Therapeutic modulation of the natural history of coronary atherosclerosis: lessons learned from serial imaging studies

False Utopia of One Unifying Description of the Vulnerable Atherosclerotic Plaque: A Call for Recalibration That Appreciates the Diversity of Mechanisms Leading to Atherosclerotic Disease

Atherosclerosis is a complex disease characterized by the formation of arterial plaques with a broad diversity of morphological phenotypic presentations. Researchers often apply one description of the vulnerable plaque as a gold standard in preclinical and clinical research that could be applied as a surrogate measure of a successful therapeutic intervention, despite the variability in lesion characteristics that may underly a thrombotic occlusion. The complex mechanistic interplay underlying progression of atherosclerotic disease is a consequence of the broad range of determinants such as sex, risk factors, hemodynamics, medications, and the genetic landscape. Currently, we are facing an overwhelming amount of data based on genetic, transcriptomic, proteomic, and metabolomic studies that all point to heterogeneous molecular profiles of atherosclerotic lesions that lead to a myocardial infarction or stroke. The observed molecular diversity implies that one unifying model cannot fully recapitulate the natural history of atherosclerosis. Despite emerging data obtained from -omics studies, a description of a natural history of atherosclerotic disease in which cell-specific expression of proteins or genes are included is still lacking. This also applies to the insights provided by genome-wide association studies. This review will critically discuss the dogma that the progression of atherosclerotic disease can be captured in one unifying natural history model of atherosclerosis.

Recent Trends in Artificial Intelligence-Assisted Coronary Atherosclerotic Plaque Characterization

Coronary artery disease is a major cause of morbidity and mortality worldwide. Its underlying histopathology is the atherosclerotic plaque, which comprises lipid, fibrous and—when chronic—calcium components. Intravascular ultrasound (IVUS) and intravascular optical coherence tomography (IVOCT) performed during invasive coronary angiography are reference standards for characterizing the atherosclerotic plaque. Fine image spatial resolution attainable with contemporary coronary computed tomographic angiography (CCTA) has enabled noninvasive plaque assessment, including identifying features associated with vulnerable plaques known to presage acute coronary events. Manual interpretation of IVUS, IVOCT and CCTA images demands scarce physician expertise and high time cost. This has motivated recent research into and development of artificial intelligence (AI)-assisted methods for image processing, feature extraction, plaque identification and characterization. We performed parallel searches of the medical and technical literature from 1995 to 2021 focusing respectively on human plaque characterization using various imaging modalities and the use of AI-assisted computer aided diagnosis (CAD) to detect and classify atherosclerotic plaques, including their composition and the presence of high-risk features denoting vulnerable plaques. A total of 122 publications were selected for evaluation and the analysis was summarized in terms of data sources, methods—machine versus deep learning—and performance metrics. Trends in AI-assisted plaque characterization are detailed and prospective research challenges discussed. Future directions for the development of accurate and efficient CAD systems to characterize plaque noninvasively using CCTA are proposed.

Does Lowering Low-Density Lipoprotein Cholesterol With Statin Restore Low Risk in Middle-Aged Adults? Analysis of the Observational MESA Study

Background

It is unclear if statin therapy in midlife can restore low cardiovascular risk in hypercholesterolemic individuals.

Methods and Results

At baseline, we grouped 5687 MESA (Multi‐Ethnic Study of Atherosclerosis) participants aged ≥50 years without clinical cardiovascular disease (CVD) by Adult Treatment Panel III statin treatment recommendation and statin treatment status. We used Cox regression to compare the risks for coronary heart disease and CVD between the untreated group with low‐density lipoprotein cholesterol (LDL‐C) <100 mg/dL (reference) and other groups, adjusting for CVD risk factors. We also grouped participants by LDL‐C level (< or ≥100 mg/dL), coronary artery calcium score (0 or >0 Agatston units), and statin status (untreated or treated) with the untreated LDL‐C <100 mg/dL and coronary artery calcium=0 Agatston units as the reference. There were 567 coronary heart disease and 848 CVD events over 15 years of follow‐up. The hazard ratios (HRs) for coronary heart disease and CVD in the group with statin‐treated LDL‐C <100 mg/dL were 1.16 (95% CI, 0.85–1.58) and 1.02 (95% CI, 0.78–1.32), respectively. However, participants with coronary artery calcium >0 Agatston units, treated to LDL‐C <100 mg/dL had HRs of 2.6 (95% CI, 1.7–4.2) for coronary heart disease and 1.8 (95% CI, 1.2–2.6) for CVD.

