EARLY CHANGES OF LEFT VENTRICULAR FUNCTION AFTER TOTAL OCCLUSION OPENING OF ARTERY RICH IN COLLATERALS VERSUS IN ARTERY WITHOUT COLLATERALS

Early changes of Left Ventricular function after Total Occlusion Opening of artery rich in Collaterals versus in artery without Collaterals

By

Hossam El Din Mohamed El Sedawy 1; Khaled A. Azem Shokry 1; Omar M. Saleh2; Mohamed Ahmed Oraby 2; Hesham Hegazy Aly 2

1 Department of Cardiology, Military Medical Academy.

• Department of Cardiology, Faculty of Medicine – Suez Canal University.

Corresponding author: Hossam El Din Mohamed El Sedawy

Email:  sedawyhosam@yahoo.com

Abstract

Background: Coronary collateral circulation (CCC) usually supplies basal level of perfusion to the ischemic myocardium and maintains tissue viability. Despite shortcomings of the data concerning the relationship between CCC and myocardial viability, CCC does not generally appear to perfuse the nonviable myocardial tissue. Despite decades of study, the functional role of coronary collateral circulation remains controversial.

Objective: To compare the early changes that occur in the left ventricular systolic function in patients with CTO after successful revascularization in presence or absence of collateral circulation.

Subjects and Methods: This was an analytical cross-sectional study that was conducted at the Military Hospitals (Air Force, Maadi and Kobri El Koba Hospitals). Eighty patients were recruited from the Cardiology department from January 2023 to December 2023. Two equal groups were included; Group 1 included patients with chronic total occlusion (CTO) in any coronary artery more than 2.5 mm in its diameter with presence of ipsilateral or contralateral collateral circulation based on coronary angiography. Group 2 included patients with CTO in any coronary artery  more than 2.5 mm in its diameter with no collateral circulation based on the coronary angiography. Trans Thoracic Echocardiography was done for all patients including both conventional (M-mode and 2D) and tissue Doppler strain rate studies 24 hours before peccutanous coronary intervention (PCI) and 3 months after successful CTO PCI with final TIMI III flow.

Results: There was a statistically significant improvement in strain rates (SRs) of all anterior and lateral wall segments three months after CTO opening in group 1 of patients, there were also statistically significant improving in SRs of mid and apical septal wall segments three months after CTO opening in group 1 of patients. Inferior wall showed statistically significant decreased SRs in its basal and mid segments before intervention, which showed statistically significant improvement three months after CTO opening in group 1 of the patients.

Conclusion: The presence of collateral circulation significantly improves the response of chronic coronary occlusion patients to revascularization compared to patients with no coronary circulation in terms of the strain rate. Additionally, detailed examination of the TDI across the three view levels provides better follow-up data for the accurate assessment of patients.

Keywords: Left Ventricular function, Collaterals, chronic occlusion.

Introduction

Coronary collaterals potentially present vascular channels, which dilate and supply alternative perfusion to the coronary arteries in case of severe stenosis. Coronary collateral circulation (CCC) usually supplies basal level of perfusion to the ischemic myocardium and maintains tissue viability (Garcia et al., 2013). Approximately, 18–33% of patients with obvious coronary disease on coronary angiography have at least one CTO (Akbari et al., 2022).

Early percutaneous coronary interventions (PCIs) of CTOs have been shown to improve the left ventricular (LV) systolic function, reduce angina, increase exercise capacity, and reduce the need for bypass surgery (Levine et al., 2011).

Several studies have demonstrated the advantages of revascularization and percutaneous coronary intervention (PCI) in individuals with coronary chronic total occlusion (CTO) (Kelshiker et al., 2022). PCI success rates in patients with CTO have grown as device technology has improved, including drug-eluting stents, specialized guidewires, and microcatheters (Sianos et al., 2012).

However, high frequencies of failed PCI, perioperative mortality, and potential lethal complications related to revascularization still exist in patients with CTO. For these reasons, some clinicians are more likely to treat patients who have CTO and abundant distal collateral flow with medical therapy alone (Abd ElFattah et al., 2019).

Until today, there are absence of studies comparing the clinical outcomes of patients with CTO and well-developed collateral circulation who underwent revascularization on early left ventricular function changes. Therefore, this study aimed to compare the early changes in left ventricle systolic function associated with revascularization in patients with at least one CTO and well-developed collateral circulation versus those having no collateral circulation.

