Diagnostic Accuracy of Optical Coherence Tomography and Integrated Backscatter Intravascular Ultrasound Images for Tissue Characterization of Human Coronary Plaques

Targeting of Vulnerable Plaque Macrophages with Polymer-Based Nanostructures

Macrophages are key cellular elements of atherosclerotic plaque pathogenesis and are a significant risk factor for plaque rupture. Current diagnostic techniques for the detection of plaque macrophages are often limited by insufficient sensitivity and selectivity and have not reached broad clinical practice until now. Supramolecular nanometer-sized structures such as conjugates, nanoparticles, micelles, or vesicles built from novel polymers promise to be useful in cell-specific delivery and may be of particular value for the detection and treatment of vulnerable plaque macrophages. Key properties of polymer-based nanostructures are high stability, improved biocompatibility, long circulation half-lives, defined biodegradation, targeting moieties, and triggerable controlled release. This review gives an insight into several promising research projects with polymer-based nanostructures for macrophage detection or treatment that might enter cardiologic practice in the near future.

[Interventional cardiology 2006]

The range of applications of percutaneous coronary intervention (PCI) continues to expand and a growing number of patients are being treated, including those with extensive cardiovascular disease, more serious comorbid conditions, and more complex lesions. Even so, the success rate is high, serious complications are rare in stable patients, and the restenosis rate has been dramatically reduced by drug-eluting stents. Nevertheless, percutaneous techniques still have major limitations restricting their use in some type of lesions, such as bifurcations and total occlusions, and their role in relation to surgical revascularization has not yet been well defined in the treatment of the left main coronary artery or multivessel disease. The development of novel types of coated stent with better mechanical characteristics and a lower risk of occlusion will further expand the ambit of PCI. The role of PCI in the management of acute coronary syndromes is already well defined, and has increased the preference for an invasive rather than a conservative approach in high-risk patients without ST elevation and the preference for primary angioplasty rather than thrombolysis in those with ST elevation. The development and implementation of integrated coronary syndrome treatment networks will enable human and material resources to be used efficiently, and will guarantee rapid access to high-quality PCI for those who need it. The potential usefulness of combining cellular therapy with interventional procedures in the treatment of acute myocardial infarction has still to be determined. At present, there is extensive research into noncoronary interventions, which, in the not too distant future, could provide percutaneous treatment for the many elderly patients with severe aortic stenosis who are not currently eligible for surgery.

Extent and distribution of coronary artery disease: a comparative study of invasive versus noninvasive angiography with computed angiography

BACKGROUND

The extent and nature of overall coronary artery disease (CAD), defined as the cumulative stenotic and nonstenotic, calcified and noncalcified atherosclerosis burden, are underestimated by invasive coronary angiography (ICA) and more accurately quantified with intravascular ultrasound. Multidetector row computed tomography (MDCT) is inferior to intravascular ultrasound but may constitute an attractive noninvasive alternative to assess overall CAD burden.

METHODS

To compare ICA with MDCT for detection of CAD (defined as luminal narrowing of any degree or calcification by ICA and any atherosclerotic plaque detection by MDCT using the 17-segment model), we studied 37 patients (age, 63 +/- 11 years) who underwent both tests.

RESULTS

A total of 508 of 586 (87%) segments were assessable, and CAD was detected in 121 of 508 (24%) segments by ICA versus 338 of 508 (67%) by MDCT (P < .01). Of the 121 segments positive for CAD by ICA, MDCT detected plaques in 117 segments (97%). In the 387 of 508 (76%) segments that were free of CAD by ICA, MDCT detected CAD in 221 (57%) segments. Overall, ICA detected CAD in only 20%, 48%, and 46% of segments with noncalcified, calcified, and mixed plaques, respectively, seen by MDCT (P = .01). Of the 221 segments negative for CAD by ICA, 119 (54%) were positively remodeled on MDCT. Overall correlation between ICA and MDCT for detection of CAD was poor (kappa = 0.25).

CONCLUSIONS

Invasive coronary angiography and MDCT differ significantly in estimating the presence and nature of CAD. Multidetector row computed tomography may provide an attractive noninvasive alternative to ICA to assess the effects of medical therapy.

Emerging approaches for imaging vulnerable plaques in patients

The diagnosis of vulnerable plaques, which have the propensity to develop atherothrombosis, remains an elusive goal in clinical medicine. The most accepted features of vulnerable plaques, such as a large lipid core, increased inflammatory milieu and thin fibrous caps, have been well characterized through pathological studies. The ability to image a vulnerable plaque in susceptible patients would theoretically result in useful prognostic information that can be used to either monitor or treat patients at risk more aggressively. Several invasive techniques, such as integrated backscatter, virtual histology, palpography, optical coherence tomography and thermal heterogeneity, have been validated ex vivo and are now being evaluated in clinical studies. Non-invasive techniques, such as nuclear imaging, show promise in identifying increased metabolic activity and characteristic features of vulnerable plaques in patients. Natural history and intervention studies will need to be performed to determine whether identifying and treating vulnerable plaques will lead to improved clinical outcomes.

Integrating Soluble Biomarkers and Imaging Technologies in the Identification of Vulnerable Atherosclerotic Patients

The clinical utility of a biomarker depends on its ability to identify high-risk individuals to optimally manage the patient. A new biomarker would be of clinical value if it is accurate and reliable, provides good sensitivity and specificity, and is available for widespread application. Data are accumulating on the potential clinical utility of integrating imaging technologies and circulating biomarkers for the identification of vulnerable (high-risk) cardiovascular patients. A multi-biomarker strategy consisting of markers of inflammation, hemostasis and thrombosis, proteolysis and oxidative stress, combined with new imaging modalities (optical coherence tomography, virtual histology plus IVUS, PET) can increase our ability to identify such thombosis-prone patients. In an ideal scenario, cardiovascular biomarkers and imaging combined will provide a better diagnostic tool to identify high-risk individuals and also more efficient methods for effective therapies to reduce such cardiovascular risk. However, additional studies are required in order to show that this approach can contribute to improved diagnostic and therapeutic of atherosclerotic disease.