Micro stent, quantitative coronary angiography, and procedural results

The Micro stent (MS) is a radiopaque stainless steel balloon expandable intracoronary stent. The stent is mounted on a rapid-exchange delivery system. From August 1994-March 1995, 127 MS were implanted in 85 patients (pts, 1.5 stents/pt, 85 in native vessels and 42 in bypass vein grafts, 61 males and 24 female, age 33-77 yr, mean age 61 +/- 10 yr). Pts studied were scheduled for either elective PTCA (n = 62, 73%) or PTCA for acute myocardial infarction (n = 23, 27%). Elective stent implantation was performed in 45 pts (53%). An MS was implanted because of a suboptimal balloon angioplasty result in 26 pts (31%). The stent was implanted because of threatened or acute vessel closure after balloon angioplasty in 14 pts (16%). During the procedure, 500 mg aspirin and 2 x 7,500 units of heparin were administered intravenously, followed by systemic heparinization for 48 hr. Pts were discharged with 100 mg aspirin daily (n = 50, 59%), or anticoagulant drugs and 100 mg aspirin daily (n = 19, 22%), or anticoagulant drugs only (n = 16, 19%). Angiographic results were analyzed with computer-assisted quantitative coronary arteriography. Angiographic success (defined as a residual stenosis of < 30%) was achieved in 124 of 127 attempts (98%). The mean minimal luminal diameter of the target lesions increased from 0.88 +/- 0.79 mm before stent implantation to 3.08 +/- 0.56 mm (P < 0.001). The percentage of diameter stenosis was reduced from 77.9 +/- 20.9% before to 13.3 +/- 10.5% (P < 0.001) after stent implantation. The average initial gain was 2.53 +/- 1.37 mm. The procedural success rate (defined as a residual stenosis of < 30% without occurrence of major clinical events within 3 wk after procedure) was 84%. Major clinical events included: death 1 pt (1%); cerebrovascular accident, 1 pt (1%); subacute stent closure, 5 pts (6%); coronary artery bypass grafting, 3 pts (4%); false femoral aneurysm, 2 pts (2%). The initial results of Micro stent implantation are promising. No anticoagulant therapy was given to most of the patients (59%). Few vascular and bleeding complications were observed. However, at this stage, no data about the restenosis rate after implantation of a Micro stent are available.