Patients and methods

This was an analytical cross-sectional study that was conducted at the in Military Hospitals (Air Force, Maadi and Kobri El Koba Hospitals). Patients were recruited from the Cardiology department from January 2023 to December 2023.

Two groups were included: Group 1 included forty patients with CTO in any coronary artery more than 2.5 mm in its diameter with presence of ipsilateral or contralateral collateral circulation based on coronary angiography. Group 2 included other forty patients with CTO in any coronary artery  more than 2.5 mm in its diameter with no collateral circulation based on the coronary angiography.

1. Data collection tools

• Questionnaire contained some informations as (name, age, sex, history of present illness and drug).
• Cardiac examination included inspection, palpation, percussion and auscultation of the precordial area.

1. Procedures: -

• Trans Thoracic Echocardiography was done for all patients including both conventional (M-mode and 2D) and tissue Doppler strain rate studies 24 hours before PCI and months after successful CTO PCI with final TIMI III flow.

The following echocardiographic variables were measured:

• Left ventricular ejection fraction was calculated with modified biplane method of Simpson. Regional LV wall motion score (LVWMS) was measured, with the following numerical score being assigned to each wall segment on the basis of its contractile function as assessed visually: 1 = normal (>40% thickening with systole); 2 = hypokinesis (10% to 40% thickening); 3 = severe hypokinesis to akinesis (<10% thickening); 4 = dyskinesis; and 5 = aneurysm.
• TDI Strain Rate: Strain rate (SRs) was obtained by placing a tissue Doppler sample volume at Anterior, Lateral, Septal and Inferior left ventricular walls, in Basal, Mid and Apical levels in different Apical views and was compared before, early after successful CTO revascularization and three months later (Nesbitt et al., 2009).
• Resting Electrocardiogram.
• Coronary angiography: The coronary vessels were viewed in different projections for better quantification and assessment.
• The left coronary system: 20^o view for the right anterior oblique (RAO) with 20^o caudal to display the entire left coronary system. A 30^o RAO 25^o cranial view can be used than to separate the diagonals from the left anterior descending artery (LAD). A posterior-anterior view (PA) with 40^o cranial angulation viewing the mid and distal portions of the LAD. The 45^o left anterior oblique (LAO) 30^o cranial view was used for separating the LAD from its diagonal branches. The 45o LAO, 30^o caudal (spider view) was used for looking at the left main coronary artery and the proximal origin of the left circumflex (LCX) (Levine et al., 2011).
• The right coronary system: The right coronary artery (RCA) was viewed in the LAO and RAO views. The 30^o RAO provided a view for the proximal and mid-RCA. The 45^o LAO with cranial angulation was for viewing the posterolateral and posterior descending arteries. The lateral view was for viewing the mid-RCA (Levine et al., 2011).
• According to the findings, if the decision is taken for CTO intervention, the procedure was done with the feasible technique according to the operator choice.
• PCI Techniques: General Electric (GE), Siemens and Philips catheterization systems were used and all possible intervention tools and techniques were used including:
• Antegrade, retrograde or hybrid approach according to feasible techniques and evident collateral branches (Sianos et al., 2012).
• Special types of guidewire specified to CTO interventions (Like Fielder XT, Asahi Sion black, Asahi Gaia I, II, III, etc.).
• Using either Microcatheter or over the wire balloon (OTW) (Libby et al., 2022): the most used microcatheters was Caraval and Crosair.
• Simultaneous contralateral injection to assess contralateral collaterals (Brilakis et al., 2012): We used all available curves of guiding and diagnostic catheters according to coronary anatomy.
• Regarding the vascular access site, 20% of patients were done via right femoral access only, 55% bilateral femoral access and 25% had a right radial and right femoral access. 85% of patients were done via an antegrade approach, and 15% were done via a retrograde approach, and all were technically successful. There was under-utilization of IVUS (6.25% of procedures in our study) to guide the procedure due to the financial limitations limiting its availability and preventing its routine use in our cases.
• Assessment of collateral circulation using Rentrop classification (Rentrop et al., 1985):
• Grade 0 No visible filling of any collateral channel.
• Grade 1 Filling of the side branches of the CTO artery.
• Grade 2 Partial filling of the epicardial vessel of the CTO artery.
• Grade 3 Complete collateral filling of the epicardial CTO vessel.

