Stent fracture, an incidental finding or a significant marker of clinical in-stent restenosis?

BACKGROUND: The predictors and clinical significance for stent fracture (SF) in drug-eluting stents (DES) remain unknown. We identified procedural factors leading to SF and its clinical consequences in DES. METHODS: Percutaneous coronary interventions were performed on 3,920 patients with DES over 12 months. In-stent restenosis (ISR) of DES was observed in 188 cases with 121 cases (64.4%) receiving a sirolimus-eluting stent (SES) and 67 (35.6%) a paclitaxol-eluting stent (PES). RESULTS: SF was identified in 35 (18.6%) of the 188 cases. The 35 cases were then compared with 153 cases of ISR without angiographic evidence of SF. SF was identified in 29 (23.9%) SES compared with 6 (9.0%) in PES (P < 0.05). With univariate analysis, additional factors associated with SF included longer mean stented segment length, male gender, overlapping stents, vessel segment angulation >75 degrees , and more stents (all P < 0.05). With multivariate adjustment, three factors, i.e., stenting on a bend >75 degrees (OR = 13.8, 95%CI 3.7 to 51; P < 0.001), SES (OR = 4.1, 95%CI 1.3 to 13.4; P < 0.018) and overlapping stented segments (OR = 3.9, 95%CI 1.1 to 14.1; P < 0.041) were statistically significant independent predictors of SF while larger stent diameter was protective (OR = 0.14, 95%CI 0.04 to 0.70; P < 0.017). CONCLUSION: SF proved to be associated with angiographically-documented clinical ISR. Although the exact mechanism is unknown, factors that appear to play a negative role in SF include vessel tortuosity, use of SES and overlapping stents. Larger stent diameter was protective. Further studies are needed to better define the factors important in the mechanism of SF.

Effect of electrical stimulation on arteriogenesis and angiogenesis after bilateral femoral artery excision in the rabbit hind-limb ischemia model.

The effects of electrical stimulation (ES) on arteriogenesis (the opening of preexisting collaterals) and angiogenesis (formation of new capillaries) were studied after acute bilateral hind limb ischemia was induced via bilateral femoral artery excision in a rabbit model. The study evaluated the rabbit hind limbs' normal response to acute ischemia and to application of ES by calculating changes in arterial and capillary densities. Comparisons were made with our prior study, in which the femoral artery was unilaterally excised, as we attempted to expand on the topics of arteriogenesis and angiogenesis. Twelve adult New Zealand white rabbits were randomly assigned to 1 of 2 series. In Series 1, the control group, both femoral arteries were excised and no ES was applied. In Series 2, both femoral arteries were excised and ES was applied to the left limb. One lead was implanted into the left adductor muscle near the site of the excised left femoral artery (Series 2), and a stimulator (Thera, Medtronic, Inc, Minneapolis, MN) was implanted in a separate pocket. ES was applied at a rate of 3 V, 30 contractions per minute, beginning immediately after surgery and continuously for 1 month. Angiography was performed in all 12 rabbits 1 month after surgery to establish the anatomy of the collateral vessels and to demonstrate that the femoral artery stump continued to be an end artery. Contrast-opacified arteries (COAs) that crossed the grid's midline, and the total number of grid lines intersected by COAs, were tallied according to an established method. Capillary density was calculated as the number of capillaries per square millimeter of muscle. In Series 1, after 1 month, the number of COAs crossing the grid's midline was 4.5 +/-1.5 on the left and 4.8 +/-1.2 on the right side. In Series 2, the number of COAs crossing the grid's midline was 7.9 +/-1.8 on the left side (p<0.05 vs Series 1) and 5.9 +/-1.6 on the right side of the same rabbit (p=NS vs Series 1). In Series 1, 36.7 +/-5.4 and 30.5 +/-7.7 total intersections were crossed by COAs on the left and right sides, respectively. In Series 2, total grid intersections crossed by COAs were 48.4 +/-8.5 and 47.5 +/-9.1 in the left and right sides, respectively (p<0.001 vs series 1). Baseline capillary density before femoral artery excision was 180.2 +/-21.3/mm(2). The capillary densities on the left sides were 94.2 +/-19.1 and 264.5 +/-7.6 in Series 1 and 2, respectively (p<0.001). The right sides showed a similar pattern with capillary densities of 88.5 +/-37.2 and 135.8 +/-6.8 (p<0.05) in Series 1 and 2, respectively. When capillary density was compared on the left and right sides of the same rabbit in Series 2, a statistically significant increase was also found; 264.5 +/-7.6 vs 135.8 +/-6.8 (p<0.001) in the left and right sides, respectively. Comparisons of the effect of electrical stimulation and the body's normal physiologic response to acute ischemia revealed a significant increase in the opening of preexisting collaterals (arteriogenesis) and the promotion of capillary density (angiogenesis) with the use of electrical stimulation.

Endovascular intervention of aortoiliac occlusive disease in high-risk patients using the kissing stents technique: long-term results.

Endovascular intervention deploying a kissing stents (KS) technique has been used as an alternative to surgical intervention in treating symptomatic aortoiliac occlusive disease. However, the long-term results on high-risk patients are unknown. We retrospectively analyzed data on high-risk patients who underwent endovascular intervention using the KS technique at our institution. Fifty high-risk patients aged 62 +/- 6.4 years with severe aortoiliac stenosis underwent stent-supported angioplasty using the KS technique. Thirty percent of the patients had total occlusion of the distal aorta and/or the iliac arteries. Twelve patients received thrombolytics prior to stenting. The procedure was successful in all 50 patients. There was a 4% acute complication rate (distal embolization). However, there were no vascular complications, myocardial infarction, or perioperative death. Primary patency during follow-up of 20 +/- 12.3 months was 92%, while secondary patency rate was 100%. Amputation-free survival was 100%. Ninety-two percent remained free of lifestyle-limiting claudication.