Lesion Complexity and Procedural Outcomes Associated With Ostial Chronic Total Occlusions: Insights From the PROGRESS-CTO Registry

Abstract

Objectives. Ostial CTOs can be challenging to revascularize. We aim to describe the outcomes of ostial chronic total occlusion (CTO) percutaneous coronary intervention (PCI).

Methods. We examined the clinical and angiographic characteristics and procedural outcomes of 8788 CTO PCIs performed at 35 US and non-US centers between 2012 and 2022. In-hospital major adverse cardiac events (MACE) included death, myocardial infarction, urgent repeat target-vessel revascularization, tamponade requiring pericardiocentesis or surgery, and stroke.

Results. Ostial CTOs constituted 12% of all CTOs. Patients with ostial CTOs had higher J-CTO score (2.9 ± 1.2 vs 2.3 ± 1.3; P<.01). Ostial CTO PCI had lower technical (82% vs. 86%; P<.01) and procedural (81% vs. 85%; P<.01) success rates compared with non-ostial CTO PCI. Ostial location was not independently associated with technical success (OR 1.03, CI 95% 0.83-1.29 P =.73). Ostial CTO PCI had a trend towards higher incidence of MACE (2.6% vs. 1.8%; P =.06), driven by higher incidence of in-hospital death (0.9% vs 0.3% P<.01) and stroke (0.5% vs 0.1% P <.01). Ostial lesions required more often use of the retrograde approach (30% vs 9%; P<.01). Ostial CTO PCI required longer procedure time (149 [103,204] vs 110 [72,160] min; P<.01) and higher air kerma radiation dose (2.3 [1.3, 3.6] vs 2.0 [1.1, 3.5] Gray; P<.01).

Conclusions. Ostial CTOs are associated with higher lesion complexity and lower technical and procedural success rates. CTO PCI of ostial lesions is associated with frequent need for retrograde crossing, higher incidence of death and stroke, longer procedure time and higher radiation dose.

Percutaneous coronary intervention (PCI) of chronic total occlusions (CTO) has been evolving with increasing success rates.^1,2 Ostial CTO location has been associated with lower procedural success in some^3,4 but not all^5-9 CTO studies often due to proximal cap ambiguity, lack of good antegrade guide support, and heavy calcification.

Ostial lesions can be divided into aorto-ostial or side-branch ostial. Aorto-ostial CTOs are often seen in patients with extensive atherosclerosis, such as patients with prior coronary artery bypass graft surgery (CABG) and are often highly calcified.¹⁰ Prior stenting of such lesions is often associated with stent underexpansion, stent recoil or significant stent extension into the aorta, hindering subsequent PCI attempts. Side-branch ostial lesions can also be challenging to recanalize. We analyzed the outcomes of ostial CTO PCI in a large contemporary multicenter CTO PCI registry.

Methods

We analyzed the baseline clinical and angiographic characteristics and procedural outcomes of 8788 CTO PCIs performed in 8614 patients at 35 US and non-US centers (Canada, Greece, Russia, and Turkey) between 2012 and 2022. Data collection was recorded in a dedicated online database (PROGRESS-CTO: Prospective Global Registry for the Study of Chronic Total Occlusion Intervention; ClinicalTrials.gov identifier: NCT02061436). Study data were collected and managed using REDCap (Research Electronic Data Capture) electronic data capture tools hosted at Minneapolis Heart Institute Foundation.^11,12 The study was approved by the institutional review board of each site.