Statistical analysis

Data collected were coded, entered, and analyzed using Microsoft excel program software. Data analysis was done by statistical package for the social sciences (SPSS) version 26.

Descriptive statistics:

Our numeric data were represented as mean (± SD). Categorical data were expressed as proportions.

Analytic statistics: The used tests were

• Chi-square test was used when comparing between qualitative data.
• Independent sample T test was used when comparing before and after the same group.
• Paired t- test when comparing before and after the same group.
• P value was considered statistically significant at p<0.05.

Results

In group 1 of our study, 87.5% were males and 12.5% were females, while group 2 was composed of 75% males, and 25% females. The mean age of our study patients in group 1 was 57.3  (± 8.6) years while the mean age of those in group 2 was 57.4 (± 9.6) years  (Table 1).

Both our study groups contained obese participants (31.8 kg/m2 in group 1 and 31.7 kg/m2 in group 2). Additionally, the majority of the patients in both groups were smokers, had hypertension, and suffered from DM. These characteristics did not vary significantly between both groups (Table 1).

Table (1): Comparison of all studied groups as regards demographic data.

t: value of independent sample t test.                                               

X²: Chi-square test.

In terms of the distribution of the culprit vessel in this current study, in the whole population LAD CTO was more prevalent (45%), the majority of our patients in group 1 suffered from coronary chronic total occlusions in the right coronary artery (RCA) (47.5%), followed by the left anterior descending artery (LAD) (42.5%), then the posterior descending artery (5%). Regarding group 2, the major occlusion were in the LAD, followed by the RCA, and the PDA (47.5%, 12.5% and 5% respectively). This difference between both groups was statistically significant (p value= 0.004) (Table 2).

Table (2): Comparison of all studied groups as regards CTO artery.

X²: Chi-square test. 

When it comes to the grade of collateral among patients of group 1 in our study, almost half of them had incomplete filling, while equal proportion of patients had faint and complete filling. Additionally, the majority of the collaterals were contralateral (Table 3).

Table (3): Description of collateral types and grades in group of patients with collaterals.

Upon investigating the difference in the wall strain rate between baseline assessment and 3 months after revascularization between both our study groups, we found statistically significant difference regarding all the view levels; basal, mid and apical regarding the anterior and lateral walls (p value= <0.001 and 0.04 in anterior walls and 0.02 and 0.04 regarding the lateral wall respectively) (Tables 4 & 5).

Table (4): Comparison of all studied groups as regard anterior wall strain rate (before and 3 months after revascularization).

Table (5): Comparison of all studied groups as regard Lateral wall strain rate (before and 3 months after revascularization)

Furthermore, the septal wall strain rate improved significantly in the collateral group as observed in the apical and mid views after 3 months post-intervention when compared to the non-collateral group (Table 6).

Table (6): Comparison of all studied groups as regard septal wall strain rate (before and 3 months after revascularization)

The same observation was found in terms of the inferior wall strain rate where the strain rate improved significantly after 3 months post revascularization in collateral group and was also significantly higher than the non-collateral group (Table 7).

Table (7): Comparison of all studied groups as regard inferior wall strain rate (before and 3 months after revascularization)

We also investigated the ejection fraction and found that despite that the EF improved numerically across the follow-up periods in the collaterals group after revascularization compared to the non-collateral group, this difference was statistically insignificant (Table 8).

Table (8): Comparison of all studied groups as regard ejection fraction (before and 3 months after revascularization).

Discussion

Despite decades of study, the functional role of coronary collateral circulation remains controversial. A beneficial effect of coronary collaterals on infarct size has been suggested by many clinical investigators but not by others. Although stenotic lesions of between 75% and 90% can produce myocardial ischemia, they are never accompanied by angiographically visible collateral circulation. More severe narrowing or complete obstruction is necessary to stimulate development of angiographically visible collaterals (Hartman et al., 2021).

