Objective: This study aimed to compare infarct size and clinical outcomes in patients with proximal versus mid left anterior descending (mLAD) infarction.
Background: The extent of myocardium at risk is an important prognostic determinate in patients with ST-segment elevation myocardial infarction.
Methods: The INFUSE-AMI trial randomized patients with anterior ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention with bivalirudin anticoagulation to intracoronary (IC) bolus abciximab versus no abciximab and to thrombus aspiration versus no aspiration. The primary end point was magnetic resonance imaging infarct size (% of left ventricular mass) at 30 days. Lesion location was independently assessed and was defined as proximal (pLAD) if present before or at first significant septal perforator branch, or mLAD if beyond.
Results: Among 452 patients, 292 (64.7%) had pLAD and 159 (35.3%) had mLAD occlusions. Patients with pLAD infarcts were significantly more likely to have Killip class >1 heart failure and ejection fraction <40% and to present earlier to the hospital. Proximal LAD infarcts had significantly lower rates of final Thrombolysis In Myocardial Infarction flow 3 and procedural success but similar rates of myocardial blush grade 2/3 and ST-segment resolution compared with mLAD infarcts. Infarct size at 30 days was significantly greater in the pLAD group (19.3% [9.2-25.9] vs 14.3% [6.2-18.9], P < .0001). Mortality at 30 days was also higher in the pLAD group (4.2% vs 0.6%, P = .04). The effect of IC abciximab on reducing infarct size was comparable in both groups.
Conclusion: ST-segment elevation myocardial infarction caused by pLAD compared with mLAD occlusion results in larger infarcts and greater mortality even with contemporary reperfusion therapy.
Trial registration: ClinicalTrials.gov NCT00976521.
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