Review Article

The Utility of CT Coronary Angiography in Chronic Total Occlusion Percutaneous Coronary Intervention

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Chronic total occlusion (CTO) of the coronary arteries is a relatively common finding in routine coronary angiography. Of late, there has been considerable improvement in the success rate of percutaneous intervention for coronary CTO, attributed to technological advancement and skills development. CT coronary angiogram (CTCA) is a simple, non-invasive, and cost-effective test that aids in the diagnosis and management of coronary artery disease, including CTOs. The development of multi-slice CT and the use of 3D volume rendering images has revolutionised the diagnostic abilities of CTCA, with improvements in imaging quality and detailed anatomical and morphological characterisation of the plaque disease. In CTO percutaneous intervention, CTCA is used in pre-procedural planning, applying scoring systems to predict the likely success of the intervention as well as the post-procedural evaluation and follow-up. This review examines the different uses of CTCA in CTO intervention, its impact on successful recanalisation and the areas for future consideration.

Disclosure:DC and VS are on the European Cardiology Review editorial board; this did not influence peer review. All other
authors have no conflicts of interest to declare.



Published online:

Correspondence Details:Vinoda Sharma, Cardiology Department, Birmingham City Hospital, Dudley Road, Birmingham B18 7QH, UK. E:

Open Access:

This work is open access under the CC-BY-NC 4.0 License which allows users to copy, redistribute and make derivative works for non-commercial purposes, provided the original work is cited correctly.

A coronary artery chronic total occlusion (CTO) is defined as a completely occluded coronary artery with Thrombolysis in MI (TIMI) 0 flow (absence of any antegrade flow) and a duration of occlusion of more than 3 months. Approximately 25% of patients with coronary artery disease (CAD) are diagnosed with a coronary CTO on coronary imaging and the incidence of these occlusions rises with the patient’s age.1,2 These lesions consist of an occluded lumen with organised, extensively recanalised thrombus, atheromatous plaque and an adventitia.3 Calcium and lipid components are also found, both intracellularly as well as extracellularly. The occluded lumen is limited proximally and distally by tough collagen-rich fibrous tissue. CTO lesions that are older than 12 months contain tough proximal and distal caps, and the lesions are more calcified, containing less neovascularisation.4 The vascular bed distal to a CTO is perfused by a network of coronary collateral circulation that can maintain adequate perfusion at rest. However, patients can develop symptoms even with well-developed collaterals, especially on exertion when perfusion via collaterals to the affected myocardium is not adequate, resulting in ischaemic myocardial regions.5 Symptoms, and perfusion to these ischaemic regions, can be improved by successful revascularisation by percutaneous coronary intervention (PCI), or bypass surgery in the case of multivessel disease. This can lead to significant improvement in angina and quality of life compared with optimum medical therapy alone.6

CT Coronary Angiography in the Diagnosis of Chronic Total Occlusion

CT coronary angiography (CTCA) is a non-invasive imaging modality that effectively determines the severity and extent of CAD, with the ability to assess plaque morphology, composition and characteristics. When interpreting the CTCA scans, a significant reduction in the size of the lumen that is contrast-filled should be identified.7–9

In the early days, electron beam CT (EBCT) was used to detect the amount of calcification and establish the possibility of coronary disease.10 Technological advancements have led to the development of multi-slice CT (MSCT) with 16, 64 or 128 slices acquired in a single rotation. These scanners have better resolution, fewer artefacts, and the ability to define more anatomical specifications of the coronary arteries and provide detection of morphological characteristics of plaque disease and the stenotic segments. The diagnostic accuracy of CTCA is good compared with invasive coronary angiography, but limitations of excess calcification causing ‘blooming artefact’ and difficulty in visualisation of the lumen still exist.11

CTOs of the coronary vessels on CTCA are a common discovery and diagnosed if there is complete absence of lumen opacification in cross-sectional views. Sometimes retrograde collateral flow of contrast opacifies the lumen distal to the blockage. A CTO can be underdiagnosed on CTCA due to the existence of retrograde collaterals that enable opacification of the artery next to the stenosis. Both total and subtotal occlusions have an interrupted contrast-enhanced lumen on CTCA and, due to the inadequate spatial resolution, it can be difficult to differentiate between the two.12,13

