Chronic total occlusions

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Adjuncts for High Risk PCI

PCI in Specific Lesion Types

Classification of the Lesion
The Calcified Lesion
The Ostial Lesion
The Angulated or Tortuous Lesion
The Bifurcation Lesion
The Long Lesion
The Bridge Lesion
The Chronic Total Occlusion
The Left Internal Mammary Artery
Multivessel Disease
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Risk calculators and risk factors for Chronic total occlusions

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editors-In-Chief: Duane Pinto, M.D.; Brian C. Bigelow, M.D.; Roger J. Laham, M.D.; Randall K. Harada, M.D.Sudarshana Datta, MD [2]

Click here to see a case of chronic total occlusion with retrograde approach on Tweetbook.


Chronic total occlusions (CTO) are often defined as coronary occlusions that have had TIMI 0 or 1 flow for an estimated duration of at least one month. Collateral flow to the distal territory maintains viability, but may be insufficient at times of increased oxygen demand, resulting in chronic stable angina or reduced exercise capacity. The tissue composition of the CTO is a variable mix of collagen-rich plaque, layered thrombus, calcium, and inflammatory cells with fibro-calcific caps at both ends. Neovascularization channels may form a neo-lumen or connect with adventitial vasa vasorum. The latter type of channels and bridging collaterals reduce the likelihood of successful guidewire advancement. Percutaneous interventions of CTO remain a technical challenge.

Rentrop Grade of Collateral Filling

Rentrop classification is helpful to define the collateral circulation of CTO. Rentrop et al. proposed the system below to grade collateral filling of recipient arteries:[1]

Rentrop Grade 0

No visible filling of any collateral channels.

Rentrop Grade 1

Collateral filling of branches of the vessel to be dilated without any dye reaching the epicardial segment of that vessel (ie, RCA injection showing retrograde filling of septal branches to their origin from the LAD, without visualization of the latter occluded artery).

Rentrop Grade 2

Partial collateral filling of the epicardial segment of the vessel being dilated.

Rentrop Grade 3

Complete collateral filling of the vessel being dilated.

Goals of Treatment

Treatment Choices

There are three main treatment choices for CTO:

Medical Therapy

All patients should receive optimal medical therapies to reduce angina and cardiovascular (CV) event risk. Revascularization attempts may be considered for patients refractory to antianginal agents.

Percutaneous Revascularization

Surgical Revascularization

Patient selection

Contraindications to treatment include:

  • Techniques to assess viability prior to the procedure include:

Clinical predictors of success are very poor. Angiographic predictors of failure include:

  • Occlusion length > 15 mm (CT may be helpful in defining the length)
  • Moderate to severe coronary calcification
  • A flush, rounded or blunt (absence of a tapered "beak" at the origin ) occlusion
  • Presence of bridging collaterals
  • Higher age of the occlusion
  • Tortuosity
  • Small vessel size
  • Non-visualization of the distal vessel bed
  • The presence of a side branch at the occlusion site (the wire may selectively want to enter this rather than the total occlusion)

These predictors may also be assessed with CT, especially occlusion length. CT angiography may aid in choosing retrograde approach via collaterals (CART and reverse CART technique) rather than the traditional antegrade approach.

PCI Techniques

The potential for vessel perforation during the procedure should be kept in mind in selecting antiplatelet agents. Pre-treatment with aspirin may be used in preparation for possible stent implantation. Some operators wait to administer a thienopyridine until the procedure is completed without vessel perforation. Heparin and a short-acting glycoprotein IIb/IIIa inhibitors are favored in case of severe arterial injury requiring anticoagulation reversal. A strategy of heparin with a low target activated clotting time (ACT), followed by supplemental heparin, and glycoprotein IIb/IIIa inhibitor to be administered only after successful guidewire crossing, may be employed.

Arterial Access and Guide Catheter Selection

Contralateral/ double coronary injection from a second catheter, and arterial access to fill the distal vessel bed via collaterals, may be useful for angiographic guidance of the distal wire.

