aortic valve stenosis ( as ) is a common valvular disease in the western world .
as the geriatric population has grown , so too has the number of patients presenting with symptomatic aortic valve disease because its prevalence increases with age .
surgical aortic valve replacement ( savr ) has produced significant results that have been well documented for elderly patients , including improved life expectancy , cardiovascular symptoms , and quality of life .
, yet , up to one - third of elderly patients with severe as have been excluded from surgery . not surprisingly , advanced age has been a leading barrier to surgical intervention in elderly patients .
this is based on the peri - operative mortality rate which is found to increase with age from 1.3% in patients  70 years old , to about 5% at age 80 - 85 years , and 10% in patients  90 years old .
, it is important , though , to realize that age , per se , is not a predictor of poor outcomes of surgery , and those patients usually enjoy the same survival rates within their age and gender matched population . to help bridge this gap in care ,
medical innovations such as transcatheter aortic valve implantation ( tavi ) have emerged as a new treatment option which improves the clinical course of as without high surgical risk .
tavi includes the insertion of a prosthetic valve into the stenotic aortic valve through a vascular access without the need for open heart surgery .
two valves are commonly used for this procedure : the edwards sapien valve which is a balloon expandable valve and the core valve which is a self - expanding one .
they may also be placed via other arteries such as the axillary artery or directly through the cardiac apex in patients with stenosed iliac and femoral arteries .
tavi is strongly indicated for symptomatic as patients with multiple comorbidities , or high operative risk [ i.e. , expected mortality > 20% with the european system for cardiac operative risk evaluation score ( euroscore ) or > 10% with the society of thoracic surgeons score ( sts ) ] , as long as life expectancy is a year or more .
pre - procedure multidisciplinary assessment is important for the appropriate selection of patients to undergo tavi .
the team usually includes cardiologists , cardiothoracic surgeons , cardiac anesthesiologists , interventional cardiologists and imaging specialists .
cardiac imaging should assess not only the severity of aortic stenosis , but also morphometric characteristics like the diameter of the aortic root , the conformation of the aortic valve and annulus , and area of valve calcification to ensure that the most appropriate valve is implanted , and that the procedure is likely to be successful .
assessment for atherosclerosis of both coronary and peripheral arteries is also important to identify patients at risk for perioperative complications and to select the optimal site for access .
following tavi , an immediate and sustained improvement in aortic valve area , trans - valvular gradient , and left ventricular ejection fraction were reported. these changes were associated with an enhancement in patients ' physical and mental functioning , as well as their quality of life .
, however , frail elderly patients were found to have smaller gains in functional status after tavi and they may require multidisciplinary interventions , such as nutrition consultation and exercise - training programs , to achieve desired outcomes . due to the mentioned hemodynamic and functional effects of tavi , the early and midterm survival in patients with as has significantly improved as shown in moat , et al .
study , who reported life expectancy rates of 92.9% , 78.6% and 73.7% at 30 days , 1 year and 2 years after tavi , respectively .
studies have shown that transfemoral approach is associated with better survival rates compared to other vascular accesses .
this , however , is still controversial because patients who are referred to transapical or transaxillary approaches usually have higher risk profiles which explains the increased mortality after these procedures .
as discussed earlier , both tavi and savr have achieved significant improvements in survival rates as well as other outcomes in patients with severe aortic stenosis .
studies have shown that savr can be performed in elderly patients with acceptable morbidity and mortality rates .
the question then becomes , can tavi be trusted as a safe and effective alternative to surgical management in elderly patients ? of the studies that looked at the outcomes of tavi compared to savr , we specifically reviewed the trials where average age of patients who underwent both procedures was  80 years .
only 8 studies were found ( 5 observational studies and 3 randomized controlled trials ) and summarized in ( table 1). in these studies , elderly individuals who underwent tavi experienced better in - hospital recovery , and similar short and mid - term mortality compared to those underwent savr ( table 1 ) .
one of the most important studies is the placement of aortic transcatheter valves ( partner ) trial which was a multicenter , randomized trial that compared tavi to surgical management and medical therapy in 1,057 as patients . in this study , patients were divided into two cohorts : group a which included those with high surgical risk ( the mean age of this group was 84 years old ) , and group b which included those who were not considered to be appropriate candidates for surgery ( the mean age was 83 years old ) . in the high - risk partner trial cohort a , mortality at 30 days was 3.4% in the tavi group , compared to 6.5% in the savr group ( p = 0.07 ) . at the 1-year and 2-year follow - up , mortality was 24.2% and 33.9% with tavi vs. 26.8% and 35.0% in the savr groups , respectively ( p = 0.44 , p = 0.78 , respectively ) .
