Journal of Clinical and Preventive Cardiology

ORIGINAL ARTICLE
Year
: 2021  |  Volume : 10  |  Issue : 3  |  Page : 95--101

Coronary collateral circulation in acute, subacute, and chronic total occlusions


Ashida Thulaseedharan Sarojadevi1, Vinayagamoorthy Venugopal2,  
1 Department of Cardiology, Sri Manakulavinayagar Medical College and Hospital, Puducherry, India
2 Department of Community Medicine, Sri Manakulavinayagar Medical College and Hospital, Puducherry, India

Correspondence Address:
Dr. Ashida Thulaseedharan Sarojadevi
Department of Cardiology, Sri Manakulavinayagar Medical College and Hospital, Puducherry
India

Abstract

Context: A study on the pattern of coronary collateral circulation is relevant in coronary artery disease (CAD) where despite advances in revascularization, the prevalence of heart failure is increasing. Aims: The aim was to study the pattern of coronary collateral circulation in acute, subacute, and chronic coronary total occlusions and to find out the association between collateral grade with the severity of CAD. Settings and Design: This was a hospital-based retrospective cross-sectional study of 141 patients with acute, subacute, or chronic total occlusion of coronaries detected by coronary angiography. Subjects and Methods: Data of 141 patients with total occlusion of coronaries detected by coronary angiography were analyzed. Collateral grading was done according to the Rentrop classification and Werner classification. The severity of CAD was assessed using Gensini score and Syntax score. Pattern of collateral circulation in different types of coronary occlusions and the association between collateral grade and severity of CAD were assessed. Statistical Analysis Used: The association of categorical clinical and angiographic features with type of occlusion was tested using Chi-square test and that of continuous variable with student t-test. All tests were two tailed and P < 0.05 was considered statistically significant. Results: Young patients presented predominantly with acute coronary occlusions (82.6%). About 73% of the patients with left ventricle (LV) dysfunction had acute coronary occlusions. Nearly 68.8% of patients with poor Rentrop collateral grades had LV dysfunction. Patients with acute occlusion had low atherosclerotic burden as evidenced by lower Gensini and Syntax scores and had poor coronary collaterals. No significant correlation was seen between Gensini and Syntax scores and collateral grade. Patients who presented with ST-elevation myocardial infarction (STEMI) had poor Rentrop collaterals and higher prevalence of single-vessel disease and double-vessel diseases when compared to those with non-ST-segment elevation acute coronary syndrome and chronic stable angina. Conclusions: Young male patients with low atherosclerotic burden tend to present with acute coronary occlusions. This subgroup has poor collateral circulation and LV dysfunction. No statistically significant difference was seen in the presence of diabetes, hypertension, number of epicardial coronary artery involvement, or the severity of CAD in the STEMI patients with good or poor Rentrop collaterals.



How to cite this article:
Sarojadevi AT, Venugopal V. Coronary collateral circulation in acute, subacute, and chronic total occlusions.J Clin Prev Cardiol 2021;10:95-101


How to cite this URL:
Sarojadevi AT, Venugopal V. Coronary collateral circulation in acute, subacute, and chronic total occlusions. J Clin Prev Cardiol [serial online] 2021 [cited 2022 Jan 24 ];10:95-101
Available from: https://www.jcpconline.org/text.asp?2021/10/3/95/326474


Full Text



 Introduction



Normal human heart contains small interconnecting anastomotic vessels which serve as the precursors of collateral circulation.[1] Angiographically, visible coronary collaterals develop when significant stenosis in a coronary artery creates a transanastomotic pressure gradient. Hence as a group, patients with collateral circulation are expected to have more severe coronary artery disease (CAD). A well-developed collateral circulation has been shown to reduce myocardial ischemia, maintain myocardial viability, and reduce the extent of myocardial damage during acute coronary occlusion.[2],[3],[4]

In developing countries like India with a high burden of CAD, patients often tend to present late, delaying reperfusion therapy, thus resulting in significant myocardial damage.[5] Hence a study on the pattern of coronary collateral circulation is relevant in CAD, as current systems do not take into account the analysis of collateral circulation anatomy. The aim of our study was to describe the pattern of coronary collateral circulation in acute, subacute, and chronic coronary total occlusions and to find out the association between collateral grade with the severity of CAD.

 Subjects and Methods



This was a hospital-based retrospective cross-sectional study carried out in the Department of Cardiology in Sri Manakula Vinayagar Medical College and Hospital, a tertiary care teaching hospital in Pondicherry. The hospital with more than 900 beds offers preventive and curative services to the population of rural Pondicherry and Villupuram district.

Records from the catheterization laboratory of the cardiology Department were assessed after obtaining approval from the Institute Ethical Committee. Records having incomplete information were excluded.

Operational definitions

Coronary occlusions were classified as chronic total occlusions as those occluded coronary arteries with a documented duration of occlusion of at least 3 months with absolutely no flow through the lesion (TIMI 0 flow). Occlusions within 1–3 months were addressed as recent occlusions and within 4 weeks as acute occlusions.[6] The duration of the occlusion was determined from a previous angiogram, the date of a previous myocardial infarction, or from the onset of symptoms.

