Clinical imaging of the vulnerable plaque in the coronary arteries: new intracoronary diagnostic methods

Optical coherence tomography characteristics of in-stent restenosis are different between first and second generation drug eluting stents

Aims

Characterization of neointimal tissue is essential to understand the pathophysiology of in-stent restenosis (ISR) after drug eluting stent (DES) implantation. Using optical coherence tomography (OCT), we compared the morphologic characteristics of ISR between first and second generation DES.

Methods and Results

OCT was performed in 66 DES-ISR, defined as > 50% angiographic diameter stenosis within the stented segment. Patients with ISR of first generation sirolimus-eluting stents (SES), paclitaxel eluting stents (PES) and second generation zotarolimus-eluting stents (ZES), everolimus-eluting stents (EES) and biolimus-eluting stents (BES) were enrolled. Quantitative and qualitative ISR tissue analysis was performed at 1-mm intervals along the entire stent, and categorised as homogeneous, heterogeneous and neo-atherosclerosis. The presence of microvessels and peri-strut low intensity area (PSLIA) was determined in all ISR. Neoatherosclerosis was identified by lipid, calcium and thin-cap fibro-atheroma (TCFA) like lesions. We compared the two DES generations at both early (< 1 year) and late (> 1 year) follow-ups.

In second generation DES a heterogeneous pattern was prevalent both before and after 1 year (57.1% and 58.6% respectively). Neo-atherosclerosis was more common in the early period in first generation DES (19.4% vs 11.7%, p < 0.01), but after one year was more prevalent in second generation DES (7.0% vs 19.3%, p < 0.01). Similar prevalence of TCFAs was observed in both groups in all comparisons.

Conclusions

When ISR restenosis occurs in second generation DES, the current data suggest a different time course and different morphological characteristics from first generation. Future prospective studies should evaluate the relationship between ISR morphology, time course and clinical events.

Incidence of residual clot strands in saphenous vein grafts after endoscopic harvest

OBJECTIVE

: Strands of clot are frequently flushed out of saphenous vein grafts (SVG) during preparation for grafting, particularly those that are endoscopically harvested. However, saline distention at uncontrolled pressures increases graft thrombogenicity and the risk of early failure after coronary artery bypass grafting. The purpose of this prospective investigation was to define the incidence of intraluminal clot within endoscopically harvested SVG and the effect of attempted removal by saline distention.

METHODS

: Endoscopically harvested SVG were intraoperatively prepared for grafting by using saline distention at uncontrolled pressure (n = 24) or without distension (n = 20). Optical coherence tomography, a catheter-based infrared imaging system, was used to identify and characterize intraluminal clot strands in surplus SVG segments (average length for analysis, 4.9 ± 2.6 cm). These segments were also assessed for luminal tissue factor activity and percent endothelial integrity by CD31-directed immunohistochemistry.

RESULTS

: Clot strands were observed in 45.4% (20 of 44) of imaged SVG segments (severity of observed clots: 54%, mild; 32%, moderate; 14%, severe). Compared with grafts distended with saline, vein segments that were not distended displayed significantly higher endothelial integrity (60.1% ± 27.2% versus 24.7% ± 24.1%, P < 0.05) and lower tissue factor activity (1.28 ± 0.95 versus12.3 ± 5.5 U/cm, P < 0.001) despite having a higher incidence of clot stands (65.0% versus 29.1%, P < 0.02, Fisher exact test). Static flow was observed in veins during endoscopic harvest.

CONCLUSIONS

: Clot strands of varying severity are a common finding after endoscopic vein harvest. Saline distention is not completely effective in removing clot strands and increases overall graft thrombogenicity. Therefore, prevention of clot or less traumatic methods of removing clot are indicated.