Advances in CTCA technologies have led to better-quality images and lower radiation exposure. Many new CTCA scan readers prefer to use 3D volume rendering (3D-VR) images and software for automatic vessel diameter analysis and vessel segmentation. CTOs can be easily diagnosed using 3D-VR images.14

CT Coronary Angiography in Pre-procedural CTO PCI Planning

The success rate of PCI for CTOs is significantly lower than that for standard PCI. Technological advances and proctoring have improved the success rates among expert operators and centres, but the overall success remains sub-optimal in national registries.15 In the most recent British Society of Intervention Cardiology national audit, a success rate of 74.93% was observed in all CTO PCI patients during 2020–21.16

There remains a need to improve the safety, efficiency and success rate of CTO procedures and CTCA may be a useful tool for this. CTCA can be used in pre-procedural complexity scoring. Conventional fluoroscopic invasive coronary angiography does not always provide the required anatomical details in complex cases.

Different scoring systems are used to assess pre-procedural CTO complexity and facilitate the selection of viable approaches, such as antegrade or retrograde routes, appropriate equipment, and the operator with the greater experience with that particular anatomy. Therefore, these refinements increase the likelihood of success. Primarily, the Japanese CTO registry score (J-CTO) is used, which assigns 1 point for each of the following five features: occlusion length >20 mm, presence of a blunt stump, presence of tortuosity, presence of calcification, and a previous failed attempt.17 The lower the J-CTO score, the higher the anticipated success rate. Other examples of such scores include the Clinical and Lesion (CL) related score by Alessandrino et al. and, recently, the Hybrid Algorithm for Treating Chronic Total Occlusions in Europe, namely The RECHARGE Registry score.18,19

Predictive Performance of CTCA-derived Scores for CTO Intervention

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Scoring systems using CTCA have utilised comparisons to data obtained from invasive coronary angiography (Table 1). Fujino et al. studied 205 patients with CTO lesions and pre-procedure CTCA, indicating that a CTCA-driven J-CTO score better predicted potential wire crossing than that of invasive coronary angiogram results.20 A recent study by Li et al. assessed the RECHARGE CTCA scores of 131 patients and compared them with the conventional coronary angiography RECHARGE scores in the prediction of wire crossing and success rate.21 They showed that the RECHARGE CTCA better predicted the success of 30-minute wire crossing. In 2015 Opolski et al. developed the CT-RECTOR scoring system that mainly uses CTCA data.22 That study included 240 participants with consecutive lesions and pre-procedural CTCA, enrolled across four centres. After multivariable analysis, 1 point was assigned for each of the following predictors: severe calcification, multiple occlusions, bending, previously failed PCI, occlusion more than 12 months old, and the presence of a blunt stump. Four different procedural difficulty groups were developed based on the total score, with ≥3 points indicating ‘very difficult’, 2 points indicating ‘difficult’ and 1 point indicating ‘intermediate’, while a score of 0 was regarded as ‘easy’. Thus, the CT-RECTOR score has proven to be more accurate when predicting 30-min wire crossing success compared with the J-CTO score.23

CTCA can also provide detailed anatomical features of the occluded segment. It reliably calculates the length of the occluded segment, which can be difficult in a conventional coronary angiography. It can give details of vessel tortuosity, angles, and the characteristics of the proximal and distal stumps or caps. In addition to the length and the anatomical course of the vessel, CTCA can provide morphological features of the occluded segment and the plaque disease. It can detect and outline the extent of calcification; both are predictors of procedure failure.24 In addition, real-time co-registration with conventional angiographic pictures can guide the CTO operators during the procedure to achieve better outcomes, including presenting the 3D-VR information in the form of angiographic projection that shows the orientation and length of the CTO.

