Visceral fat index: a novel predictor for coronary collateral circulation

ABSTRACT Objective This study was designed to investigate the role of visceral adiposity along with other clinical parameters in predicting poor coronary collateral circulation (CCC) among patients with severe obstructive coronary artery disease (CAD). Subjects and methods A total of 135 patients with severe obstructive CAD and good (n = 70) or poor (n = 65) CCC were included. Data on angiographically detected CCC, the quality criteria for CCC (Rentrop scores) and visceral fat index (VFI) obtained via bioelectrical impedance were compared between good and poor CCC groups. Independent predictors of poor CCC, the correlation between VFI and Rentrop score and the role of VFI in the identification of CCC were analyzed. Results A significant negative correlation was noted between VFI and Rentrop scores (r = -0.668, < 0.001). The presence of hypertension (OR 4.244, 95% CI 1.184 to 15.211, p = 0.026) and higher VFI (OR 1.955, 95% CI 1.342 to 2.848, p < 0.001) were shown to be independent predictors of an increased risk for poor CCC. ROC analysis revealed a VFI > 9 (AUC [area under the curve] (95% CI): 0.898 (0.834-0.943), p < 0.0001) to be a potential predictor of poor CCC with a sensitivity of 95.38% and specificity of 85.71%. Conclusion In conclusion, our findings revealed comorbid hypertension and higher VFI to significantly predict the risk of poor CCC in patients with severe obstructive CAD.

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

SUMMARY OBJECTIVE Coronary collateral development (CCD) predicts the severity of coronary heart disease. Hemogram parameters, such as mean platelet volume (MPV), eosinophil, red cell distribution width, and platelet distribution width (PDW), are supposed novel inflammatory markers. We aimed to compare hemogram parameter values in patients presenting with non-ST-elevation myocardial infarction (NSTEMI) with adequate or inadequate CCD. METHODS A total of 177 patients with NSTEMI undergoing coronary arteriography were enrolled and divided into two groups based on the development of CCD: one group with adequate CCD (n=88) and the other with impaired CCD (n=89). RESULTS Baseline demographics and clinical risk factors were similar between the groups. Hemogram parameters were not significantly different between the two groups. However, compared to the inadequate CCD group, the median PDW was significantly higher in the adequate CCD group, 17.6 (1.4) vs. 17.8 (1.6) p=0.004. In a multivariate analysis, PDW (p=0.001, 95% CI for OR: 0.489(0,319-0,750) was found to be significantly different in the adequate CCD group compared to the inadequate CCD group. Pearson's correlation analysis revealed that PDW was significantly correlated with the Rentrop score (r=0.26, p<0.001). CONCLUSIONS We suggest that since PDW is an index that is inexpensive and easy to assess, it could serve as a marker of CCD in patients with NSTEMI.

RESUMO OBJETIVO O desenvolvimento colateral coronariano (CCD) prediz a gravidade da doença coronariana. Parâmetros de hemograma como volume plaquetário médio (VPM), eosinófilo, largura de distribuição de glóbulos vermelhos e largura de distribuição de plaquetas (PDW) são supostos novos marcadores inflamatórios. Nosso objetivo foi comparar os valores do parâmetro hemograma em pacientes com infarto do miocárdio sem supradesnivelamento do segmento ST (IAMSSST) com DCC adequado ou inadequado. MÉTODOS Um total de 177 pacientes com NSTEMI submetidos à arteriografia coronariana foram incluídos e divididos, com base no desenvolvimento de CCD, em dois grupos: grupo com CCD adequado (n = 88) e grupo com CCD alterado (n = 89). RESULTADOS Os dados demográficos e os fatores de risco clínicos basais foram semelhantes entre os grupos. Os parâmetros do hemograma não foram significativamente diferentes entre os dois grupos. Mas, em comparação com a mediana inadequada do grupo CCD, o PDW foi significativamente maior em CCD adequado de 17,6 (1,4) vs. 17,8 (1,6) p = 0,004. Na análise multivariada, PDW (p = 0,001, IC 95% para OR: 0,489 (0,319-0,750) foi significativamente diferente no grupo CCD adequado em comparação com o grupo CCD inadequado. A análise de correlação de Pearson revelou que PDW foi significativamente correlacionado com escore de aluguel (r = 0,26, p <0,001). CONCLUSÃO Sugerimos que, uma vez que a PDW é um índice barato e de fácil avaliação, pode servir como um marcador de DCC em pacientes com IAMSSST.

