Assessment of intracoronary stent location and extension in intravascular ultrasound sequences

PURPOSE

An intraluminal coronary stent is a metal scaffold deployed in a stenotic artery during percutaneous coronary intervention (PCI). In order to have an effective deployment, a stent should be optimally placed with regard to anatomical structures such as bifurcations and stenoses. Intravascular ultrasound (IVUS) is a catheter-based imaging technique generally used for PCI guiding and assessing the correct placement of the stent. A novel approach that automatically detects the boundaries and the position of the stent along the IVUS pullback is presented. Such a technique aims at optimizing the stent deployment.

METHODS

The method requires the identification of the stable frames of the sequence and the reliable detection of stent struts. Using these data, a measure of likelihood for a frame to contain a stent is computed. Then, a robust binary representation of the presence of the stent in the pullback is obtained applying an iterative and multiscale quantization of the signal to symbols using the Symbolic Aggregate approXimation algorithm.

RESULTS

The technique was extensively validated on a set of 103 IVUS of sequences of in vivo coronary arteries containing metallic and bioabsorbable stents acquired through an international multicentric collaboration across five clinical centers. The method was able to detect the stent position with an overall F-measure of 86.4%, a Jaccard index score of 75% and a mean distance of 2.5 mm from manually annotated stent boundaries, and in bioabsorbable stents with an overall F-measure of 88.6%, a Jaccard score of 77.7 and a mean distance of 1.5 mm from manually annotated stent boundaries. Additionally, a map indicating the distance between the lumen and the stent along the pullback is created in order to show the angular sectors of the sequence in which the malapposition is present.

CONCLUSIONS

Results obtained comparing the automatic results vs the manual annotation of two observers shows that the method approaches the interobserver variability. Similar performances are obtained on both metallic and bioabsorbable stents, showing the flexibility and robustness of the method.

[In hospital and mid-term outcome of patients with NIR stent implantation: multicenter ESPORT-NIR registry]

BACKGROUND AND OBJECTIVE

Despite improvements in the results and techniques of catheter-based revascularization, few studies have evaluated the clinical results of the application of new stent designs. We describe the in-hospital and mid-term outcome of patients undergoing a stent NIR implantation.

PATIENTS AND METHOD

At least 1 Stent NIR was implanted in 1.004 patients (1.136 lesions) recruited from 50 centers in an international, multicenter, prospective, registry (Spain and Portugal NIR stent registry). Inclusion criteria were objective coronary ischemia related to a severe de novo lesion or first restenosis in native vessels with a reference diameter >= 2.75 mm. The primary end-point was the incidence of major adverse cardiac events within the first 7 months of follow-up.

RESULTS

The mean age of the patients was 60 years and 82% were male. Angioplasty was indicated due to unstable angina in 61% of the cases. Stent implantation was successfully achieved in 99.6%. Clinical success (angiographic success without in-hospital major events) was achieved in 98.6% of patients. The rate of angiographic restenosis (> 50% stenosis narrowing) was 16% (CI 95%; 11.7-21.2). The accumulated major cardiac adverse event rate at seven months of follow-up was 8.7%: death (0.9%), acute myocardial infarction (1.2%) and target lesion revascularization (6.6%).

CONCLUSION

In the wide setting of the population included in the ESPORT-NIR registry, stent NIR implantation was a highly effective therapy with a good mid-term clinical and angiographic outcome.