The study is designed as a multicentre open label prospective feasibility trial to capture preliminary efficacy and safety information on Solitaire device to plan an appropriate pivotal study.

We hypothesize that Solitaire device could be effectively and safely used as an adjunctive interventional technique in ACS patients found to have refractory thrombus during PCI.

1. Primary Objectives To evaluate intra-procedure efficacy of using Solitaire in ACS patients with refractory thrombus.
2. Secondary Objectives To evaluate clinical efficacy of using Solitaire in ACS patients with refractory thrombus, up to one year post-procedure.

To evaluate safety of using Solitaire in ACS patients with refractory thrombus.

The target enrolment is 51 patients diagnosed with STEMI, NSTEMI or UA and found to have refractory thrombus during PCI. Eligible patients will be identified at the ED or Inpatient ward of the 5 participating hospitals. The projected enrolment period is for two years and follow up for one year. A screening log will be maintained at each site to keep record of patients who were eligible for the study but not enrolled, to establish any selection bias.

Inclusion Criteria:

Subjects meeting all of the inclusion criteria listed below will be included in this study:

1. Index event of ST segment elevation or non-ST segment elevation MI or Unstable Angina defined as:

   1. Presentation to hospital with symptoms of myocardial ischemia (Chest pain or angina equivalent) lasting for ≥10 minutes at rest

      AND 1 of the following:

   2. Persistent ST segment elevation ≥1mm (0.1 mV) in two or more contiguous limb leads or ≥2mm (0.2 mV) in ) in one or more contiguous precordial leads OR

   3. New or presumed new left bundle branch block (LBBB) OR

   4. ST segment depression ≥1mm (0.1 mV) in two or more contiguous leads (not known to be pre-existing or due to a known cause such as LV hypertrophy or digoxin) OR

   5. Troponin T or I greater than the laboratory upper normal limit.

2. Referred for urgent or emergency PCI AND Thrombus burden of TG 4 or above OR TIMI flow grade of 1 or less in at least one native infarct related artery following either

   1. Manual aspiration thrombectomy OR
   2. Balloon Angioplasty OR
   3. AngioJet RT OR
   4. Patient having deferred PCI due to heavy thrombus but continue to demonstrate recalcitrant thrombus upon repeat angiography.

Exclusion Criteria:

Subjects meeting any of the exclusion criteria listed below will be excluded from this study:

1. Age ≤ 21 years

2. Cardiogenic shock

3. killip class 3 or above at presentation

4. Known relative contraindications for the use of Solitaire:

   1. Prior stent in infarct related artery
   2. Significant proximal stenosis OR Ostial lesion at angiography
   3. Extensive calcification

5. Life expectancy less than six months due to non-cardiac condition

6. Participants categorised as vulnerable subjects (ex: prisoners, pregnant women, and mentally disabled persons)

7. Patients at high risk of being lost to follow up (ex: non-residents)

8. Participation in any study with an investigational drug or device within the last 30 days

9. Patients who are unable to provide informed consent prior to any procedure .

Investigator initiated multicentre open label prospective feasibility trial.