Prevalence and Treatment of "Balloon-Uncrossable" Coronary Chronic Total Occlusions

Abstract: Background. The frequency and outcomes of “balloon-uncrossable” coronary chronic total occlusions (CTOs) have received limited study. Methods. We retrospectively examined 373 consecutive CTO percutaneous coronary interventions (PCIs) performed at our institution between 2005 and 2013 to determine the frequency and treatment of balloon-uncrossable CTOs. Results. Mean age was 63.7 ± 8.3 years and 98.9% of the patients were men. Twenty-four patients (6.4%, 95% confidence intervals 4.2% to 9.4%) were found to have a balloon-uncrossable CTO. Compared to the other CTO PCI patients, those with balloon-uncrossable CTOs had similar clinical and angiographic characteristics. Successful crossing of the balloon-uncrossable CTO was achieved in 22 of 24 patients (91.7%) using a variety of techniques, such as successive balloon inflations (43.5%), microcatheter advancement (21.7%), laser (8.7%), techniques that increase guide catheter support (13.0%), and subintimal lesion crossing (13.0%). Patients with balloon-uncrossable CTOs had longer procedure time (184.5 ± 77.9 vs 134.0 ± 69.0 min, P<.01), fluoroscopy time (55.2 ± 24.9 vs 37.9 ± 20.8 min, P<.01), and received high contrast volume (404.4 ± 137.9 vs 351.7 ± 138.5 mL, P=.08), but had similar incidence of major complications (8.3% vs 3.2%, P=.25) as compared with patients who did not have balloon-uncrossable CTOs. Conclusion. Balloon-uncrossable CTOs are encountered in 6.4% of contemporary CTO PCIs and can be successfully treated in most patients using a variety of techniques.

J INVASIVE CARDIOL 2015;27(2):78-84

Key words: chronic total occlusion, percutaneous coronary intervention, balloon angioplasty, complications, techniques

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Percutaneous coronary intervention (PCI) of coronary chronic total occlusions (CTOs) can be challenging, mainly due to inability to cross the lesion with a guidewire. ^1,2 The second most common cause of technical failure in recanalizing CTOs is inability to cross the lesion with a balloon after successful guidewire crossing (“balloon-uncrossable” CTOs).^1-3 Various techniques have been described for approaching the balloon-uncrossable CTOs, which can be grouped into two categories: (1) techniques for lesion modification;^3-12 and (2) techniques that increase guide catheter support.^13-21 Occasionally combinations of these techniques are successfully utilized.^22,23

There is limited published information on the frequency and outcomes of balloon-uncrossable CTOs. In the present study, we sought to examine the prevalence of balloon-uncrossable CTOs, as well as treatment strategies and outcomes. 

Methods

Patient population. We reviewed the procedural and clinical records and coronary angiograms of 373 consecutive patients that underwent CTO-PCI between 2005 and 2013 at our institution to determine the prevalence, procedural techniques and outcomes of balloon-uncrossable CTO-PCI. The study was approved by our institutional review board.

Definitions. A balloon-uncrossable CTO was defined as inability to cross the lesion with the first balloon after successfully crossing the lesion with a guidewire. Balloon-uncrossable CTOs were identified by review of the procedure notes and angiograms of all patients included in the study.

Coronary CTOs were defined as coronary lesions with thrombolysis in myocardial infarction (TIMI) grade 0 flow of at least 3-month duration. Estimation of the occlusion duration was based on first onset of anginal symptoms, prior history of myocardial infarction in the target vessel territory, or comparison with a prior angiogram.

Technical success of CTO-PCI was defined as successful CTO revascularization with achievement of <30% residual diameter stenosis within the treated segment and restoration of TIMI grade 3 antegrade flow. Procedural success was defined as achievement of technical success with no in-hospital major adverse cardiac events (MACE). In-hospital MACE included any of the following adverse events prior to hospital discharge: death from any cause, Q-wave myocardial infarction (defined as development of ischemic symptoms, in addition to creatine kinase MB fraction increase >3x upper limit of normal and  development of Q-waves on the electrocardiogram), recurrent angina requiring urgent repeat target vessel revascularization with PCI or coronary bypass surgery, tamponade requiring pericardiocentesis or surgery, and stroke.

Statistical analysis. Clinical characteristics, angiographic measures and in-hospital outcomes were reported using descriptive statistics for patients with and without balloon-uncrossable CTOs. Continuous variables were presented as mean and standard deviation and compared using the t-test or the Wilcoxon rank-sum test, as appropriate. Categorical variables were expressed as percentages and compared using the chi-square or the Fisher’s exact test, as appropriate. All statistical analyses were performed with JMP version 9.0 (SAS Institute) and STATA (StataCorp). Two-sided P-values of <.05 were considered to be statistically significant.

