Commentary: CTO-PCI: An Emerging New Subspecialty in Interventional Cardiology

Percutaneous coronary intervention (PCI) of coronary chronic total occlusions (CTOs) represents the most technically challenging lesions in contemporary interventional cardiology.^1,2 Despite the absence of randomized trials comparing outcomes of CTO-PCI against medical therapy or coronary artery bypass graft (CABG), a growing body of evidence suggests that successful percutaneous CTO revascularization relieves symptoms, improves left ventricular systolic function, reduces the need for surgical coronary bypass, and (especially in the context of complete coronary revascularization) improves survival.^3-5 While some clinical studies do not show a clear benefit to CTO-PCI, even those neutral studies do not demonstrate a negative impact associated with CTO-PCI procedures.⁶ 

Despite the benefit of CTO recanalization, the CTO attempt rates in the United States (US) have remained disappointingly low. A recent examination of the National Cardiovascular Data Registry confirmed this sobering finding. Over a 3-year period, CTO-PCI represented 3.8% of the total PCI volume, and had lower procedural success (59% vs 96%, P<.001) and higher adverse event rate (1.6% versus 0.8%; P<.001) compared with non-CTO PCI. Of note, only 8 operators were reported to perform more than 50 CTO-PCI procedures per year and almost 20% of participating sites never performed CTO-PCI. Concerns regarding low success rates, unacceptably high complication rates, increased procedural time and resource utilization, and prohibitively high cost associated with CTO-PCI may account for these findings.^1,7 However, a closer look at the available data from expert centers challenges these misconceptions.

When CTO-PCI is part of a comprehensive complex and higher-risk indicated patient (CHIP) program and performed in a systematic way (similar to the concept of a transcatheter aortic valve replacement program), CTO-PCI can be safe, efficient, economically sound, and associated with high procedural success rates.⁸ During the first year after development of a CTO program with dedicated CTO operators, and implementation of quality and performance guidelines, the overall CTO success rate was 85.6%. In-hospital adverse outcomes included: death 0.6%; emergency bypass surgery, 0.6%; tamponade, 0.6%; myocardial infarction, 1.9%; and transient nephropathy, 1.2%. Compared with patients undergoing non-CTO PCI, procedural and total costs per patient were significantly higher among the CTO cohort, but the contribution margins were comparable ($5173 ± 12,052 vs $5730 ± 8958; P=.58).⁸ Reports from US multicenter registries have demonstrated excellent procedural outcomes at high-volume centers. The technical and procedural success rates were 85.5% and 84.2%, respectively. The mean procedural time, fluoroscopy time, and contrast utilization were 113 ± 61 minutes, 42 ± 29 minutes, and 294 ± 158 mL, respectively. Major complications occurred in 1.8% of patients.⁹

How are these excellent results achieved? A major breakthrough in CTO-PCI in the US was the development and implementation of the “hybrid algorithm” — an attempt to standardize a reproducible and teachable approach to CTO-PCI.¹⁰ Avoidance of ad hoc CTO-PCI is fundamental to this algorithm, since meticulous study of the angiogram and preprocedural planning is essential for successful outcomes.⁸ CTO operators must be expert in all available CTO angioplasty techniques (antegrade wire escalation, antegrade dissection and reentry, and retrograde wire escalation and dissection reentry). The procedure starts with “dual” or simultaneous contralateral injections in order to carefully assess four angiographic parameters: (1) proximal cap ambiguity; (2) distal vessel quality and branching; (3) lesion length; and (4) presence or absence of “interventional” collaterals that may be used for retrograde CTO recanalization. The operator can decide on the initial strategy that will provide the safest, most efficient, and most effective way to recanalize the CTO, as well as alternative strategies if the initial approach fails. The operator can switch from one strategy to another in order to complete the procedure successfully in a reasonable timeframe.¹⁰ Recent reports from centers after adopting the hybrid approach have shown further improvements in success rates (91%) while maintaining acceptable complication rates (1.8%).¹¹ Undoubtedly, these procedures are time consuming and require longer fluoroscopy time and greater radiation and contrast utilization, but with increased operator experience, there are favorable trends toward reduction of these requirements.¹² Despite the ability to readily transmit the hybrid approach to new operators and centers, CTO-PCI is associated with a steep learning curve. Indeed, in multivariable models, years since initiation of CTO-PCI at each center was an independent predictor of procedural success.⁹ This is especially relevant in the most complex subset of CTO-PCI involving the application of the retrograde approach.¹³ Case selection and proctoring are both fundamental to early implementation of the hybrid approach to CTO-PCI. Even in high-volume CTO-PCI centers with experienced CTO operators, the practice of two operators participating in CTO is emerging.

