Correlations between epicardial flow, microvascular reperfusion, infarct size and clinical outcomes in patients with anterior versus non-anterior myocardial infarction treated with primary or rescue angioplasty: Analysis from the EMERALD trial

Aims: We compared epicardial and microvascular reperfusion, infarct size, and clinical outcomes after primary and rescue PCI with and without GuardWire distal protection in patients with LAD vs. non-LAD acute myocardial infarction (AMI). In the general AMI population undergoing primary PCI, the use of GuardWire did not yield higher reperfusion success, reduced infarct size, or enhanced event-free survival. Whether GuardWire is beneficial in patients with AMI in certain territories of the coronary circulation is unknown. Methods and results: In the EMERALD trial, 501 patients with AMI were randomised to PCI with vs. without distal protection. The outcomes were analysed as a function of culprit vessel (LAD vs. non-LAD) and the use of GuardWire. Patients with LAD vs. non-LAD infarcts had significantly (P≤0.0001) lower rates of final TIMI flow grade 3 (85.2% vs. 94.4%), myocardial blush grade 3 (40.1% vs. 67.6%), and complete ST-segment resolution (35.1% vs. 79.6%). Patients with LAD infarcts also had larger infarct size (25.8±21.8% vs. 11.3-13.7%, p<0.0001) and a trend towards higher rates of 6-month mortality (5.5% vs. 2.1%, p=0.09) and new-onset severe heart failure (3.5% vs. 1.1%, p=0.08). Rates of reperfusion were not related to GuardWire use in patients with LAD infarcts. In patients with non-LAD infarcts, the use of GuardWire was associated with a trend towards better epicardial and microvascular reperfusion. Conclusions: Myocardial infarction in the territory of the LAD is associated with worse epicardial and microvascular reperfusion and worse 6-month clinical outcomes. Use of the GuardWire showed a trend towards better epicardial and microvascular flow in patients with a non-LAD infarct-related artery.