Coronary CTOs were defined as coronary lesions with TIMI (Thrombolysis in Myocardial Infarction) grade 0 flow of at least 3 months in duration. Estimation of the duration of occlusion was clinical, based on the first onset of angina, prior history of myocardial infarction (MI) in the target-vessel territory, or comparison with a prior angiogram. CTO was defined as an ostial lesion if the location of the proximal cap was within 5 mm of the aortocoronary ostium (aorto-ostial), or a side-branch occlusion cap was within 5 mm of the main branch ostium (side-branch ostial). Calcification was assessed by angiography as mild (spots), moderate (involving ≤50% of the reference lesion diameter), or severe (involving >50% of the reference lesion diameter). Moderate proximal vessel tortuosity was defined as the presence of at least 2 bends >70° or 1 bend >90° and severe tortuosity as 2 bends >90° or 1 bend >120° in the CTO vessel. A procedure was defined as retrograde if an attempt was made to cross the lesion through a collateral vessel or bypass graft supplying the target vessel distal to the lesion. Antegrade dissection/re-entry was defined as antegrade PCI during which a guidewire was intentionally introduced into the extraplaque space proximal to the lesion, or re-entry into the distal true lumen was attempted after intentional or inadvertent extraplaque guidewire crossing.

Technical success 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 the achievement of technical success without any in-hospital major adverse cardiac event (MACE). In-hospital MACE included any of the following adverse events prior to hospital discharge: death, MI, recurrent symptoms requiring urgent repeat target-vessel revascularization with PCI or coronary artery bypass graft (CABG) surgery, tamponade requiring either pericardiocentesis or surgery, and stroke. MI was defined using the Third Universal Definition of Myocardial Infarction (type 4a MI).¹³ The Japanese CTO (J-CTO) score was calculated as described by Morino et al⁵ and the PROGRESS-CTO score as described by Christopoulos et al.⁶

Statistical analysis. Categorical variables were expressed as percentages and were compared using Pearson’s Chi-square test or Fisher’s exact test. Continuous variables were presented as mean ± standard deviation or median (interquartile range [IQR]) unless otherwise specified and were compared using the student’s t-test for normally distributed variables and the Wilcoxon rank-sum test for non-parametric variables, as appropriate. The variables associated with technical success and MACE were examined using univariable logistic regression; variables that had P<.10 and were deemed clinically/angiographically significant were included in the multivariable analysis. All statistical analyses were performed using JMP, version 16.0 (SAS Institute). A P-value of <.05 was considered to indicate statistical significance.

Results

Ostial lesions were present in 1058 (12%) of all 8788 CTOs.¹² Of all ostial CTOs, 68.1% were aorto-ostial and 31.9% were side-branch ostial. The baseline clinical characteristics of the study patients are summarized in Table 1. When compared with patients with non-ostial CTOs, patients with ostial CTOs were older and more likely to have had prior PCI, prior coronary artery bypass graft surgery (CABG), diabetes mellitus, hypertension, dyslipidemia, lower body mass index (BMI), prior myocardial infarction, cerebrovascular disease, family history of coronary artery disease (CAD), history of congestive heart failure and peripheral arterial disease, and lower left ventricular ejection fraction.

The baseline angiographic characteristics of the study lesions are presented in Table 1. The most common CTO target vessel was the right coronary artery (52.4%), and it was more often the target vessel in ostial CTOs (63.7% vs 50.9% P<.001). When compared with non-ostial CTO lesions, ostial CTOs were more complex with higher J-CTO and PROGRESS CTO scores, and had higher prevalence of moderate to severe calcification, moderate to severe tortuosity, proximal cap ambiguity, blunt or no stump, and in stent occlusions, longer occlusion length and larger proximal target proximal vessel diameter (3.3 ± 7.2 mm vs. 2.9 ± 0.5 mm; P =.04). Ostial CTOs had lower prevalence of good quality distal target vessel (62.7% vs 67.7% P=.001) and required more stents (2.4 ± 1.2 vs. 2.2 ± 1.2; P <.001).  Ostial CTOs were more likely to be balloon uncrossable (11.5% vs 9.1% P =.02) and balloon undilatable (13.4% vs 7.5%, P<.01) when compared with non-ostial CTOs.

The overall use of intravascular ultrasound (IVUS) was 48.1%. When compared with non-ostial CTOs, use of IVUS was significantly higher in ostial CTO PCI (59.8% vs 46.5% P<.001). In procedures where IVUS was used, reasons for use of IVUS included wiring guidance (9.4%), stent sizing (60.9%), facilitating the reverse controlled antegrade and retrograde tracking (2.1%), stent optimization 58.7% and resolving proximal cap ambiguity/ IVUS guided puncture 7.1%.

