Myocardial Ischemia and Transfusion (MINT)

Myocardial Ischemia and Transfusion: A Pilot, Multi-centre, Open-label Randomized Controlled Trial of Two Commonly Used Transfusion Strategies in Patients With Myocardial Infarction.

MINT: A pilot, multi-centre, open-label randomized controlled trial of two commonly used transfusion strategies in patients with myocardial infarction.

Heart attacks are conditions where blood flow to the heart muscle is dangerously low - eventually causing heart muscle to die. Drugs improving the blood flow, and procedures such angioplasty, are the mainstay of therapies. They will only work if there is enough oxygen transported in blood. In fact, the heart may be deprived of oxygen not only because of the heart attack itself but also because of low blood counts (or anemia). Anemia, or low blood counts, may be caused by bleeding or by conditions such as cancer, kidney failure, chronic infections or conditions such as severe arthritis. A transfusion increases the delivery of oxygen to the heart muscle. However, we do not know at what level of anemia to initiate blood transfusion to prevent permanent heart damage. Indeed, having low blood counts may be harmful but blood transfusions also carries important risks including extra fluid in the lungs and heart inability to pump effectively. In previous studies, investigators demonstrated that giving less blood is safer in most patients. But, there is little evidence in patients with heart attack. This first pilot trial aims to make sure that a large study that will answer the question is doable. The large trial aims to determine when and how much blood to give to minimize damage. In both studies, patients who have a heart attack will be divided into two groups in the hopes of preventing patients from dying. One group will receive more blood and the other group less blood. In the pilot trial, it will be evaluated if we can recruit patients with heart attack in a timely fashion. This trial will span over 12 months. If patient recruitment goes well, investigators will move ahead with the second phase of the project involving over 3500 patients. The numbers of patients who die or have another heart attack as well as if doctors follow treatment plans will be recorded. The 5-year large scale project will provide a definitive answer to the amount and optimal timing of blood transfusion.

We will permit but not require red cell transfusions once a hemoglobin value falls below 80 g/L (required below 70 g/L) during the 30 days following randomization

Non-adherence will be defined as transfusing a patient allocated to the restrictive group if the hemoglobin level is greater than 80 g/L; in the liberal group, not transfusing a patient who has a hemoglobin less than 100 g/L for at least 48 hours with at least 2 consecutive values.

The 3rd Universal Definition of MI will be used. Recurrent MI within 30 days of the incident MI will require: a) an increase in troponin concentration of 20% or greater from the last measured value and b) clinical symptoms or signs including i) recurrence of ST elevation ≥0.1 mV, or new pathognomonic Q waves in at least two contiguous leads; or ii) ischemic symptoms for 20 minutes or longer. Acute myocardial infarction will be adjudicated by an independent blinded committee to minimize ascertainment bias.

Inclusion Criteria: Hospitalized patients with hemoglobin level less than 100 g/L who present with an ST-segment Elevation Myocardial Infarction (STEMI), or Non-ST-Elevation Myocardial Infarction (NSTEMI); Rise in cardiac biomarker values with at least one value above the 99th percentile (preferably cardiac troponin cTn ) Presence of one of the following: symptoms of ischemia; new/presumed new ST segment-T wave (ST-T) changes or new left bundle branch (LBBB); development of pathological Q waves; imaging evidence of new loss of viable myocardium or new regional wall motion abnormality; identification of an intracoronary thrombus by angiography Exclusion Criteria: Patients with uncontrolled acute bleeding at the time of randomization defined as the need for uncrossed or non-type specific blood; Patients who decline blood transfusion; Patients who have a planned cardiac surgery or immediate post-cardiac surgery;Patients who have been deemed palliative by their treatment team (no commitment to aggressive on-going care); If known that follow-up will not be possible at 30 days; Previous participation in the MINT Trial.

Carson JL, Stanworth SJ, Dennis JA, Trivella M, Roubinian N, Fergusson DA, Triulzi D, Doree C, Hebert PC. Transfusion thresholds for guiding red blood cell transfusion. Cochrane Database Syst Rev. 2021 Dec 21;12(12):CD002042. doi: 10.1002/14651858.CD002042.pub5.