Greater support is often required for CTO interventions, and good guiding catheter support may facilitate both wire and balloon passage. For the right coronary artery, a left or right Amplatz guiding catheter can provide excellent coaxial support. A guide with sideholes is often helpful in dilating the right coronary artery. Extra backup (EBU or XB) guides are useful for the left coronary system. Consideration should be given to the use of 7-8 Fr guide sizes to accommodate extra equipment that may be needed. Further back-up support could be provided by larger caliber guide catheters (7 or 8 French).

Crossing The Lesion With The Wire

There are several potential choices for crossing a total occlusion. One standard progression in technique might include the following:

  1. Begin with a conventional softer tipped, less traumatic guidewire as a first step, before progressing to stiffer wires for occlusions with tougher caps. A conventional guidewire crosses > 90% of acute (< 3 month old) total occlusions.
  2. Several dedicated wires of graded stiffness were developed for CTO crossing, and a successful crossing frequently requires trials of multiple different wires.
  • Non-hydrophilic or hydrophobic wires with an intermediate stiffness are a good first choice as they have a better tactile response, are less likely to lead to a subintimal position than a hydrophilic wire, and may have an additional advantage in their ability to cross the proximal cap of the occlusion. Choices in this class include the Miracle Bros 3 and the Asahi intermediate wires.
  • Hydrophilic wires may track better after the proximal cap of the occlusion has been crossed. Hydrophilic/coated wires have better maneuverability in tortuous or calcified vessels. Intermediate stiffness hydrophilic wire choices include the Choice PT XS (Extra Support), the Pilot 50, the Pilot 100 or the PT Graphix.
  • Shaping the wire tip using a modest angulation is better for blunted stump occlusions.
  • A low-profile balloon or exchange catheter adds back-up support for wire penetration of fibro-calcific caps and may also be used cautiously for balloon-assisted progression within the occlusion.
  • Intra-luminal position of the wire distal to the occlusion is suggested by a freely rotating wire tip or angiography in different views by distal catheter or contralateral injections.
  • Stiffer wire tips will allow for a greater chance of crossing the proximal cap of the occlusion at the cost of an increased risk of vessel dissection or perforation.
  • Stiff non-hydrophilic wires: The Miracle Bros 6, 9 and 12, Cross-IT, Confienza, Persuader
  • Stiff and hydrophilic (most aggressive): Pilot 200 and Shinobi

Crossing Lesions That Cannot Be Crossed With A Conventional Wire

Tapered-tip wires are occasionally better at navigating into a smaller channel than on 0.014” wire. Lasers, vibrational energy, blunt dissection (e.g. Lumend Frontrunner) and ultrasound catheters have been used with variable success to recanalize chronic total occlusions resistant to standard wires. Fixed wire-balloon systems do not offer the ability to switch out wires and perform distal injection.

Crossing The Lesion With A Balloon

Once the wire crossed the lesion, the next step is to perform angiography to confirm that you are intraluminal (i.e. that no dissection is present) and that wire perforation is not present. If dissection and wire perforation are not present, then an attempt is made to cross the lesion with a balloon. Fixed wire-balloon systems lack track ability and steer ability therefore over-the-wire systems are usually favored. Fixed wire systems may, however, occasionally be useful because their very low profile which may allow passage in some cases in which a conventional over-the-wire system will not cross. Monorail systems inferior to over-the-wire systems in this setting, because of their inferior balloon tracking characteristics, the inability to exchange guidewires, and the inability to make a distal injection through the central lumen of the balloon to confirm your position. Often a low profile short over the wire balloon is a good first choice. An example would be a 1.5 mm X 6 mm balloon. Many investigators will remove the wire from the central lumen of the balloon and perform a distal injection at this point to confirm an intraluminal location of the balloon. If intraluminal guidewire position cannot be confirmed, balloon inflation should not be performed. If balloon cannot be inserted all the way across lesion, an inflation in proximal part of lesion can be performed to favorably alter anatomy and potentially facilitate eventual crossing. Consider aborting procedure if, despite multiple attempts with various guidewires, lesion cannot be crossed or successfully dilated; the risk of dissection or perforation may outweigh benefit.

Special Techniques

If a wire enters a dissection plane, then a second wire may be used (parallel wire technique) to find a different pathway with the first wire serving as a reference or blocking repeat entry into the false lumen. Also, if a wire favors entering a side-branch near the site of occlusion, then a balloon may be inflated in that side-branch effecting a block to further wire entry.