Correlation between GDF-15 gene polymorphism and the formation of collateral circulation in acute ST-elevation myocardial infarction

Summary Objective: To explore the correlation between growth differentiation factor 15 (GDF-15) -3148C/G polymorphism and the formation of collateral circulation in acute ST-elevation myocardial infarction (STEMI) in Han population of Taiyuan area. Method: The present study included 92 STEMI patients and 56 normal controls based on coronary angiography; STEMI group was divided into collateral group and non-collateral group according to Rentrop's grading method. Polymerase chain reaction (PCR) and DNA sequencing methods were used to detect and analyze the GDF-15 -3148C/G polymorphism in all participants. Results: There was significant difference in GDF-15 -3148C/G CC and GC distribution between STEMI group and control group (p=0.009); the allele frequencies between these two groups were also significant different (p=0.016); and the risk genotype for STEMI was CC with increased OR=2.660. For STEMI group, GDF-15 -3148C/G CC and GC distribution was also significantly different between patients with and without collateral (p=0.048), and CC genotype significantly promote the formation of collateral circulation. However, there were no significant differences in allele frequencies between these two subgroups of STEMI. Conclusion: There was correlation between GDF-15-3148C/G polymorphism and the formation of collateral circulation in patients with acute STEMI.

Which Coronary Lesions Are More Prone to Cause Acute Myocardial Infarction? / Quais Lesões Coronarianas São Mais Propensas a Causar Infarto Agudo do Miocárdio?

Abstract 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.

Resumo Fundamento: Há uma crença geral de que a maioria dos infartos agudos do miocárdio (IAM) ocorrem devido à ruptura de placas vulneráveis, não graves, com obstrução < 70%. Dados de ensaios recentes desafiam esta crença, sugerindo que o risco de oclusão coronariana é, na realidade, muito maior após estenose grave. O objetivo deste estudo foi investigar se a presença ou não de IAM com supradesnível do segmento ST resulta de estenoses de alto grau através da avaliação da presença de circulação colateral coronariana (CCC). Métodos: Nós incluímos retrospectivamente 207 pacientes consecutivos submetidos à intervenção coronariana percutânea primária devido à ocorrência de IAM com supradesnível do segmento ST. O fluxo sanguíneo colateral distal à lesão culpada foi avaliado por dois investigadores com utilização do sistema de escores de Rentrop. Resultados: Dos 207 pacientes incluídos no estudo, 153 (73,9%) apresentavam vasos coronarianos colaterais (Rentrop 1-3). Os escores Rentrop foram de 0, 1, 2 e 3 em 54 (26,1%), 50 (24,2%), 51 (24,6%) e 52 (25,1%) pacientes, respectivamente. Triglicérides, volume plaquetário médio (VPM), contagem de células brancas (CCB) e contagem de neutrófilos estiveram significativamente mais baixos no grupo com bons vasos colaterais (p = 0,013, p = 0,002, p = 0,003 e p = 0,021, respectivamente). Conclusão: Mais de 70% dos pacientes com IAM apresentaram CCC com escores de Rentrop de 1-3 durante angiografia coronariana primária. Isto demonstra que a maioria dos casos de IAM em nosso estudo originou a partir de estenoses subjacentes de alto grau, contrariamente à sabedoria comum. Níveis séricos mais elevados de triglicérides, maior VPM e elevação na CCB e na contagem de neutrófilos estiveram independentemente associados com comprometimento no desenvolvimento de vasos colaterais.

