Longitudinal stent deformation elongating to left main trunk

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.

In vivo measurement of stent length by using intravascular ultrasound

Background

What happens to stent length when deployed in a coronary artery? It is the aim of this study.

Results

Consecutive 95 balloon-expandable stents (BES) were studied by intravascular ultrasound (IVUS) imaging. The stent length was measured from the longitudinal view in two ways: (1) edge-to-edge length (E-E) measured between distal and proximal stent frames located at one IVUS quadrant and (2) area-to-area length (A-A) measured between distal and proximal stent frames located at two or more IVUS quadrants. IVUS measurements were compared with the manufacturer-stated length (M-L). The median E-E length was significantly longer than M-L, 18.76 mm [interquartile range (IQR) 15.65–23.60] versus 18.00 mm (IQR 15.00–23.00), respectively, p < 0.0001. Also, the median A-A length was significantly longer, 18.36 mm (IQR 15.19–23.47), p < 0.0001, than M-L. Moreover, the E-E length was significantly different from A-A length, p < 0.0001. Among the stent groups, the differences were significantly present in all drug-eluting stent and bare metal stent (BMS) comparisons, p < 0.0001, except the A-A length versus M-L in BMS only. By multivariate analysis, the predictors of difference in stent length were as follows: lesion length, p = 0.01; pre-intervention minimal diameter of the external elastic membrane (EEM), p = 0.03; lesions present in the left anterior descending branch, p = 0.03; and M-L, p = 0.04.

Conclusions

In the present study, the length of BES measured by IVUS was significantly different from the manufacturer-stated length. In addition to the manufacturer length, other important factors such as lesion length, pre-intervention diameter of EEM, and affected vessel determine the stent length.

Longitudinal Stent Elongation of a Tapered Lesion during Percutaneous Coronary Intervention: A Case Report

The therapeutic strategy for percutaneous coronary intervention (PCI) of a tapered lesion is still being developed. Herein, we describe a 67-year-old man with stable angina who underwent elective PCI of a tapered lesion. The coronary angiogram showed diffuse, severe stenosis in the tapered left anterior descending artery. A third-generation sirolimus-eluting stent (2.5 × 24-mm Ultimaster, Terumo, Tokyo, Japan) was deployed, and the distal side was selected as the reference. Postdilatation with a balloon diameter 2.0 mm larger than the stent was needed because of the tapered lesion. We performed postdilatation from the distal side to the proximal side of the stent with a noncompliant balloon (4.5 × 8-mm Powered Lacrosse2, Goodman, Aichi, Japan). The final angiogram showed that the total stent length was 6 mm longer than the original length. Therefore, physicians should be aware of longitudinal stent elongation of a tapered lesion during PCI to ensure appropriate treatment.