Figure 1: CT Coronary Angiography Prior to Attempted Chronic Total Occlusion Percutaneous Coronary Intervention in a Post-coronary Artery Bypass Graft Patient

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For example, Figure 1 shows a post-coronary artery bypass graft (CABG) patient with an occluded vein graft to his right coronary artery and ongoing angina despite optimal anti-anginal medications who underwent CTCA prior to attempted CTO PCI. The CTCA demonstrated the angle for the proximal cap visualisation, the length of the CTO, presence and extent of calcification and the potential re-entry zone. The CTO PCI was performed using similar angles, which opened up the ambiguous proximal cap, resulting in a successful CTO PCI.

Another advantage of the pre-procedural CTCA is that it can help minimise the amount of contrast used, the radiation dosage and the procedure duration, all of which are important factors in every PCI procedure.25–28 In their randomised control study comparing patients undergoing CTCA or no CTCA prior to CTO PCI, Hong et al. showed that contrast volume was lower in the CTCA group, with no difference in the fluoroscopy time between the two groups (contrast volume: CTCA group, 280 ml versus no CTCA group, 300 ml, p=not significant; fluoroscopy time: CTCA group, 35 min versus no CTCA group, 36 min, p=not significant).29

The Role of CT Coronary Angiography in Post-CTO Intervention

Unsuccessful entry into the proximal cap or unsuccessful re-entry into the distal lumen indicates failure of the CTO PCI. Although unsuccessful, plaque modification and development of new channels may increase the likelihood of further successful intervention.30 For this reason, this initial procedure is commonly called an investment procedure.

CTCA after an investment procedure (failed to re-enter and/or only ballooning of the extra-plaque space) could play an important role in increasing subsequent procedural success by facilitating the detection of details such as the development of new tracks, the direction of the dissection plane, how far the distal entry cap is, and the likelihood of successful antegrade dissection re-entry (by determining the degree of calcification and identifying the area of the artery where this is most likely to be successful).

Figure 2: CT Coronary Angiography After Investment Procedure Facilitates Successful Stenting

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For example, Figure 2 shows a case where the CTO PCI attempt utilised an antegrade dissection re-entry technique in which re-entry into the distal vessel was unsuccessful despite multiple manoeuvres. The sub-intimal tract was ballooned as an investment procedure and the patient underwent outpatient CTCA. This demonstrated heavy calcification in the areas where the re-entry was being attempted. A second attempt at re-entry via the areas that were identified as being free of calcification was successful and the artery was stented. In this case, the CTCA helped in identification of the area where re-entry would be successful.

Another use of post-procedure CTCA is to confirm the success of recanalisation and as a follow-up scan for patients who presented with angina symptoms after previous angiographically successful interventions.

Outcome of CTO Intervention with Prior CTCA Planning

CTO intervention is associated with a higher risk of failure than non-CTO intervention, which has an average estimated success rate of around 70%.31 Although successful CTO intervention is of significant clinical benefit, including improvement of angina symptoms, reduction in the use of medications and reduction in the need for CABG surgery, it is imperative that there is a good clinical indication for proceeding with CTO PCI.32,33 Only then can the optimal clinical risk–benefit–resource usage be justified.

Multiple factors contribute to the increase in the success rate of CTO PCI. Advancements in technology such as wire development, microcatheters, calcium modification technology and the use of intracoronary imaging all play a valuable role. More importantly, however, careful pre-procedural planning, dual injections, the availability of new equipment with specialised wires and support catheters and techniques have all helped increase the success rate.

Impact of Prior CT Coronary Angiogram Assessment on the Outcome of Percutaneous Coronary Intervention on Chronic Total Occlusions

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What is the role of CTCA pre-CTO PCI? Different studies have investigated the success rate of CTO PCI after a pre-procedure CTCA (Table 2). Rolf et al. compared 30 patients who had CTCA prior to CTO PCI with 45 patients who did not and found a significant increase in the procedural success rate with CTCA.34 Another study by Yokoyama et al. investigated the use of CTCA prior to CTO intervention and found that CTCA can accurately assess the route of the lesion and provide details on the amount of calcification.35 Both factors resulted in an excellent success rate. Hong et al. conducted the first randomised trial on the use of CTCA in CTO PCI: 400 patients were randomised into either pre-procedural CTCA or no CTCA. A higher success rate was seen in the CTCA group (93.5%) than in the angiography-only group (84%). They also noted fewer immediate complications in the CTCA-guided group. In that study, patients with all J-CTO scores were included, with the average J-CTO score being <2 and successful revascularisation in the CTCA arm was driven by the higher J-CTO (≥2) group.29

Anecdotally, interventional cardiologists limit the use of CTCA routinely in CTO PCI to failed procedures or to patients who have had previous CABG. This could be because one of the limiting factors in the utility of CTCA prior to CTO PCI appears to be the availability of timely scans and/or a paucity of personnel who can explain to the CTO operator the details of the CTO anatomy in a manner that will aid in procedure planning.