Over the past three decades, accumulating evidence has documented that pre-existing well-developed CCC at the onset of acute myocardial infarction plays an important role in preserving left ventricular function, reducing infarct size, preventing left ventricular aneurysm formation, and survival. But there is dispute whether the extent of collaterals is directly related to viability and functional recovery (Lee et al., 2017)

The demographic and clinical characteristics of our patients were consistent with Keulards et al. (2002), Erdogan et al. (2013) and Wang et al. (2020). This is explained by the fact that advancing age,  dyslipedemia ,obesity, DM, and HTN increase the incidence of IHD in concomitant with smoking.

Moreover, the most prevalent affected vessels among our patients was consistent with  Ahmed (2023) reported in his study, where they found 68% of the patients had affection of the LAD. He proved that the LAD artery was the most commonly occluded artery among the coronary arteries (42.4%), followed by the right coronary artery (26.8%) then the left circumflex artery (19.1%).

On the other hand, Keulards et al. (2002) found that 65.4% of their patients had affection of the RCA, and this may be due to selection of patients and the difference of Epidemiology among the study groups.

When it comes to the grade of collateral among patients of group 1 in our study, almost half of them had incomplete filling, while equal proportion of patients had faint and complete filling. Additionally, the majority of the collaterals were contralateral. These findings were unlike those stated by Lee et al. (2017) and Wang et al. (2020), where the grade of collaterals among their patients was mostly grade 3. This difference between our study and theirs could be attributed to the variation in the mean BMI of our patients than theirs, since our patients had a higher mean BMI than the patients in both studies, and therefore this could have affected the grade of collateral circulation.

There is a strength in our study than previous studies represented in the lack of previous studies investigating the wall strain in each segment alone and each view in details as our study investigated; as well as the lack of studies investigating the wall motion score index as well as the wall motion of each segment and comparing the findings in terms of the presence versus absence of collaterals.

Upon investigating the difference in the wall strain rate between baseline assessment and 3 months after revascularization between both our study groups, we found that the statistically significant difference was observed in the 3 months post-revascularization period in all the view levels; basal, mid and apical regarding the anterior and lateral walls .

Furthermore, the septal wall strain rate improved significantly in the collateral group as observed in the apical and mid views at the 3 months period when compared to the non-collateral group.

The same observation was found in terms of the inferior wall strain rate where the strain rate improved significantly after 3 months post revascularization in collateral group and was also significantly higher than the non-collateral group.

This is consistent with the literature that strain rates reflect the viability of the myocardium and are a specific and sensitive measure for the myocardial response to collateral flow and degree of occlusion, where reduced strain rates reflect worsened coronary circulation (Aktan et al., 2021).

In our study, we also investigated the ejection fraction and found that despite that the EF improved numerically across the follow-up periods in the collaterals group after revascularization compared to the non-collateral group, this difference was statistically insignificant.

This agrees with the study by Mashayekhi et al. (2018) which investigated whether PCI CTO improves left ventricular function. Despite observing that the CTO PCI resulted in clinical benefit over no CTO PCI, as evidenced by reduced major adverse coronary event rates at 12 months, they stated that no benefit was seen for CTO PCI in terms of the left ventricular function.

Afterwards, Ybarra et al. (2018) evaluated the potential benefits of CTO PCI on left ventricular function and found similar results to ours. Even in The EXPLORE study which included patients with acute myocardial infarction (AMI) who underwent primary PCI and presented CTO in a non-infarct-related artery. At the 4-month follow-up, similar left ventricular function was observed in both groups, although a significant improvement in the ejection fraction was observed in the subgroup of patients with anterior wall infarction. The inclusion of patients without viability research may have limited a possible PCI positive result.

Lately, Ahmed (2023) and Zhou et al. (2023) concluded that the left ventricular ejection fraction did not substantially improve after CTO PCI. Nevertheless, after Zhou et al. (2023) conducted pairwise analysis including only those with a baseline LVEF ≤60%. In patients with normal flow of coronary circulation immediately after PCI for CTO, there was a significant improvement in LVEF in comparison with patients with slow flow, mainly due to a decreased left ventricular end systolic diameter. They also highlighted that patients who had slow-to-normal flow did not benefit from CTO recanalization, and in patients with consistent slow flow, there was even a trend of decreased LVEF. In contrast, LVEF could still be improved in patients with normal flow after CTO PCI even if they developed slow flow at follow-up.