After failed attempts of recanalizing the true lumen, a subintimal tracking and re-entry (STAR) technique may be considered. This is more safely performed in the RCA where major side branches are absent. Retrograde approaches through robust collaterals from the contralateral vessel have been employed with variable success rates.

Special Crossing Devices

  • Blunt micro-dissection catheters
  • Optical coherence reflectometry guidance of the wire
  • Radiofrequency ablation, ultrasonic energy, or microscopic oscillations delivered by special catheter/wire systems to penetrate fibro-calcific caps

Dilation of the Totally Occluded Lesion

Following initial conventional balloon angioplasty of the lesion, stent placement reduces restenosis, revascularization, and reocclusion rates. Placement of a drug eluting stent is a rational choice given the high risk of restenosis with this lesion type. Given that the lesion was totally occluded, the occurrence of stent thrombosis and complete reocclusion, while unfavorable, may not be as dangerous as it would be in an artery that was patent prior to placement of the stent. Other dilation techniques include rotational atherectomy and laser debulking.

More Tips

Advanced approaches to chronic total occlusions include

  • Anchor balloon technique Mother-child catheter (5 Fr within an 8 Fr guide)
  • Parallel wire and seesaw wiring
  • IVUS guidance to look for the true lumen
  • Retrograde approach (especially in previous antegrade failures)
  • Controlled antegrade and retrograde technique (CART)


Success rates of 50-80% have been reported, but may be affected by selection or publication biases. If the occlusion is less than 3 months old, the angiographic success rate is >90%, while patients with occlusions greater than 3 months old have a success rate of 70% and higher acute closure rates. The most common reason for failure is the inability to cross the occlusion with a guidewire (80-90%). Other common reasons for failure are the inability for the balloon to cross the lesion (15%), and lesions cannot be dilated adequately (5%) (>30% residual stenosis). Calcifications are often a major obstacle to crossing the lesion.

Restenosis and reocclusion rates following successful PCI are higher in CTO compared to non-occlusive stenoses. These rates are improved with the use of DES. Successful PCI of CTO is associated with a 50-70% rate reduction of future CABG. The salient complication of CTO PCI is perforation, which requires a rapid response: proximal balloon inflation, protamine administration for heparin reversal, consideration of a covered stent placement, and pericardiocentesis, if indicated.

Integration of several angiographic factors helps determine likelihood of success (see above). No single factor should preclude a revascularization attempt.

Long-term outcomes


Other Concerns

The decision to terminate the procedure if guidewires fail to cross the occlusion is based on the severity of symptoms (i.e. angina) weighted against the risk of more aggressive techniques/devices, fluoroscopy time, and contrast load.

2017 ACCF/AHA/SCAI Guidelines for Percutaneous Coronary Intervention

  • Up to 2011, only observational data had indicated the success of PCI over OMT (Optimal Medical therapy) in improving cardiovascular outcomes in patients with CTO.
  • However, three major randomized control trials were conducted between 2011-17. They were called EURO-CTO, DECISION-CTO and EXPLORE.[4]
  • These trials concluded that PCI was non-superior to OMT in patients with at least 1 CTO.[5]
  • In 2017, the updated ACC/AATS/AHA/ASE/ASNC/SCAI/SCCT/STS 2017 Appropriate Use Criteria (AUC) for Coronary Revascularization in Patients With Stable Ischemic Heart Disease (SIHD) was characterized by:[6]

2011 ACCF/AHA/SCAI Guidelines for Percutaneous Coronary Intervention (DO NOT EDIT)[7]

Chronic Total Occlusions[7]

  • In 2011, The AHA assigned a Class IIa recommendation for CTO-PCI.
Class IIa
"1. PCI of a chronic total occlusion in patients with appropriate clinical indications and suitable anatomy is reasonable when performed by operators with appropriate expertise.[2][8][9][10][11] (Level of Evidence: B)"