Optical coherence tomography: its value in intravascular diagnosis today

Optical coherence tomography is a recently developed high-resolution intravascular diagnostic technique. Initially, it was mainly used for characterizing atherosclerotic plaque because it served a number of functions, from identifying plaque with high lipid content to detecting macrophage accumulation, both of which are associated with plaque instability. Currently, there is growing interest in the value of optical coherence tomography in the area of coronary intervention, where the technique offers significant advantages over more widespread intravascular diagnostic techniques such as intravascular ultrasound: its higher resolution means that the vessel lumen diameter can be measured more precisely, periprocedural complications such microdissection of the coronary artery can be detected, stent apposition relative to the vessel wall can be optimized, neointimal hyperplasia can be detected after stent implantation, and neointimal thickness can be measured. It would therefore appear to be a very useful technique for interventional cardiologists. This review article considers the technical details of the technique and its applications, and compares it with other intravascular diagnostic techniques.

Local Atherosclerotic Plaques Are a Source of Prognostic Biomarkers for Adverse Cardiovascular Events

Objective— Atherosclerotic cardiovascular disease is a major burden to health care. Because atherosclerosis is considered a systemic disease, we hypothesized that one single atherosclerotic plaque contains ample molecular information that predicts future cardiovascular events in all vascular territories.

Methods and Results— AtheroExpress is a biobank collecting atherosclerotic lesions during surgery, with a 3-year follow-up. The composite primary outcome encompasses all cardiovascular events and interventions, eg, cardiovascular death, myocardial infarction, stroke, and endovascular interventions. A proteomics search identified osteopontin as a potential plaque biomarker. Patients undergoing carotid surgery (n=574) served as the cohort in which plaque osteopontin levels were examined in relation to their outcome during follow-up and was validated in a cohort of patients undergoing femoral endarterectomy (n=151). Comparing the highest quartile of carotid plaque osteopontin levels with quartile 1 showed a hazard ratio for the primary outcome of 3.8 (95% confidence interval, 2.6–5.9). The outcome did not change after adjustment for plaque characteristics and traditional risk factors (hazard ratio, 3.5; 95% confidence interval, 2.0–5.9). The femoral validation cohort showed a hazard ratio of 3.8 (95% confidence interval 2.0 to 7.4) comparing osteopontin levels in quartile 4 with quartile 1.

Conclusion— Plaque osteopontin levels in single lesions are predictive for cardiovascular events in other vascular territories. Local atherosclerotic plaques are a source of prognostic biomarkers with a high predictive value for secondary manifestations of atherosclerotic disease.

Optical coherence tomography imaging in complicated acute myocardial infarction treated with primary angioplasty and AngioJet

We describe the case of a 47-year-old man presenting with inferior acute myocardial infarction complicated by complete atrioventricular block and cardiogenic shock, who underwent primary angioplasty and rheolytic thrombectomy with AngioJet and subsequent evaluation by optical coherence tomography. Optical coherence tomography is a rather novel technique in the management of coronary disease, and as far as we know, this is the first report about optical coherence tomography imaging after AngioJet thrombectomy. Moreover, we provide a brief discussion on advantages and disadvantages of this imaging modality on the basis of current practice.

Noninvasive cardiac imaging with computed tomography

Despite major improvements in the treatment of heart disease, it remains a major source of morbidity and mortality on a global scale. Currently, invasive coronary angiography remains the gold standard for identification of obstructive coronary artery disease. However, recent advances in computerized tomographic (CT) techniques of the heart allow for accurate, noninvasive characterization of atherosclerotic coronary disease and other cardiac abnormalities. The calculation of coronary artery calcium scores with electron beam CT has largely been supplanted by high-resolution CT angiography using multislice detectors (MSCT) which can provide detailed multidimensional visualization of cardiac structures. Although evaluation of obstructive coronary disease is the primary use of MSCT, its use in identifying congenital defects, planning thoracic procedures and characterizing cardiac function continues to grow. Accordingly, appropriate incorporation of MSCT/CT angiography into clinical practice continues to be defined. Several limitations to MSCT remain which reduce its accuracy, such as in patients with arrhythmia and in patients with either coronary stents or heavily calcified coronaries. Despite its current limitations, MSCT remains a rapidly advancing field and an increasingly valuable tool for the noninvasive evaluation of cardiac pathology.