Longitudinal straightening effect of stents is an additional predictor for major adverse cardiac events

OBJECTIVES The aim of this study was to perform an investigation of the effects of the longitudinal straightening of coronary arteries by stents and the possible association with major adverse cardiac events (MACE) (primary end point) and angiographic restenosis (secondary end point). BACKGROUND Stent deployment straightens a tortuous artery, and any consequent arterial longitudinal stretch may contribute to MACE and stent restenosis severity. Clinical, qualitative and quantitative angiographic data on 404 patients with Dingle stent implantation were subjected to multivariate nominal logistic regression analysis for the prediction of MACE. The predictive accuracy, sensitivity and specificity values and cut-off points of the continuous variables were determined via receiver operating characteristics curves. The longitudinal straightening effect of stents was characterized through the changes in vessel angle (defined by the tangents to the proximal and distal parts of the stenoses/stents). RESULTS Follow-up angiography on 354 patients revealed 73 cases of stent restenosis (greater than or equal to 50% diameter stenosis). Coronary bypass surgery was performed in 4 patients and repeated percutaneous transluminal coronary angioplasty in 56 patients; acute myocardial infarction (AMI) occurred in 2 patients, and 4 patients died during the follow-up. The overall incidence of MACE (death, AMI and revascularization) was 16.3% (66 patients). The best predictive accuracies and sensitivities/specificities of factors indicative of MACE were found for the minimal lumen diameter (MLD) at follow-up (predictive accuracy: 0.9305, sensitivity/specificity: 86.6%), the post-stent MLD (0.773, 77.2%), the percent diameter stenosis (%DS) at follow-up (0.9432, 87.1%), the prestent vessel angulation (0.6797, 68.2%) and the poststent changes in vessel angulation (0.6279, 62.2%). Multivariate nominal logistic regression analysis demonstrated that a poststent MLD less than or equal to 2.63 mm (p = 0.0017, odds ratio [OR] = 17.961, 95% confidence interval [CI] = 17.45-20.428), an MLD at follow-up less than or equal to 1.7 mm (p 0.0059, OR = 11.880, 95% CI = 11.490-14.093), a %DS at follow-up greater than or equal to 42.2% (p = 0.0000, OR = 49.553, 95% CI = 48.024-53.507), a prestent vessel angulation greater than or equal to 33.5 degrees (p = 0.0477, OR = 5.404, 95% CI = 5.382-7.142) and poststent changes in vessel angulation greater than or equal to 9.1 degrees (p = 0.0026, OR = 19.161, 95% CI = 18.562-21.750) were significant predictors for MACE. Multiple linear regression revealed that the poststent MLD (multivariate p = 0.0001), the MLD at follow-up (p = 0.0000), the prestent vessel angulation (p = 0.0431) and the changes in vessel angulation after stent implantation (p = 0.0316) were significant independent variables predicting angiographic stent restenosis severity. CONCLUSIONS The longitudinal straightening effect of coronary artery stents contributes significantly to the occurrence of MACE and angiographic restenosis, and this finding may have an impact on future stent design. (C) 2000 by the American College of Cardiology.