, partner trial also showed that the incidences of stroke , myocardial infarction , acute kidney injury ( aki ) , endocarditis , and pacemaker placement at one and two years after tavi and savr were comparable .
, however , patients who underwent savr experienced more major bleedings , and less major vascular injuries compared to those treated with tavi .
the authors concluded that tavi is not - inferior to savr as a treatment of as in high risk surgery patients .
another randomized controlled study was the staccato trial which initially planned to assign 200 patients ( age > 75 years ) to either tavi vs. savr .
however , after the inclusion of 70 patients , the trial was prematurely terminated due to unexpectedly poor outcomes in the tavi cohort .
authors of this trial concluded that current indications for tavi should remain restricted only to surgically inoperable patients .
only a few studies have focused on elderly patients with intermediate or low risk for procedural complications .
these include the surgical replacement and transcatheter aortic valve implantation ( surtavi ) trial and the observant trial .
the surtavi investigators prospectively enrolled patients with symptomatic severe aortic stenosis and intermediate surgical risk ( sts score between 3% and 8% ) to either tavi or savr .
all - cause mortality at 30 days ( 7.8% vs. 7.1% , p = 0.74 ) and 1 year ( 16.5% vs.16.9% , p = 0.64 ) was comparable between the two groups .
the italian observant study reported similar 30 days mortality for its intermediate risk , propensity - matched subgroups .
differences in rates of blood transfusion ( higher in savr ) , vascular damage , permanent atrioventricular block , and residual aortic valve regurgitation ( all higher in tavi ) were reported .
f / u : duration of follow up ; mo : months ; os : observational study ; rct : randomized controlled trial ; savr : surgical aortic valve replacement ; tavi : transcatheter aortic valve implantation .
lastly , while the early and mid - term survival rates seem comparable in tavi and savr in most of the outlined studies , not much is known about long - term outcomes of tavi in elderly patients .
observations by holzhey , et al . showed that kaplan - meier curves diverged between tavi and savr patients after 6 months in favor of conventional surgery .
follow - up studies , therefore , are necessary to assess whether tavi will remain a comparable approach to savr on long - term basis as well .
given the growing geriatric population in the western countries , more and more of nonagenarians are expected to undergo tavi as the principal treatment for severe as . yet
, relatively few studies have examined the outcomes of this procedure in very old patients .
jabs , et al . have reported their experience with a 99 year old as patient who underwent tavi after presenting with syncope and progressive dyspnea .
following tavi , aortic valve area improved from 0.6 cm to 1.5 cm and the patient was discharged to a geriatric rehabilitation unit 2 days after the procedure . for the next four years , the patient remained independent , with mild exertional dyspnea , and without recurrent syncopes .
transesophageal echocardiography at 3.5 years follow - up showed aortic valve area of 1.5 cm with persistent optimal positioning of the implanted valve . a recent swedish study reviewed post - procedure mortality in 29 nonagenarian patients who underwent tavi between 2008 and 2011 .
one - year , two years , and three years mortality were found as 11% , 28% , and 40% , respectively .
the available literature shows only three trials that studied the outcomes of tavi in very old patients comparing to younger patients .
all of these studies were observational and no randomized controlled trials were identified as shown in table 2. in a study of 1,386 patients who underwent tavi at ages ranging between 4099 years , the researchers divided the patients into four age groups and analyzed the outcome of tavi in each group . despite the difference in the groups ' characteristics , all groups , including the oldest one , showed immediate and marked improvement of the hemodynamic valve status , functional status , and overall quality of life .
also , each group had similar rates of technical success and 30 day all - cause mortality regardless of age .
havakuk , et al . evaluated 293 patients who underwent tavi ( patients ' age ranged between 63 and 98 years and average age was 83 years ) .
the cohort was divided depending on age into 2 groups : younger vs. older than 85 years .