In this context, the article by Vo et al in this month’s Journal of Invasive Cardiology demonstrated that a single operator can learn CTO-PCI techniques with a high success rate and acceptable complication rates.¹⁴ After appropriate education and proctoring, the operator performed 50 CTO-PCIs on 48 consecutive patients over a 6-month period. Successful CTO recanalization was achieved in 92% of cases, with low rates of major complications. These results were achieved despite high complexity of the CTO lesions, which had an average J-CTO score >2. Additionally, a primary retrograde approach was used in 33%, and multiple strategies were implemented in 50% of cases. Considering the complexity of CTO-PCI, are these results surprising? Despite the inherent difficulty of CTO-PCI, in recent years, with the adoption of a standardized approach, CTO-PCI success rates in expert centers are above 90%, with very acceptable complication rates.^9,15 This important study demonstrates that the excellent results seen in expert centers can be translated to new operators and CTO teams, across settings including community hospitals and tertiary or academic centers.

In the modern era, CTO-PCI has emerged as a new subspecialty of interventional cardiology, with specialized equipment, methodology, and expertise. Modern CTO operators have set a new benchmark for CTO success rates of above 90%. With appropriate training and dissemination of the hybrid approach to new operators in the academic as well as community setting, this goal can be accomplished.  

References

1. Grantham JA, Marso SP, Spertus J, House J, Holmes DR Jr, Rutherford BD. Chronic total occlusion angioplasty in the United States. JACC Cardiovasc Interv. 2009;2(6):479-486.
2. Stone GW, Kandzari DE, Mehran R, et al. Percutaneous recanalization of chronically occluded coronary arteries: a consensus document: part I. Circulation. 2005;112(15):2364-2372.
3. Joyal D, Afilalo J, Rinfret S. Effectiveness of recanalization of chronic total occlusions: a systematic review and meta-analysis. Am Heart J. 2010;160(1):179-187.
4. Mehran R, Claessen BE, Godino C, et al. Long-term outcome of percutaneous coronary intervention for chronic total occlusions. JACC Cardiovasc Interv. 2011;4(9):952-961.
5. George S, Cockburn J, Clayton TC, et al. Long-term follow-up of elective chronic total coronary occlusion angioplasty: analysis from the UK Central cardiac audit database. J Am Coll Cardiol. 2014;64(3):235-243.
6. Jolicoeur EM, Sketch MJ, Wojdyla DM, et al. Percutaneous coronary interventions and cardiovascular outcomes for patients with chronic total occlusions. Catheter Cardiovasc Interv. 2012;79(4):603-612. Epub 2011 Dec 12.
7. Brilakis E, Banerjee S, Karmpaliotis D, et al. TCT-192. Procedural outcomes of chronic total occlusion percutaneous coronary intervention: a report from NCDR. J Am Coll Cardiol. 2014;64(11_S).
8. Karmpaliotis D, Lembo N, Kalynych A, et al. Development of a high-volume, multiple-operator program for percutaneous chronic total coronary occlusion revascularization: procedural, clinical, and cost-utilization outcomes. Catheter Cardiovasc Interv. 2013;82(1):1-8.Epub 2013 Apr 11. 
9. Michael TT, Karmpaliotis D, Brilakis ES, et al. Procedural outcomes of revascularization of chronic total occlusion of native coronary arteries (from a multicenter United States registry). Am J Cardiol. 2013;112(4):488-492.
10. Brilakis ES, Grantham JA, Rinfret S, et al. A percutaneous treatment algorithm for crossing coronary chronic total occlusions. JACC Cardiovasc Interv. 2012;5(4):367-379.
11. Christopoulos G, Karmpaliotis D, Alaswad K, et al. The efficacy of “hybrid” percutaneous coronary intervention in chronic total occlusions caused by in-stent restenosis: insights from a US multicenter registry. Catheter Cardiovasc Interv. 2014;84(4):646-651. Epub 2014 Jul 4.
12. Michael TT, Karmpaliotis D, Brilakis ES, et al. Temporal trends of fluoroscopy time and contrast utilization in coronary chronic total occlusion revascularization: insights from a multicenter United States registry. Catheter Cardiovasc Interv. 2015;85(3):393-399. Epub 2014 Jan 31.
13. Karmpaliotis D, Michael TT, Brilakis ES, et al. Retrograde coronary chronic total occlusion revascularization: procedural and in-hospital outcomes from a multicenter registry in the United States. JACC Cardiovasc Interv. 2012;5(12):1273-1279.
14. Vo MN, McCabe JM, Lombardi WL, Ducas J, Ravandi A, Brilakis ES. Adoption of the hybrid CTO approach by a single non-CTO operator: procedural and clinical outcomes. J Invasive Cardiol. 2015;27(3):139-144.
15. Galassi AR, Tomasello SD, Reifart N, et al. In-hospital outcomes of percutaneous coronary intervention in patients with chronic total occlusion: insights from the ERCTO (European Registry of Chronic Total Occlusion) registry. EuroIntervention. 2011;7(4):472-479.

___________________________________________

From the Center for Interventional Vascular Therapy, Division of Cardiology, Department of Medicine, Columbia University Medical Center, New York, New York.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Karmpaliotis reports speak honoraria from Boston Scientific, Abbott Vascular, Asahi Intecc, and Medtronic. Dr Green reports no conflicts of interest regarding the content herein.

Address for correspondence: Dimitri Karmpaliotis, MD, 161 Fort Washington Avenue, 6th Floor, New York, NY 10032. Email: dk2787@cumc.columbia.edu