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.

Collateral blood vessels in acute ischemic stroke: a physiological window to predict future outcomes / Circulação colateral no acidente vascular cerebral isquêmico: uma janela fisiológica para prever resultados futuros

ABSTRACT Collateral circulation is a physiologic pathway that protects the brain against ischemic injury and can potentially bypass the effect of a blocked artery, thereby influencing ischemic lesion size and growth. Several recent stroke trials have provided information about the role of collaterals in stroke pathophysiology, and collateral perfusion has been recognized to influence arterial recanalization, reperfusion, hemorrhagic transformation, and neurological outcomes after stroke. Our current aim is to summarize the anatomy and physiology of the collateral circulation and to present and discuss a comprehensible review of the related knowledge, particularly the effects of collateral circulation on the time course of ischemic injury and stroke severity, as well as imaging findings and therapeutic implications.

RESUMO A circulação colateral é um circuito fisiológico de proteção contra alterações isquêmicas que, potencialmente, evita os efeitos de uma oclusão arterial e com isso pode influenciar nas dimensões e no crescimento de uma lesão isquêmica. Vários estudos recentes forneceram informações a respeito do papel das colaterais na fisiopatologia do acidente vascular encefálico isquêmico e demonstraram a capacidade da circulação colateral de influenciar as taxas de reperfusão, recanalização, transformação hemorrágica e com isso desfecho clínico dos pacientes. O objetivo desta revisão é sintetizar a anatomia e a fisiologia da circulação colateral encefálica, apresentando e discutindo, o que se conhece atualmente acerca do seu efeito na cronologia e gravidade da lesão isquêmica, além dos achados de imagens e implicações terapêuticas.

Superior Vena Cava Syndrome Associated with Right-to-Left Shunt through Systemic-to-Pulmonary Venous Collaterals

Superior vena cava (SVC) obstruction is associated with the gradual development of venous collaterals. We present a rare form of systemic-to-pulmonary subpleural collateral pathway that developed in the bridging subpleural pulmonary veins in a 54-year-old woman with complete SVC obstruction. This uncommon collateral pathway represents a rare form of acquired right-to-left shunt due to previous pleural adhesions with an increased risk of stroke due to right-to-left venous shunting, which requires lifelong anticoagulation.

Venous drainage from the tail of the pancreas to the lienal vein and its relationship with the distal splenorenal shunt selectivity / Drenagem venosa da cauda do pâncreas para a veia lienal e sua relação com a seletividade da anastomose esplenorrenal

PURPOSE: To identify the veins draining from the pancreatic tail to the lienal vein and its possible relationship with the loss of the distal splenorenal shunt selectivity. METHODS: Thirty eight human blocks including stomach, duodenum, spleen, colon and pancreas, removed from fresh corpses, were studied with the replenish and corrosion technique, using vinilic resin and posterior corrosion of the organic tissue with commercial hydrochloric acid, in order to study the lienal vein and its tributaries. RESULTS: The number of veins flowing directly to the splenic vein varied from seven to twenty two (14.52 ± 3.53). Pancreatic branches of the pancreatic tail flowing to the segmentary veins of the spleen were found in 25 of the anatomical pieces studied (65.79 percent). These branches varied from one to four, predominating one branch (60 percent) and two branches (24 percent). CONCLUSIONS: In 65.79 percent of the anatomical pieces studied, the veins of the pancreatic tail flowed in segmentary branches of the splenic vein. These branches could be responsible for the loss of distal splenorenal shunt selectivity. The complete disconnection of the pancreatic tail could increase the selectivity in this procedure.

