Is spontaneous coronary artery dissection (SCAD) related to vascular inflammation and epicardial fat? -insights from computed tomography coronary angiography

Pericoronary adipose tissue density is increased in patients with recent spontaneous coronary dissection

OBJECTIVE

Inflammatory activity is one of the potential mechanisms of spontaneous coronary artery dissection (SCAD). Recently, the pericoronary adipose tissue attenuation (PCAT) derived from CT angiography (CTA) has been established as a method for measuring vascular inflammation. We aimed to characterise the pancoronary and vessel-specific PCAT in patients with and without recent SCAD.

METHODS

The study comprised patients with SCAD referred to a tertiary centre between 2017 and 2022 who underwent CTA and were compared with individuals with no prior SCAD. PCAT was analysed on end-diastolic CTA reconstructions along proximal 40 mm of all major coronary vessels as well as the SCAD-related vessel. We analysed 48 patients with recent SCAD (median 6.1 (IQR 3.5-14.9) months since SCAD, 95.8% female) and 48 patients in the group without SCAD.

RESULTS

Pancoronary PCAT was higher in patients with SCAD compared with those without SCAD (-80.6±7.9 vs -85.3 HU±6.1, p=0.002). Vessel-specific PCAT in patients with SCAD compared with patients without SCAD was higher for both the RCA (-80.9±9.5 vs -87.1±6.9 HU, p=0.001) and the LCA (-80.3±7.8 vs -83.4±7.2 HU, p=0.04). In patients with SCAD, PCAT of the SCAD-related vessel was not significantly different from averaged PCAT of unaffected vessels (-81.2±9.2 vs -80.6±7.6, p=0.74). There was no association between PCAT and the interval from SCAD to CTA.

CONCLUSIONS

Patients with recent SCAD have higher PCAT compared with patients without SCAD, suggesting an increased perivascular inflammatory activity. This association is not restricted to the dissected vessel.

Spontaneous coronary artery dissection: the emerging role of coronary computed tomography

Spontaneous coronary artery dissection (SCAD) is a cause of acute coronary syndrome and myocardial infarction, more frequent among young women. Invasive coronary angiography (ICA) is the gold standard for the diagnosis of SCAD, although the risk of propagating dissection flap is considerable. Therefore, coronary computed tomography angiography (CCTA) is an emerging alternative modality to diagnose SCAD with the advantage of being a non-invasive technique. Clinicians should be aware of the predisposing conditions and pathophysiology to raise the pre-test probability of SCAD and select the most appropriate diagnostic tools. In recent times, improvements in spatial and temporal resolution and the use of semi-automated software providing quantitative assessment make CCTA a valid alternative to ICA also for the follow-up. Moreover, CCTA may be helpful to screen and evaluate extra-coronary arteriopathies closely related to SCAD. In this review, we illustrate the current and the potential role of CCTA in the diagnosis of SCAD, highlighting advantages and disadvantages of this imaging modality compared to ICA.

Computed tomography and nuclear medicine for the assessment of coronary inflammation: clinical applications and perspectives

There is increasing evidence that in patients with atherosclerotic cardiovascular disease (ASCVD) under optimal medical therapy, a persisting dysregulation of the lipid and glucose metabolism, associated with adipose tissue dysfunction and inflammation, predicts a substantial residual risk of disease progression and cardiovascular events. Despite the inflammatory nature of ASCVD, circulating biomarkers such as high-sensitivity C-reactive protein and interleukins may lack specificity for vascular inflammation. As known, dysfunctional epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT) produce pro-inflammatory mediators and promote cellular tissue infiltration triggering further pro-inflammatory mechanisms. The consequent tissue modifications determine the attenuation of PCAT as assessed and measured by coronary computed tomography angiography (CCTA). Recently, relevant studies have demonstrated a correlation between EAT and PCAT and obstructive coronary artery disease, inflammatory plaque status and coronary flow reserve (CFR). In parallel, CFR is well recognized as a marker of coronary vasomotor function that incorporates the haemodynamic effects of epicardial, diffuse and small-vessel disease on myocardial tissue perfusion. An inverse relationship between EAT volume and coronary vascular function and the association of PCAT attenuation and impaired CFR have already been reported. Moreover, many studies demonstrated that 18F-FDG PET is able to detect PCAT inflammation in patients with coronary atherosclerosis. Importantly, the perivascular FAI (fat attenuation index) showed incremental value for the prediction of adverse clinical events beyond traditional risk factors and CCTA indices by providing a quantitative measure of coronary inflammation. As an indicator of increased cardiac mortality, it could guide early targeted primary prevention in a wide spectrum of patients. In this review, we summarize the current evidence regarding the clinical applications and perspectives of EAT and PCAT assessment performed by CCTA and the prognostic information derived by nuclear medicine.

Perivascular fat attenuation index measured by coronary computed tomography angiography as a tool for assessment of ischaemia-causing lesions: a case report

BACKGROUND

It can be difficult to diagnose coronary artery disease in patients with acute coronary syndrome if coronary angiography does not identify stenosis. Coronary inflammation, which can contribute to the pathogenesis of coronary artery disease and acute coronary syndrome, can be quantified using the perivascular fat attenuation index. Furthermore, the perivascular fat attenuation index is a marker for all-cause mortality, cardiac-related mortality and impaired global coronary flow reserve.

