Time-dependent differences in femoral artery plaque characteristics of peripheral arterial disease patients

Epidemiology of atherosclerotic cardiovascular disease in polygenic hypercholesterolemia with or without high lipoprotein(a) levels

Background and aims

Epidemiology of atherosclerotic cardiovascular disease might be different in patients with polygenic hypercholesterolemia plus high levels (≥30 mg/dl) of Lp(a) (H-Lpa) than in those with polygenic hypercholesterolemia alone (H-LDL). We compared the incidence of peripheral artery disease (PAD), coronary artery disease (CAD), and cerebrovascular disease (CVD) in patients with H-Lpa and in those with H-LDL.

Methods

Retrospective analysis of demographics, risk factors, vascular events, therapy, and lipid profile in outpatient clinical data. Inclusion criteria was adult age, diagnosis of polygenic hypercholesterolemia, and both indication and availability for Lp(a) measurement.

Results

Medical records of 258 patients with H-Lpa and 290 H-LDL were reviewed for occurrence of vascular events. The median duration of follow-up was 10 years (IQR 3-16). In spite of a similar reduction of LDL cholesterol, vascular events occurred more frequently, and approximately 7 years earlier (P = 0.024) in patients with H-Lpa than in H-LDL (HR 1.96 1.21-3.17, P = 0.006). The difference was around 10 years for acute events (TIA, Stroke, acute coronary events) and one year for chronic ones (P = 0.023 and 0.525, respectively). Occurrence of acute CAD was higher in H-Lpa men (HR 3.1, 95% CI 1.2-7.9, P = 0.007) while, among women, PAD was observed exclusively in H-Lpa subjects with smoking habits (P = 0.009).

Conclusions

Patients with high Lp(a) levels suffer from a larger and earlier burden of the disease compared to those with polygenic hypercholesterolemia alone. These patients are at higher risk of CAD if they are men, and of PAD if they are women.

Characteristics of atherosclerosis in femoropopliteal artery and its clinical relevance

Atherosclerosis is a systemic disease with different faces. Despite identical or similar pathogenetic mechanisms, atherosclerotic lesions and their clinical manifestations vary in different parts of the vascular system. Peripheral arterial disease (PAD) represents one of the most frequent clinical manifestations of atherosclerosis with predominant location in the superficial femoral artery (SFA). Morphological characteristics of atherosclerotic plaques in peripheral arteries differ from lesions in the coronary and carotid arteries. Plaques in SFA have more fibrotic components, less lipids and inflammatory cells, which makes them more stable and less prone to rupture. Factors that determine the different structure of plaques in SFA compared to coronary arteries include hemodynamic forces, vasa vasorum and calcification. Low shear stress in SFA in the adductor canal is one of the factors which determines frequent atherosclerotic lesions in this region. Lower lipid content and fewer inflammatory cells explain higher stability of SFA plaques. The specific structure of SFA plaques may require preventive and therapeutic measures, which to some extent differ from prevention of coronary atherosclerosis and may include inhibition of fibrotic proliferation in SFA plaques and calcification. Revascularization of PAD differs from procedures used in coronary arteries and requires specific technical expertise and devices.

Calcifying characteristics of peripheral vascular smooth muscle cells of chronic kidney disease patients with critical limb ischemia

The role of vascular smooth muscle cells (VSMCs) in vascular calcification, which is related to chronic kidney disease (CKD), has been studied in greater detail in the major arteries relative to the peripheral arteries. We compared the calcifying characteristics of peripheral VSMCs relative to non-pathologic major VSMCs in patients with severe peripheral artery disease (PAD). We isolated peripheral VSMCs from the posterior tibial artery of 10 patients with CKD who underwent below-knee amputation for critical limb ischemia (CLI). Using normal human aortic VSMCs as a control group, we cultured the cells in normal and high phosphate media for 10 days, and subsequently tested by immunofluorescence staining. We compared the calcification levels between the two groups using various assays, tests for cell viability, and scanning electron microscopy. As a result, calcification of pathologic peripheral VSMCs increased significantly with time (p = 0.028) and was significantly higher than that in human aortic VSMCs in calcium assays (p = 0.043). Dead cells in the pathologic VSMC group were more distinct in high phosphate media than in human aortic VSMCs. In conclusion, VSMCs from the peripheral artery of patients with severe CKD and CLI who underwent amputation surgery showed marked calcifying characteristics compared to normal human aortic VSMCs.

The Impact of Diabetes and Time on the Atherosclerotic Plaque and Cardiovascular Outcome in Patients Undergoing Iliofemoral Endarterectomy

OBJECTIVE

The incidence of diabetes is rapidly increasing and diabetes is associated with an increased risk of peripheral artery disease. Recent studies have shown a time dependent decline in vulnerable plaque features and secondary cardiovascular events in iliofemoral endarterectomy (IFE) patients. IFE patients with diabetes have a high risk of cardiovascular events. It is not known, however, whether vulnerable plaque features and cardiovascular events reduce over time in IFE patients with diabetes.

