Abstract 4719: Reducing Myocardial Injury in Late Presentation Acute ST-Elevation Myocardial Infarction With Proximal Embolic Protection
Background: ST-elevation myocardial infarction (STEMI) presenting 12–24 h after chest pain onset benefit less from primary angioplasty than earlier presenters. Organized thrombus may resist traditional pharmacological and mechanical therapies. We hypothesized that proximal embolic protection would decrease myocardial injury in late primary angioplasty.
Methods: 31 patients with first STEMI presenting 12–24h after onset and TIMI 0 –1 flow were treated with or without proximal embolic protection using the Proxis system (cohort design matched for age, gender, and infarct-related artery). Contrast-enhanced magnetic resonance imaging was performed within 24h (median 8.3h, p=0.8 between groups) to determine effects on function, inflammation, perfusion and necrosis.
Results: 81% of patients were male with mean age 60 y (95%CI 56 – 65 y). Mean pain to balloon time was 18 h (95%CI 15.5–21.2 h, p=0.7 between groups) and Q waves were present in 87%. 15 patients underwent late primary angioplasty with Proxis and 16 without. The target vessel was LAD in 39%, LCX in 29%, and RCA in 31% (p=0.9 between groups). Ancillary medications were identical. Left ventricular volumes and ejection fraction were similar (EF 46.9% vs. 49.0% without Proxis, p=0.9). Proximal embolic protection improved segmental wall thickening of infarct-related segments (IRS) (27.3 vs. 20.2%, p=0.03), inflammation by relative T2 imaging of IRS (26.8% vs. 32.8%, p=0.05), rest perfusion by time to 50% maximum upslope of the contrast kinetics curve of IRS (21.3 vs. 26.7msec, p=0.01), and the arrythmogenic peri-infarct penumbra zone (20.9 vs. 29.6%, p<0.0001). However, in this small cohort total necrosis was not different (32.5 vs. 37.3%, p=0.3). On multivariate analysis, the use of Proxis was an independent predictor of IRS wall thickening, myocardial perfusion, inflammation, and peri-infarct penumbra.
Conclusion: Proximal embolic protection significantly improves IRS segmental function, myocardial perfusion, inflammation, and arrythmogenic peri-infarct penumbra in STEMI patients treated late with angioplasty. Therefore, proximal embolic protection should be studied in clinical trials as a potentially effective means of reducing myocardial injury in late-presentation STEMI.