304 patients enrolled!

Study Information

Explore Hypothesis

There are two main mechanisms involved in the hypothesis of the Explore trial. First, recanalization of the CTO will possibly restore the contractile function of the hibernating myocardium. Furthermore, recanalization of the CTO might improve the healing of the infarct border zone. This assumption is based on the coronary anatomy where the perfusion area of the infarct related coronary artery and the CTO are adjacent or overlapping. In recently perfused myocardium, the revascularization of a CTO will improve the myocardial perfusion in this overlapping region and therefore might improve the healing of this border zone and might protect against negative remodelling and preserving residual left ventricular function. The EXPLORE trial will determine whether recanalization of a CTO within one week after primary PCI for STEMI results in a better preserved residual left ventricular ejection fraction and reduced end-diastolic volume, measured by cardiac MRI.

Figure 1. EXPLORE flow chart.

Study information flowchart arial

Inclusion Criteria

  • STEMI:typical chest pain, ST-elevation according to the guidelines 
  • Successful PPCI
  • CTO:
    • Located in a non infarct related artery.
      • 100% luminal narrowing or without anterograde flow or antegrade or retrograde filling through collaterals.
        • amenable to PCI treatment
          • reference diameter of ≥ 2.5 mm

Exclusion Criteria

  • Age ≥ 80 years
  • Atrial fibrillation
  • Renal insufficiency (creatinin ≥ 265 µmol/L or ≥ 3.5 mg/L)
  • More than 48 hrs of pre-shock or shock after primary PCI
  • Cardiac events between primary PCI and randomization
  • Significant left main stenosis
  • Indication for CABG
  • Severe valvular heart disease
  • Indication for ICD
  • Contra-indications for MRI
  • Baseline MRI not suitable for endpoint assessment
  • Serious known concomitant disease
  • Circumstances that prevent follow-up
  • Previous participation in this trial
  • Current participation in another trial

Primary Endpoints

Measured by cardiovascular magnetic resonance imaging at 4 months:

  • Left ventricular ejection fraction
  • Left ventricular end-diastolic volume

Secondary Endpoints

Safety Endpoints

  • Major Adverse Cardiac Events, defined as cardiac death, myocardial infarction or CABG at 30 days, 4 months, and 1, 2, 3, 4, and 5 years.
  • Stent thrombosis, classified as definite, probable or possible

Other Secondary Endpoints

Measured by cardiac magnetic resonance imaging at 4 months:

  • Left ventricular end systolic volume
  • Left ventricular segmental wall thickening
  • Left ventricular massÍnfarct size 
  • Infarct size
  • N-terminal-proBrain Natriuretic Peptide (at 4 months and 1 year, relative to baseline)
  • Heart rate adjusted QT duration measured by resting electrocardiogrpahy (at 4 months and 1 year, relative to baseline)
  • Quantitative Coronary Angiography of the treated chronic total occlusions: in-stent and in-segment late luminal loss at 12 months 
  • In-stent and in-segment minimal luminal diameter
  • In-stent and in-segment binary restenosis rate
  • Repeat hospitalization for cardiac causes at 30 days, 4 months, and 1, 2, 3, 4, and 5 years
  • Presence of clinically overt heart failure at 30 days, 4 months, and 1, 2, 3, 4, and 5 years
  • Implantation of implantable cardioverter-defibrillator devices
  • Functional Class: NYHA classification at 30 days, 4 months, and 1, 2, 3, 4, and 5 years