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Circulation. Author manuscript; available in PMC 2017 July 11. Published in final edited form as: Circulation. 2016 May 03; 133(18): 1818–1825. doi:10.1161/CIRCULATIONAHA.115.017798.
Chronic Total Occlusion Should Not Routinely be Treated with Coronary Artery Bypass Grafting William S. Weintraub, MD and Kirk N. Garratt, MD Christiana Care Health System, Newark, DE
Abstract Author Manuscript Author Manuscript
Chronic total occlusions (CTOs) of the coronary arteries are common. In addition, they are often treated by coronary artery bypass graft (CABG) surgery. The decision to perform CABG for CTOs should be predicated on the demonstration of viability of the subtended myocardium and based on evidence that revascularization will increase the probability of some demonstrably better outcome, whether improved quality of life, prevention of future non-fatal everts or prolongation of life. The literature on surgical revascularization of CTOs is limited, and largely descriptive with only one post-hoc analysis from a randomized trial. There are two small non-randomized studies comparing PCI and to medical therapy. That the outcomes data are so limited affects the ability to justify CABG in this setting. The literature on PCI for CTOs is far more extensive, although there is also limited clinical trial data or comparative effectiveness data concerning choice of therapy for CTOs. Nonetheless, CABG for CTOs can be more easily justified in the setting of multivessel disease where bypass of the CTO is part of an overall strategy of complete revascularization. Thus, CABG for CTOs can be best justified where there is multivessel disease, poorly controlled angina pectoris, and evidence of viability in the subtended zone. While carrying out studies concerning CABG for CTOs will be difficult, a research agenda in this space is clearly needed.
Keywords cardiac surgery; chronic total occlusion
Journal Subject Term Cardiovascular Surgery
Author Manuscript
Should chronic total occlusions (CTOs) of coronary arteries be revascularized by coronary artery bypass graft (CABG) surgery? It would seem that this is not a question that is often asked. And yet CTOs are common, and more commonly revascularized by CABG than by percutaneous coronary intervention (PCI). In this paper we review the epidemiology of CTOs, discuss issues and viability of the subtended zone, how viability could be assessed, indications for revascularization of CTOs, the literature on CABG for CTO and conclude
Correspondence: William S. Weintraub, MD, Cardiology Section, Christiana Care Health System, 4755 Ogletown-Stanton Road, Newark, DE 19718, Phone: 302-733-1200, Fax: 302-733-4998, [email protected]. Disclosures: None.
Weintraub and Garratt
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Author Manuscript
with recommendations for future research. The fundamental positions put forward here 1) the literature on CABG for CTOs is not strong enough to justify this common procedure on a routine basis, 2) decisions on care still need to be made, and 3) additional research is needed.
Background on Chronic Total Occlusions
Author Manuscript
CTOs are common findings on coronary arteriograms.1, 2 While there has been an extensive literature on the subject concerning PCI for CTOs, there is less literature on CABG for CTOs.3–5 This is despite data from the early 2000’s showing that patients with CTO are treated more often with CABG than with PCI.1 Christofferson et al1 studied 8,004 consecutive patients undergoing diagnostic catheterization at a single institution between 1990 and 2000. CTOs were defined as 100% coronary occlusion present for at least 3 months. Patients with previous CABG or recent myocardial infarctions (n=1,423) were excluded. Of the remaining 6,581 patients, 3,087 (47%) had significant coronary artery disease (>70% coronary stenosis). Of patients with significant coronary artery disease, a CTO was present in 1,612 (52%) patients, of whom 375 (12%) had more than 1 CTO. Among patients with significant CAD and a CTO, 11% were treated with PCI, 40% CABG and 49% medical therapy. In comparison, among patients with significant CAD but no CTO, 36% were treated with PCI, 28% with CABG and 35% medically (p40 mm were present in 74.9% and 37.8% of patients respectively. One-year mortality was higher in patients with CTO length >40 mm compared to ≤20 mm (p = 0.04). CTO length >40 mm was an independent predictor of one year mortality controlling for age, number of CTOs, comorbidity, clopidogrel use, severity of coronary artery disease, renal failure, and left ventricular ejection fraction. The authors speculated that the length of the CTO might be a surrogate for disease burden. The authors concluded that CABG achieved high success in bypassing CTOs, and that CTO length >40 mm is an independent predictor of post-CABG mortality. This paper did not address who should undergo CABG for CTOs, the issue of viability in the zone, and the difference in decision making between those patients where the CTO drove the decision for CABG and where the CTO was bypassed but where non-CTO vessels drove the decision making.
