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Page 4 of 17 Arisha et al. Vessel Plus 2018;2:14 I http://dx.doi.org/10.20517/2574-1209.2018.29

dose. In contrary, relative increase in total body fat resulted from reduction of adipose-free body mass in
elderly people leads to increased volume of distribution of fat-soluble medications such as lidocaine and
prolongation of their half-life . Another issue is that the recommended use of dual antiplatelet therapy
[21]
(DAPT) in the elderly PCI patients has many additional complications which may influence the choice
of the stent and the mode of management of these patients, including; higher risk of bleeding, need for
concomitant warfarin therapy for atrial fibrillation, the increased likelihood of having future non-cardiac
surgery, and the increased risk of falls . When added to therapy, anti-coagulants dosing is also altered
[13]
with advanced age. It has been shown that old age is usually associated with a lower warfarin maintenance
dose with patients aged 80 to 89 years usually requiring only half of a total weekly dose (TWD) of warfarin
compared to patients aged between 20 and 59 years .
[22]

HEMATOLOGICAL AND VASCULAR CHANGES
A lot of changes that occur with aging may cause the elderly to paradoxically experience hemorrhagic or
thrombotic complications after PCI. Age is a significant independent predictor of major bleeding in ACS
patients who had PCI and it is associated with higher in-hospital mortality rates . Case fatality has been
[23]
shown to be more than 18% in patients who experienced any major bleeding following PCI while 5% in
patients without major bleeding . Interestingly, thrombotic complications such as stent thrombosis and
[23]
restenosis occurred more frequently with advanced age as well. In a previous study, 47% of all patients
aged 75 years and older who had PCI with stenting experienced a 50% or more restenosis at the stent site
or adjacent to it compared to only 28% in younger patients. Also, older patients experienced more diffuse
restenosis (1 cm or more in length) than their younger counterparts . Increased risk of bleeding in elderly
[24]
can be explained by several hematological alterations such as higher level of tissue plasminogen activator
(tPA) , lower platelets aggregation , and the presence of more advanced and complicated vascular disease
[26]
[25]
with more local changes, more atherosclerosis and hypertension . In contrary, older people have a higher
[23]
blood viscosity, higher activity of several coagulation factors, and a lower fibrinolytic activity as it has been
proven that plasminogen activator inhibitor (PAI-1) level increases with age [27,28] . These changes cause a
prothrombotic state in older patients that potentially increases risk of post-PCI thrombotic complications as
well. In addition, aging is associated with impairment of vascular structure and endothelial function caused
by several interacting histological and molecular alterations such as increased collagen content, smooth
muscle changes, and altered composition of the extracellular matrix of the arterial wall. This can lead to
a gradual decrease in elastic fibers, arterial wall rigidity, and increased risk of atherosclerosis and arterial
thrombosis . Many PCI-related vascular complications such as large hematomas in femoral regions,
[28]
pseudoaneurysms, and arteriovenous fistulas have been also associated with advanced age . Also, the
[29]
gradual impairment of endothelial cells function that occur with aging leads to lower production of nitric
oxide and prostacyclin which play an important role in promoting vasodilatation as well as preventing
platelets aggregation [28,30] .

CORONARY LESIONS COMPLEXITY
Older patients usually have more complex and advanced coronary lesions which make PCI procedures more
difficult with a higher risk of complications and a lower chance of procedure success. Batchelor et al. compared
[31]
the angiographic characteristics of 7472 octogenarian patients with 102,236 younger others undergoing PCI.
Older patients had more left main coronary artery (LMCA) and proximal left anterior descending (LAD) lesions
than patients aged 79 and younger, 7.3% vs. 5.7% (P < 0.01) and 24% vs. 20% (P < 0.01), respectively. In a different
sample of patients, the angiographic characteristics based on the modified ACC/AHA criteria revealed that
863 out of 2551 (33.8%) patients aged less than 75 years had coronary lesions of type B1 or less, in contrast to
only 37 out of 137 (27%) patients aged 75 years or more (P = 0.002). On the other hand, lesion types B2 and
C were more prevalent in older than younger patients, 72% vs. 65% (P = 0.002), respectively . Older patients
[24]
had a higher number of affected vessels as well, as 55% of patients aged 75 or more had 3 diseased coronary