October 24, 2016
4 min read

CTO PCI: When to Continue, When to Stop

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It is wonderful when a chronic total occlusion is crossed within minutes after starting crossing attempts. However, more often than not, chronic total occlusions can be challenging to cross and initial attempts may fail.

Several questions arise: How long should one continue to try? When is it time to stop?

Every case is different and decisions must be individualized, but the decision about when to stop is generally based on the following five parameters:

  1. radiation;
  2. contrast;
  3. complication;
  4. futility; and
  5. risk > benefit.


High radiation dose can have severe adverse consequences, potentially leading to radiation skin injury or increased risk for cancer. In general, deterministic effects (skin injury) do not appear until after 5-Gy air kerma dose has been administered. In most laboratories, the procedure is stopped after 7 Gy to 8 Gy has been reached, unless it is close to completion (for example, the CTO is crossed and stents are being delivered).

Emmanouil S. Brilakis
Emmanouil S. Brilakis

With meticulous attention to radiation protection (low-dose fluoroscopy, image intensifier “in contact” with patient, not using X-ray when not needed and using the “fluoro-store” function instead of cine-angiography to document balloon/stent inflation), radiation dose has been steadily decreasing.

Moreover, use of newer X-ray systems further reduces radiation dose. In our laboratory, we recently started using a Philips Clarity system and have not exceeded 3-Gy air kerma dose despite doing some highly complex procedures with more than 100 minutes of fluoroscopy time. Indeed, with use of these newer systems, radiation is rarely, if ever, the limiting factor for CTO PCI attempts.


Contrast nephropathy remains of concern, especially for patients with decreased renal function. Excellent preprocedural hydration and minimizing the volume of contrast are important preventive measures. Keeping the ratio of volume of contrast to creatinine clearance less than 3.7 x estimated glomerular filtration rate (eGFR) markedly reduces the risk for contrast nephropathy. With use of newer X-ray systems described earlier, contrast volume is becoming the more common limiting factor for CTO PCI. Although the retrograde approach has been proposed as a contrast-sparing crossing technique, it may actually require large volume of contrast to cross the collateral, although after collateral crossing the need for contrast injections is low.


Occurrence of a complication is in most cases an indication to stop the procedure, as safety should always be first. For example, after a perforation occurs and is treated it is usually best to abort the procedure and reverse anticoagulation (after coronary equipment is removed), as the high activated clotting time required for CTO PCI may prevent sealing of the perforation or, sometimes, result in re-bleeding after initial hemostasis. In some cases, however, completing the procedure may be the safest course of action; for example, when perforation of an epicardial collateral occurs requiring embolization from both sides of the perforation to achieve sealing.



Sometimes, every possible crossing option is attempted without achieving progress. Is this a reason to stop? The answer is: It depends. If, indeed, every possible option has been attempted, then stopping would be reasonable, although sometimes repeat attempts (with or without modifications) may eventually lead to success.

Decisions about futility are challenging and can be greatly facilitated by careful preprocedural planning because planning increases the certainty of the operator that every possible approach has been attempted. A mid-case “time out,” ie, stopping for a few minutes and engaging every member of the cath team in a discussion about subsequent treatment options, can be a very productive exercise, leading to new insights and approaches and, hopefully, success.

Risk > Benefit

In some cases, additional options exist for continuing the procedure, but those options may carry increased risk. A classic example is antegrade failure to cross a CTO with the only remaining crossing option being retrograde via an epicardial collateral. Collateral perforation could be a serious event, especially in patients with prior CABG, in whom a loculated effusion may form, causing localized compression of a cardiac chamber and cardiogenic shock. In such cases, it is important to weigh the potential benefits vs. the risks: In a patient who is debilitated by angina on maximal medical therapy and is not a candidate for CABG, it may make perfect sense to attempt crossing the collateral, although the risk is higher, provided that the operator has experience and expertise in treating these complex lesions (and any potential complications). Conversely, in a patient with the same anatomy who only has moderate symptoms or in the hands of a less experienced operator, it may be preferable to stop.

Operator Judgment, Individualization

In the end, the decision about when to stop relies heavily on operator judgment and must be individualized. On several occasions, I was close to quitting but kept on pursuing “one more try” — and, in many of those cases, the procedure was eventually successful. Persistence is key for the success and an integral part of the “art” of CTO PCI, but in some cases stopping may be the best course of action. Stopping can be hard for the interventionalist’s ego, yet the patient’s best interest should always prevail. Stopping does not mean that the procedure cannot be attempted again in the future with better odds for success.

Developing the serenity to accept failure and stop as well as the courage to keep on trying, when appropriate, can be a lifelong process, as is developing the wisdom to tell at any given moment the difference between the things that we can and the things that we cannot change.

Disclosure: Brilakis reports receiving consultant and speaker honoraria from Abbott Vascular, Asahi, Cardinal Health, Elsevier, GE Healthcare and St. Jude Medical; research support from InfraRedx and Boston Scientific; and his spouse is an employee of Medtronic.