  1. Rentrop, K. P. (1985-03). "Changes in collateral channel filling immediately after controlled coronary artery occlusion by an angioplasty balloon in human subjects". Journal of the American College of Cardiology. 5 (3): 587–592. ISSN 0735-1097. PMID 3156171. Unknown parameter |coauthors= ignored (help); Check date values in: |date= (help)
  2. 2.0 2.1 Olivari Z, Rubartelli P, Piscione F; et al. (2003). "Immediate results and one-year clinical outcome after percutaneous coronary interventions in chronic total occlusions: data from a multicenter, prospective, observational study (TOAST-GISE)". J. Am. Coll. Cardiol. 41 (10): 1672–8. PMID 12767645. Unknown parameter |month= ignored (help)
  3. Rahel BM, Laarman GJ, Kelder JC, Ten Berg JM, Suttorp MJ (2009). "Three-year clinical outcome after primary stenting of totally occluded native coronary arteries: a randomized comparison of bare-metal stent implantation with sirolimus-eluting stent implantation for the treatment of total coronary occlusions (Primary Stenting of Totally Occluded Native Coronary Arteries [PRISON] II study)". Am. Heart J. 157 (1): 149–55. doi:10.1016/j.ahj.2008.08.025. PMID 19081412. Unknown parameter |month= ignored (help)
  4. "Appropriateness of CTO PCI in Patients With SIHD - American College of Cardiology".
  5. "Optimal Medical Therapy With or Without Stenting For Coronary Chronic Total Occlusion - American College of Cardiology".
  6. "Appropriate Use Criteria for Coronary Revascularization in Stable Ischemic Heart Disease - American College of Cardiology".
  7. 7.0 7.1 Levine GN, Bates ER, Blankenship JC, Bailey SR, Bittl JA, Cercek B, Chambers CE, Ellis SG, Guyton RA, Hollenberg SM, Khot UN, Lange RA, Mauri L, Mehran R, Moussa ID, Mukherjee D, Nallamothu BK, Ting HH (2011). "2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention: Executive Summary A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Society for Cardiovascular Angiography and Interventions" (PDF). Journal of the American College of Cardiology. 58 (24): 2550–83. doi:10.1016/j.jacc.2011.08.006. PMID 22070837. Retrieved 2011-12-08. Text "PDF" ignored (help); Unknown parameter |month= ignored (help)
  8. Suero JA, Marso SP, Jones PG, Laster SB, Huber KC, Giorgi LV, Johnson WL, Rutherford BD (2001). "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". Journal of the American College of Cardiology. 38 (2): 409–14. PMID 11499731. Retrieved 2011-12-15. Unknown parameter |month= ignored (help)
  9. de Labriolle A, Bonello L, Roy P, Lemesle G, Steinberg DH, Xue Z, Kaneshige K, Suddath WO, Satler LF, Kent KM, Pichard AD, Lindsay J, Waksman R (2008). "Comparison of safety, efficacy, and outcome of successful versus unsuccessful percutaneous coronary intervention in "true" chronic total occlusions". The American Journal of Cardiology. 102 (9): 1175–81. doi:10.1016/j.amjcard.2008.06.059. PMID 18940287. Retrieved 2011-12-15. Unknown parameter |month= ignored (help)
  10. Rathore S, Matsuo H, Terashima M, Kinoshita Y, Kimura M, Tsuchikane E, Nasu K, Ehara M, Asakura Y, Katoh O, Suzuki T (2009). "Procedural and in-hospital outcomes after percutaneous coronary intervention for chronic total occlusions of coronary arteries 2002 to 2008: impact of novel guidewire techniques". JACC. Cardiovascular Interventions. 2 (6): 489–97. doi:10.1016/j.jcin.2009.04.008. PMID 19539251. Retrieved 2011-12-15. Unknown parameter |month= ignored (help)
  11. Stone GW, Reifart NJ, Moussa I, Hoye A, Cox DA, Colombo A, Baim DS, Teirstein PS, Strauss BH, Selmon M, Mintz GS, Katoh O, Mitsudo K, Suzuki T, Tamai H, Grube E, Cannon LA, Kandzari DE, Reisman M, Schwartz RS, Bailey S, Dangas G, Mehran R, Abizaid A, Moses JW, Leon MB, Serruys PW (2005). "Percutaneous recanalization of chronically occluded coronary arteries: a consensus document: part II". Circulation. 112 (16): 2530–7. doi:10.1161/CIRCULATIONAHA.105.583716. PMID 16230504. Retrieved 2011-12-15. Unknown parameter |month= ignored (help)