Comparison of Pathology of CTO With and Without CABG
Comparison of Pathology of CTO With and Without CABG
Aims. The aim of our study was to investigate chronic total occlusion (CTO) in human coronary arteries to clarify the difference between CTO with prior coronary artery bypass graft (CABG) and those without prior CABG.
Methods and Results. A total of 95 CTO lesions from 82 patients (61.6 ± 14.0 years, male 87.8%) were divided into the following three groups: CTO with CABG (n = 34) (CTO+CABG), CTO without CABG—of long-duration (n = 49) (LD-CTO) and short-duration (n = 12) (SD-CTO). A histopathological comparison of the plaque characteristics of CTO, proximal and distal lumen morphology, and negative remodelling between groups was performed. A total of 1127 sections were evaluated. Differences in plaque characteristics were observed between groups as follows: necrotic core area was highest in SD-CTO (18.6%) (LD-CTO: 7.8%; CTO+CABG: 4.5%; P = 0.02); calcified area was greatest in CTO+CABG (29.2%) (LD-CTO: 16.8%; SD-CTO: 12.1%; P = 0.009); and negative remodelling was least in SD-CTO [remodelling index (RI) 0.86] [CTO+CABG (RI): 0.72 and LD-CTO (RI): 0.68; P < 0.001]. Approximately 50% of proximal lumens showed characteristics of abrupt closure, whereas the majority of distal lumen patterns were tapered (79%) (P < 0.0001).
Conclusion. These pathological differences in calcification, negative remodelling, and presence of necrotic core along with proximal and distal tapering, which has been associated with greater success, help explain the differences in success rates of percutaneous coronary intervention in CTO patients with and without CABG.
Coronary chronic total occlusion (CTO) is a common finding with a reported prevalence of 18.4% in patients undergoing non-urgent coronary angiography in the absence of previous coronary artery bypass or those presenting with acute myocardial infarction. Revascularization of CTO is associated with the improvement of cardiac function and long-term clinical outcome. Although the success rate of percutaneous coronary intervention (PCI) for revascularizing CTOs was low (51–74%) up to 2009, recent technological advances and interventional strategies have improved the success rate of PCI of CTO. The introduction of stiffer guidewires, microcatheters, tapered guidewires, and retrograde approach has contributed to the incremental improvements in success rates of >85%. On the other hand, PCI for CTO with prior coronary artery bypass graft (CABG) remains a challenge. Since approximately half the patients with prior CABG have CTO and the patients with saphenous vein graft often develop recurrent symptoms, the need to revascularize CTO with prior CABG is high. Furthermore, since the short- and long-term outcomes of PCI of saphenous vein graft are poor with drug-eluting stents as well as with bare-metal stents, PCI of coronary CTO following CABG is, therefore, likely to result in more favourable outcome. However, the success rate for CTO with prior CABG is still lower (80%) than those without CABG (88%) even though newer techniques are being utilized.
The pathological understanding of CTO from human autopsy studies has contributed to significant refinements of PCI techniques leading to improved results of revascularization. Histological correlates of angiographic CTOs have shown the influence of the duration of total occlusion on the presence of calcification, inflammation, and neovascularization. Another important finding in angiographic CTOs was the absence of complete occlusion on histological examination (78%) and, therefore, higher success rate is not surprising. Furthermore, the presence of microchannel diameter of 160–230 μm in human pathological study has encouraged the development of smaller diameter guidewires. In the present study, we sought to further investigate the extent of calcification, necrotic core size, remodelling, and proximal and distal lumen shape to understand better the differences in CTO characteristics in patients with and without CABG.
Abstract and Introduction
Abstract
Aims. The aim of our study was to investigate chronic total occlusion (CTO) in human coronary arteries to clarify the difference between CTO with prior coronary artery bypass graft (CABG) and those without prior CABG.
Methods and Results. A total of 95 CTO lesions from 82 patients (61.6 ± 14.0 years, male 87.8%) were divided into the following three groups: CTO with CABG (n = 34) (CTO+CABG), CTO without CABG—of long-duration (n = 49) (LD-CTO) and short-duration (n = 12) (SD-CTO). A histopathological comparison of the plaque characteristics of CTO, proximal and distal lumen morphology, and negative remodelling between groups was performed. A total of 1127 sections were evaluated. Differences in plaque characteristics were observed between groups as follows: necrotic core area was highest in SD-CTO (18.6%) (LD-CTO: 7.8%; CTO+CABG: 4.5%; P = 0.02); calcified area was greatest in CTO+CABG (29.2%) (LD-CTO: 16.8%; SD-CTO: 12.1%; P = 0.009); and negative remodelling was least in SD-CTO [remodelling index (RI) 0.86] [CTO+CABG (RI): 0.72 and LD-CTO (RI): 0.68; P < 0.001]. Approximately 50% of proximal lumens showed characteristics of abrupt closure, whereas the majority of distal lumen patterns were tapered (79%) (P < 0.0001).
Conclusion. These pathological differences in calcification, negative remodelling, and presence of necrotic core along with proximal and distal tapering, which has been associated with greater success, help explain the differences in success rates of percutaneous coronary intervention in CTO patients with and without CABG.
Introduction
Coronary chronic total occlusion (CTO) is a common finding with a reported prevalence of 18.4% in patients undergoing non-urgent coronary angiography in the absence of previous coronary artery bypass or those presenting with acute myocardial infarction. Revascularization of CTO is associated with the improvement of cardiac function and long-term clinical outcome. Although the success rate of percutaneous coronary intervention (PCI) for revascularizing CTOs was low (51–74%) up to 2009, recent technological advances and interventional strategies have improved the success rate of PCI of CTO. The introduction of stiffer guidewires, microcatheters, tapered guidewires, and retrograde approach has contributed to the incremental improvements in success rates of >85%. On the other hand, PCI for CTO with prior coronary artery bypass graft (CABG) remains a challenge. Since approximately half the patients with prior CABG have CTO and the patients with saphenous vein graft often develop recurrent symptoms, the need to revascularize CTO with prior CABG is high. Furthermore, since the short- and long-term outcomes of PCI of saphenous vein graft are poor with drug-eluting stents as well as with bare-metal stents, PCI of coronary CTO following CABG is, therefore, likely to result in more favourable outcome. However, the success rate for CTO with prior CABG is still lower (80%) than those without CABG (88%) even though newer techniques are being utilized.
The pathological understanding of CTO from human autopsy studies has contributed to significant refinements of PCI techniques leading to improved results of revascularization. Histological correlates of angiographic CTOs have shown the influence of the duration of total occlusion on the presence of calcification, inflammation, and neovascularization. Another important finding in angiographic CTOs was the absence of complete occlusion on histological examination (78%) and, therefore, higher success rate is not surprising. Furthermore, the presence of microchannel diameter of 160–230 μm in human pathological study has encouraged the development of smaller diameter guidewires. In the present study, we sought to further investigate the extent of calcification, necrotic core size, remodelling, and proximal and distal lumen shape to understand better the differences in CTO characteristics in patients with and without CABG.
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