Longitudinal stent elongation or shortening after deployment in the coronary arteries: which is dominant?

BACKGROUND: Stent manufacturers always record stent shortening data while they do not record stent elongation data. The aim of this study is to identify both stent shortening and elongation occurring after deployment in the coronary arteries and know their percentage. RESULTS: The length of coronary stents was measured by intravascular ultrasound (IVUS) by (1) edge-to-edge (E-E) length, measured from the appearance of the first distal strut to the last proximal strut, and (2) area-to-area (A-A) length, measured from the first distal struts seen at more than one IVUS quadrant to the last proximal struts seen at more than one IVUS quadrant. Stent shortening was defined as both E-E and A-A lengths were shorter than the manufacturer box-stated length (shortened group). Stent elongation was defined as both E-E and A-A lengths were longer than the manufacturer box-stated length (elongated group), otherwise unchanged group. Consecutive 102 stents deployed in ischemic patients were included. Stent elongation was detected in 67.6% (69 stents), and shortening was detected in 15.7% (16 stents), while unchanged stents were detected in 16.7% (17 stents). Although the 3 groups had similar box-stated length and predicted foreshortened length, they had significantly different measurements by IVUS, p<0.001 for each comparison. Differences from box-stated length were 1.9±1.4mm, −1.4±0.4mm, and 0.4±0.3mm, respectively, p<0.001. The elongated group had significantly longer differences from the corresponding box-stated and predicted foreshortened lengths, while the shortened group had significantly shorter differences from the corresponding box-stated length and similar foreshortened length. By multinomial regression analysis, the plaque-media area and stent deployment pressure were the independent predictors of the stent length groups, p=0.015 and p=0.026, respectively. CONCLUSIONS: Change in stent length is not only shortening—as mentioned in the manufacturer documents—but also stent elongation. Stent elongation is dominant, and the most important predictors of longitudinal stent changes are plaque-media area and stent deployment pressure.