METHODS

Between 2003 and 2014, 691 atherosclerotic plaques were obtained by IFE, from 212 patients with and 479 patients without diabetes. Plaques were immunohistochemically stained and analysed for the presence of intraplaque haemorrhage, lipid core, calcification, collagen, smooth muscle cells, and macrophages. Patients were stratified according to their diabetic status and year of inclusion. All patients had a follow up of three years in which cardiovascular adverse events were recorded.

RESULTS

A time dependent decrease was observed in intraplaque haemorrhage, plaque lipid core, and percentage of macrophages in IFE patients with diabetes. After multivariable correction for changes in risk factors over time, intraplaque haemorrhage (64.2% [2002-2005] vs. 39.6% [2012-2014], p = .01) became significantly less prevalent. Interestingly, the percentage of severely calcified plaques remained high over time. The number of secondary events decreased over time in patients without diabetes (HR 1.80, 95% CI 1.15-2.81 (p = .010) for 2002-2005 vs. 2012-2014), but remained high and unchanged in patients with diabetes.

CONCLUSION

In patients with diabetes undergoing IFE, a time dependent stabilisation of atherosclerotic plaque features was found in line with previous observations in patients with severe atherosclerosis. The presence of severely calcified lesions remained high and unchanged. The secondary event rate remained high in patients with diabetes in contrast to a significant decrease in patients without diabetes. These findings stress the need for improvement of care in IFE patients with diabetes.

Magnetic resonance imaging characteristics of lesions relate to the difficulty of peripheral arterial endovascular procedures

OBJECTIVE

Limitations with current peripheral arterial imaging modalities make selection of patients for percutaneous vascular interventions difficult. The purpose of this study was to determine whether a novel preprocedural magnetic resonance imaging (MRI) method can identify lesions that would be more challenging to cross during percutaneous vascular intervention.

METHODS

Fourteen patients with peripheral arterial disease underwent MRI before their intervention. A novel steady-state free precession flow-independent magnetic resonance (MR) angiogram was used to locate lesions, and an ultrashort echo time image was used to characterize hard lesion components including calcium and dense collagen. Lesions were characterized as hard if ≥50% of the lumen was occluded with calcium or collagen (as determined by MR image characteristics) in the hardest cross section within the lesion. The primary outcome was the time it took to cross a guidewire through the target lesion. The secondary outcome was the need for stenting.

RESULTS

Of 14 lesions, 8 (57%) were defined as hard and 6 (43%) were soft on the basis of MR image characteristics. Hard lesions took significantly longer to cross than soft lesions (average, 14 minutes 49 seconds vs 2 minutes 17 seconds; P = .003). Hard lesions also required stenting more often than soft lesions (Fisher exact test, P = .008). Of 14 lesions, 2 (14%) could not be crossed with a guidewire, and both lesions were hard. MR images also detected occult patencies and noncalcified hard lesions that could not be seen on X-ray angiography.

CONCLUSIONS

MRI can be used to determine which peripheral arterial lesions are more difficult to cross with a guidewire. Future work will determine whether MRI lesion characterization can predict long-term endovascular outcomes to aid in procedure planning.

Time-dependent trends in cardiovascular adverse events during follow-up after carotid or iliofemoral endarterectomy

BACKGROUND

Recent observations have suggested a decline in vulnerable carotid artery and iliofemoral atherosclerotic plaque characteristics over the past decade. The aim of this study was to determine whether, in the presence of clinically manifest carotid or peripheral artery disease, secondary adverse cardiovascular events decreased over this period.

METHODS

Patients included in the Athero-Express biobank between 2003 and 2012 were analysed. During 3-year follow-up, composite cardiovascular endpoints were documented yearly, including: myocardial infarction, coronary interventions, stroke, peripheral interventions and cardiovascular death. The major cardiovascular endpoint consisted of myocardial infarction, stroke and cardiovascular death.

RESULTS

Some 1684 patients who underwent carotid endarterectomy (CEA) and another 530 who had iliofemoral endarterectomy (IFE) were analysed. In total, 405 (25·2 per cent) and 236 (45·9 per cent) patients had a composite cardiovascular endpoint within 3 years after CEA and IFE respectively. Corrected for possible confounders, the percentage of patients with a secondary cardiovascular event after CEA did not change over time (hazard ratio (HR) 0·91, 95 per cent c.i. 0·65 to 1·28; P = 0·590, for 2011-2012 versus 2003-2004). In patients who had IFE, the incidence of secondary cardiovascular events significantly decreased only in the last 2 years (HR 0·62, 0·41 to 0·94; P = 0·024), owing to a decrease in peripheral (re)interventions in 2011-2012 (HR 0·59, 0·37 to 0·94; P = 0·028). No decrease in major cardiovascular events was observed in either group.

CONCLUSION

In patients who had undergone either CEA or IFE there was no evidence of a decrease in all secondary cardiovascular events. There were no differences in major cardiovascular events.