CTCA has facilitated the diagnosis of coronary artery disease by enabling accurate assessment of the anatomical features without the need for an invasive procedure.36 It is a rapidly advancing technology with new-generation scanners providing greater resolution, better quality images and lower levels of radiation exposure. CTO is a frequent finding in CT image analysis. Successful revascularisation of CTO with PCI results in improvements in patient outcomes and better left ventricular function while reducing the need for CABG.37

CTCA has its uses during the various steps of CTO PCI, starting from the initial diagnosis, followed by pre-interventional planning, and finally, post-procedure outcome and follow-up. In particular, pre-interventional use has been shown to have a significant impact on the success rate of CTO PCI. Coronary CT can reliably provide details about these anatomical characteristics and hence increase the likelihood of procedural success. The use of the CT-based scoring system in the pre-procedural planning is another useful tool that can help predict the success rate of CTO intervention. All of these features help select the appropriate patient for intervention, aid in planning and help determine the best strategy.

Post-CTO intervention CTCA can be used after an investment procedure to guide further intervention and as a follow-up tool in patients presenting with recurrence of symptoms after previously successful intervention.

New studies, such as CT Coronary Angiography Prior to CTO PCI (NCT05364827), may help identify whether complex CTOs would benefit from pre-procedural CTCA. In this proposed randomised study, patients will be randomly assigned to either CTCA-guided CTO PCI, or direct PCI. The primary endpoint is the success rate in the CTCA arm compared with the non-CTCA arm, while secondary endpoints include the assessment of angina, the need for a repeat procedure, complication rate, procedure length, and wire crossing time. It also aims to provide some health economic and cost-effectiveness data.

Pre-CTO intervention CTCA is a promising technology that appears to predict the success rate of CTO intervention better than the conventional invasive coronary angiography. The rapid advance in technologies and the positive clinical data indicate the usefulness of the routine use of CTCA before CTO intervention to maximise the success rate. Although these data are promising, future large-scale studies are needed to further support these claims. In addition, CTCA (level 2) certification is now more widespread among cardiologists, and this factor may circumvent the limitations mentioned above. The authors concur that the utility of CTCA prior to CTO PCI has the greatest advantage not only in failed procedures and those with prior CABG but also in those with high-score CTOs (e.g. J-CTO ≥2).