Results

Patient characteristics. The clinical and angiographic characteristics of the study patients are presented in Tables 1 and 2. Balloon-uncrossable CTOs were identified in 24 of the 373 patients undergoing CTO-PCI [6.4%, 95% confidence interval (CI), 4.2%-9.4%] during the study period. After excluding lesions that were crossed with a subsequent balloon without other lesion modification, the prevalence of balloon-uncrossable CTO decreased to 3.8% (95% CI, 2.1%-6.2%). Both patient groups had similar clinical characteristics. The most common CTO target vessel was the right coronary artery. Moderate or severe calcification was present in 58.3% of balloon-uncrossable CTOs compared with 42.4% of all other CTOs (Table 2). 

Angiographic and procedural characteristics. Procedural outcomes of the study patients are presented in Table 2. Antegrade wire escalation was the primary approach in 100% of balloon-uncrossable CTO patients and 94.2% of the other CTO patients (P=.10). Antegrade dissection/re-entry accounted for 20.8% of crossing attempts in balloon-uncrossable CTOs and for 30.9% of attempts in all other CTO cases (P=.28). The retrograde approach was utilized in 25.0% of balloon-uncrossable CTOs and 28.0% of all other CTOs (P=.74). Technical success was achieved in 91.7% of balloon-uncrossable CTO cases and in 77.9% of all other CTO cases (P=.08). As anticipated, the balloon-uncrossable CTO patients had longer procedure (P<.01) and fluoroscopy (P<.01) times, and received more stents (2.9 ± 1.7 vs 2.0 ± 1.7, P=.01). Two patients with balloon-uncrossable CTOs suffered complications: one had a post-procedural myocardial infarction (MI) after unsuccessful intervention, and one died. The patient who died had prior coronary artery bypass graft (CABG) surgery and underwent successful treatment of a right coronary artery chronic total occlusion using the retrograde approach with a reverse controlled antegrade and retrograde tracking and dissection (CART) technique. The patient developed ST-segment elevation immediately after the procedure. Repeat left heart catheterization revealed that the recently placed coronary stents were patent but a lesion was visible in the left internal mammary artery graft anastomosis that was treated with placement of two additional stents. The following day the patient had ventricular tachycardia and could not be resuscitated.  

Of all other CTO patients, 11 had complications: four had an MI, two underwent emergency CABG, one patient had donor vessel dissection, and one each experienced major bleeding, repeat PCI due to acute stent thrombosis, tamponade requiring pericardiocentesis, and transient ischemic attack.

Crossing strategies for balloon-uncrossable CTOs. Table 3 summarizes the techniques used in each of the balloon-uncrossable CTO cases. A total of 56 crossing techniques were utilized (the mean number of techniques per case was 2.3 ± 1.9). The balloon-uncrossable CTO was successfully crossed with a balloon in 22 of the 24 cases (91.7%). The techniques used in these cases are displayed in Figure 1. 

Use of multiple balloons was the most commonly used technique, accounting for 24 of the 56 attempts (42.9%) and was successful in 10 of those attempts (41.7%). The balloon was advanced as far as possible into the CTO followed by successive balloon inflation in an effort to modify the proximal cap of the lesion (6 out of 10 successes). Exchanging the balloon for one of a smaller size allowed for crossing of the lesion in two cases. Switching from an over-the-wire to a rapid exchange system resulted in success in one patient. Finally, balloon upsizing to a 2.0 mm balloon after both 1.5 and 1.25 mm balloons failed to advance was successful in 1 case.

Microcatheter advancement was the second most commonly attempted technique, accounting for 18 of 56 attempts (32.1%) and was successful in 5 of those 18 attempts (27.8%). The Corsair (Asahi Intecc) was the most commonly used microcatheter, accounting for 6 of 18 attempts (33.3%) and one success. Advancement of a Tornus catheter (Asahi Intecc) accounted for 5 of 18 attempts (27.8%) and was successful in crossing the lesion in 2 cases (40.0%). Other microcatheters used include the Gopher (Vascular Solutions) (1 attempt, no success), FineCross (Terumo) (2 attempts, 1 success), Progreat (Asahi Intecc) (1 attempt, no success), CrossBoss (Boston Scientific) (1 attempt, no success), Quick-Cross (Spectranetics) (1 attempt, no success), and Valet (Volcano) (1 attempt, no success).

Laser atherectomy was utilized in 6 attempts (10.7%) and was successful in 2 cases (33.3%). Techniques that increase guide catheter support were utilized 5 times (8.9%) with success in 3 of them (60.0%). These techniques consisted of side-branch anchoring (1 attempt, no success), distal anchoring via a retrograde balloon (2 attempts, 2 successes), and sub-intimal distal anchoring (1 attempt, 1 success). Crossing the lesion subintimally was attempted in 3 cases (5.4%), and was successful in all 3 (100.0%). 

Discussion

The major findings of our study are that balloon-uncrossable CTOs: (1) are encountered in 6.4% of contemporary CTO PCI; and (2) can be successfully treated in most cases using various techniques that either modify the lesion or increase guide catheter support. 