The procedural strategies of the study lesions are summarized in Table 2 and Figure 1.  Antegrade wiring was the first and most successful crossing strategy in all CTO lesions (85.1% and 57% respectively), however it was less likely to be successful in ostial CTOs (38.6% vs 59.6% P<.001). PCI of ostial CTOs more often required use of the retrograde approach (32.4% vs 16.2%, P<.01). The success of antegrade dissection re-entry was similar in both groups (11.8% vs 11.0%). PCI of ostial CTOs required longer procedure time (149 [103,204] vs 110 [72,160] minutes; P<.001), fluoroscopy time (57 [35, 85] vs 41 [25,64] minutes; P<.001) and higher air kerma radiation dose (2.3 [1.3,3.6] vs 2.0 [1.1,3.5] Gray; P=.002). There was no significant difference in contrast volume used during PCI between the 2 groups (200 [150,280] vs 200 [150,280] mL; P=.5).

The overall technical (82.3% vs 86.2%; P=.001) and procedural success rates (80.6% vs 84.8.1%; P=.001) were significantly lower in ostial CTOs (Table 2; Figure 2A). Ostial CTO PCI had a trend towards higher incidence of in-hospital major adverse cardiovascular events (MACE) (2.6% vs. 1.8%; P=.06), driven by significantly higher incidence of in hospital death (0.9% vs 0.3%, P=.002) and stroke (0.5% vs 0.1%, P=.002). There was a higher incidence of donor vessel injury in ostial CTO lesions, likely related to higher use of the retrograde approach. The incidence of aortocoronary dissection was low and not different between the groups. There was no significant difference in the incidence of acute myocardial infarction, repeat PCI, emergency CABG, coronary perforation, and pericardiocentesis (1.1% vs 0.9%: P=.51) (Table 2; Figure 2B) between the 2 groups.

On multivariable analysis, ostial CTO location was not independently associated with technical success (OR 1.03, CI 95% 0.83-1.29, P=.73) (Figure 3A) in contrast to other anatomic characteristics, such as moderate to severe calcification (OR 0.7, CI 95% 0.60-0.84 P<.001), moderate to severe tortuosity (OR 0.84, CI 95% 0.72-0.99 P=.04), proximal cap ambiguity (OR 0.45, CI 95% 0.39-0.53 P<.001),  distal cap at bifurcation (OR 0.75, CI 95% 0.64-0.87 P<.001), poor quality distal target vessel (OR 0.63, CI 95% 0.55-0.73 P<.001), and interventional collaterals (OR 1.56, CI 95% 1.35-1.81 P<.001). Ostial CTO location was not independently associated with in hospital MACE (1.15, CI 95% 0.71-1.86 P=.56) (Figure 3B).

The procedural strategies used in aorto-ostial and side-branch ostial CTO lesions are summarized in Table 3. In aorto-ostial lesions, antegrade wiring was less likely (33% vs 50% and 59.6% P<.001) and the retrograde approach was more likely (37.7% vs 21.1 and 16.2% P<.001) to be the successful crossing strategies when compared with side-branch ostial and non-ostial lesions. Technical (80.4% vs 83.1% and 86.2% P=.001) and procedural (78.9% vs 81.4% and 84.8% P=.002) success was significantly lower for side-branch ostial lesions vs aorto-ostial and non-ostial lesions (Table 3). Side-branch ostial lesions were also associated with significantly higher incidence of in hospital MACE when compared with aorto-ostial and non-ostial lesions (3.9% vs 2.1% and 1.8%, P=.02). This was mainly driven by higher incidence of in-hospital death (1.8% vs 0.6% and 0.3% P<.001) and cardiac tamponade (2.4% vs 0.6% and 0.9% P=.01). Aorto-ostial CTO PCI was associated with significantly higher incidence of stroke (0.6% vs 0.3% and 0.1% P=.03) when compared with side-branch ostial and non-ostial lesions. The incidence of aorto-coronary dissection was low and not significantly different between the 3 groups.