OBJETIVO: Identificar as veias da cauda do pâncreas afluentes da veia lienal e a possível relação destes ramos com a perda de seletividade da derivação esplenorrenal distal. MÉTODOS: Foram estudadas 38 peças humanas, retiradas de cadáveres, contendo estômago, duodeno, baço, cólon e pâncreas, utilizando-se a técnica de repleção vascular com resina vinílica e posterior corrosão do tecido orgânico com o objetivo de se estudar o molde vascular da veia lienal e seus afluentes. RESULTADOS: O número de veias afluindo diretamente para a veia esplênica variou de sete a vinte dois (MA 14.52±3.53). Ramos pancreáticos da cauda do pâncreas afluindo para as veias segmentares do baço estavam presentes em 25 das peças estudadas (65,79 por cento). Estes ramos variaram de um a quatro, predominando um ramo (60 por cento) e dois ramos (24 por cento). CONCLUSÕES: Em 65,79 por cento das peças veias da cauda do pâncreas desembocavam em ramos segmentares da veia esplênica. Estes ramos poderiam ser responsáveis pela perda de seletividade da derivação esplenorrenal distal e a esqueletização completa da cauda do pâncreas poderia aumentar a seletividade neste procedimento.

Pathophysiology of Portal Hypertension, What's New? / 대한소화기학회지

Portal hypertension (PHT) is associated with changes in the intrahepatic, systemic and portosystemic collateral circulations. Alteration in vasoreactivity (vasodilation and vasoconstriction) plays a central role in the pathogenesis of PHT by contributing to increased intrahepatic resistance, hyperdynamic circulation and the expansion of the collateral circulation. PHT is also importantly characterized by changes in vascular structure; termed vascular remodeling, which is an adaptive response of the vessel wall that occurs in response to chronic changes in the environment such as shear stress. Angiogenesis, the sprouting of new blood vessels, also occurs in PHT, especially in the expansion of the portosystemic collateral circulation. These complementary processes of vasoreactivity, vascular remodeling and angiogenesis represent important targets in the research for the treatment of portal hypertension.

Hemodynamic alterations in cirrhosis and portal hypertension / 대한간학회지

Portal hypertension (PHT) is associated with hemodynamic changes in intrahepatic, systemic, and portosystemic collateral circulation. Increased intrahepatic resistance and hyperdynamic circulatory alterations with expansion of collateral circulation play a central role in the pathogenesis of PHT. PHT is also characterized by changes in vascular structure, termed vascular remodeling, which is an adaptive response of the vessel wall that occurs in response to chronic changes in the environment such as shear stress. Angiogenesis, the formation of new blood vessels, also occurs with PHT related in particular to the expansion of portosystemic collateral circulation. The complementary processes of vasoreactivity, vascular remodeling, and angiogenesis represent important targets for the treatment of portal hypertension. Systemic and splanchnic vasodilatation can induce hyperdynamic circulation which is related with multi-organ failure such as hepatorenal syndrome and cirrhotic cadiomyopathy.

Trombólise tardia e espontânea de artéria renal sem comprometimento funcional / Late and spontaneous thrombolysis of renal artery without functional impairtment

A aterosclerose em artérias renais é um importante fator desencadeante de tromboses com subsequente comprometimento da função e da viabilidade renal. A oclusão aguda das artérias renais por trombo ou êmbolo é causa incomum e potencialmente reversível de falência renal. Todavia, a duração e ograu de oclusão arterial compatível com a manutenção da viabilidade do parênquima renal ainda não estão bem estabelecidos, razão pela qual o diagnóstico precoce e a intervenção são importantes. O objetivo deste artigo é descrever um caso de trombose de artéria renal de rim funcional único, com lise espontânea e tardia do trombo seguida de recuperação funcional inesperada.

Atherosclerosis in the renal arteries is an important triggering factor for thrombosis with subsequent impairment of renal function and viability. Acute occlusion of the renal arteries by a thrombus or embolus is unusual and potentially reversible cause of renal failure. However, the duration of arterial occlusion and ograu compatible with maintaining the viability of renal parenchyma are not well established, which is why early diagnosis and intervention are important. The aim of this paper is to describe a case of renal artery thrombosis functional single kidney with spontaneous lysis of thrombus and late functional recovery after unexpected.

