Residual atherothrombotic material after stenting in acute myocardial infarction - An optical coherence tomographic evaluation

Background: Thrombus aspiration (TA) in patients with ST segment elevation myocardial infarction (STEMI) results in a better myocardial perfusion. Optical coherence tomography (OCT) after stenting in STEMI, however, often reveals residual atherothrombotic material. We assessed the feasibility of quantification of residual atherothrombotic burden and its relation to indices of myocardial perfusion. The effect of TA on residual in-stent atherothrombotic burden (ATB) is explored. Methods and results: Forty patients with STEMI within 12 h of symptom onset, underwent OCT after stent implantation. No complication related to the invasive imaging was detected and all cases had good image quality. All 40 cases revealed ATB (median, range; 2.85, 0.08-8.84) despite an optimal angiographic result. Patients were divided into two groups according to the ATB: ≥ 4 = ATB_high (n = 15) and < 4 = ATB_low (n = 25). Patients with ATB_low more often obtained a myocardial blush grade (MBG) of 2/3: 24 (96%) vs. 11 (73%), p = 0.04 and a ≥ 50% ST segment resolution 24 (96%) vs. 8 (53%) p = 0.02. Incomplete stent apposition is more often detected with ATB_low: 1.97 (0.62-4.73) vs. 0.33 (0.04-0.92), p = 0.002. TA was performed in 20 (50%) patients. ATB was numerically lower in patients with TA: 2.37 (1.70-5.10) vs. 3.40 (1.45-4.96), p = 0.67. Logistic regression identified ATB as predictor of ST resolution failure (OR: 2.5 (95% confidence interval: 1.27-4.98), p value = 0.008). Conclusions: OCT can be safely performed in patients presenting for primary PCI and allows quantification of residual atherothrombotic material, the amount of which is associated with worse myocardial perfusion.