Biosensors, the Sponsor would like to determine if the Biosensors Microcatheter is safe and effective in treating patients with CTO by assessing a composite of in-hospital cardiac death or myocardial infarction and device success (defined as successfully facilitate placement of a guidewire beyond the occluded coronary segment), respectively.

Prospective, multi-center, open-label single-arm trial designed to enroll 100 patients undergoing attempted CTO-PCI at up to 10 centers in the United Kingdom and N. Ireland. For assessment of efficacy, the ability of the BM to successfully facilitate placement of a guidewire beyond the occluded coronary segment will be assessed. Patients will be followed up until hospital discharge or 7 days post index procedure, whichever comes first. For the assessment of safety, the incidence of in-hospital cardiac death or myocardial infarction will be assessed at hospital discharge or 7 days post index procedure, whichever comes first.

Inclusion Criteria:

1. Adult aged > 18 years
2. Patient understands and has signed the consent form.
3. Patient has an angiographically documented chronic total occlusion (i.e. estimated to be >3 months duration) showing distal TIMI 0 flow. Occlusion with absence of antegrade flow through the lesion and with a presumed or documented duration of 3 months.
4. Suitable candidate for non-emergent PCI
5. Left ventricle ejection fraction > 25%

Exclusion Criteria:

1. Patient unable to give informed consent.
2. Current participation in another study with any investigational drug or device.
3. Known or suspected contrast allergy.
4. in-stent CTO.
5. Planned treatment of a second CTO during the index procedure
6. Intolerance to Aspirin and/or inability to tolerate a second antiplatelet agent (Clopidogrel or Prasugrel or Ticagrelor).
7. Recent major cerebrovascular event (history of stroke or TIA within 1 month)
8. Renal insufficiency (serum creatinine of > 200μmol/L)
9. Active gastrointestinal bleeding
10. Active infection or fever that may be due to infection
11. Life expectancy < 2 years due to other illnesses
12. Significant anaemia (haemoglobin < 10.0g/L)
13. Severe uncontrolled systemic hypertension (> 240 mmHg within 1 month of procedure)
14. Severe electrolyte imbalance
15. Congestive heart failure [New York Heart Association (NYHA) Class III\IV] CSA Class IV.
16. Unstable angina requiring emergent PCI or coronary artery bypass graft (CABG)
17. Recent myocardial infarction (MI) (within the past one week)
18. Unwillingness or inability to comply with any protocol requirements
19. Subject is pregnant or nursing. Female subjects of child-bearing potential must have a negative pregnancy test done within 7 days prior to the index procedure per site standard test.
20. Extensive prior dissection from a coronary guidewire use
21. Drug abuse or alcoholism.
22. Patients under custodial care.
23. Bleeding diathesis or coagulation disorder
24. Kawasaki's disease or other vasculitis

The emphasis in all scientific publications and presentations will be placed on the endpoint at discharge.