Relation of drug-eluting stent strut distribution to stent thrombosis in coronary arteries.

The distribution of stent struts is critical to drug deposition and, therefore, may affect the amount of neointima and the risk of thrombosis after drug-eluting stent (DES) implantation. The aim of our study was to evaluate stent strut distribution in the setting of a drug-eluting stent thrombosis (ST). We retrospectively analyzed postprocedural intravascular ultrasound (IVUS) images of 13 patients who subsequently developed ST (14 DES thrombotic lesions) and a control group of 27 patients (30 DES lesions) matched for stent type and presence of chronic renal failure. In addition to standard IVUS measurements, visible struts were counted and maximum interstrut angle was measured at 1-mm intervals. Early ST was defined as < or =30 days after DES deployment and late ST as >30 days after DES deployment. Compared with DES controls, the ST group had a larger maximum interstrut angle (60.8 +/- 8.3 degrees vs 55.7 +/- 4.8 degrees , p = 0.014) and a similar number of stent struts (8.4 +/- 0.6 vs 8.7 +/- 0.6, p = NS). Maximum interstrut angle tended to be larger in late ST than in early ST (66.1 +/- 10.8 degrees vs 57.8 +/- 5.0 degrees , p = 0.071). The incidence of maximum interstrut angles > or =90 degrees and > or =120 degrees observed continuously for > or =2 mm of stent length was higher in the ST group (p = 0.009 and p = 0.096, respectively). In conclusion, DES-treated lesions leading to ST had larger maximum interstrut gaps distributed circumferentially and longitudinally, but a similar number of struts at the time of DES implantation compared with DES controls.

Intravascular ultrasound and 3D angle measurements of coronary bifurcations.

OBJECTIVE: To standardize the intravascular ultrasound (IVUS) analysis of coronary bifurcations. BACKGROUND: Percutaneous treatment of bifurcation lesions is difficult particularly at the side branch ostium. Imaging techniques may improve our understanding of treatment options. There is no established IVUS methodology to assess the bifurcation. The present study aims to develop standards for bifurcation imaging. METHODS: Quantitative IVUS analysis and 3D bifurcation angle measurements were performed in 34 patients who were selected from the Washington Hospital Center Database. Patients were included if both left anterior descending (LAD) and first diagonal (DX) pullbacks in the same procedure were done. Angiograms were available in 27 patients to measure the 3D bifurcation angle using specialized software. Pullbacks were analyzed proximal and distal to the bifurcation, and at the bifurcation. RESULTS: Prox(LAD) versus Prox(LAD(DX)) were similar for vessel area (15.5 +/- 4.6 mm(2) vs. 15.9 +/- 4.0 mm(2), P = 0.19), lumen area (8.3 +/- 3.6 mm(2) vs. 8.6 +/- 3.3 mm(2), P = 0.25), and plaque area (7.2 +/- 2.0 mm(2) vs. 7.3 +/- 1.9 mm(2), P = 0.55). However, Bifurcation(LAD) was larger than Bifurcation(DX) for vessel area (17.3 +/- 4.0 mm(2) vs. 16.6 +/- 3.9 mm(2), P = 0.0083). The 3D angiographic bifurcation angle was 50 degrees +/- 13 degrees (range of 26 degrees -84 degrees), and did not affect the IVUS measurements. IVUS analysis showed that bifurcation lesions did obey Murray's Law, as Prox(LAD) lumen area measured 36.7 +/- 25.1 mm(3) versus Dist(LAD)/Dist(DX) measured 38.0 +/- 29.1 mm(3), P = 0.56. CONCLUSIONS: Two IVUS pullbacks should be performed for a complete assessment of the bifurcation and comparison with Murray's Law. The proposed IVUS analysis was not influenced by the bifurcation angle.