CASE PRESENTATION

Here we report a case of a patient presenting with symptoms of acute coronary syndrome. The patient had hypokinesis of the lateral-posterior wall of the left ventricle, decreased myocardial perfusion in the posterior wall myocardium and elevated myocardial troponin-T and creatine phosphokinase levels. However, coronary computed tomography angiography did not identify arterial stenosis. The patient did have an increased perivascular fat attenuation index, indicating coronary inflammation. Moreover, the fat attenuation index was higher around the left circumflex artery than around the right coronary artery or left anterior descending artery. Intravascular ultrasonography identified an intramural haematoma, leading to a diagnosis of type 3 spontaneous coronary artery dissection in the left circumflex artery.

CONCLUSIONS

Perivascular fat attenuation index may be a useful tool to help identify and localise disease-causing lesions, and to direct further testing to confirm a diagnosis of spontaneous coronary artery dissection in acute coronary syndrome patients without significant arterial stenosis.

In Vivo Based Fluid-Structure Interaction Biomechanics of the Left Anterior Descending Coronary Artery

A fluid-structure interaction-based biomechanical model of the entire left anterior descending coronary artery is developed from in vivo imaging via the finite element method in this paper. Included in this investigation is ventricle contraction, three-dimensional motion, all angiographically visible side branches, hyper/viscoelastic artery layers, non-Newtonian and pulsatile blood flow, and the out-of-phase nature of blood velocity and pressure. The fluid-structure interaction model is based on in vivo angiography of an elite athlete's entire left anterior descending coronary artery where the influence of including all alternating side branches and the dynamical contraction of the ventricle is investigated for the first time. Results show the omission of side branches result in a 350% increase in peak wall shear stress and a 54% decrease in von Mises stress. Peak von Mises stress is underestimated by up to 80% when excluding ventricle contraction and further alterations in oscillatory shear indices are seen, which provide an indication of flow reversal and has been linked to atherosclerosis localization. Animations of key results are also provided within a video abstract. We anticipate that this model and results can be used as a basis for our understanding of the interaction between coronary and myocardium biomechanics. It is hoped that further investigations could include the passive and active components of the myocardium to further replicate in vivo mechanics and lead to an understanding of the influence of cardiac abnormalities, such as arrythmia, on coronary biomechanical responses.

The Emerging Role of CT-Based Imaging in Adipose Tissue and Coronary Inflammation

A large body of evidence arising from recent randomized clinical trials demonstrate the association of vascular inflammatory mediators with coronary artery disease (CAD). Vascular inflammation localized in the coronary arteries leads to an increased risk of CAD-related events, and produces unique biological alterations to local cardiac adipose tissue depots. Coronary computed tomography angiography (CTA) provides a means of mapping inflammatory changes to both epicardial adipose tissue (EAT) and pericoronary adipose tissue (PCAT) as independent markers of coronary risk. Radiodensity or attenuation of PCAT on coronary CTA, notably, provides indirect quantification of coronary inflammation and is emerging as a promising non-invasive imaging implement. An increasing number of observational studies have shown robust associations between PCAT attenuation and major coronary events, including acute coronary syndrome, and 'vulnerable' atherosclerotic plaque phenotypes that are associated with an increased risk of the said events. This review outlines the biological characteristics of both EAT and PCAT and provides an overview of the current literature on PCAT attenuation as a surrogate marker of coronary inflammation.

Lack of Association of Spontaneous Coronary Artery Dissection With Autoimmune Disease

BACKGROUND

Case reports and referral-based studies suggest spontaneous coronary artery dissection (SCAD) is associated with autoimmune diseases and causes 2% to 4% of acute coronary syndromes.

OBJECTIVES

This study determined the association of SCAD with autoimmune diseases, together with incidence and recurrence, in a population-based study.

METHODS

This case-control study took place from 1995 to 2018 within the Rochester Epidemiology Project. The study identified cases with SCAD from diagnosis codes and verified them using coronary angiography images, matching each case to 3 control subjects on age, sex, county, and years of medical history. Autoimmune disease history came from a validated, code-based definition. A multivariable logistic regression model calculated the odds ratio (OR) for SCAD among patients with a history of autoimmune disease, adjusting for race and body mass index.

RESULTS

The study identified 114 cases with SCAD (mean age 51 years and 90% women) and 342 matched control subjects. Autoimmune disease occurred in 13 (11%) cases with SCAD and 40 (12%) control subjects (p = 0.93). Even after adjustment, autoimmune diseases were not associated with SCAD (OR: 0.81; 95% confidence interval [CI]: 0.40 to 1.66). SCAD incidence between 2010 and 2018 (2.7 per 100,000; 95% CI: 1.7 to 3.7) was 10-fold higher than the incidence between 1995 and 2009 (0.3 per 100,000; 95% CI: 0.0 to 0.6). SCAD recurrence was 10% (95% CI: 3% to 16%) at 5 years.

CONCLUSIONS

These findings suggested SCAD pathogenesis is noninflammatory and screening for autoimmune diseases based on SCAD alone is not warranted. The code-based incidence of SCAD has increased over time, highlighting the importance of considering SCAD among patients with acute coronary syndromes.