The effect of thrombectomy on myocardial blush in primary angioplasty: the Randomized Evaluation of Thrombus Aspiration by two thrombectomy devices in acute Myocardial Infarction (RETAMI) trial.

BACKGROUND: In patients with ST-segment elevation myocardial infarction (STEMI), primary percutaneous coronary intervention (PCI) may cause thrombus dislodgment leading to microvascular function impairment, which is a negative independent predictor of myocardial function recovery. Compared with conventional stenting, pretreatment with aspiration thrombectomy during primary PCI significantly improves coronary epicardial flow and myocardial tissue perfusion parameters. We sought to evaluate the angiographic findings of two different manual aspiration thrombectomy devices (Diver-Invatec (DI) and Export-Medtronic (EM)) in STEMI patients undergoing primary angioplasty.

METHODS: We randomized 103 STEMI patients referred to our hospital to undergo primary PCI (<12 hr from symptoms onset) to DI (n = 52) and EM (n = 51) devices. The primary angiographic composite end-points were the rates of post-thrombectomy thrombus score (TS) < or =2, TIMI flow grade > or =2, and post-stenting myocardial blush grade (MBG) > or =2 in the two groups.

RESULTS: Baseline, clinical, and angiographic preprocedural findings did not differ between the two groups. After aspiration thrombectomy, a TS < or = 2 was more frequently present in EM group (92.3 vs. 69.3%, P = 0.0052). Also the rate of post-thrombectomy TIMI > or = 2 (69.3 vs. 92.2%, P = 0.0052) and post-stenting MBG > or =2 (88.2 vs. 69.3%, P = 0.029) were significantly higher in EM group. No significative differences were observed in terms of clinical events at 1 and 12 months.

CONCLUSIONS: In this single-center, prospective, randomized study, a EM use before stenting in STEMI patients seems to remove more thrombotic burden compared with DI, providing a greater post-thrombectomy epicardial flow and a better post-stenting microvascular perfusion.