Background Rapid recanalisation of the culprit lesion is the main goal of primary angioplasty for acute ST-segment elevation myocardial infarction (STEMI), but strategy for treatment of culprit and non-culprit lesions in multi-vessel coronary artery disease remains unclear. Objectives Aims to examine the 6-month outcomes for non-culprit interventions performed at the time of the primary percutaneous coronary intervention (PCI) in multi-vessel coronary artery disease.

Methods A total of 1120 patients treated with primary angioplasty between 2008 and 2009 were classified in groups of patients with multi-vessel coronary artery disease (MVD). We examined the associated 6 month outcomes following non-culprit interventions performed at the time of primary PCI. Patients were subdivided in two groups on the basis of the revascularization strategy: 1) patients undergoing PCI of the culprit coronary artery only; 2) patients undergoing PCI of both the culprit coronary artery and non-culprit coronary artery during the initial procedure. All the patients were followed up for 6-month for major adverse cardiac events (MACE).

Results The two groups did not differ with respect to baseline clinical and angiographic characteristics. At 6-month, compared with PCI restricted to the culprit coronary artery only, multivessel PCI was associated with higher rates of re-infarction (7.9% vs 2.6%, p<0.001), revascularization (14.5% vs 6.8%, p<0.001), and MACEs (26.7% vs 14.8%, p<0.001).

Conclusions Non-culprit coronary interventions were significantly associated with increased mortality. Our data suggest that in patients with MVD, primary PCI should be directed at the culprit coronary artery only, with decisions about PCI of non-culprit lesions guided by objective evidence of residual ischaemia at late follow-up. Further studies are needed to confirm these findings.