  1. Tsai T, Stanislawski M, Shunk K, et al. Contemporary incidence, management, and long-term outcomes of percutaneous coronary interventions for chronic coronary artery total occlusions: insights from the VA CART program. JACC Cardiovasc Interv 2017;10:866–75.
    Crossref | PubMed
  2. Cohen HA, Williams DO, Holmes Jr DR, et al. Impact of age on procedural and 1-year outcome in percutaneous transluminal coronary angioplasty: a report from the NHLBI dynamic registry. Am Heart J 2003;146:513–9.
    Crossref | PubMed
  3. Srivatsa SS, Edwards WD, Boos CM, et al. Histologic correlates of angiographic chronic total coronary artery occlusions: influence of occlusion duration on neovascular channel patterns and intimal plaque composition. J Am Coll Cardiol 1997;29:955–63.
    Crossref | PubMed
  4. Stone GW, Kandzari DE, Mehran R, et al. Percutaneous recanalization of chronically occluded coronary arteries: a consensus document: part I. Circulation 2005;112:2364–72.
    Crossref | PubMed
  5. Sachdeva R, Agrawal M, Flynn SE, et al. The myocardium supplied by a chronic total occlusion is a persistently ischemic zone. Catheter Cardiovasc Interv 2014;83:9–16.
    Crossref | PubMed
  6. Werner GS, Martin-Yuste V, Hildick-Smith D, et al. A randomized multicentre trial to compare revascularization with optimal medical therapy for the treatment of chronic total coronary occlusions. Eur Heart J 2018;39:2484–93.
    Crossref | PubMed
  7. Budoff MJ, Dowe D, Jollis JG, et al. Diagnostic performance of 64-multidetector row coronary computed tomographic angiography for evaluation of coronary artery stenosis in individuals without known coronary artery disease: results from the prospective multicenter ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial. J Am Coll Cardiol 2008;52:1724–32.
    Crossref | PubMed
  8. Hoffmann MH, Shi H, Schmitz BL, et al. Noninvasive coronary angiography with multislice computed tomography. JAMA 2005;293:2471–8.
    Crossref | PubMed
  9. Barker A, Curtin J. CT coronary angiography (CTCA) in patients with chest pain and coronary artery calcium score (CACS) zero. Is there diagnostic benefit? Clin Rad 2013;68(Suppl 1):S2.
  10. Agatston AS, Janowitz WR, Hildner FJ, et al. Quantification of coronary artery calcium using ultrafast computed tomography. J Am Coll Cardiol 1990;15:827–32.
    Crossref | PubMed
  11. Raff GL, Gallagher MJ, O’Neill WW, Goldstein JA. Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography. J Am Coll Cardiol 2005;46:552–7.
    Crossref | PubMed
  12. Hoe J. CT coronary angiography of chronic total occlusions of the coronary arteries: how to recognize and evaluate and usefulness for planning percutaneous coronary interventions. Int J Cardiovasc Imaging 2009;25(Suppl 1):43–54.
    Crossref | PubMed
  13. Abdulla J, Abildstrom SZ, Gotzsche O, et al. 64-multislice detector computed tomography coronary angiography as potential alternative to conventional coronary angiography: a systematic review and meta-analysis. Eur Heart J 2007;28:3042–50.
    Crossref | PubMed
  14. Orkisz M, Hoyos MH. Models for 3D vascular image analysis. J Med Inform Technol 2001;2:IP13–22.
  15. Sharma V, Jadhav ST, Harcombe AA, et al. Impact of proctoring on success rates for percutaneous revascularisation of coronary chronic total occlusions. Open Heart 2015;2:e000228.
    Crossref | PubMed
  16. Ludman P. BCIS audit report for 2020–2021 activity. 2021. (accessed on 23 January 2023).
  17. Morino Y, Abe M, Morimoto T, et al. Predicting successful guidewire crossing through chronic total occlusion of native coronary lesions within 30 minutes: the J-CTO (Multicenter CTO Registry in Japan) score as a difficulty grading and time assessment tool. JACC Cardiovasc Interv 2011;4:213–21.
    Crossref | PubMed
  18. Alessandrino G, Chevalier B, Lefèvre T, et al. A clinical and angiographic scoring system to predict the probability of successful first-attempt percutaneous coronary intervention in patients with total chronic coronary occlusion. JACC Cardiovasc Interv 2015;8:1540–8.
    Crossref | PubMed
  19. Maeremans J, Spratt JC, Knaapen P, et al. Towards a contemporary, comprehensive scoring system for determining technical outcomes of hybrid percutaneous chronic total occlusion treatment: the RECHARGE score. Catheter Cardiovasc Interv 2018;91:192–202.
