Left Ventricular Unloading in Anterior ST-Segment Elevation Myocardial Infarction Without Shock: The ST-Segment Elevation Myocardial Infarction Door to Unload Randomized Controlled Trial.

Summary

In this multicenter randomized trial of 527 patients with anterior STEMI without shock, pre-reperfusion LV unloading using a transvalvular microaxial pump with a 30-minute delay before PCI did not reduce infarct size by CMR compared with immediate PCI. The unloading strategy lengthened total ischemic time and was associated with higher major bleeding and vascular complications.

Key Findings

• CMR-measured infarct size normalized to LV mass was similar with unloading+delay vs immediate PCI (30.8% vs 31.9%; P=0.50).
• Total ischemic time was longer in the unloading arm.
• Major bleeding or vascular complications at 30 days were more frequent in the unloading group.

Clinical Implications

For anterior STEMI without cardiogenic shock, immediate PCI should remain the standard; delaying reperfusion to permit LV unloading is not beneficial and may increase bleeding/vascular harm.

Limitations

• Open-label design could introduce procedural performance biases
• Increased ischemic time inherent to the unloading strategy may confound mechanistic interpretation

Future Directions

Identify subgroups (e.g., high thrombus burden, microvascular obstruction risk) where unloading without intentional reperfusion delay or alternative MCS strategies might confer benefit; focus on harm mitigation and rapid reperfusion.