Conclusions

Individuals treated with statins to LDL‐C <100 mg/dL had similar levels of risk for atherosclerotic CVD as individuals with untreated LDL‐C <100 mg/dL. However, individuals with coronary artery calcium >0 Agatston units have substantially higher risks despite lipid‐lowering therapy, suggesting that statin treatment in midlife may not restore a low‐risk state in primary prevention patients with established coronary atherosclerosis.

The role of intracoronary imaging in translational research

Atherosclerotic cardiovascular disease is a key public health concern worldwide and leading cause of morbidity, mortality and health economic costs. Understanding atherosclerotic plaque microstructure in relation to molecular mechanisms that underpin its initiation and progression is needed to provide the best chance of combating this disease. Evolving vessel wall-based, endovascular coronary imaging modalities, including intravascular ultrasound (IVUS), optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS), used in isolation or as hybrid modalities, have been advanced to allow comprehensive visualization of the pathological substrate of coronary atherosclerosis and accurately measure temporal changes in both the vessel wall and plaque characteristics. This has helped further our appreciation of the natural history of coronary artery disease (CAD) and the risk for major adverse cardiovascular events (MACE), evaluate the responsiveness to conventional and experimental therapeutic interventions, and assist in guiding percutaneous coronary intervention (PCI). Here we review the use of different imaging modalities for these purposes and the lessons they have provided thus far.

Progression of coronary atherosclerosis in patients without standard modifiable risk factors

Background and aims

The outcome of patients with clinical coronary artery disease despite traditional risk factors is poorly understood.

Methods

Clinical characteristics and plaque burden on serial intravascular ultrasonography were compared in patients without (n ​= ​165) and with (n ​= ​492) standard modifiable risk factors after matching on age, sex and use of statins from a database of 5823 patients participating in clinical trials of anti-atherosclerotic therapies.

Results

Patients without standard modifiable risk factors had lower baseline systolic blood pressure (118 ​± ​12 vs. 129 ​± ​17 ​mmHg, p ​< ​0.001), low-density lipoprotein cholesterol (87 ​± ​21 vs. 104 ​± ​34 ​mg/dl, p ​< ​0.001), triglycerides [106 vs. 136 ​mg/dl, p ​< ​0.001)] and C-reactive protein [1.5 vs. 2.1 ​mg/l, p ​= ​0.001]. At baseline, patients without modifiable risk factors had a lower percent atheroma volume (35.7 ​± ​8.6 vs. 38 ​± ​8.8%, p ​= ​0.004) and total atheroma volume (174.7 ​± ​80 vs. 190.9 ​± ​84 ​mm³, p ​= ​0.03) and less images with calcification (22.2 vs. 26.5%, p ​= ​0.025). The use of aspirin and statin prior to and during the trials was similar. The use of ACE inhibitors and beta blockers was lower in the no risk factor group prior to and during the trials. The change in percent atheroma volume (−0.2 ​± ​2.8 vs. −0.1 ​± ​3.6%, p ​= ​0.71), total atheroma volume (−5.5 ​± ​23.4 vs. −3.8 ​± ​22.7 ​mm³, p ​= ​0.42), and the percentage of patients demonstrating any degree of progression (50.9% vs 45.1%, p ​= ​0.20) were similar in those without and with standard modifiable risk factors, respectively.

Conclusion

Patients who develop clinical coronary atherosclerosis without standard modifiable risk factors have similar rates of plaque progression to those with traditional risk factors.

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Outcome of patients with CAD despite no traditional risk factors is poorly understood.

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Serial intravascular ultrasound studies provide an opportunity to examine this.

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Patients without standard risk factors had lower plaque burden and calcification.

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Use of aspirin and statin was similar in patients with and without standard risk factors.

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Plaque progression was similar in those without and with standard risk factors.

A post-market, multi-vessel evaluation of the imaging of peripheral arteries for diagnostic purposeS comparing optical Coherence tomogrApy and iNtravascular ultrasound imaging (SCAN)

Background

Intravascular imaging plays an important part in diagnosis of vascular conditions and providing insight for treatment strategy. Two main imaging modalities are intravascular ultrasound (IVUS) and optical coherence tomography (OCT). The objective of this study was to prove non-inferiority of OCT imaging to IVUS images in matched segments of peripheral vessels in patients with suspected peripheral vascular disease.