On multivariable analysis, side-branch ostial location of CTO lesions was not independently associated with technical success (OR 0.96, CI 95% 0.67-1.39 P=.86) (Figure 3C), but was independently associated with in-hospital MACE (OR 2.23, CI 95% 1.1-4.1 P=.01) (Figure 3D).

Discussion

The main findings of our study are that ostial CTO PCI is associated with: (1) higher lesion complexity; (2) more frequent use of the retrograde approach and less frequent use of antegrade wiring as the successful crossing strategies; (3) lower technical and procedural success rates; (4) trend towards higher in-hospital MACE and (5) longer procedure time and radiation dose. On multivariable analysis, however, ostial CTO lesions were not significantly associated with lower technical success or higher in hospital MACE. Moreover, side-branch ostial CTO PCI was independently associated with higher in hospital MACE (Central Illustration).

To the best of our knowledge, our study is the largest to date evaluating outcomes with CTO PCI in ostial CTO lesions. The prevalence of ostial CTOs was 12% and these patients had a higher risk of coronary artery disease risk factors (diabetes mellitus, hypertension and dyslipidemia). Guelker et al¹⁴ reported the prevalence of ostial CTOs to be 11.1% among 600 patients in a single high volume German center; Galassi et al³ reported 14.1% prevalence of ostial CTOs among 1,073 patients from a single center in Italy, while in a multicenter Japanese CTO PCI Expert Registry including 8,720 patients, it was only 3.7%.¹⁵ Patients with ostial CTOs had more comorbidities when compared to patients with non-ostial CTOs, especially prior CABG. Other studies had similar findings^14-16 although in our study the proportion of patients with prior CABG was much higher.

Ostial CTO PCI required more often the use of the retrograde approach as the initial and successful crossing strategy, especially for aorto-ostial lesions. Antegrade wiring was less likely to be the successful crossing strategy in ostial CTOs when compared to non-ostial CTOs. Also, PCI of these lesions was associated with longer procedure time and radiation dose. These findings are likely related to higher lesion complexity (calcification, tortuosity, proximal cap ambiguity and longer lesion length) as reflected in higher J-CTO and PROGRESS CTO scores in this patient population.

The technical and procedural success rates were overall high, albeit significantly lower in ostial CTOs when compared with non-ostial CTOs. This is likely related to higher lesion complexity and more frequent need for advanced CTO PCI techniques in ostial CTO PCI, especially the retrograde approach that is associated with lower technical success.¹⁷ These findings are similar to prior reports.^3,4,10,14,15 In a meta-analysis of 61 studies that included 69, 886 patients, ostial CTO location was associated with reduced technical and clinical success.¹⁸  Galassi et al created the ORA-score (Ostial location of proximal cap, Rentrop <2 collateral filling, patient Age ≥75), based on 1,076 CTO PCIs performed by a single operator over a period of 10 years with higher score predicting lower technical success.³ In the Ellis scoring system ostial CTO location was associated with procedure failure along with several other variables (proximal cap ambiguity, operator experience, adequate distal target, lesion length >10 mm, tortuosity, calcification, and collateral score). Ostial CTOs can be challenging to treat and often require longer procedure time and radiation dose. In addition to the retrograde approach, ostial CTO PCI often requires creative and unconventional selection of equipment and techniques such as electrocautery assisted re-entry and power flush for aorto-ostial lesions and IVUS guided proximal cap entry, side branch cutting, and side balloon assisted subintimal entry (side BASE) for side-branch ostial lesions.^19-25

In our study, ostial CTO location was not independently associated with lower technical success rate, suggesting that the higher technical failure of ostial CTO PCI is likely due to higher overall lesion complexity rather than the ostial location itself. Most commonly used CTO risk stratification scores, such as the J-CTO and PROGRESS CTO scores, do not include ostial location.