Involução de artérias colaterais aneurismáticas após a correção da coarctação da aorta / Involution of aneurysmal collateral arteries after correction of aortic coarctation

Paciente de 47 anos de idade, com diagnóstico de coarctação da aorta, foi submetido ao implante de tubo extra-anatômico por toracotomia esquerda. Dez anos após o procedimento, o paciente retorna com hipertensão arterial de difícil controle relacionada a coarctação da aorta residual, obstrução do tubo e múltiplos aneurismas de artérias colaterais entre a artéria subclávia e a aorta. O paciente foi submetido então a correção extra-anatômica entre a aorta ascendente e a descendente por esternotomia mediana, com auxílio de circulação extracorpórea convencional. Sua recuperação pós-operatória foi boa, e houve involução completa de todas as artérias colaterais aneurismáticas após a operação.

A 47 year-old man with aortic coarctation had undergone extra-anatomic bypass through a left thoracotomy. He presented 10 years later with uncontrolled arterial hypertension due to residual aortic coarctation, graft obstruction and multiple collateral artery aneurysms between the subclavian artery and the aorta. He underwent extra-anatomic correction between the ascending aorta to descending aorta through a median sternotomy with the aid of conventional cardiopulmonary bypass. His postoperative recovery was unremarkable, and there was complete involution of all aneurysmal collateral arteries after the operation.

Tratamento cirúrgico de paciente adulto com origem anômala da artéria interventricular anterior do tronco da artéria pulmonar / Adult patient with anomalous origin of anterior interventricular artery at main pulmonary artery

Das cardiopatias congênitas, a origem anômala da artéria interventricular anterior apresenta incidência de 1:300.000, com alta mortalidade até o primeiro ano de vida, mas que na presença de boa circulação colateral para a artéria relacionada à anomalia, pode manter o paciente assintomático até a vida adulta. Relatamos o caso, raro, de um paciente de 43 anos, oligossintomático e com função ventricular normal que apresentava essa doença e foi submetido a tratamento cirúrgico sem circulação extracorpórea.

From all congenital cardiopathies, anomalous origin of anterior interventricular artery occurs once per 300,0000 live births, reporting high mortality in the first year after birth. However, if good collateral circulation is available for the artery related to the abnormality, the patient may be kept asymptomatic until mature age. This is the report on a rare case of a 43-year-old patient who was oligosymptomatic, with normal ventricular function in this pathology presentation. The patient was submitted to surgical treatment with no extracorporeal circulation.

Leino-renal collaterals causing left pelviureteric junction obstruction.

Pelviureteric junction obstruction of the kidneys secondary to crossing renal vessels is a known entity. We report a 26-year-old woman with obstruction secondary to portosystemic collaterals; she was incidentally detected to have extrahepatic portal vein obstruction.

Slender versus threatening angiodysplasias. Observe, operate or obturate? a delusive decision / Angiodisplasias pequeñas y tolerables versus extensas y peligrosas

Aparte del éxito inmediato de la cirugía y embolización terapéutica de las angiodisplasias, un cierto número de pacientes regresan a la consulta médica con recanalización de las fístulas arteriovenosas, después de haber sido resecadas o embolizadas. A partir de la presentación y discusión de dos casos clínicos de angiodisplasias torácicas: una simple y poco complicada y otra compleja y peligrosa, que amenazaba la vida de la paciente, los autores ponen de relieve las complicaciones y recidivas que siguen al tratamiento quirúrgico o a la embolización arterial terapéutica. La ocurrencia de recidivas tiene lugar aún cuando sea una sóla arteria la que persiste después de la resección quirúrgica o la embolización y hay cosas tan rebeldes al tratamiento que los enfermos imploran la amputación del miembro afectado por la angiodisplasia, la cual renace en el muñón del miembro amputado. La evolución, natural o postoperatoria, de la angiodisplasia está marcada por la angiogénesis incontrolable, cuya causa probable es un error en el programa genético, que persiste a pesar de la resección de la malformación vascular y es la causa del fracaso terapéutico