Author Manuscript
CABG for CTOs was studied by Fefer et al38 in 405 patients undergoing CABG in 2005 and 2007, with 221 CTOs in 174 patients: 132 patients had 1 CTO; 37 had 2 CTOs and 5 had 3 CTOs. Of the 221 CTOs, 191 (86%) were bypassed, including all in the LAD. However, 12% of left circumflex and 22% of right coronary artery CTOs were not bypassed. Incomplete CTO revascularization was associated with older age, more comorbidities, and lower ejection fraction. Incomplete CTO revascularization was not associated with increased long-term mortality. Furthermore, there was no difference in long-term mortality between patients with and without CTOs. There was no assessment of viability or return of function, and no assessment of functional status. This study does show that CABG for CTOs can be done, but offers little guidance for whom it should be done. Circulation. Author manuscript; available in PMC 2017 July 11.
Weintraub and Garratt
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Author Manuscript Author Manuscript
A potentially useful surgical intervention would be to perform CABG to a CTO of the LAD with minimally invasive surgery. This was studied in 1800 patients from 1996 to 2007 undergoing left internal mammary artery bypass to the LAD.39 There were 420 patients with and 1380 without a CTO. Prior MI had occurred in just 5.3% of the CTO and 4% of the nonCTO cases. The LAD could be bypassed in all of the stenosed vessels and all but one of the occluded vessels. Periprocedural mortality was 1.1% and 0.7% for the CTO and non-CTO groups respectively (p = 0.36). Survival for the CTO and non-CTO groups were 98.0% (95% CI 96.5% to 99.5%) and 98.0% (95% CI 96.4% to 99.5%) at 1 year (p = 0.87) and 90.5% (95% CI 85.8% to 95.5%) versus 90.4% (95% CI 85.8% to 95.1%) at 5 years respectively (p = 0.98). Angiography at 6 to 12 months postoperatively showed a patency rate of the LIMA bypass of 98% (94 of 96 patients) in the CTO group and 96% (290 of 301 patients) in the non-CTO group (p = 0.45). Freedom from major adverse cardiac and cerebrovascular events and angina with or without CTO at 5 years was 83.2% (95% CI 77.6% to 88.8%) and 85.5% (95% CI 82.6% to 88.1%), respectively (p = 0.64). Recurrence of angina occurred in 1.41% and 1.16% of the CTO and non-CTO patients respectively. The authors concluded that minimally invasive CABG of a totally occluded LAD is almost always possible and that a CTO is not a negative predictor for short or long-term outcome in patients undergoing this operation. As impressive as these results appear, it is not clear that these patients benefited from surgery. The need for benefit from bypassing the CTO is critical as in these patients the CTO would be the only obstruction bypassed. We do not know about the severity of angina before the operation. We also do not know about the extent of the coronary disease or about whether there are threatened collaterals. If there are no threatened collaterals, and if angina was not present or at least not disabling, then it is hard to see the benefit of the surgery. In addition, we do know if there was hibernating myocardium is the distribution of the CTO and then return of function after surgery.
Author Manuscript Author Manuscript
There is a small, preliminary, non-randomized study comparing the outcomes of patients with CTOs treated with medical therapy, PCI or CABG.40 From 2003 to 2012, 2024 patients were enrolled in single-center registry, which included 393 with multiple CTOs. With a median 46.5 month followup, 169 patients (43%) were referred to CABG, 130 (33%) to PCI, 94 (24%) to medical therapy. Baseline characteristics and statistical methods were not reported. CABG had the lowest incidence of major adverse cardiac and cerebral events (11.2%) compared with PCI (20.0%, p
Circulation. Author manuscript; available in PMC 2017 July 11. Published in final edited form as: Circulation. 2016 May 03; 133(18): 1818–1825. doi:10.1161/CIRCULATIONAHA.115.017798.
