Intravascular ultrasound and quantitative coronary angiography

Development of an innovative technology to segment luminal borders of intravascular ultrasound image sequences in a fully automated manner

Although intravascular ultrasound (IVUS) is the commonest intravascular imaging modality, it still is inefficient for clinical use as it requires laborious manual analysis. This study demonstrates the feasibility of a near real-time fully automated technology for accurate identification, detection, and quantification of luminal borders in intravascular images. This technology uses a combination of the novel approaches of a self-tuning engine, dynamic and static masking systems, radar-wise scan, and contour correction cycle method. The performance of the computer algorithm developed based on this technology was tested on a sequence of IVUS and True Vessel Characterization (TVC) images obtained from the left anterior descending (LAD) artery of 6 patients with coronary artery disease. The accuracy of the algorithm was evaluated by comparing luminal borders traced manually with those detected automatically. The processing time of the developed algorithm was also tested on a Dell laptop with an Intel Core i7-8750H Processor (4.1 GHz with 6 cores, 9 MB Cache). Linear regression and Bland-Altman analyses indicated high correlation between manual and automatic tracings (Y = 0.80 × X+1.70, R² = 0.88 & 0.67 ± 1.31 (bias±SD)). Whereas analysis of 2000 IVUS images using one CPU core with a 30% load took 23.12 min, the same analysis using six CPU cores with 90% load took 1.0 min. The performance, accuracy, and speed of the presented state-of-the-art technology demonstrates its capacity for use in clinical settings.

Invasive assessment modalities of unprotected left main stenosis

Among all coronary lesions, the decision-making process for the treatment of unprotected left main (ULM) stem lesions is still challenging. Indeed, the optimal therapeutic strategy for patients with ULM disease remains controversial: coronary artery bypass grafting was established as the gold standard, but it is without doubt that percutaneous coronary intervention (PCI) performed by experienced operators achieves good results at long term follow up, especially in cases where the ostium and/or shaft of ULM are treated. Thanks to the widespread use of invasive assessment of atherothrombotic ULM stenosis, improved selection of PCI cases and techniques of stenting, better outcomes are now possible. This review seeks to define the place of PCI in ULM disease by describing the different modalities of ULM stenosis assessment.

The LightWire technology for catheter-based interventions

BACKGROUND

The LightWire is a newly developed opto-acoustic coronary imaging guidewire that was designed to be used during angioplasty procedures and provide 'online' information on lumen and vessel wall dimensions.

METHODS

We designed in vitro models and performed animal trials to confirm proper device sensing capabilities and performance in the coronary arteries. This report focuses on maneuverability, compatibility with other catheterization devices, and vessel measurements.

RESULTS

Measurement ability was initially validated in vitro. Diameter measurements of coronary and peripheral arteries with and without stent based on ultrasound technology were then demonstrated in a pig model, whereas retaining easy navigation and maneuverability, as well as compatibility with other catheterization equipments. The LightWire device acquired proper and accurate multi-location measurements of coronary and femoral artery diameters.

CONCLUSION

Using a miniaturized opto-acoustic technology can aid incoronary imaging, while maintaining standard guidewire performances. Thus, the LightWire device holds promise as a diagnostic and guidance tool during coronary and peripheral angioplasty procedures.

Left main coronary artery stenosis: state-of-the-art

Patients with stenosis of the left main coronary artery present difficult challenges. The risks associated with this lesion have been known since the early days of angiography when patients were found to have increased mortality during follow-up. This information led to the general guidelines that surgical revascularization should be considered the treatment of choice in patients with significant left main coronary artery stenosis. Current advances in invasive cardiology have brought important information to the field. Intravascular ultrasound is now used routinely to evaluate angiographically indeterminate lesions with criteria now set forward as to what constitutes an indication for revascularization. Stents have even further dramatically changed the landscape. There are substantial issues, however, that need to addressed. These include the following: (1) the effect of specific lesion location on outcome - it is known that patients with distal bifurcation left main disease have worse outcome; (2) the potential for subacute thrombosis of the left main coronary artery; (3) the impact of left ventricular function and patient comorbidities irrespective of the degree and location of left main coronary artery stenosis; and (4) the risk-benefit ratio of stenting versus coronary artery bypass graft surgery. These issues are currently being addressed in two seminally important trials including the SYNTAX trial, which randomizes patients with left main and/or three-vessel disease to either coronary artery bypass graft surgery or a TAXUS drug-eluting stent. This trial is in the final stages of patient recruitment and will have important implications for the field. The other trial is the COMBAT trial, which is focused exclusively on left main coronary artery stenosis and randomizes patients with left main coronary artery disease either to a Sirolimus-eluting stent (Cypher, Johnson and Johnson Cordis, USA) or to coronary artery bypass graft surgery. The field of left main coronary artery disease continues to expand in terms of the evidence available for optimal patient evaluation and selection of treatment modalities.

