, 0.02-0.17, P = 0.02).

CONCLUSIONS

Lower eGFR is associated with poorer coronary collateral vessel development in patients experiencing mild to moderate renal insufficiency. Moreover, eGFR represents an independent factor affecting coronary collateral vessel development.

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.

The influence of genotype on vascular endothelial growth factor and regulation of myocardial collateral blood flow in patients with acute and chronic coronary heart disease

OBJECTIVE

To test the hypothesis that mutations in the vascular endothelial growth factor (VEGF) gene are associated with plasma concentration of VEGF and subsequently the ability to influence coronary collateral arteries in patients with coronary heart disease (CHD).

METHODS

Blood samples from patients with chronic ischemic heart disease (n=53) and acute coronary syndrome (n=61) were analysed. Coronary collaterals were scored from diagnostic biplane coronary angiograms.

RESULTS

The plasma concentration of VEGF was increased in patients with acute compared to chronic CHD (p=0.01). The genotype frequencies differed significantly from Hardy-Weinberg equilibrium in three of 15 examined loci. Four new mutations in addition to the already described were identified. The VEGF haplotype did not seem to predict plasma VEGF concentration (p=0.5). There was an association between the genotype in locus VEGF-1154 and coronary collateral size (p=0.03) and a significant association between the VEGF plasma concentration and the collateral size (p=0.03).

CONCLUSION

VEGF plasma concentration seems related to coronary collateral function in patients with CHD. The results did not support the hypothesis that polymorphisms in the untranslated region of the VEGF gene were associated with the concentration of circulating VEGF. Increased understanding of VEGF in the regulation of myocardial collateral flow may lead to new therapies in CHD.

Improvement of fractional flow reserve and collateral flow by treatment with external counterpulsation (Art.Net.-2 Trial)

BACKGROUND

Arteriogenesis (collateral artery growth) is nature's most efficient rescue mechanism to overcome the fatal consequences of arterial occlusion or stenosis. The goal of this trial was to investigate the effect of external counterpulsation (ECP) on coronary collateral artery growth.

MATERIALS AND METHODS

A total of 23 patients (age 61 +/- 2.5 years) with stable coronary artery disease and at least one haemodynamic significant stenosis eligible for percutaneous coronary intervention were prospectively recruited into the two study groups in a 2 : 1 manner (ECP : control). One group (ECP group, n = 16) underwent 35 1-h sessions of ECP in 7 weeks. In the control group (n = 7), the natural course of collateral circulation over 7 weeks was evaluated. All patients underwent a cardiac catheterization at baseline and after 7 weeks, with invasive measurements of the pressure-derived collateral flow index (CFIp, primary endpoint) and fractional flow reserve (FFR).

RESULTS

In the ECP group, the CFIp (from 0.08 +/- 0.01 to 0.15 +/- 0.02; P < 0.001) and FFR (from 0.68 +/- 0.03 to 0.79 +/- 0.03; P = 0.001) improved significantly, while in the control group no change was observed. Only the ECP group showed a reduction of the Canadian Cardiovascular Society (CCS, P = 0.008) and New York Heart Association (NYHA, P < 0.001) classification.

CONCLUSION

In this study, we provide direct functional evidence for the stimulation of coronary arteriogenesis via ECP in patients with stable coronary artery disease. These data might open a novel noninvasive and preventive treatment avenue for patients with non-acute vascular stenotic disease.

Influence of coronary collateral flow on coronary diagnostic parameters: an in vitro study

Functional severity of coronary stenosis is often assessed using diagnostic parameters. These parameters are evaluated from the combined pressure and/or flow measurements taken at the site of the stenosis. However, when there are functional collaterals operating downstream to the stenosis, the coronary flow-rate increases, and the pressure in the stenosed artery is altered. This effect of downstream collaterals on different diagnostic parameters is studied using a physiological representative in vitro coronary flow-loop. The three diagnostic parameters tested are fractional flow reserve (FFR), lesion flow coefficient (LFC), and pressure drop coefficient (CDP). The latter two were discussed in recent publications by our group (Banerjee et al., 2007, 2008, 2009). They are evaluated for three different severities of stenosis and tested for possible misinterpretation in the presence of variable collateral flows. Pressure and flow are measured with and without downstream collaterals. The diagnostic parameters are then calculated from these readings. In the case of intermediate stenosis (80% area blockage), FFR and LFC increased from 0.74 to 0.77 and 0.58 to 0.62, respectively, for no collateral to fully developed collateral flow. Also, CDP decreased from 47 to 42 for no collateral to fully developed collateral flow. These changes in diagnostic parameters might lead to erroneous postponement of coronary intervention. Thus, variability in diagnostic parameters for the same stenosis might lead to misinterpretation of stenosis severity in the presence of operating downstream collaterals.

Atherogenesis and atherothrombosis--focus on diabetes mellitus

Diabetes mellitus represents a major cause of cardiovascular morbidity and mortality in developed countries, and atherothrombosis accounts for most deaths among patients with diabetes mellitus. Atherothrombosis is defined as atherosclerotic lesion disruption with superimposed thrombus formation. As a long-term, progressive disease process, atherosclerosis often results in an acute atherothrombotic event through plaque rupture and formation of a platelet-rich thrombus. The principal clinical manifestations of atherothrombosis are sudden cardiac death, myocardial infarction, ischaemic stroke, and peripheral arterial ischaemia comprising both intermittent claudication and critical limb ischaemia. Atherosclerosis is the leading cause of morbidity and mortality in the industrialized world, and diabetes mellitus magnifies the risk of cardiovascular events. In addition to the well-known microvascular complications of diabetes mellitus - such as nephropathy, retinopathy and neuropathy - the risk of macrovascular complications affecting the large conduit arteries markedly increases in patients with diabetes mellitus.

Collateral function in patients with coronary occlusion evaluated by 201 thallium scintigraphy

The present study evaluated the impact of the angiographically documented collaterals on regional myocardial perfusion measured by 201thallium scintigraphy in patients with a chronic total occlusion. The study included 60 patients with chronic total occlusion who underwent rest-stress myocardial perfusion scintigraphy and coronary angiography. All patients had angiographic evidence of coronary collaterals. Patients were divided into two groups: group one had well-developed coronary collateral vessels (n=35) and group II had poor coronary collateral development (n=25). Patients with chronic total occlusion had severe and extensive stress-induced myocardial perfusion defects regardless of the grade of angiographic coronary collaterals. The perfusion defects in the group with good collaterals were predominantly reversible, suggesting that coronary collaterals preserved myocardial viability in the regions subtended by a total coronary occlusion. A significant correlation between good collaterals with complete protection and poor collaterals with no protection was noted. Our results demonstrate a protective effect of collaterals on myocardial perfusion during coronary occlusion. The effective angiographic collaterals may prevent resting regional wall motion abnormalities but do not appear to protect against stress-induced perfusion defect.