Chronic Total Occlusion Should Not Routinely be Treated with Coronary Artery Bypass Grafting William S. Weintraub, MD and Kirk N. Garratt, MD Christiana Care Health System, Newark, DE
Abstract Author Manuscript Author Manuscript
Chronic total occlusions (CTOs) of the coronary arteries are common. In addition, they are often treated by coronary artery bypass graft (CABG) surgery. The decision to perform CABG for CTOs should be predicated on the demonstration of viability of the subtended myocardium and based on evidence that revascularization will increase the probability of some demonstrably better outcome, whether improved quality of life, prevention of future non-fatal everts or prolongation of life. The literature on surgical revascularization of CTOs is limited, and largely descriptive with only one post-hoc analysis from a randomized trial. There are two small non-randomized studies comparing PCI and to medical therapy. That the outcomes data are so limited affects the ability to justify CABG in this setting. The literature on PCI for CTOs is far more extensive, although there is also limited clinical trial data or comparative effectiveness data concerning choice of therapy for CTOs. Nonetheless, CABG for CTOs can be more easily justified in the setting of multivessel disease where bypass of the CTO is part of an overall strategy of complete revascularization. Thus, CABG for CTOs can be best justified where there is multivessel disease, poorly controlled angina pectoris, and evidence of viability in the subtended zone. While carrying out studies concerning CABG for CTOs will be difficult, a research agenda in this space is clearly needed.
Keywords cardiac surgery; chronic total occlusion
Journal Subject Term Cardiovascular Surgery
Author Manuscript
Should chronic total occlusions (CTOs) of coronary arteries be revascularized by coronary artery bypass graft (CABG) surgery? It would seem that this is not a question that is often asked. And yet CTOs are common, and more commonly revascularized by CABG than by percutaneous coronary intervention (PCI). In this paper we review the epidemiology of CTOs, discuss issues and viability of the subtended zone, how viability could be assessed, indications for revascularization of CTOs, the literature on CABG for CTO and conclude
Correspondence: William S. Weintraub, MD, Cardiology Section, Christiana Care Health System, 4755 Ogletown-Stanton Road, Newark, DE 19718, Phone: 302-733-1200, Fax: 302-733-4998, [email protected]. Disclosures: None.
Weintraub and Garratt
Page 2
Author Manuscript
with recommendations for future research. The fundamental positions put forward here 1) the literature on CABG for CTOs is not strong enough to justify this common procedure on a routine basis, 2) decisions on care still need to be made, and 3) additional research is needed.
Background on Chronic Total Occlusions
Author Manuscript
CTOs are common findings on coronary arteriograms.1, 2 While there has been an extensive literature on the subject concerning PCI for CTOs, there is less literature on CABG for CTOs.3–5 This is despite data from the early 2000’s showing that patients with CTO are treated more often with CABG than with PCI.1 Christofferson et al1 studied 8,004 consecutive patients undergoing diagnostic catheterization at a single institution between 1990 and 2000. CTOs were defined as 100% coronary occlusion present for at least 3 months. Patients with previous CABG or recent myocardial infarctions (n=1,423) were excluded. Of the remaining 6,581 patients, 3,087 (47%) had significant coronary artery disease (>70% coronary stenosis). Of patients with significant coronary artery disease, a CTO was present in 1,612 (52%) patients, of whom 375 (12%) had more than 1 CTO. Among patients with significant CAD and a CTO, 11% were treated with PCI, 40% CABG and 49% medical therapy. In comparison, among patients with significant CAD but no CTO, 36% were treated with PCI, 28% with CABG and 35% medically (p40 mm were present in 74.9% and 37.8% of patients respectively. One-year mortality was higher in patients with CTO length >40 mm compared to ≤20 mm (p = 0.04). CTO length >40 mm was an independent predictor of one year mortality controlling for age, number of CTOs, comorbidity, clopidogrel use, severity of coronary artery disease, renal failure, and left ventricular ejection fraction. The authors speculated that the length of the CTO might be a surrogate for disease burden. The authors concluded that CABG achieved high success in bypassing CTOs, and that CTO length >40 mm is an independent predictor of post-CABG mortality. This paper did not address who should undergo CABG for CTOs, the issue of viability in the zone, and the difference in decision making between those patients where the CTO drove the decision for CABG and where the CTO was bypassed but where non-CTO vessels drove the decision making.