Methods

The SCAN study was a prospective, non-inferiority clinical study of matched IVUS and OCT images collected along defined segments of peripheral vessels from twelve subjects (mean age 68 ± 10.3 years; 10 men) displaying symptoms of vascular disease. Luminal diameters were measured by both imaging systems at the distal, middle, and proximal points of the defined segments. Three blinded interventional radiologists evaluated the quality of both imaging modalities in identifying layered structures (3-point grading), plaque (5-point grading), calcification (5-point grading), stent structure (3-point grading), and artifacts (3-point grading) from 240 randomly ordered images. Mean grading scores and luminal diameters were calculated and analyzed with Student’s t-Test and Mann-Whitney-Wilcoxon testing. Intrareader reproducibility was calculated by intraclass correlation (ICC) analysis.

Results

The mean scoring of plaque, calcification, and vascular stent struts by the three readers was significant better in terms of image quality for OCT than IVUS (p < 0.001, p = 0.001, p = 0.004, respectively). The mean scores of vessel wall component visibility and artifacts generated by the two imaging systems were not significantly different (p = 0.19, p = 0.07, respectively). Mean vessel luminal diameter and area at three specific locations within the vessels were not significantly different between the two imaging modalities. No patient injury, adverse effect or device malfunction were noted during the study.

Conclusions

Imaging by OCT provides the physician with better visualization of some vessel and plaque chacteristics, but both IVUS and OCT imaging are safe and effective methods of examining peripheral vessels in order to perform diagnostic assessment of peripheral vessels and provide information necessary for the treatment strategy of peripheral artery disease.

Trial registration

NCT03480685 registered on 29 March 2018.

Current approach to the diagnosis of atherosclerotic coronary artery disease: more questions than answers

Despite its commonality in routine clinical practice, the approach to a diagnosis of atherosclerotic coronary artery disease remains complex and, in part, contentious. The traditional dogma linking ischaemia to hard clinical outcomes has been questioned and reframed over the years; rather than being a predictor of hard clinical outcomes, the degree of ischaemia may simply be a marker of atherosclerotic disease burden. A renewed interest in the imaging of plaque burden has spawned the contemporary role of CT imaging for not only diagnosis and prognosis, but also for dictating downstream management. As the technology develops and evidence expands, decisions on investigative modalities remain centred around patient factors, local availability, test performance and cost. This review summarizes the available methods for diagnosis in the symptomatic patient and provides an overview of the current evidence behind functional and anatomical approaches.

Pronounced Coronary Arteriosclerosis in Cirrhosis: Influence on Cardiac Function and Survival?

BACKGROUND

The relation between excessive alcohol consumption and coronary arteriosclerosis has remained controversial. The etiology of cirrhosis has been considered a substantial risk factor for development of arteriosclerotic lesions. The coronary artery calcium-score derived from coronary CT angiography is a robust marker of coronary arteriosclerosis.

AIMS

To study the burden of coronary arteriosclerosis in cirrhotic patients of various etiologies and association to cardiac dysfunction and survival.

METHODS

Fifty-seven patients with cirrhosis without cardiovascular disease underwent coronary CT angiography, tissue Doppler echocardiography, electrocardiogram and registration of clinical and biochemical characteristics.

RESULTS

In patients with cirrhosis the median coronary artery calcium-score was increased in comparison with age and race-adjusted healthy reference values (men: 328 vs. 9 HU and women: 136 vs. 0 HU; p < 0.001). Moreover, the coronary artery calcium-score in alcohol-related cirrhosis was significantly higher than in nonalcohol-related cirrhosis (362 vs. 46 HU, p < 0.001). Coronary artery calcium-score correlated with age (p = 0.002) but not with established cardiovascular risk factors including smoking, type 2 diabetes, hypertension, gender, or hypercholesterolemia. Coronary artery calcium-score was associated with diastolic dysfunction, lateral e´ (p = 0.025), but not with other markers of cardiac dysfunction. During a median follow-up of 25 months 12 patients (21%) died but coronary artery calcium-score was not associated with survival.

CONCLUSIONS

Coronary arteriosclerosis was particular extensive in patients with alcoholic cirrhosis. However, the current results suggest that coronary arteriosclerosis only have limited influence on cardiac function and survival. Surprisingly, no other established risk factors apart from age seemed to interfere with coronary arteriosclerosis in cirrhotic patients.