The overall incidence of MACE was numerically higher but not significantly different in ostial CTOs when compared with non-ostial CTOs in both univariable and multivariable analysis. The incidence of stroke was significantly higher in ostial CTOs and was twice as high in aorto-ostial lesions versus branch ostial lesions. Aorto-ostial disease is associated with more advanced atherosclerosis and significant calcification and may require additional gear/catheter manipulations in proximity to the aorta, increasing the risk of systemic thromboembolism. The higher incidence of death with ostial CTO PCI is likely related to higher baseline co-morbidities, higher risk of stroke, and possibly higher risk of coronary perforation.

When comparing aorto-ostial, side-branch ostial and non-ostial CTOs, the side-branch ostial lesions were associated with the lowest technical success and highest in-hospital MACE (driven by significantly higher incidence of death, stroke, and cardiac tamponade). Side-branch ostial CTO PCI was also independently associated with higher MACE. Similar to aorto-ostial CTOs, side-branch ostial CTOs often have proximal cap ambiguity and require the retrograde approach or other CTO PCI techniques such as side BASE and side-branch cutting. Moreover, they are subjected to multiple issues related to bifurcation (extreme take off angles, side-branch loss, kissing balloon inflation, 2-stent strategies, etc.) that can lead to complications. Given the association of ostial CTOs with higher risk of procedural and in-hospital complications, the threshold for treating these lesions might need to be higher than non-ostial CTOs.

Study limitations. PROGRESS-CTO is an observational retrospective study without long-term follow-up and no core laboratory assessment of the study angiograms or clinical event adjudication. The procedures were performed at dedicated, high-volume CTO centers by experienced operators, and these results may not be reproducible by less experienced operators.

Conclusions

Ostial CTO PCI is associated with higher lesion complexity and lower technical and procedural success rates. When compared with non-ostial lesions, PCI of ostial CTOs is associated with frequent need for retrograde crossing, a trend toward higher incidence of in-hospital MACE, higher incidence of death and stroke, longer procedure time and higher radiation dose. Ostial CTO location, however, was not an independently associated with lower technical success. Between the aorto-ostial, branch ostial and non-ostial CTOs, the branch ostial lesions were associated with the lowest technical success and highest in hospital MACE rates.

Acknowledgments. The authors are grateful for the philanthropic support of our generous anonymous donors, and the philanthropic support of Drs Mary Ann and Donald A Sens, Mrs Diane and DrCline Hickok, Mrs Wilma and Mr Dale Johnson, Mrs Charlotte and Mr Jerry Golinvaux Family Fund, the Roehl Family Foundation and the Joseph Durda Foundation. The generous gifts of these donors to the Minneapolis Heart Institute Foundation & Science Center for Coronary Artery Disease (CCAD) helped support this research project. Study data were collected and managed using Research Electronic Data Capture (REDCap) electronic data capture tools hosted at the Minneapolis Heart Institute Foundation (MHIF), Minneapolis, Minnesota.^1,2 REDCap is a secure, web-based application designed to support data capture for research studies, providing: (1) an intuitive interface for validated data entry; (2) audit trails for tracking data manipulation and export procedures; (3) automated export procedures for seamless data downloads to common statistical packages; and (4) procedures for importing data from external sources.

Affiliations and Disclosures

From ¹Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Abbott Northwestern Hospital, Minneapolis, Minnesota; ²Henry Ford Cardiovascular Division, Detroit, Michigan; ³Meshalkin Novosibirsk Research Institute, Novosibirsk, Russia; ⁴Gagnon Cardiovascular Institute, Morristown Medical Center, New Jersey; ⁵Massachusetts General Hospital, Boston, Massachusetts; ⁶Cleveland Clinic, Cleveland, Ohio; ⁷University Hospitals, Case Western Reserve University, Cleveland, Ohio; ⁸UCSD Medical Center, La Jolla, California; ⁹Red Cross Hospital of Athens, Athens, Greece; ¹⁰Acibadem Kocaeli Hospital, Izmit, Turkey; ¹¹St. Boniface General Hospital, Winnipeg, Manitoba, Canada; ¹²Emory University Hospital Midtown, Atlanta, Georgia; ¹³North Oaks Health System, Hammond, Louisiana; ¹⁴Memorial Bahcelievler Hospital, Istanbul, Turkey; ¹⁵Aswan Heart Center, Magdi Yacoub Foundation, Cairo, Egypt.