Collateral grading

Collateral grading was done by two blinded investigators who evaluated the angiographic images independently and in the case of disagreement, a consensus was obtained. The coronary collateral connection (CCC) was graded according to the Rentrop classification which describes the collaterals according to their effect in filling the occluded arterial segment.[7] Accordingly, Grade 0 was classified as no filling; Grade 1 classified as filling of side branches via collateral channels without visualization of the epicardial segment; Grade 2 classified as a partial filling of epicardial major coronary artery via collateral channels; and Grade 3 classified as complete filling of epicardial major coronary artery. In patients with more than one coronary lesion, and when there was more than one CCC, the CCC with the highest Rentrop was used. Rentrop Grade 0/1 were classified as poor collaterals and Grades 2/3 were classified as good collaterals. Collateral grading was also done according to the semi-quantitative assessment of collaterals by Werner et al.[8] Collateral connection (CC) Grade 0 was defined as no continuous connection between collateral supplying and receiving vessel, CC1 as those with thread-like continuous connection, and CC2 as side branch-like connection.

Severity of coronary artery disease

Severity of CAD was assessed using Gensini score and Syntax score. A Gensini score >40 but ≤100 was defined as advanced CAD, and a Gensini score >100 was defined as heavy CAD. The Syntax score was divided into tertiles as low (<22), intermediate (22-32), and high (>33).

Statistical analysis

Data were entered in Epi data software version 4.2 and analyzed using SPSS (windows XP) software version 24. Description of the categorical variable was done in frequency and percentage and that of continuous variable in mean and standard deviation. The association of categorical clinical and angiographic features with type of occlusion was tested using Chi-square test and that of continuous variable using Student's t-test. All tests were two tailed and P < 0.05 was considered statistically significant.

 Results



One hundred and forty-one patients fulfilled the eligibility criteria for inclusion into the study. Of these 141 patients, 41.8% were in the age category of 46 – 60 years and above 60 years each. The remaining 16.4% of them belonged to the age group of 30–45 years. Majority of them were male (84.4%) and the rest were female. Regarding the presentation of CAD, 32.6% presented with chronic stable angina, and 67.4% of the patients presented with acute coronary syndrome (ACS). Majority of patients (65.2%) had acute coronary occlusion, 31.9% had subacute occlusions, and 2.9% of patients had chronic total occlusions [Table 1].{Table 1}

On analyzing the sociodemographic and risk factors associated with duration of presentation of CAD, patients in the age group of 30–45 years had more acute occlusion (82.6), males had more acute occlusions (67.2%), but the difference in age and gender with type of occlusion was not significant. There was no significant association between duration of occlusion and presence of diabetes, hypertension, dyslipidemia, and smoking status. Patients with past CAD had less acute occlusion (16.7%) and more subacute (66.7%) and chronic (16.7%) occlusion compared with patients not having a past history of CAD. This difference was statistically significant.

About 63.8% of patients had left ventricle (LV) dysfunction (LV ejection fraction (EF] <50%). Nearly 31.9% had left main coronary artery involvement. Almost 83.7% had advanced or high CAD by Gensini scores. About 35.5% had intermediate or high Syntax scores. On grading the collaterals, 54.6% of angiograms showed good collateral circulation (Rentrop 2/3). Werner's CC2 collaterals were seen in only 22.7% of patients [Table 2].{Table 2}

Majority of the CAD patients with LV dysfunction presented with acute occlusion (73.3%) compared to those with EF >50 (51%). Single (71.9%) and double-vessel diseases (DVD) (81%) had more acute occlusion and those with triple-vessel disease had more subacute (39.7%) and chronic occlusion (6.3%) and these findings were statistically significant (P < 0.05). When compared to patients with subacute or chronic coronary occlusions, patients with acute occlusions had poor collaterals as per the Rentrop classification (73.4%vs. 58.4%), but this was not statistically significant [Table 3].{Table 3}

The patients with acute occlusion had lower Gensini score and Syntax score, whereas those who had chronic occlusion had higher scores. There was an increasing trend in these scores gradually from acute towards chronic occlusions. These differences were statistically significant [Table 4] and [Table 5].{Table 4}{Table 5}

On correlating adequacy of collateral circulation with EF, 68.8% of patients with poor Rentrop collateral grades had LV dysfunction (EF <50%). Similarly, patients with CC2 Werner grade collaterals had better EF than those with CC0 and CC1 collaterals [Table 6] and [Table 7].{Table 6}{Table 7}

Patients were divided into three groups, those who presented with ST-elevation myocardial infarction (STEMI), non-ST-segment elevation acute coronary syndrome (NSTEACS), and cross-sectional area (CSA), and data were analyzed. Patients who presented with STEMI were predominantly young males. Among the traditional risk factors, diabetes and hypertension were less prevalent in the STEMI group [Table 8]. More than 50% of STEMI patients had LV dysfunction (53.3%). STEMI patients also had poor Rentrop collaterals and higher prevalence of single-vessel disease and DVD when compared to those with NSTEACS and CSA [Table 9]. There was no statistically significant difference in the presence of diabetes, hypertension, number of epicardial coronary artery involvement, or the severity of CAD in the STEMI patients with good or poor Rentrop collaterals [Table 10].{Table 8}{Table 9}{Table 10}