The influence of diabetes mellitus on plaque volume and vessel size in patients undergoing percutaneous coronary intervention

We evaluated the influence of diabetes on plaque volume and vessel size at a reference segment in diabetic patients undergoing percutaneous coronary intervention using both angiograms and quantitative intravascular ultrasound. A total of 344 patients with 449 de novo coronary lesions including 97 diabetics (133 lesions) who underwent elective percutaneous coronary intervention under intravascular ultrasound guidance were included in this study. Eleven diabetic patients (19 lesions) received insulin and 52 patients (77 lesions) oral hypoglycemic drugs. The other 34 patients (37 lesions) received diet/exercise therapy alone. We measured vessel area (VA) and lumen area (LA) at proximal and distal reference segments by intravascular ultrasound, which were averaged. Plaque area (VA-LA) and % plaque area (100 x plaque area/VA) were subsequently calculated. Although VA was similar between diabetic and non-diabetic patients (13.46 +/- 4.49 mm2 in diabetics versus 14.11 +/- 5.24 mm2 in non-diabetics, P = 0.214), LA was smaller (6.51 +/- 2.63 mm2 versus 7.38 +/- 3.08 mm2, P = 0.004) and % PA was larger (50.4 +/- 11.7 versus 46.5 +/- 11.3, P < 0.001) in diabetic patients, especially the group receiving a hypoglycemic drug or insulin. VA, LA, and % PA were similar between patients with and without insulin treatment. These results potentially might cause undersized device selection without intravascular ultrasound guidance.

Impact of intravascular ultrasound-guided stenting on long-term clinical outcome: a meta-analysis of available studies comparing intravascular ultrasound-guided and angiographically guided stenting

To date, only a few studies have compared the clinical efficacy of intracoronary ultrasound (IVUS)-guided to angiographically guided stenting. Furthermore, it is not yet known whether the lower restenosis rate shown with the former strategy would translate into a substantial clinical advantage. Therefore, the aim of the present investigation was to improve the level of evidence of these studies by means of a formal meta-analysis. Nine studies were considered suitable for analysis. Odds ratios (ORs) were calculated for 6-month clinical follow-up. Primary endpoint was a composite of death and nonfatal myocardial infarction (MI), as considered in every single study. Secondary endpoints were major adverse cardiac events (MACEs), according to single study definition, the individual cardiac events, as well as several pre- and postprocedure and follow-up angiographic parameters. Overall, 2,972 patients were included. At 6 months, the OR for death and nonfatal MI was 1.13 (95% CI = 0.79-1.61; P = 0.5) for patients with IVUS-guided stenting. However, patients with IVUS-guided stenting had less target vessel revascularizations (OR = 0.62; 95% CI = 0.49-0.78; P = 0.00003) and MACEs (OR = 0.79; 95% CI = 0.64-0.98; P = 0.03) compared to angiographically guided stenting. In addition, subjects treated with IVUS-guided stenting had significantly less binary restenosis (OR = 0.75; 95% CI = 0.60-0.94; P = 0.01). The present meta-analysis demonstrates that IVUS-guided stenting implantation has a neutral effect on long-term death and nonfatal MI compared to an angiographic optimization. However, IVUS-guided stenting significantly lowers 6-month angiographic restenosis and target vessel revascularizations. Whether these benefits could be very helpful when dealing with lesions at high risk for restenosis is still an issue.