Abstract 13857: Reduction of Infarct Size in Anterior ST Segment Elevation Myocardial Infarction (STEMI) With LAD Occlusion and LV Unloading Using a Micro-Axial Pump for 30 Minutes Before PCI: A Per Protocol Analysis of the STEMI DTU Pilot Study

BACKGROUND: The STEMI-DTU pilot trial was the first exploratory study to identify that LV unloading and delaying reperfusion is safe and feasible in anterior STEMI without cardiogenic shock. We now report new findings in patients who met all protocol inclusion and exclusion criteria (per protocol cohort). Methods: In a multicenter, prospective, randomized safety and feasibility trial, we assigned 50 patients with anterior STEMI to LV unloading by using the Impella CP followed by immediate reperfusion (U-IR) versus delayed reperfusion after 30 minutes of unloading (U-DR). Cardiac magnetic resonance (CMR) imaging assessed infarct size normalized to the area at risk (IS/AAR) 3-5 days after PCI. Patients without CMR at 3-5 days (n=10; 5/arm), without PCI of a culprit LAD lesion (n=2; 1/arm) and without STEMI (n=5; 4 in U-IR, 1 in U-DR) were not per protocol and thus excluded from this analysis. Results: A total of 33 patients met all inclusion and exclusion criteria (U-IR n=15; U-DR n=18) with respective door-to-balloon times of 75±26 and 89±23 minutes (p=.10) and mean unload-to-balloon times of 10±5 and 34±3 (p<0.01). In the total cohort, IS/AAR was significantly associated with microvascular obstruction (MVO), 30-day IS normalized to total LV mass, 90 day LVEF, and 90dday LV end systolic volume with or without a delay to reperfusion (Table, R>0.5, p<0.005 for all). Despite longer symptom to balloon times in the U-DR arm (174±59 vs 228±78, p<0.01), IS/AAR was lower in the U-DR arm (62±16 vs 48±16, p=0.04) and remained significantly lower irrespective of the magnitude of precordial STE. MVO was significantly lower in the U-DR arm among patients with the highest precordial STE (Figure). Conclusion: A per protocol analysis of the STEMI-DTU Pilot trial identified a significant reduction in infarct size among patients with unloading and delayed reperfusion irrespective of precordial STE magnitude. These findings are currently under investigation in the STEMI-DTU Pivotal trial.