Using IMR to measure the effects of alteplase on heart attack outcomes

The T-TIME trial coronary physiology study (Dr Annette Maznyczka)

Professor Colin Berry’s team is investigating whether a measurement taken during percutaneous coronary intervention (PCI) - a procedure where doctors open up a blocked coronary artery with a stent - can detect which patients have had blood flow successfully restored to their heart muscle after a heart attack. PCI markedly improves survival after a heart attack. But even with PCI, many survivors still have decreased blood supply to the affected area, particularly in the small blood vessels supplying the heart. This can cause heart failure. An ECG can pick up severe cases where PCI hasn’t worked well, but not more subtle cases. In this project, they will test the accuracy of a measurement called the index of microvascular resistance, or IMR. This is more sensitive than ECG at measuring small blood vessel function in the heart muscle. Professor Berry is running a clinical trial called T-TIME, looking at whether administering a clot buster drug directly into the coronary arteries before a stent is implanted can restore blood vessel function in heart attack patients. In this project the team will carry out the IMR test on some of the participants in this trial to find out whether IMR can accurately measure the effects of the drug, and whether it relieves the mini-blockages in the small blood vessels in the heart. Developing a more sensitive test to measure the success of PCI will help improve the treatment of people having a heart attack.