ARTERIES OF LOW EXTRAMITAS
It is estimated that in 2016 around 120 million people were afflicted
with lower extremity PAD and as much as 48% of them could have CAD or
other CVD 51. Moreover, PAD can lead to acute limb
ischemia, amputation, or even death. It is often caused by
atherosclerotic plaque in the lower extremity artery (LEA) and
classically it manifests as cramping and pain, which is alleviated by
rest. These symptoms may present in different areas depending on the
afflicted artery or be completely absent. Among risk factors of PAD, we
can find many cardiovascular risks factors like age, tobacco usage,
hypertension, and diabetes mellitus 52. The interest
of researchers in LEA was usually directed toward femoral bifurcation
and common femoral and superficial femoral arteries. The range of
examinations differed from paper to paper, but most of the time was
between 1-2 cm proximally and distally from bifurcation. Sometimes,
other arteries like popliteal and tibial were described.
Khoury et al. showed that patients with CAD with extra coronary arteries
assessed by the US had a significantly higher incidence of
atherosclerotic plaques in the femoral arteries than those with normal
coronary arteries (77% vs. 42%) 9. Moreover, the
risk of CAD was significantly associated with femoral plaques (OR 5.6,
p=0.02). Cho et. al observed a high prevalence of asymptomatic CAD in
patients with lower extremity PAD 53. The prevalence
of CAD in patients with PAD was 62%, and only 13% of them had angina
and 72% had multi-vessel disease. Diabetes significantly increased the
risk of CAD in patients with PAD and the odds risk (OR) of having
multi-vessel CAD was 2.5 (1.1-5.9, p=0.037). In another study, Kumar et
al. rated the sensitivity of PAD in predicting coronary artery stenosis
as 80%, the specificity as 82%, and the accuracy as 81%54. The Peripheral Arterial Disease in Interventional
Patients Study (PIPS), a prospective cohort study revealed, that among
patients who had confirmed CAD by CA (n=5745), those with PAD had a
higher prevalence of left main and multivessel CAD (87.2% vs. 75.5%,
p=0.006), and previous coronary artery bypass surgery (CABG) (35.8% vs.
23.1%, p=0.008) 55. In post mortem study authors
found among patients who died for stroke significant correlations
between the deep femoral artery and left anterior descendent coronary
arteries (r=0.513; p=0.012) 39.
During a 10-year follow-up observation after performing an ultrasound
examination of carotid and femoral bifurcations, there was no CVE in the
group with a completely normal ultrasonographical image of those
arteries 56. With increased severity of lesions risk
of both progression to more advanced group and CVE grew. Worth noting is
that 68% of registered CVEs in the study group were myocardial
infarctions (MI). In another observational study, femoral plaques were
presented as an individual risk factor of CVE 57.
Unfortunately, some research came to different conclusions as only
irregular surface and ulcerations of plaques in common femoral arteries
were found to be the sole predictors of major adverse CVE58. Classical cardiovascular risk (CVR) factors
corresponded with the presence of subclinical atherosclerosis in femoral
arteries. Femoral plaques alone are strongly associated with CCT-
assessed CACS, however, adding CVR factors and carotid plaques to the
model diagnostic OR was further increased 59.
Traditional risk factors including previous CVE were also associated
with the Ultrasonographic Lower Limbs Atherosclerosis (ULLA) score
calculated during an ultrasonographical examination of LEA from
femoropopliteal to para malleolar region 60. This way
of examining patients is better in detecting PAD than the ankle-brachial
index (ABI) 61. US assessment of femoral total plaque
area (TPA), maximal plaque height (MPH), and IMT associated with
severity of CAD detected by CA 62-64. Examination of
femoral TPA had the biggest sensitivity of detecting CAD and was a
better method than calculating ABI 62. However, we
must bear in mind that reproducibility of IMT results is worse in older,
and patients afflicted with CVDs. Moreover, it also decreases, when IMT
increases 65. Another study noticed that the best way
of assessing the risk may be sex- dependent. In women, the most
important risk factor was femoral TPA, but in men, it was femoral MPH.
However, in both women and men, the most representative lesions were
localized in the proximal femoral artery 66. The
elevated CVD risk is only partially attributable to shared CVD risk
factors, such that at any given level of CVD risk factors, PAD is
independently related to future CVD events and mortality67. PAD has also been shown to be predictive of future
CVD events even when adjusted for other markers of subclinical
atherosclerosis 68.