Chronic Total Occlusion (CTO) Revascularization: Seeing the Future

Disclosure: Dr. Kern reports he is a consultant and speaker for St. Jude Medical and Volcano Therapeutics, and a consultant for Boston Scientific, Opsens, ACIST Medical, and Merit Medical.

I know a good idea when I see it and recanalization of CTOs is one. After observing several remarkable CTO cases by experts like Bill Lombardi of the University of Washington, and hearing him and several of his disciples talk about CTO work, I am dumbstruck by how my previous concepts of percutaneous coronary intervention (PCI) had stagnated. This experience, coupled with questions asked of me by the interventional fellows at the American College of Cardiology San Diego meeting about what the direction of the field is and where they should be looking for new things, made my answer easy. Beyond the obvious advances in structural heart interventions (i.e. transcatheter aortic valve replacement [TAVR], new methods for percutaneous mitral valve repair, etc.), I told them the future is conquering the CTO. From what I saw during several live cases at our major cardiology meetings, CTOs are the future for the young interventional cardiologist going into practice as well as the established interventionalist looking to expand current PCI practice. 

Several things that Dr. Lombardi said about CTOs impressed me greatly. First, if your patient needs complete revascularization, why is he not getting it? Reason: You (meaning me and other interventionalists who cannot do CTOs — yet) accept that medical therapy is the only suitable option. Second, if the CTO were a lesion you knew you open easily, like a 95% proximal stenosis, would you hesitate to attempt it? Of course not. Third, if you could open a long CTO with new techniques, what would keep you from helping your patient avoid surgery? Nothing but the learning curve.

While Bill’s enthusiasm is tremendous and some of his comments may at times be over the top, his CTO discussion is really on point. Can everyone do CTO revascularization to his level at this time? Of course not, but many will be able to, and provide the labs and patients they serve with special skills, expanding the PCI population. In support of CTO as the next frontier in the lab, I’ll briefly review some of the data about CTOs to put current thinking in perspective. 

What’s known about CTOs?

CTOs occur in 1 of 5 patients having a cardiac catheterization. The success rate of CTO PCI in everyday practice is only 30-35%. Many, if not most, CTOs are not attempted, and these patients receive medical therapy or coronary artery bypass graft surgery (CABG). Cardiac mortality is 3-fold higher in patients with persistent coronary occlusions.  

Brilakis et al¹ reviewed data from the National Cardiovascular Data Registry (NCDR). CTO PCI was only 4% of procedures (22,365 of 594,510 procedures). CTO PCI success rates were lower than non-CTO success (59 vs 96%) and had twice as many complications (1.6 vs 0.8%). Successful CTO opening reduced angina and need for urgent or elective CABG compared to failed CTO PCI attempts.

CTO revascularization improves survival

Successful recanalization of a CTO is associated with better survival than those having unsuccessful procedures.¹ Jang et al² in 2014 reported the long-term survival benefit of revascularization compared with medical therapy in patients with CTO and well-developed collaterals. Of 738 patients with grade III (large) collaterals, 236 were randomized to medical therapy, 170 to CABG, and 332 to PCI. At 42 months follow-up those have revascularization, either by PCI or CABG had significantly reduced incidence of death and major adverse cardiac events (P=0.01). 

Brilakis et al¹ also found that successful CTO PCI had lower in-hospital mortality than failed CTO PCI (0 vs 1.1%). It was worth noting that the successful CTO PCI patients were younger, with less incidence of diabetes, myocardial infarction, cerebrovascular accidents (CVA), or CABG.  We should not forget that a CTO is an overall marker of severe coronary artery disease and a risk factor for higher morbidity and mortality. Nonetheless, patients with CTO-associated ischemia despite the presence of angiographic collaterals benefit from revascularization

What are the barriers to starting a CTO PCI program?

A CTO is one of the highest complexity lesion subsets we see in the cath lab. Barriers to starting a CTO program include appreciating the clinical benefits, costs, time, and the acquisition of the needed special skill set. It is known that high costs are associated with CTO PCI procedures. An average CTO case requires 5-10 guide wires, adjunctive imaging, multiple stents, specialized catheters, and additional vascular access sites.³ The lab and operators must devote several hours (initially) to these procedures until the team’s skill sets have developed to the level of the experts performing multiple CTOs in less than an hour. The acquisition of special techniques includes increased expertise in wiring collaterals, retrograde wire tracking, and the use of micro catheters with special subintimal luminal reentry systems. Contrast load and radiation exposure will need to be monitored more closely. It is worth remembering that success rates correlate to procedure volumes. Brilakis et al’s evaluation of the NCDR found that procedural success and MACE for interventionalists performing >10 CTO PCIs/year was 74.6% and 1.4%, respectively, versus 53.1% and 1.7% for those doing <5 CTO PCIs/year.¹ Operators will need to learn the retrograde entry methods. Patency of side branches near the CTO is improved by using the retrograde technique over the antegrade approach. One of the barriers to CTO work will be overcoming our fear of working in the “sacred” adventitial space and producing a perforation. Blunt entry methods into the adventitia, while initially appearing daunting, have been associated with excellent results. After seeing the subintimal space stented, connecting the proximal artery to the distal vessel, I was actually seeing an internal bypass “graft” that just replaced surgery. I can foresee a future in which a CTO is no longer an indication for CABG and that a second surgery for failed coronary conduits will be made irrelevant by CTO PCI of the previously bypassed artery.

As a senior observer across the nearly 4 decades of PCI history, CTO PCI is a needed programmatic development. Recall that the initial years of balloon-only angioplasty required operators to overcome trepidation about coronary complications that in some case limited the scope of PTCA. This fear dissolved with experience and successes in multivessel PTCA. The introduction of stents, PTCA for ST-elevation myocardial infarction, then atherectomy devices followed by more and better drug-eluting stents increased the spectrum of PCI patients. We now enter the era of TAVR and structural interventions. The conquering of CTOs is only a matter of desire, training, and shared experiences, as with all innovations. 

To bring you up to speed on CTOs, I recommend reading 2 editorials which nicely condense the state of the art, one by Dr. John Bittl³ and the other by Drs. Barbato and Wijns⁴, with whom I must agree — we should be ready to change from the stance “leave ‘em all” to “stent ‘em all”. I think we’re almost there.

References

1. Brilakis ES, Banerjee S, Karmpaliotis D, Lombardi WL, Tsai TT, Shunk KA, et al. Procedural outcomes of chronic total occlusion percutaneous coronary intervention: a report from the NCDR (National Cardiovascular Data Registry). JACC Cardiovasc Interv. 2015 Feb; 8(2): 245-553. doi: 10.1016/j.jcin.2014.08.014.
2. Jang WJ, Yang JH, Choi SH, Song YB, Hahn JY, Choi JH, et al. Long-term survival benefit of revascularization compared with medical therapy in patients with coronary chronic total occlusion and well-developed collateral circulation. JACC Cardiovasc Interv. 2015 Feb;8(2):271-279. doi: 10.1016/j.jcin.2014.10.010.
3. Bittl JA. Percutaneous coronary intervention for chronic total occlusions: the power of negative thinking. JACC Cardiovasc Interv. 2015 Feb;8(2):254-256. doi: 10.1016/j.jcin.2014.09.012.
4. Barbato E, Wijns W. Are we ready for a new paradigm shift in percutaneous revascularization of chronically occluded vessels with well-developed collaterals?: from leaving ‘em all to stenting ‘em all. JACC Cardiovasc Interv. 2015 Feb; 8(2): 280-282. doi: 10.1016/j.jcin.2014.12.003.