To the best of our knowledge, this is the first study to systematically assess the frequency of balloon-uncrossable CTOs.²¹ Balloon-uncrossable CTOs were encountered in 6.4% of CTO-PCIs and were not associated with any specific clinical or angiographic factors. Hence, it is difficult to predict which CTO will be “balloon uncrossable,” and knowledge on how to approach them is important for every CTO-PCI program. 

Our study also provides important insights on management of balloon-uncrossable CTOs. Several techniques to approach these lesions have been described in the literature (Table 4) and can be grouped into two broad categories: (1) lesion modification techniques; and (2) techniques that increase guide catheter support.² The easiest way to modify a lesion is to attempt crossing with another (ideally lower profile) balloon or microcatheter. The balloon is inserted as far as possible into the occlusion and inflated, which may modify the proximal cap and allow subsequent passage of the same or other balloons.² A modification of this technique is intentional balloon rupture (also called “balloon-assisted microdissection” or “BAM” technique) which can modify the proximal cap and carries low risk of perforation due to the small size of balloons utilized.² Successive balloon inflations and exchanging balloons was the most commonly used strategy in our series and was successful in 10 of 24 cases. 

Advancing a microcatheter across the lesion can also modify the lesion and facilitate subsequent balloon entry. The Tornus catheter (Asahi Intecc) was specifically designed for this purpose and consists of 8 stainless steel wires stranded in a coil.^{2,6-8,11,22-24} It is available in 2 sizes (2.1 and 2.6 Fr) and is advanced with counter-clockwise rotation and withdrawn by clockwise rotation.² The Tornus catheter “scores” the lesion modifying it sufficiently to allow passage of additional equipment. Several other microcatheters can be used, such as the Corsair catheter (Asahi Intecc) (can be advanced by rotating in any direction, unlike the Tornus catheter), the Finecross (Terumo) and the Valet (Volcano).² If a microcatheter crosses the lesion, it can be used to exchange the curent guidewire for another more supportive guidewire or for a rotational atherectomy wire.

Additional lesion modification techniques include laser and rotational atherectomy. Laser can be used over any standard 0.014˝ guidewire, whereas rotational atherectomy requires a specialized 0.009˝ guidewire, which may fail to advance through the CTO. Hence rotational atherectomy is a last resort solution.^2,3,10 Laser was successful in 2 of the 6 cases in which it was utilized in our series.

Techniques that increase guide catheter support may facilitate crossing of the balloon-uncrossable CTOs. Such techniques include the side branch anchor and guide catheter extensions.^17,19,21 In the side-branch anchor technique a guidewire is advanced into a side branch proximal to the occlusion and a balloon is inflated “anchoring” the guide catheter and increasing the pushability of the balloon. Guide catheter extensions, such as the Guideliner (Vascular Solutions) and the Guidezilla (Boston Scientific) allow deep intubation of the vessel also enhancing deliverability of balloons or other equipment.²

A last resort technique for balloon-uncrossable CTOs is subintimal wiring and stenting that “crushes” the undilatable occlusion segment and allows adequate stent expansion.² However, this technique has limitations, such as occasional difficulty re-entering the distal true lumen, which can be facilitated by use of dedicated equipment (Stingray balloon and guidewire; Boston Scientific). Subintimal wiring was successfully used in 3 patients in our series. In 1 patient, a modification of this technique was used, in which a subintimal balloon “anchored” the guidewire located into the distal true lumen, enabling balloon crossing.²⁰

Study limitations. Our study has some important limitations. First, it was a retrospective study, hence some balloon-uncrossable CTOs may have been omitted if the documentation in the cardiac catheterization report or the angiographic film was not adequate. Second, nearly all patients included were men, limiting extrapolation of the results to women. Third, all cases were performed at a single center. Fourth, some of the techniques utilized in our series (ie, laser) may not be available in all cardiac catheterization laboratories.

Conclusion

In summary, balloon-uncrossable CTOs are not uncommon (encountered in 6.4% of CTO-PCIs at our institution) and can be successfully treated in most cases using techniques for lesion modification and for enhancing guide catheter support.

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From the Veterans Affairs North Texas Health Care System and University of Texas Southwestern Medical School, Dallas, Texas.

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Banerjee reports research grants from Gilead and the Medicines Company; consultant/speaker honoraria from Covidien and Medtronic; ownership in MDCARE Global (spouse); intellectual property in HygeiaTel. Dr Brilakis reports consulting/speaker honoraria from Abbott Vascular, Asahi, Boston Scientific, Elsevier, Somahlution, St Jude Medical, and Terumo; research grant from Guerbet and InfraRedx; spouse is an employee of Medtronic.

Manuscript submitted February 18, 2014, provisional acceptance given June 2, 2014, final version accepted August 18 2014.

Address for correspondence: Emmanouil S. Brilakis, MD, PhD, VA North Texas Health Care System, The University of Texas Southwestern Medical Center at Dallas, Division of Cardiology (111A), 4500 S. Lancaster Rd, Dallas, TX 75216. Email: esbrilakis@gmail.com