On the other hand, Wang et al. (2020) found significant improvement in the EF post revascularization. Nevertheless, this difference between our findings and theirs is due to the fact that their study recruited patients with single chronic vessel occlusion only, while our study included multiple vessels. Moreover, 43.09% of their patients had full filling of their collateral circulations, while our patients 55% of our patients had incomplete filling and only 22.5% had complete filling.

Nevertheless, a limitation existed in our study, which is represented in the relatively small sample size, where larger sample size could have yielded more clinically significant outcomes.

Conclusion

Revascularization of chronic total occlusion in presence of collateral circulation significantly improves wall motion assessed by strain rate but not ejection fraction compared to patients without collateral coronary circulation.

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التغيرات المبكرة في وظيفة البطين الأيسر بعد فتح الشريان التاجي المنغلق كليا عن طريق القسطرة القلبية و علاقتها بوجود تغذية مرتجعة من الشرايين المقابلة

حسام الدين محمد السداوي 1 , خالد عبد العظيم شكري 1 , عمر محمد صالح 2 , محمد احمد عرابي 2 , هشام حجازي علي 2

1 قسم القلب و الأوعية الدموية, الأكاديمية الطبية العسكرية.

2 قسم القلب و الأوعية الدموية, كلية الطب, جلمعة قناة السويس.

خلفية البحث: ذكرت العديد من الدراسات فوائد التدخلات الناجحة للشريان التاجي عن طريق الجلد في المرضى الذين يعانون من الانسداد الكلي المزمن للشريان التاجي، إلا انه حتى الآن، لم تقارن أي دراسات للنتائج السريرية للمرضى المصابين بـانسداد كلي مزمن مع وجود دورة دموية جانبية متطورة الذين خضعوا لتدخلات الشريان التاجي الناجحة عن طريق الجلد حدوث تغييرات مبكرة في وظيفة البطين الأيسر من عدمه.

الهدف من البحث: هو تقييم التغيرات المبكرة في كفاءة البطين الأيسر بعد نجاح فتح الانغلاق الكلي المزمن في الشرايين التاجية، ومقارنتها في وجود تداول شرياني جانبي من عدمه.

المرضى و طرق البحث: تم إجراء هذه الدراسة بأقسام القلب بمستشفيات القوات المسلحة و تم تجميع البيانات الخاصة بالمرضى قبل فتح الشريان المنغلق كليا و بعد ذلك بأسبوعين ثم بعد ذلك بثلاثة أشهر. وقد تم اختيار 80 مريضا من المترددين على المستشفى لعمل القسطرة القلبية وتقسيمهم على مجموعتين متساويتين طبقا لوجود تداول شرياني جانبي من عدمه . و قد تم تحليل البيانات إحصائيا باستخدام البرامج المتخصصة وتم استخدام الجداول لوصف النتائج أيضا, كما تم التعبير عن المتغيرات الرقمية من حيث المتوسط والانحراف المعياري و تم التعبير عن المتغيرات النوعية من حيث التكرار ونسبة التردد.

نتائج البحث:

1. عانى معظم مرضى المجموعة الأولى من انسداد في الشريان التاجي الأيمن، بينما وجدت الدراسة ان معظم مرضى المجموعة الثانية يعانون من انسداد في الشريان الأمامي النازل و كانت هذه الفروق ذات دلالة إحصائية.
2. وجدت هذه الدراسة فروق ذات دلالة إحصائية فيما يخص مقاييس معدلات جهد البطين الأيسر من خلال قياسات تصوير الدوبلر النسيجي بين مجموعتي الدراسة بعد عمل القسطرة، حيث كانت نتائج المجموعة الأولى افضل من الثانية بعد ثلاثة أشهر من اجراء العملية.
3. لم تجد الدراسة علاقة ذات دلالة إحصائية فيما يخص قياس كفاءة البطين الأيسر بالطرق التقليدية بين مجموعتي الدراسة قبل و بعد عمل العملية.

الاستنتاج: تواجد دورة دموية جانبية متطورة يحسن من الاستجابة المبكرة لكفاءة البطين الأيسر باستخدام تصوير الدوبلر النسيجي و ذلك بعد عملية الفتح الناجح للإنسداد الكلي المزمن للشرايين التاجية عن طريق القسطرة القلبية.

الكلمات الدالة: وظيفة البطين الأيسر, جانبية, انسداد مزمن.