On the Frontier of CTO PCI for STEMI Patients: Answers Lead to More Questions in EXPLORE

Data presented at last year’s Transcatheter Cardiovascular Therapeutics symposium demonstrating the feasibility and safety of additional PCI for chronic total occlusions (CTOs) within a week after primary PCI are now published.

However, despite the results also showing no improvement in LV function and dimensions, there has been no “lack of enthusiasm” for performing the procedure in the last 12 months, Kevin J. Croce, MD, PhD (Brigham and Women’s Hospital, Boston, MA), who was not involved in the study, told TCTMD. “I haven’t had anyone in my experience say I’m not going to do CTO PCI because it doesn’t help, because despite this publication, I think people are pretty cognizant of the fact that CTO PCI gets rid of angina and ischemic chest discomfort very well.”

The EXPLORE trial, published this week in the Journal of the American College of Cardiology, randomized 304 STEMI patients to CTO PCI or no CTO intervention within 7 days of primary PCI at multiple centers in Canada and Europe. While the second procedure was deemed successful in 77% of cases (73% on core-lab adjudication) in the intervention arm, LVEF and LV end-diastolic volume did not differ between the study groups on MRI at 4 months. Additionally, there were no overall differences in MACE.

In a subgroup analysis, lead author José P.S. Henriques, MD (University of Amsterdam, the Netherlands), and colleagues found an interaction with CTO location such that patients with a CTO in the LAD appeared to have improved LVEF with the intervention (P = 0.02).

Several Gripes

“At first glance, the study results appear disappointing,” write Emmanouil Brilakis, MD, PhD (Minneapolis Heart Institute, MN), Shuaib Abdullah, MD (VA North Texas Healthcare System, Dallas), and Subhash Banerjee, MD (University of Texas Southwestern Medical School, Dallas), in an accompanying editorial.

But they outline several caveats that might affect physicians’ understanding of EXPLORE. Not only do they note that the success rate of CTO PCI was “relatively low,” but also that the “completeness of revascularization achieved in the CTO PCI group is unclear and could still be relatively low despite CTO PCI attempts.”

Croce agreed with both of these points, noting that high-volume centers typically have CTO PCI success rates closer to 90%.

Additionally, “4 months may not be long enough to achieve myocardial recovery,” Brilakis and colleagues write, also taking issue with the connotation that < 75% transmurality also means viability.

Specifically, Croce said, “there's no sense of how likely patients were to benefit from having their particular arteries a priori. It brings the question of whether or not maybe, if you stratify opening CTOs in people that have a lot of viability, that might be a beneficial thing to do.”

The editorial also took issue with the lack of evaluation of regional wall motion at baseline and follow-up, as well as the study’s low power, and the absence of verification of stent patency. Lastly, although the study was designed to only look at STEMI patients, they represent “a minority of patients currently undergoing CTO PCI and results could be different in patients with stable angina or patients with non-ST-segment elevation acute coronary syndromes,” Brilakis and colleagues observe.

Until More Data Comes, Experts Urge ‘Judicious Use’

The “main takeaway” from EXPLORE, Croce said, is that while there might be “little value of in-hospital CTO PCI for non-LAD CTO in STEMI patients if your only goal is to improve their EF, . . . this study in no way should reduce enthusiasm for treating CTO patients with PCI for chronic stable angina if the goal is to reduce their ischemic symptoms.”

The ongoing DECISION-CTO and EURO-CTO studies as well as the SHINE CTO sham procedure trial should give more clarity to the issue, according to the editorial, but results will not be available until 2018 at the earliest.

In the meantime, “many patients need treatment now and cannot wait,” they write. “Clinical decision making for such patients should be made on the basis of the best available data. This situation is not unique to CTO PCI.”

CTO PCI is “not panacea,” the editorialists conclude, but “it is an important tool in our armamentarium to achieve coronary revascularization. Judicious use of this and other tools, such as non-CTO PCI and coronary artery bypass graft surgery and guideline-directed medical therapy, can and likely will improve the outcomes of patients with coronary artery disease.”

Related Stories:

• EXPLORE: Treating CTOs After STEMI Does Not Improve LV Function
• Trials Prompt Interventionalists to Reconsider Complete Revascularization for STEMI
• Study Explores Procedural Success, Failure of Hybrid Approach to PCI in Chronic Total Occlusions