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Allana: consulting honoraria from Boston Scientific Corp and Abiomed. Dr Alaswad: consultant and speaker for Boston Scientific, Abbott Cardiovascular, Teleflex, and Cardiovascular Systems Inc. Dr Karmpaliotis: honoraria: Boston Scientific, Abbott Vascular, Abiomed; Equity: Saranas, Soundbite, Traverse Vascular. Dr Jaffer: Sponsored research: Canon, Siemens, Shockwave, Teleflex, Mercator, Boston Scientific, HeartFlow, Amarin; Consultant: Boston Scientific, Siemens, Magenta Medical, International Medical Device Solutions, Asahi Intecc, Biotronik, Philips, Intravascular Imaging, DurVena. Equity interest – Intravascular Imaging Inc, DurVena, Massachusetts General Hospital – licensing arrangements: Terumo, Canon, Spectrawave, for which FAJ has right to receive royalties. Dr Khatri: Personal honoria for proctoring and speaking: Abbott Vascular, Medtronic, Terumo, Shockwave Medical. Dr Poommipanit: consultant: Medtronic, Asahi Intecc, Inc, Abbott Vascular, Boston Scientific. Dr Patel: Consulting honoraria from Abbott, Medtronic, Terumo, Cardiovascular Systems, Inc, Dr Mahmud: consultant for Abiomed, Medtronic, Boston Scientific, and chairs multiple Data, Safety and Monitoring Boards. Dr Nicholson: Proctor and is on the speakers bureau and advisory board for Abbott Vascular, Boston Scientific, and Asahi Intecc; he reports intellectual property with Vascular Solutions. Dr Jaber: Medtronic and proctoring fees from Abbott. Dr Rinfret: Abbott Vascular, Abiomed, Boston Scientific Corporation, SoundBite Medical, Teleflex-Consultant. Dr Abi-Rafeh: proctor and speaker honoraria from Boston Scientific and Abbott Vascular. Dr ElGuindy: Consulting honoraria: Medtronic, Boston Scientific, Asahi Intecc, Abbott; Proctorship fees: Medtronic, Boston Scientific, Asahi Intecc, Terumo; Educational grants: Medtronic. Dr Sandoval: previously served on the advisory boards for Roche Diagnostics and Abbott Diagnostics without personal compensation; and has also been a speaker without personal financial compensation for Abbott Diagnostics. Dr Burke: consulting and speaker honoraria from Abbott Vascular and Boston Scientific. Dr Brilakis: Consulting/speaker honoraria from Abbott Vascular, American Heart Association (associate editor Circulation), Amgen, Asahi Intecc, Biotronik, Boston Scientific, Cardiovascular Innovations Foundation (board of directors), ControlRad, CSI, Elsevier, GE Healthcare, IMDS, InfraRedx, Medicure, Medtronic, Opsens, Siemens, and Teleflex; research support: Boston Scientific, GE Healthcare; owner, Hippocrates LLC; shareholder: MHI Ventures, Cleerly Health, Stallion Medical. The remaining authors report no disclosures.

Manuscript accepted February 23, 2023.

Address for correspondence: Emmanouil S. Brilakis, MD, PhD, Director of the Center for Complex Coronary Interventions, Minneapolis Heart Institute, Chairman of the Center for Coronary Artery Disease at the Minneapolis Heart Institute, Foundation, 920 E 28th Street #300, Minneapolis, Minnesota, 55407. Email: esbrilakis@gmail.com

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