Backgrounds and Objectives: Stent fracture(SF) is an potential cause of restenosis, which acquire special significance in the treatment failure with DES. We hypothesized that chronic fatigue stress associated with angle and angular momentum is the most important mechanism in SF. We quantitatively analyzed the initial maximal, minimal physiologic angle(Ai-max,Ai-min) and the change of angle(ΔAi) in repetitive bending movement of coronary lesion before PCI, angles(Ap-max,Ap-min,ΔAp) after immediate PCI, corrected angle[Δ(Ap-Ai)max] by PCI, and angles(Asf-max,Asf-min,ΔAsf) after SF in delayed DES fracture patients. Methods: From October 2005 to July 2006 in Chungbuk Naiotnal University Hospital, 139 patients underwent follow-up CAG after 258 DES implantation. DES fractures were detected at 13 patients(M:F=12:1, Age:60.3±9.4). We quantitatively analyzed the angles(Ai,Ap,ΔA,Asf) at the same plane view by Nexus 1.0 in 13 patients. Results: 1) The follow-up duration was 255.7±75.7days. All 13 DES fractured patients had no clinical symptoms or binary restenosis associated with SF. 2) The number of stent implantation at target lesion associated fracture site was 1.9±0.6. Stent diameter and length were 3.00±0.25 and 53.0±17.4mm. 3) 4 of 13 patients had multiple fracture(LAD;2,RCA:2). 9 patients had single fracture(LAD;1,LCX;3,RCA;5). 4) All most all fracture sites(92.3%, 12/13cases) were angulated and bending lesion. Only 1 fracture site was not angulated lesion. 5) The Mean ΔAi, Ai-max and Ai-min were 18.9, 145.5 and 125.8◦. Mean ΔAp, Ap-max and Ap-min were 4.9, 158.8 and 154.1◦. Mean maximal corrected angle by PCI was 28.3◦. In SF, The mean ΔAsf, Asf-max and Asf-min were 13.8, 149.4 and 133.5◦. These Asf values had a strong tendency to recover the initial physiologic angle(Ai) against corrected angle by PCI. Conclusion: Theses findings suggest that the initial angle and extent of corrected angle against physiologic coronary configuration are important at delayed DES fracture. And it has considering potential as a marker for assessing risk of DES fracture. Further large randomized clinical studies were needed.
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