Background In the Preventive Angioplasty in Myocardial Infarction trial (PRAMI; ISRCTN73028481), immediate multivessel PCI (MV-PCI) of non-IRA lesions in patients with acute ST elevation myocardial infarction (STEMI) and multivessel coronary disease (MVD) improved long term prognosis. We assessed infarct distribution and size in a pre-specified cardiac magnetic resonance (CMR) sub-study.

Methods In this single centre prospective sub-study, PRAMI participants were invited to undergo 1.5 Tesla CMR 1 week and 1 year after primary PCI. The CMR scans were analysed using semi-automated software by a clinician blinded to treatment group assignment and clinical outcomes. The presence and extent of infarction were assessed quantitatively with late gadolinium enhancement (LGE) imaging (Gadovist, 0.1 mmol/kg). The infarct was delineated as an area of myocardial enhancement (cm²) using a signal intensity threshold of >5SDs above a remote region, and expressed as a% of total LV mass. The incidence of new LGE in non-infarct related artery territories at baseline and 1 year were assessed. Data were analysed by an independent statistician.

Results Of 465 randomised trial participants in 6 UK hospitals, 138 (30%) were enrolled in Glasgow. Of these 80 patients underwent CMR 1 week post primary PCI of whom 41 (51%) were in the multi-vessel PCI group and 39 (49%) were in the IRA-only group. At 1 year, 69 (86%) patients had a follow up CMR scan. Infarct size and distribution are described in Table 1.

Conclusion Infarct size and distribution were similar in patients treated by MV-PCI or IRA-only PCI. MV-PCI is not associated with additional MI acutely which supports the safety of this procedure in line with the benefits observed with preventive PCI in PRAMI.

Funding Golden Jubilee National Hospital; PRAMI was funded by Barts and the London Charity.