    Crossref | PubMed
  20. Fujino A, Otsuji S, Hasegawa K, et al. Accuracy of J-CTO score derived from computed tomography versus angiography to predict successful percutaneous coronary intervention. JACC Cardiovasc Imaging 2018;11:209–17.
    Crossref | PubMed
  21. Li J, Wang R, Tesche C, et al. CT angiography-derived RECHARGE score predicts successful percutaneous coronary intervention in patients with chronic total occlusion. Korean J Radiol 2021;22:697–705.
    Crossref | PubMed
  22. Opolski MP, Achenbach S, Schuhbäck A, et al. Coronary computed tomographic prediction rule for time-efficient guidewire crossing through chronic total occlusion: insights from the CT-RECTOR multicenter registry (Computed Tomography Registry of Chronic Total Occlusion Revascularization). JACC Cardiovasc Interv 2015;8:257–67.
    Crossref | PubMed
  23. Tan Y, Zhou J, Zhang W, et al. Comparison of CT-RECTOR and J-CTO scores to predict chronic total occlusion difficulty for percutaneous coronary intervention. Int J Cardiol 2017;235:169–75.
    Crossref | PubMed
  24. Noguchi T, Miyazaki S, Morii I, et al. Percutaneous transluminal coronary angioplasty of chronic total occlusions. Determinants of primary success and long-term clinical outcome. Catheter Cardiovasc Interv 2000;49:258–64.
    Crossref | PubMed
  25. Ghoshhajra BB, Takx RAP, Stone LL, et al. Real-time fusion of coronary CT angiography with X-ray fluoroscopy during chronic total occlusion PCI. Eur Radiol 2017;27:2464–73.
    Crossref | PubMed
  26. Carroll JD, Chen SJ. The use of CTCA for planning PCI: using the 3D coronary tree information. JACC Cardiovasc Interv 2020;13:2571–3.
    Crossref | PubMed
  27. Abada HT, Larchez C, Daoud B, et al. MDCT of the coronary arteries: feasibility of low-dose CT with ECG-pulsed tube current modulation to reduce radiation dose. AJR Am J Roentgenol 2006;186(Suppl 2):S387–90.
    Crossref | PubMed
  28. Sianos G, Werner GS, Galassi AR, et al. Recanalisation of chronic total coronary occlusions: 2012 consensus document from the EuroCTO club. EuroIntervention 2012;8:139–45.
    Crossref | PubMed
  29. Hong S, Kim B, Cho I, et al. Effect of coronary CTA on chronic total occlusion percutaneous coronary intervention: a randomized control trial. JACC Cardiovasc Interv 2021;14:1993–2004.
    Crossref | PubMed
  30. Xenogiannis I, Choi JW, Alaswad K, et al. Outcomes of subintimal plaque modification in chronic total occlusion percutaneous coronary intervention. Catheter Cardiovasc Interv 2020;96:1029–35.
    Crossref | PubMed
  31. Suero JA, Marso SP, Jones PG, et al. Procedural outcomes and long-term survival among patients undergoing percutaneous coronary intervention of a chronic total occlusion in native coronary arteries: a 20-year experience. J Am Coll Cardiol 2001;38:409–14.
    Crossref | PubMed
  32. Mehran R, Claessen BE, Godino C, et al. Long-term outcome of percutaneous coronary intervention for chronic total occlusions. JACC Cardiovasc Interv 2011;4:952–61.
    Crossref | PubMed
  33. Sapontis J, Salisbury AC, Yeh RW, et al. Early procedural and health status outcomes after chronic total occlusion angioplasty: a report from the OPEN-CTO registry (outcomes, patient health status, and efficiency in chronic total occlusion hybrid procedures). JACC Cardiovasc Interv 2017;10:1523–34.
    Crossref | PubMed
  34. Rolf A, Werner GS, Schuhbäck A, et al. Preprocedural coronary CT angiography significantly improves success rates of PCI for chronic total occlusion. Int J Cardiovasc Imaging 2013;29:1819–27.
    Crossref | PubMed
  35. Yokoyama N, Yamamoto Y, Suzuki S, et al. Impact of 16-slice computed tomography in percutaneous coronary intervention of chronic total occlusions. Catheter Cardiovasc Interv 2006;68:1–7.
    Crossref | PubMed
  36. Doris M, Newby DE. Coronary CT angiography as a diagnostic and prognostic tool: perspectives from the SCOT-HEART trial. Curr Cardiol Rep 2016;18:18.
    Crossref | PubMed
  37. Guo L, Lv H, Yin X. Chronic total occlusion percutaneous coronary intervention in patients with prior coronary artery bypass graft: current evidence and future perspectives. Front Cardiovasc Med 2022;9:753250.
    Crossref | PubMed