Chronic Remote Ischemic Conditioning to Modify Post-MI Remodeling (CRIC-RCT)

Chronic Remote Ischemic Conditioning Following Primary Percutaneous Intervention for ST-Elevated Myocardial Infarction

During a heart attack, an artery carrying blood and oxygen to the heart becomes blocked, which causes damage to the heart muscle. When possible, a clot-busting drug is given or a procedure called angioplasty is performed soon after a heart attack starts, to open up the blocked artery and restore blood flow to the heart. While this can be an effective treatment to reduce permanent damage to the heart, patients can still experience heart failure afterwards. Consequently many patients require medications to support their heart after a heart attack. Recent research has shown a new technique called Remote Ischemic conditioning or RIC, is effective at protecting the heart muscle in a heart attack. RIC is produced simply by repeated inflation and deflation of a blood pressure cuff on an arm or leg to temporarily cut off and then restore blood flow to that limb. The investigators believe this triggers the release of molecular factors that protect heart muscle. In a recent study in humans, it reduced the amount of permanent damage to the heart muscle when applied before the angioplasty procedure. The investigators recent animal studies have shown that RIC may also help the heart muscle recover after a heart attack if applied everyday during the month after a heart attack, by preventing heart failure. This is important for two reasons: first, currently the investigators can only treat heart failure with medications, and second, some people have heart attacks but are not suitable to have angioplasty and so are at greater risk of heart failure. Daily RIC may provide an easy and effective new treatment to prevent heart failure after a heart attack. This application proposes a preliminary study in humans to see if daily RIC can help heart muscle recovery after a heart attack.

Remote ischemic conditioning will be induced using an AutoRIC device (occluding arm bloodflow exactly like manual bloodpressure cuff). With the participant in a supine or seated upright position, the AutoRIC device will be placed on the right arm and will inflate to a pressure of 200mmHg for 5 minutes (ischemia). The device will then auto-deflate (reperfusion), completing one cycle of ischemia-reperfusion. A total of 4 inflation and deflation cycles will occur. This will be initiated at first medical contact just prior to the performance of primary PCI in eligible subjects (RIPerC), and then repeated daily for 28 days following MI.

Sham conditioning will involve the AutoRIC device being placed on the right arm and will inflate to a pressure of 10mmHg for 5 minutes (ie. no limb ischemia will occur). The device will then auto-deflate, completing one cycle. A total of 4 inflation and deflation cycles will occur. This will be initiated at first medical contact just prior to the performance of primary PCI in eligible subjects (RIPerC), and then repeated daily for 28 days following MI.

The primary outcome of this study will be the change from baseline in left ventricular end diastolic volume (LVEDV) at 28 days post-PCI by cardiac MRI.

change from baseline in left ventricular end systolic volume (LVESV), ejection fraction (LVEF) and mass at 28 days post-PCI by cardiac MRI

Inclusion Criteria: (i) Admitted for primary PCI for STEMI involving the LAD within 12 hours of onset of symptoms. STEMI will be defined as typical ECG changes (ST segment elevation ≥2mm in 2 or more precordial leads) associated with acute chest pain or an elevation of cardiac enzymes; (ii) Antegrade TIMI 0 or 1 prior to PCI; (iii) Age ≥18 years; (iv) Informed consent from patient or next of kin. Exclusion Criteria: (i) Known history of diabetes; (ii) Coronary anatomy warranting emergent coronary artery bypass graft surgery; (iii) Mechanical complication of STEMI (ventricular septal rupture, free wall rupture, acute severe mitral regurgitation); (iv) Need for hemodialysis; (v) Malignancy, HIV, or central nervous system disorder; (vi) Cardiopulmonary resuscitation >15 min and compromised level of consciousness; (vii) Cardiogenic shock; (viii) Current participation in any research study involving investigational drugs or devices; (ix) Inability to safely undergo cMRI