During percutaneous coronary intervention, slow coronary flow and distal embolization are still important problems, especially in cases with intracoronary thrombus. The aim of this study was to learn the effectiveness and early term results of thrombectomy with the X-SIZER catheter system in acute coronary syndrome. Twenty-nine patients (22 [76%] men; 55.9 +/- 11.1 years) with acute coronary syndrome and intracoronary thrombus detected in coronary angiography were included into the study. X-sizer thrombectomy was applied to 14 of the patients, and conventional percutaneous transluminal coronary angioplasty (PTCA) was applied to the others. Baseline characteristics were similar in both groups. Mean thrombolysis in myocardial infarction (TIMI) flow increased from 0.8 +/- 0.9 to 2.4 +/- 0.6 in X-sizer-treated patients (p < 0.001) and TIMI 3 flow was maintained in 71.4% of the patients. Similary, mean TIMI flow increased from 0.36 +/- 0.81 to 2.73 +/- 0.47 in conventional PTCA-treated patients (p < 0.001) and TIMI 3 flow was maintained in 73% of the patients (NS). Mean myocardial blush grade (MBG) increased from 0.7 +/- 0.7 to 2.6 +/- 0.6 in X-sizer-treated patients (p < 0.001) and from 0.27 +/- 0.65 to 2.36 +/- 0.67 in the conventional PTCA-treated patients (p < 0.001). Postprocedural MBG 3 was obtained in 64.3% of X-Sizer-rreated patients and in 45% of controls. Although microvascular function in the thrombectomy-applied patients was found better, there was no significant difference between the two groups. Furthermore it was detected that the use of tirofiban yielded no additional improvement in epicardial and microvascular flow. In acute coronary syndromes, use of X-sizer in addition to primary percutaneous coronary interventions is a safe and relatively effective method in the prevention of distal embolization.