 Discussion



The timely delivery of reperfusion therapy for STEMI is a challenge in developing countries like India. A well-developed coronary collateral circulation should preserve LV function in the incidence of a coronary occlusion. In the Study by Ajayi et al., a significant positive correlation was seen between coronary collateral grades and mean EF calculated for the different collateral grades. LV myocardial perfusion was greater in patients with well-developed coronary collaterals and resulted in better preservation of LV function even in the face of an acute coronary event.[9]

Collateral grade and type of coronary occlusion

In this study, young males presented more (73.4%vs. 58.4%) commonly with acute coronary occlusions. On analyzing the coronary collateral circulation, poor collaterals were seen in majority of the patients with acute coronary occlusions. About 41.6% of patients with good Rentrop collaterals presented with subacute or chronic coronary occlusions.

A protective role of coronary collaterals in preserving myocardial function and prevention of LV aneurysm formation in the setting of severe coronary stenosis has been reported by various studies.[10],[11] On the contrary, studies by Banerjee et al. and Ilia et al. showed no protective role for coronary collaterals in the preservation of LV function in patients with significant CAD.[12],[13]

About 63.8% of patients had LV dysfunction. On correlating adequacy of collateral circulation with EF, patients with good Rentrop collaterals had better EF than those with poor collaterals. Similarly, patients with CC2 Werner grade collaterals had better EF than those with CC0 and CC1 collaterals.

Although statistically not significant, CAD patients with EF <55 had more acute occlusion (73.3%) compared to those with >50 (51%). This could be explained as majority of the patients with acute occlusions had poor collaterals, thus jeopardizing the LV function.

Collateral grade and severity of coronary artery disease

Coronary stenosis is the strongest known stimulus for collateral development. However, it is still unclear as to why some patients develop sufficient collateral circulation while others do not despite significant coronary stenosis. Association between multi-vessel disease and coronary collateral circulation has been reported by several studies. Börekçi et al. reported a higher Syntax score in patients with poor coronary collaterals.[14] Cetin et al. observed that in the poor coronary collateral group, Syntax score were significantly higher compared to the good coronary collateral group.[15] In this study, both Gensini score and Syntax score did not show any significant correlation with collateral grade. Although significant coronary stenosis is the key stimulator to start the development of coronary collaterals, it alone cannot explain the adequacy of collateral connections.

Presentation with ST-elevation myocardial infarction and coronary collaterals

Traditional risk factors were less common among STEMI patients and this could be due to the younger age at presentation. Out of the 52 STEMI patients, 51 had anterior wall myocardial infraction and left anterior descending (LAD) was the occluded artery. The presence of angiographically detectable collaterals, especially Rentrop Grade 2/3, has been shown to have a protective effect on enzymatic infarct size, microvascular perfusion of the myocardium, and pre- and postinterventional hemodynamic conditions in patients with acute ST-segment-elevation myocardial infarction treated with percutaneous coronary intervention (PCI), particularly if the infarct-related vessel is LAD.[16] Compared to patients with NSTEACS and CSA, patients with STEMI had a higher prevalence of poor coronary collaterals in this study and this could have an impact on their long-term prognosis.

Therapeutic implications

Collateral promoting therapy, especially for at-risk young patients with CAD, should be part of the therapeutic armamentarium. This may help in preserving LV function and improving quality of life and long-term prognosis.

A significant improvement in collateral flow index (CFI) was demonstrated in response to moderate- and high-intensity exercise performed for 10 h per week in patients with stable CAD in the EXCITE trial.[16] In another study, a three months of cardiac rehabilitation utilizing exercise-based regimen augmented coronary collateral supply to normal vessels, and also to previously stenosis arteries undergone PCI.[17]

Genes encoding pathways for angiogenesis have been related to the extent of preexisting collateral network as well as development of a functional collateral circulation.[18],[19],[20]

Various studies have shown promising results on gene therapy in CAD by promoting collateral development through the administration of angiogenic growth factors.

 Conclusions



Although mortality from CAD is declining, the incidence of associated heart failure is rising. A well-developed coronary collateral circulation can reduce the extent of myocardial damage during acute coronary occlusions and may extend the time buffer for successful reperfusion. A good functional coronary collateral circulation long-term cardiac mortality is reduced to one-fourth compared with the situation without collateral supply.[21],[22]

Young male patients with low atherosclerotic burden tend to present with acute coronary occlusions. This subgroup has poor collateral circulation resulting in LV dysfunction unless revascularization is done in an emergent manner. Analyzing the adequacy of the coronary collateral circulation anatomically or via functional measurements like CFI will help to identify those with no or sparse endogenous collateral connections. Strategies aimed at augmenting collateral circulation are an attractive investigation subject, especially in young patients with CAD. Cardiac rehabilitation utilizing exercise-based regimens is often underutilized. Therapeutic angiogenesis by gene therapy, cell therapy, and their combination are promising areas of research in patients with poor functional collateral collaterals.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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