Association between spontaneous internal carotid artery dissection and perivascular adipose tissue attenuation on computed tomography angiography.

BACKGROUND: Spontaneous cervical artery dissection (sCAD) is a leading cause of ischemic stroke in young patients. Studies using high-resolution magnetic resonance imaging and positron emission tomography have suggested vessel wall inflammation to be a pathogenic factor in sCAD. Computed tomography (CT) attenuation of perivascular adipose tissue (PVAT) is an established non-invasive imaging biomarker of inflammation in coronary arteries, with higher attenuation values reflecting a greater degree of vascular inflammation. OBJECTIVES: We evaluate the CT attenuation of PVAT surrounding the internal carotid artery (PVATcarotid) with and without spontaneous dissection. METHODS: Single-center prospective observational study of 56 consecutive patients with CT-verified spontaneous dissection of the internal carotid artery (ICA). Of these patients, six underwent follow-up computed tomography angiography (CTA). Twenty-two patients who underwent CTA for acute neurological symptoms but did not have dissection formed the control group. Using semi-automated research software, PVATcarotid was measured as the mean Hounsfield unit (HU) attenuation of adipose tissue within a defined volume of interest surrounding the ICA. RESULTS: PVATcarotid was significantly higher around dissected ICA compared with non-dissected contralateral ICA in the same patients (-58.7 ± 10.2 vs -68.9 ± 8.1 HU, p < 0.0001) and ICA of patients without dissection (-58.7 ± 10.2 vs -69.3 ± 9.3 HU, p < 0.0001). After a median follow-up of 89 days, there was a significant reduction in PVATcarotid around dissected ICA (-57.5 ± 13.4 to -74.3 ± 10.5 HU, p < 0.05), while no change was observed around non-dissected contralateral ICA (-71.0 ± 4.4 to -74.1 ± 4.1 HU, p = 0.19). ICA dissection was an independent predictor of PVATcarotid following multivariable adjustment for age and the presence of ICA occlusion. CONCLUSION: PVATcarotid is elevated in the presence of sCAD and may decrease following the acute event.

The utility of coronary computed tomography angiography in elderly patients.

BACKGROUND: Coronary computed tomography angiography (CCTA) is often avoided in elderly patients due to a presumption that a high proportion of patients will have heavily calcified plaque limiting an accurate assessment. We sought to assess the image quality, luminal stenosis and utility of CCTA in elderly patients with suspected coronary artery disease (CAD) and stable chest pain. METHODS: Retrospective analysis of elderly patients (> 75 years) who underwent 320-detector row CCTA between 2012-2017 at MonashHeart. The CCTA was analysed for degree maximal coronary stenosis by CAD-RADS classification, image quality by a 5-point Likert score (1-poor, 2-adequate, 3-good, 4-very good, 5-excellent) and presence of artefact limiting interpretability. RESULTS: 1011 elderly patients (62% females, 78.8 ± 3.3 years) were studied. Cardiovascular risk factor prevalence included: hypertension (65%), hyperlipidaemia (48%), diabetes (19%) and smoking (21%). The CCTA was evaluable in 68% of patients which included 52% with non-obstructive CAD (< 50% stenosis), 48% with obstructive CAD (> 50%) stenosis. Mean Likert score was 3.1 ± 0.6 corresponding to good image quality. Of the 323 (32%) of patients with a non-interpretable CCTA, 80% were due to calcified plaque and 20% due to motion artefact. Male gender (P = 0.009), age (P = 0.02), excess motion (P < 0.01) and diabetes mellitus (P = 0.03) were associated with non-interpretable CCTA. CONCLUSION: Although CCTA is a feasible non-invasive tool for assessment of elderly patients with stable chest pain, clinicians should still be cautious about referring elderly patients for CCTA. Patients who are male, diabetic and >78 years of age are significantly less likely to have interpretable scans.

Remnant cholesterol and coronary atherosclerotic plaque burden assessed by computed tomography coronary angiography.

BACKGROUND AND AIMS: There remains a substantial residual risk of ischaemic heart disease (IHD) despite optimal low-density lipoprotein cholesterol (LDLC) reduction. Part of this risk may be attributable to remnant cholesterol, which is carried in triglyceride-rich lipoproteins. We evaluated the relationship between remnant cholesterol and coronary atherosclerotic plaque burden assessed non-invasively by computed tomography coronary angiography (CTCA) in patients with suspected coronary artery disease (CAD). METHODS AND RESULTS: This was a multicentre study of 587 patients who had a CTCA and fasting lipid profile within 3 months. Calculated remnant cholesterol was total cholesterol minus LDLC minus high-density lipoprotein cholesterol (HDLC). Significant coronary atherosclerotic burden was defined as CT-Leaman score >5 (CT-LeSc), an established predictor of cardiac events. Mean age was 61 ±â€¯12 years and mean pretest probability of CAD was 23.2 ±â€¯19.8%. LDLC levels were <1.8 mmol/L in 134 patients (23%), of whom 82% were statin-treated. Patients with CT-LeSc >5 had higher mean remnant cholesterol than those with CT-LeSc ≤5 (0.76 ±â€¯0.36 mmol/L vs. 0.58 ±â€¯0.33 mmol/L, p = 0.01). On univariable analysis, remnant cholesterol (p = 0.01), LDLC (p = 0.002) and HDLC (p < 0.001) levels predicted CT-LeSc >5, whilst triglycerides (p = 0.79) had no association with CT-LeSc >5. On multivariable analysis in the subset of patients with optimal LDLC levels, remnant cholesterol levels remained predictive of CT-LeSc >5 (OR 3.87, 95% confidence interval 1.34-7.55, p = 0.004), adjusted for HDLC and traditional risk factors. CONCLUSIONS: Remnant cholesterol levels are associated with significant coronary atherosclerotic burden as assessed by CTCA, even in patients with optimal LDLC levels. Future studies examining whether lowering of remnant cholesterol can reduce residual IHD risk are warranted.

The deleterious effects of arteriovenous fistula-creation on the cardiovascular system: a longitudinal magnetic resonance imaging study.

AIM: Arteriovenous fistula-formation remains critical for the provision of hemodialysis in end-stage renal failure patients. Its creation results in a significant increase in cardiac output, with resultant alterations in cardiac stroke volume, systemic blood flow, and vascular resistance. The impact of fistula-formation on cardiac and vascular structure and function has not yet been evaluated via "gold standard" imaging techniques in the modern era of end-stage renal failure care. METHODS: A total of 24 patients with stage 5 chronic kidney disease undergoing fistula-creation were studied in a single-arm pilot study. Cardiovascular magnetic resonance imaging was undertaken at baseline, and prior to and 6 months following fistula-creation. This gold standard imaging modality was used to evaluate, via standard brachial flow-mediated techniques, cardiac structure and function, aortic distensibility, and endothelial function. RESULTS: At follow up, left ventricular ejection fraction remained unchanged, while mean cardiac output increased by 25.0% (P<0.0001). Significant increases in left and right ventricular end-systolic volumes (21% [P=0.014] and 18% [P<0.01]), left and right atrial area (11% [P<0.01] and 9% [P<0.01]), and left ventricular mass were observed (12.7% increase) (P<0.01). Endothelial-dependent vasodilation was significantly decreased at follow up (9.0%±9% vs 3.0%±6%) (P=0.01). No significant change in aortic distensibility was identified. CONCLUSION: In patients with end-stage renal failure, fistula-formation is associated with an increase in cardiac output, dilation of all cardiac chambers and deterioration in endothelial function.