Oxford Acute Myocardial Infarction - Pressure-controlled Intermittent Coronary Sinus Occlusion

The OxAMI-PICSO is a study about the use of pressure controlled intermittent coronary sinus occlusion (PICSO) to improve the treatment of patients presenting with heart attack. PICSO is a device consisting of a balloon which is deployed in the coronary sinus. When inflated the balloon can improve the blood flow to the region of heart affected by the heart attack. The study aims to analyse the potential benefit of PICSO in improving blood flow to heart muscle in a selected group of patients admitted with a large heart attack involving the anterior wall of the heart. The comparator group will be a well-matched group of participants of the ongoing OxAMI study. In order to select patients with a large heart attack, we will measure the index of microcirculatory resistance (IMR), before completion of the heart attack treatment procedure. The IMR value provides measurement of the blood flow at the level of the tiny vessels branching from the large coronary arteries. Our preliminary data from the OxAMI study have shown that an IMR \> 40 suggests that the patient is having a large myocardial infarction (heart attack). Only patients with starting IMR \> 40 will be considered eligible for the PICSO treatment. The benefit of PICSO will be assessed by measuring 1) indexes of coronary blood flow, 2) the extension of the infarcted area and 3) the levels of different molecules released in the blood.