EXPLORE: Treating CTOs After STEMI Does Not Improve LV Function

Opening chronic total occlusions (CTOs) shortly after primary PCI for STEMI does not have an impact on left ventricular function, according to a late-breaking clinical trial presentation on Monday. 

For the EXPLORE trial, José P.S. Henriques, MD, of Academic Medical Center, Amsterdam, the Netherlands, and colleagues randomized 302 STEMI patients to CTO PCI or no CTO intervention within 7 days of primary PCI at multiple centers in Canada and Europe. Patients had a high level of risk, with triple-vessel disease in 43%, multiple CTOs in 12% and a Syntax score of 29 and a J-CTO score of 2 in each group. In the intervention arm, mean time from primary PCI to CTO PCI was 5 days. The second procedure was deemed successful in 80% of cases (72% on core-lab adjudication).

On MRI assessment at 4 months, LV ejection fraction and LV end-diastolic volume (co-primary endpoints) did not differ between the CTO PCI and control groups (P = .59 and P = .70, respectively). In a subgroup analysis, there was an interaction with CTO location (P = .002 for interaction) such that patients with a CTO in the LAD appeared to have improved LVEF with the intervention. A similar trend was not seen for LV end-diastolic volume. The interaction P-value for CTO location was significant (P = .04)

In terms of clinical outcomes, there were four cardiac deaths in the CTO PCI group and none in the control group (P = .05). MACE rate did not significantly differ between arms (5.4% vs 2.6%; P = .21). The trial was not powered for clinical outcomes, Henriques noted.

He concluded that CTO PCI within 1 week of primary PCI is feasible and safe. Because of the “clear signal” of benefit seen in the subgroup analysis, Henriques said, “we therefore believe that additional PCI of a CTO located in the LAD may improve ejection fraction and potentially improve clinical outcome during follow-up.”

Questions about safety, viable myocardium

 In a related press conference, Marco Valgimigli, MD, PhD, of the University Hospital of Bern, Switzerland, referred to EXPLORE as “a very important study which is… downplaying evidence which was previously generated by observational and retrospective studies.” He questioned whether CTO PCI was actually safe, citing the increased number of cardiac deaths in the intervention group, which “is a matter of big concern to me.”

Valgimigli and others also raised questions about whether testing was done to determine if the artery blocked by the CTO supplied viable myocardium. Although Henriques could not provide exact data, he said fewer than 10% of trial participants had nonviable myocardium. Ischemia testing will be the subject of a future subanalysis, he added.

Sanjit S. Jolly, MD, MSc, of McMaster University, Hamilton, Canada, cautioned against reading too much into the suggested benefit of CTO PCI in patients with blocked LADs, saying that a larger trial would be needed to confirm the subgroup finding.

The fact that enrollment in the trial took more than 7 years to complete was an issue for Stuart Spencer, MD, executive editor of The Lancet. “Things have moved on quite a lot since 2007 in terms of our techniques and what happens to patients,” he said, “so I wonder how much that has influenced the results.”

Disclosures:

• Henriques reports receiving grant/research support from Abbott Vascular, Abiomed, B. Braun and Biotronik. 
• Jolly, Spencer and Valgimigli report no relevant conflicts of interest.