The StentBoost Imaging Enhancement Technique as Guidance for Optimal Deployment of Adjacent-Sequential Stents

Abstract: Implantation of two or more adjacent-sequential stents is frequently required during coronary interventions, especially when treating long lesions.  We present two cases illustrating that plain fluoroscopic imaging may be misleading when used for guiding optimal deployment of adjacent-sequential stents, whereas implementation of the StentBoost^™ (Philips Medical Systems) fluoroscopic technique, which greatly enhances stent visualization in such procedures, may improve the assessment of stent positioning, preventing overlap failure or excessive overlapping. 

J INVASIVE CARDIOL 2011;23(10):427–429

Key words: enhanced stent visualization, StentBoost^™, contiguous stent deployment, suboptimal stent positioning

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Implantation of two or more adjacent-sequential stents is frequently required during percutaneous coronary interventions (PCI), mainly when treating long lesions, especially with different proximal and distal reference diameters, or when an edge dissection occurs from a previously implanted stent. Stent deployment is usually performed under plain fluoroscopy, using device markers for guidance, an approach posing the risk of stent overlap failure or excessive overlapping. There are few studies referring to the necessity and significance of precise positioning of contiguous stents, but the implementation of such a technique may significantly affect the outcome of PCI. The StentBoost^™ technique (Philips Medical Systems) constitutes a new x-ray image enhancing technique, which provides improved stent visualization by eliminating motion artefacts.¹ We present two cases indicating the potential applicability of this technique in preventing overlap failure or excessive overlapping when implantation of adjacent-sequential stents is performed.

Case Description

We present two patients with myocardial infarction (MI) in whom implantation of adjacent-sequential stents was required during PCI and a different approach was applied in each case.

Patient 1. A 71-year-old, male smoker with a positive history of coronary artery disease was transferred to our tertiary center for catheterization due to an inferior non-ST elevation MI. Coronary angiography (CAG) disclosed a significant proximal stenosis of the right coronary artery (Figure 1A; arrow). PCI was performed and two adjacent-sequential drug eluting stents (DES), 3.5 x 18 mm and 3.5 x 10 mm, were deployed under plain fluoroscopic guidance, with visual estimation of “optimal” overlapping by the operator (Figures 1B and 1C). The result of PCI was deemed successful with no residual stenosis (Figure 1D). Subsequent imaging with the StentBoost^™ technique indicated sufficient expansion of both stents but no overlap, with clear visualization of a gap between the deployed stents (Figure 1E; arrow).

Patient 2. A 63-year-old, male smoker with a known history of diabetes, hypertension, and hyperlipidemia was admitted to our center for primary PCI due to an inferior ST-elevation MI. Initial CAG showed proximal total occlusion of the right coronary artery (Figure 2A). After crossing the lesion with a soft BMW guidewire, diffuse atheromatosis was revealed up to the distal part of the vessel (Figure 2B). After predilation with a regular 2.5 x 15 mm balloon, a long 3 x 24 mm DES was implanted and a second 3 x 14 mm DES adjacent-sequential to the first was deemed necessary by the operator following angiography. In order to implant the sequential stent optimally, StentBoost was performed just before inflation of the balloon (Figure 2C). Following deployment of the latter, a repeat StentBoost indicated sufficient stent expansion and optimal overlap between the two stents (Figure 2D; arrow). The result of PCI as deemed by final angiography was successful (Figure 2E).

Discussion

The use of intracoronary stents definitely improves the clinical outcome of patients undergoing PCI.² The incidence of in-stent restenosis (ISR) can affect the outcome of PCI, although it has been significantly reduced by the development of DES.³ However, numerous other factors are also related to the occurrence of ISR, including PCI procedural aspects.⁴

The implantation of multiple adjacent-sequential stents, mainly prompted by excessive target lesion length and incomplete lesion coverage, is performed in about one-third of PCI procedures.^5-7 ISR frequently occurs in cases where a gap is present after the implantation of adjacent-sequential stents.⁸ Moreover, stent strut overlap has been considered as a stimulus for neointimal hyperplasia and associates with late angiographic restenosis.^9,10

Therefore, in such cases, optimal stent positioning is of great importance. Visual assessment with plain fluoroscopy of optimal stent positioning predeployment can be difficult due to poor visualization of the non-deployed rapidly moving stent. In the same manner, post-deployment fluoroscopic assessment of optimal stent positioning also suffers from the same drawbacks. On the other hand, intracoronary imaging techniques, such as intravascular ultrasound and optical coherence tomography, can only denote a problem poststenting and not prevent geographic misses.^11,12 StentBoost is a technique that greatly enhances the visualization of stents during coronary interventions. The application of this technique is relatively simple and non-time consuming. A short digital cine run (around 2 seconds) is acquired and stored in the system. At present, this technique requires detectable markers located on the stent delivery system, for motion compensation to enhance stents and reduce quantum noise.¹ Therefore, it can only be applied immediately pre- or poststenting when the balloon is still inside the stent. This process improves signal-to-noise ratio and produces an enhanced visualization of the implanted stent compared to plain fluoroscopy. An average effective radiation dose of 1.4 mSv with StentBoost application was calculated in our laboratory, while a similar duration of cinefluoroscopy exposed the patient to an average of 0.26 mSv. Despite the relatively increased dosage of radiation, the clinical implications seem to be significant.

Application of this technique in the guidance and assessment of sequential stents deployment, as described in the above cases, to the best of our knowledge has not been described. Obviously, the latter might be of clinical significance.

Conclusion

The above cases illustrate that implantation of adjacent-sequential stents under plain fluoroscopy may have a suboptimal result. By greatly enhancing stent visualization, the StentBoost technique may assist the interventional cardiologist in the optimal positioning of sequential stents, preventing both overlap failure and excessive overlapping. This concept needs further testing.  

References

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12. Tsigkas G, Davlouros P, Alexopoulos D. Angiographic and OCT imaging of a Nobori stent fracture. Eurointervention. 2009;5(1):E28.

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From the Cardiology Department, Patras University Hospital, Patras, Greece.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Manuscript submitted April 14, 2011, provisional acceptance given May 9, 2011, final version accepted June 27, 2011.
Address for correspondence: Grigorios Tsigkas, MD, Interventional Cardiologist, Patras University Hospital, Cardiology Department, Rion 26500, Patras, Greece. Email: gregtsig@hotmail.com