December 03, 2015
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An Update on Recent Trials of CTO PCI

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“When you start on the way to Ithaca, wish that the way be long, full of adventure, full of knowledge.” – “Ithaca” by Constantine P. Cavafy

The annual Transcatheter Cardiovascular Therapeutics meeting, held in San Francisco in October 2015, was a fruitful meeting for chronic total occlusion PCI, with important results and high interest from attendees who filled up the chronic total occlusion PCI sessions.

Emmanouil S. Brilakis
Emmanouil S. Brilakis

This CTO Corner summarizes findings of two trials of interest: EXPLORE and OPEN CTO.

The EXPLORE Trial

Results of the first prospective randomized controlled trial of CTO PCI vs. medical therapy ever to be completed — EXPLORE — were presented by José P.S. Henriques, MD, of Academic Medical Center in Amsterdam.

Investigators for the EXPLORE trial randomly assigned 304 patients who presented with STEMI and were found to have a CTO in a nonculprit vessel to CTO PCI within 7 days of STEMI or no CTO PCI. MRI was performed at 4 months to determine left ventricular ejection fraction and end-diastolic volume.

Physician self-reported procedural success in the CTO PCI arm was 80% and core lab-adjudicated procedural success was 72%. At 4 months, the mean ejection fraction was similar in the CTO PCI and the non-CTO PCI arms (44.1 ± 12.2% vs. 44.9 ± 12.1%; P = .597; Figure 1A). Similar results were also reported between the groups for LV end-diastolic volume (215.6 ± 62.5 mL vs. 212.9 ± 60.2 mL; P = .71). On subgroup analysis, CTO PCI appeared to be beneficial in patients with left anterior descending (LAD) CTO, but not among those with right coronary or circumflex CTOs (Figure 1B). The 4-month incidence of MACE was similar in the two groups (5.4% vs. 2.6%; P = .25).

EXPLORE is a landmark study that required more than 7 years of enrollment at 14 sites. The study team is to be congratulated for the herculean effort required to bring the project to completion.

Figure 1A Figure 1B
Figures 1A and 1B. Primary results of the EXPLORE trial for left ventricular ejection fraction (panel A) and subgroup analyses (panel B).

Figures 1A and 1B courtesy of Dr. José PS Henriques, MD; reprinted with permission.

Although the results of the study do not support routine CTO PCI for improving ejection fraction among STEMI patients with concomitant CTO, the data raise important questions about the viability of the myocardial territories supplied by the CTO vessel and whether the results could be different if higher success rates were achieved, which is currently feasible given the rapid evolution of equipment and techniques. The contrast between the benefit observed among LAD CTO target lesions and the harm among non-LAD lesions is intriguing and builds on prior studies that demonstrated mortality benefit after CTO PCI of the LAD but not with non-LAD CTO target vessels. Going forward, more randomized clinical trials similar to EXPLORE will be crucial to better understand the advantages and limitations of CTO PCI and optimize its use in clinical practice.

The OPEN CTO Trial

Another important CTO PCI study presented at TCT was the OPEN CTO trial, which was presented by J. Aaron Grantham, MD, of Saint Luke’s Health System and University of Missouri-Kansas City School of Medicine.

Investigators for the OPEN CTO trial prospectively enrolled 1,000 patients at 12 experienced CTO PCI centers in the United States and collected detailed information on acute and subsequent procedural outcomes, including quality-of-life outcomes, with core lab analysis and central events committee adjudication.

According to results presented, technical success was 89%, mean procedure time was 119 ± 72 minutes, mean air kerma radiation dose was 2.5 ± 1.9 Gy and mean contrast volume was 265 ± 194 mL, suggesting high efficiency. Thirty-day mortality was 1.3%, rehospitalization was 14.7%, repeat revascularization was 2.6% and skin change was 3.1%. Patients experienced significant improvement in angina, dyspnea and depression scores (Figures 2A and 2B).

Figure 2A Figure 2B
Figures 2A and 2B. Quality of life improvement in the OPEN CTO trial.

Figures 2A aand 2B courtesy of Dr. J. Aaron Grantham, MD; reprinted with permission.

OPEN CTO is a methodologically rigorous snapshot of the current status of hybrid CTO PCI, demonstrating that high success rates can be achieved with significant improvement in patient quality of life. It also demonstrates that the risk of CTO PCI may be higher than non-CTO PCI as demonstrated in a recent analysis from the American College of Cardiology’s National Cardiovascular Data Registry. High success rates similar to OPEN CTO were reported by several other contemporary CTO PCI registries from around the world.

High Success Rates, Future Efforts

In summary, it is now clear that, by using contemporary techniques, high success rates can be achieved among multiple experienced centers around the world, providing significant clinical benefits.

However, much more needs to be done, such as expanding the number of centers that can achieve the excellent results achieved at expert centers so as to increase local availability to high-quality CTO PCI; creating a better understanding of which patients are most likely to benefit from CTO PCI and how to minimize procedure-related risks; and performing the next-generation clinical trials that will bring CTO PCI to the next level and consolidate its role as an effective and safe treatment strategy for complex CAD.

TCT 2015 confirms that many clinicians and centers around the world have embarked “on the way to Ithaca” and that the journey is indeed full of adventure and knowledge. The journey will likely continue for many years to come.

Disclosures: Brilakis reports receiving speaker honoraria/consultant fees from Abbott Vascular, Asahi, Boston Scientific, Elsevier, Somahlution, St. Jude Medical and Terumo; research support from Boston Scientific and Infraredx; and his spouse is an employee of Medtronic.