Does rich coronary collateral circulation distal to chronically occluded left anterior descending artery compete with
Daisuke Kaku1, Atsushi Nakahira, Hidekazu Hirai
1Department of Cardiovascular Surgery, Osaka City University Graduate School of Medicine, Abeno-ku, Osaka, Japan.
Insights
Rich collateral circulation in coronary artery bypass grafting (CABG) can compete with graft flow, but does not impact long-term outcomes. Rentrop grade effectively assesses collateral hemodynamics, guiding intraoperative graft flow evaluation.
Area of Science:
- Cardiovascular Surgery
- Interventional Cardiology
- Vascular Biology
Background:
- Coronary artery bypass grafting (CABG) involves bypassing blockages in coronary arteries.
- Chronic total occlusions (CTOs) rely on collateral circulation for myocardial viability.
- Graft flow can be affected by native flow through stenoses or collateral circulation.
Purpose of the Study:
- To investigate if rich collateral circulation distal to CTO competes with graft flow.
- To assess the association between Rentrop grade and graft flow competition.
- To evaluate the impact of collateral circulation on graft patency and clinical outcomes.
Main Methods:
- Retrospective analysis of 666 CABG patients (2001-2012).
- Focus on 70 patients with left internal thoracic artery (ITA) grafted distal to CTO in the left anterior descending artery (LAD).
- Patients categorized into Poor (Grade 0-1), Moderate (Grade 2), and Rich (Grade 3) collateral groups based on Rentrop grade.
Main Results:
- Significant differences in mean graft flow (MGF) and pulsatility index (PI) among collateral groups (P=0.025, P=0.046).
- Lower Rentrop grades correlated with higher MGF and lower PI.
- Group P (poor collaterals) showed higher MGF and lower PI than Group R (rich collaterals).
- All grafts were patent post-operatively; long-term outcomes were comparable across groups.
Conclusions:
- Rich collateral circulation distal to CTO can compete with graft flow.
- This competition does not appear to affect long-term clinical outcomes, likely due to collateral regression.
- Rentrop grade is a reliable indicator of collateral hemodynamics and crucial for intraoperative graft flow assessment.
Objectives:
In coronary artery bypass grafting (CABG), graft flow distal to a mild stenosis can compete with relatively preserved native flow through the stenosis and the competition can result in graft stenosis. In chronic total occlusion (CTO), coronary collateral circulation, which is essential to maintain myocardial viability distal to CTO, varies in extent among patients and the extent can be scored by Rentrop grade in coronary angiography. We investigated whether rich collateral circulation distal to CTO competes with distally anastomosed graft flow in association with Rentrop grade.
Methods:
Of 666 patients who underwent CABG from January 2001 to December 2012, 70 patients whose left internal thoracic artery (ITA) was grafted distal to CTO in the left anterior descending artery (LAD) were divided into three groups: Poor collaterals (Rentrop grades 0 and 1, Group P, n = 22), Moderate collaterals (grade 2, Group M, n = 23) and Rich collaterals (grade 3, Group R, n = 25). The intraoperative measurements of mean graft flow (MGF) and pulsatility index (PI) of left ITA grafts, early graft patency and long-term clinical outcomes were compared.
Results:
The MGF and PI of left ITA grafts differed significantly among the three groups (P = 0.025 and P = 0.046, respectively). Lower Rentrop grade was associated with preferable results of higher MGF and lower PI. The graft flow pattern in Group P showed a significantly higher MGF (P = 0.020) and lower PI (P = 0.041) than those in Group R. All early postoperative coronary angiograms showed patent left ITA grafts. Serial echocardiographic evaluations, survival rates and cardiac event-free rates were comparable with the follow-up of 5.00 ± 3.11 years.
Conclusions:
Rich collateral circulation distal to CTO in LADs can potentially compete with graft flow, although the competition seems not to affect clinical outcomes probably due to the regression of collaterals surmounted by the graft flow. Rentrop grade is shown to certainly reflect the degree of collateral haemodynamic circulation distal to CTO and especially important to evaluate intraoperative graft flow appropriately, considering the possible phenomenon of graft flow competition.
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