Sonothrombolysis in Patients With STEMI

This study evaluates what effect sonothrombolysis may have on spontaneous reperfusion, microvascular obstruction, left ventricular function and infarct size in patients presenting with their first ST-segment Elevation Myocardial Infarction.

This is a prospective, single center, single-arm study that examines pre-procedural sonothrombolysis as an adjuvant to contemporary therapy in patients with ST-segment elevation myocardial infarction receiving PPCI.This study is to examine what effect adding emergent diagnostic ultrasound (DUS) guided high mechanical index (HMI) impulses (sonothrombolysis), applied both before and after primary percutaneous coronary intervention (PPCI) during an intravenous commercially available microbubble infusion (Definity), have on spontaneous reperfusion (i.e. pre PCI coronary artery patency rates), microvascular obstruction, left ventricular function and infarct size in patients presenting with their first ST-segment Elevation Myocardial Infarction.

Patients will immediately receive an intravenous infusion of commercially available ultrasound contrast agent (Definity). After starting the infusion, myocardial contrast echocardiography will be performed. 4-, 2- and 3-chamber views will be recorded to document the size of the perfusion defect. Loops of 15 cardiac cycles will be recorded using low mechanical index (MI) ultrasound with a 'flash' delivered after the second cardiac cycle of the loop. The flash is a short impulse of HMI ultrasound which is transmitted to destroy the ultrasound contrast in the myocardium and then to assess the replenishment of myocardial contrast. These recordings will also be used to assess regional wall motion as well as the LV volumes and ejection fraction. Immediately after the diagnostic ultrasound, the therapeutic ultrasound will start using the same transducer by applying multiple HMI ultrasound impulses. The HMI are the same as those which are used for assessment of myocardial perfusion in diagnostic ultrasound. These pulses will be applied in the apical 4-, 2-, and 3-chamber views to the apical windows that contained the risk area. The intervals between HMI impulses will vary from 5 to 15 s depending on the time required for myocardial contrast replenishment. Diagnostic echocardiography will also be scheduled prior to discharge (Day2) and 90 days post procedure.

If this study is successful, a larger study will be designed in order to collect the evidence for using contrast ultrasound for treatment of myocardial infarction in clinical practice.

Eligibility Criteria:
Inclusion Criteria:

Patients presenting with STEMI within 6 hours of symptom onset and:

1. Are expected to receive reperfusion therapy with primary PCI
2. Have a high-risk STEMI ECG defined as:

   * ≥2mm ST-segment elevation in 2 anterior or lateral leads; or
   * ≥2 mm ST-segment elevation in 2 inferior leads coupled with ST segment depression in 2 contiguous anterior leads for a total ST-segment deviation of ≥4mm
3. Age ≥30 years.
4. Adequate apical and/or parasternal images by echocardiography

Exclusion Criteria:

1. Isolated inferior STEMI without anterior ST-segment depression
2. Previous coronary bypass surgery
3. Cardiogenic shock
4. Known or suspected hypersensitivity to ultrasound contrast agent used for the study
5. Life expectancy of less than two months or terminally ill.
6. Known bleeding diathesis or contraindication to glycoprotein 2b/3a inhibitors, anticoagulants, or aspirin
7. Known large right to left intracardiac shunts.