Author Manuscript
CABG for CTOs was studied by Fefer et al38 in 405 patients undergoing CABG in 2005 and 2007, with 221 CTOs in 174 patients: 132 patients had 1 CTO; 37 had 2 CTOs and 5 had 3 CTOs. Of the 221 CTOs, 191 (86%) were bypassed, including all in the LAD. However, 12% of left circumflex and 22% of right coronary artery CTOs were not bypassed. Incomplete CTO revascularization was associated with older age, more comorbidities, and lower ejection fraction. Incomplete CTO revascularization was not associated with increased long-term mortality. Furthermore, there was no difference in long-term mortality between patients with and without CTOs. There was no assessment of viability or return of function, and no assessment of functional status. This study does show that CABG for CTOs can be done, but offers little guidance for whom it should be done. Circulation. Author manuscript; available in PMC 2017 July 11.
Weintraub and Garratt
Page 6
Author Manuscript Author Manuscript
A potentially useful surgical intervention would be to perform CABG to a CTO of the LAD with minimally invasive surgery. This was studied in 1800 patients from 1996 to 2007 undergoing left internal mammary artery bypass to the LAD.39 There were 420 patients with and 1380 without a CTO. Prior MI had occurred in just 5.3% of the CTO and 4% of the nonCTO cases. The LAD could be bypassed in all of the stenosed vessels and all but one of the occluded vessels. Periprocedural mortality was 1.1% and 0.7% for the CTO and non-CTO groups respectively (p = 0.36). Survival for the CTO and non-CTO groups were 98.0% (95% CI 96.5% to 99.5%) and 98.0% (95% CI 96.4% to 99.5%) at 1 year (p = 0.87) and 90.5% (95% CI 85.8% to 95.5%) versus 90.4% (95% CI 85.8% to 95.1%) at 5 years respectively (p = 0.98). Angiography at 6 to 12 months postoperatively showed a patency rate of the LIMA bypass of 98% (94 of 96 patients) in the CTO group and 96% (290 of 301 patients) in the non-CTO group (p = 0.45). Freedom from major adverse cardiac and cerebrovascular events and angina with or without CTO at 5 years was 83.2% (95% CI 77.6% to 88.8%) and 85.5% (95% CI 82.6% to 88.1%), respectively (p = 0.64). Recurrence of angina occurred in 1.41% and 1.16% of the CTO and non-CTO patients respectively. The authors concluded that minimally invasive CABG of a totally occluded LAD is almost always possible and that a CTO is not a negative predictor for short or long-term outcome in patients undergoing this operation. As impressive as these results appear, it is not clear that these patients benefited from surgery. The need for benefit from bypassing the CTO is critical as in these patients the CTO would be the only obstruction bypassed. We do not know about the severity of angina before the operation. We also do not know about the extent of the coronary disease or about whether there are threatened collaterals. If there are no threatened collaterals, and if angina was not present or at least not disabling, then it is hard to see the benefit of the surgery. In addition, we do know if there was hibernating myocardium is the distribution of the CTO and then return of function after surgery.
Author Manuscript Author Manuscript
There is a small, preliminary, non-randomized study comparing the outcomes of patients with CTOs treated with medical therapy, PCI or CABG.40 From 2003 to 2012, 2024 patients were enrolled in single-center registry, which included 393 with multiple CTOs. With a median 46.5 month followup, 169 patients (43%) were referred to CABG, 130 (33%) to PCI, 94 (24%) to medical therapy. Baseline characteristics and statistical methods were not reported. CABG had the lowest incidence of major adverse cardiac and cerebral events (11.2%) compared with PCI (20.0%, p
