Evaluating Xience and left ventricular function in PCI on occLusiOns afteR STEMI - EXPLORE

Mar 09, 2017
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Author/Summarized by Author:
Dharam J. Kumbhani, MD, SM, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
Academic Medical Center, University of Amsterdam; Abbott Vascular
Date Presented:
10/31/2016
Date Published:
10/03/2016
Date Updated:
03/09/2017
Original Posted Date:
10/13/2015
References

Contribution To Literature:

The EXPLORE trial showed that routine CTO-PCI performed within 1 week of PPCI for STEMI does not result in improved LV function or clinical outcomes over 4 months of follow-up.

Description:

The goal of the trial was to assess the safety and efficacy of staged chronic total occlusion (CTO)-percutaneous coronary intervention (PCI) in improving left ventricular (LV) function in patients undergoing primary PCI (PPCI) for ST-segment elevation myocardial infarction (STEMI).

Study Design

Patients with STEMI treated with PPCI and with evidence of noninfarct artery CTO were randomized to CTO-PCI within 7 days (n = 150) or conservative management (n = 154).

  • Total number of enrollees: 304
  • Duration of follow-up: 4 months
  • Mean patient age: 60 years
  • Percentage female: 15%

Inclusion criteria:

  • Concurrent CTO in a non–infarct-related artery was found during successful PPCI for STEMI
  • CTO reference vessel diameter ≥2.5 mm

Exclusion criteria:

  • Hemodynamic  instability persisting for >48 hours after PPCI
  • Factors precluding reliable cardiac magnetic resonance (CMR) imaging such as persistent or permanent  atrial fibrillation,  severe  renal  insufficiency, and indications for pacemaker or implantable cardioverter-defibrillator insertion
  • Valvular disease  requiring  surgical  treatment

Other salient features:

  • Three-vessel disease: 43%
  • Multiple CTOs: 12%
  • Baseline LV ejection fraction (LVEF): 41%
  • CTO location: right coronary artery: 47%, left anterior descending (LAD): 25%
    J-CTO score: 2
  • Number of days between PPCI and CTO-PCI: 5
  • Successful PCI: 72%

Principal Findings:

The co-primary endpoints, final LVEF at 4 months for CTO-PCI vs. conservative management, were 44.1% vs. 44.8%, p = 0.6; LV end-diastolic volume (LVEDV) at 4 months: 215.6 vs. 212.8 ml, p = 0.70.

On subgroup analysis, there was a significant improvement in LVEF (p = 0.002) and LVEDV (p = 0.039) in the LAD CTO subset.

Secondary outcomes:

  • Periprocedural complications in CTO arm: dissections: 13, tamponade 1, emergency coronary artery bypass grafting/stroke/death: 0
  • Major adverse cardiac events at 4 months: 5.4% vs. 2.6%, p = 0.21
  • Cardiovascular death: 2.7% vs. 0%, p = 0.06
  • MI: 3.4% vs. 1.9%, p = 0.49

In the CMR substudy (n = 161), the change in LVEF for CTO-PCI vs. conservative management was 4.6% vs. 3.8%, p = 0.52; change in LVEDV: 5.5% vs. 3.0%, p = 0.57; change in % segmental wall thickening in CTO territory in all segments: 15% vs. 14%, p = 0.09.

Interpretation:

The results of this trial indicate that routine CTO-PCI performed within 1 week of PPCI for STEMI does not result in improved LV function or clinical outcomes over an intermediate period of follow-up. The findings of a possible benefit in patients with LAD CTOs are hypothesis generating and merit further research.

CTOs are commonly observed in patients presenting with STEMI and are associated with adverse clinical outcomes. There are scant randomized data comparing CTO-PCI to medical management overall, but particularly in this patient subset. There are a few caveats to consider: Procedural success in this trial was low (~72%), so it is unknown if a higher success rate would have resulted in better outcomes. There was also no assessment of ischemia or viability in the noninfarct CTOs, which may have helped enrich the population.

References:

Henriques JP, Hoebers LP, Råmunddal T, et al. Percutaneous Intervention for Concurrent Chronic Total Occlusions in Patients With STEMI: The EXPLORE Trial. J Am Coll Cardiol 2016;68:1622-32.

Presented by Dr. Jose P.S. Henriques at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2016), Washington, DC, October 31, 2016.

Presented by Dr. Jose P.S. Henriques at the Transcatheter Cardiovascular Therapeutics meeting (TCT 2015), San Francisco, CA, October 13, 2015.

Keywords: Angioplasty, Balloon, Coronary, Coronary Artery Bypass, Magnetic Resonance Imaging, Myocardial Infarction, Percutaneous Coronary Intervention, Stroke, Transcatheter Cardiovascular Therapeutics, Vascular Diseases, Ventricular Function, Left


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