Remodelación vascular: comportamiento arterial para tener en cuenta

La remodelación vascular es la capacidad de una arteria en adaptar su tamaño estructural ante estímulos crónicos por crecimiento o reducción del tamaño externo para mantener un lumen funcional. Se puede comportar como el mantenimiento del área luminal a pesar del cúmulo de tejido extraño (remodelación compensatoria) o como reducción del tamaño del vaso con compromiso del lúmen (remodelación constrictiva). La remodelación vascular es un proceso ampliamente descrito en hipertensión arterial, ateroesclerosis, circulación colateral y recientemente como el principal factor en la génesis de la reestenosis post angioplastia coronaria. Es el resultado de múltiples procesos con acción humoral autocrina y paracrina, en los cuales desempeñan papel importante la disfunción endotelial, la proliferación de células de musculo liso vascular, síntesis de matriz extracelular y la adventicia. Describimos el análisis de remodelación vascular (ïndice de remodelación, crecimiento medialneointimal y estenosis residual tardía) en un modelo experimental en porcinos de comportamiento histlógico ante el barotrauma coronario, en 24 arterias coronarias intervenidas con angioplastia con una realción balón:arteria 1.3:1 en el Instituto de Cardiología de la Fundación Cardio-Infantil

Left ventricular aneurysm: angiographic determinants.

To determine antiographic factors involved in left ventricular aneurysm formation after myocardial infarction, 50 patients with a first anterior wall myocardial infarction who underwent cardiac catheterisation within 6 months of infarction were evaluated. Extent of coronary artery disease and status of collateral circulation were studied in detail. Thirty patients had aneurysm in apical region while 20 patients showed aneurysm in anteroapical region. Coronary angiography revealed single-vessel disease in 17 patients, double-vessel disease in 17 patients and triple-vessel disease in 15 patients while in one patient coronary angiogram was normal. Fortynine patients showed significant involvement of left anterior descending artery which was poorly collateralised. Left anterior descending artery disease in association with inherent poor collateral blood supply may predispose for aneurysm formation after anterior wall myocardial infarction.

Collateral arteries in the presence of obstructive coronary disease.

BACKGROUND. The clinical importance of coronary collaterals in the presence of obstructive coronary artery disease is not clearly defined. METHODS. We retrospectively analysed the clinical and angiographic features of 100 patients with > or = 90% luminal diameter stenosis involving at least one major coronary artery. Coronary collaterals were graded 0 to 4 (Nitzberg's classification) and studied to determine their influence on clinical parameters. RESULTS. Thirty patients had no collaterals (group I) and 70 showed collaterals (group II). There were no significant differences between groups I and II in age and sex distribution, prevalence of risk factors of coronary artery disease (hypertension, diabetes, smoking, hypercholesterolaemia), duration of symptoms of coronary artery disease and prior myocardial infarction. Groups I and II had similar types (left anterior descending 73% v. 71%; left circumflex 50% v. 50% and right coronary 37% v. 56%) and numbers of arteries involved (one 47% v. 41%; two 47% v. 40%; three 7% v. 19%). Group II had a significantly lower prevalence of rest angina (14% v. 47%, p = 0.002). This difference was also evident when the patients were re-classified according to the extent of flow through the collaterals. Those with good collateralization (Nitzberg grades 3 and 4) had a lower prevalence of rest angina (13%) compared to those with poor collateralization (Nitzberg grades 0 to 2; 35%, p = 0.02). CONCLUSION. Coronary artery collaterals may reduce the incidence of rest angina in patients with obstructive coronary artery disease.