OBJECTIVETo compare the efficacy and safety between the interventional and conservative treatment options for borderline vulnerable plaque lesion in acute coronary syndrome (ACS) patients by intravascular ultrasound (IVUS).

METHODSA total of 100 ACS patients [78 male, age 43 - 74 (60.4 ± 14.1) years] undergoing coronary angiography (CAG) with borderline lesion (coronary artery stenosis between 50% - 70%) were enrolled in May 2007 to February 2009, who were randomly divided into PCI group (50 patients) and conservative therapy group (50 patients). According to minimal lumen area (MLA) detected by IVUS, patients were further divided into MLA ≥ 4.0 mm(2) sub-group and MLA < 4.0 mm(2) sub-groups. Outcomes during hospitalization and after 10 - 12 month follow-up were compared.

RESULTSIVUS was performed in 40 patients at 10 - 12 months post PCI, there was no in-stent thrombosis and the extent of stent neointimal hyperplasia was comparable as at the time of immediately post PCI. IVUS was performed in 35 patients at 10 - 12 months post conservative therapy, IVUS results showed that MLA increased significantly [(7.32 ± 1.42) mm(2) vs. (4.98 ± 0.89) mm(2), P < 0.01], while plaque area [(7.70 ± 2.09) mm(2) vs. (10.01 ± 2.55) mm(2), P < 0.05], plaque burden [(55.94 ± 8.36)% vs. (67.97 ± 9.36)%] and low echo area [(4.08 ± 0.80) mm(2) vs. (2.27 ± 0.79) mm(2)] were significantly decreased at follow up compared to those as baseline (all P < 0.01). There was one patient in PCI group with MLA ≥ 4.0 mm(2) developed acute in-stent thrombosis in left anterior descending artery two days after the procedure and 9 patients in conservative therapy and MLA < 4.0 mm(2) group received PCI due to recurrent angina pectoris during follow-up.

CONCLUSIONSFor the borderline lesion with MLA ≥ 4.0 mm(2) detected by IVUS, adequate medication could effectively attenuate and or reverse the plaque progression and stabilize plaque.