older patients experienced length of in - hospital stay , readmission rates , and 30-day mortality similar to those reported in younger patients . however , overall mortality rate during the entire follow - up ( median 480 days , interquartile range 330 to 770 days ) was higher in the older age group . in another study ,
yamamoto et al . compared the clinical outcomes of tavi in patients  90 years old to patients  90 years old and found similar procedural success in both groups .
although 30-day and 6-month mortality trended to be higher in patients older than 90 years old , the differences in mortality rates were statically insignificant ( 6% vs. 15% , p = 0.22 ; and 14% vs. 27% , p = 0.14 , respectively ) . moreover , the cumulative survival after 13.4  8.0 months of follow - up was comparable between both groups ( p = 0.22 ) .
bmi : body mass index ; cabg : coronary artery bypass graft ; copd : chronic obstructive pulmonary disease ; dm : diabetes mellitus ; hf : heart failure ; icu : intensive care unit ; mi : myocardial infarction ; nyha : new york heart association ; os : observational study ; tavi : transcatheter aortic valve implantation . in conclusion
, the available literature gives an impression that tavi is a beneficial and tolerable procedure in very old patients with severe as .
this hypothesis , however , still needs further testing in randomized controlled trials in order to be confirmed .
although tavi has a high success rate with few surgical complications , it still carries risks .
common procedure complications include vascular injuries , bleeding , stroke , atrioventricular conduction system injuries , aki , and aortic regurgitation .
complication rates differ with operator experience , the size of the device , the site of catheter access , as well as the use of pre - procedural screening .
vascular injuries are the most common complications after tavi , and range from dissection , to perforation , to acute thrombotic occlusion .
yamamoto , et al . reported more frequent major vascular complications in nonagenarians ( 19% vs. 5% , p = 0.022 ) .
, though , found that only minor vascular injuries increased in older patients ( 7.5% vs. 16% , p = 0.02 ) , and reported similar rates of major vascular complications in both age groups of their study ( 4.3% vs. 2.5% , p = 0.41 ) , as shown in figure 1 .
patients also are at risk for cerebrovascular accidents ( cva ) after tavi . in the high - risk cohort of the partner trial ( cohort a )
, there was a trend toward more strokes in the tavi group at 30 days when compared to the savr group ( 4.6% vs. 2.4% , p = 0.12 ) and at 1-year ( 6.0% vs. 3.2% , p = 0.08 ) .
up to 10% of tavi patients experienced cva , regardless of their age ( figure 1 ) .
 the cva are mostly ischemic , felt to be due to showering of emboli from the aorta or during valve positioning and deployment . to reduce
the risk of stroke , aspirin , clopidogrel , or warfarin has been used in tavi patients . in a small retrospective study that included 171 patients ( average age 81.6 years )
, the use of post - tavi dual antiplatelet did not protect patients from stroke , but has been associated with worse bleeding compared to the use of single antiplatelet or warfarin .
durand , et al . retrospectively compared the use of mono antiplatelet therapy vs. dual antiplatelet therapy in 292 patients underwent tavi ( average age was 83.6 years ) , and found that monotherapy reduced life - threatening and major bleedings without increasing the risk of stroke and myocardial infarction compared to dual antiplatelet therapy . another study has showed that the safest post tavi regimen was a combination of clopidogrel and vitamin k antagonists . in this study ,
advanced age increased risk of early bleeding after tavi ( or : 5.96 , 95% ci : 1.4724.13 , p = 0.01 ) .
more studies are needed to evaluate the efficacy and risks of different antithrombotic regimens before recommendations can be made regarding stroke prevention in tavi patients .
x axis includes age groups of tavi patients as presented in buellesfeld , et al .
, havakuk , et al . , and yamamoto , et al . , trials .
represents the youngest group of tavi patients with mean age of 73.4  4.5 years ; b : represents the second group of tavi patients with mean age of 80.6  1.1 years ; c : represents the third group of tavi patients with mean age 84.5  1.1 years ; d : represents the second group of tavi patients with mean age 88.9  2.2 years ; e : represents patients who are  85 years old ; f : represents patients who are  85 years old ; g : represents patients who are  90 years old ; h : represent patients who are  90 years old .
tavi : transcatheter aortic valve implantation . due to the proximity of the aortic valve to the atrioventricular node and bundle of his
, tavi is associated with a risk of atrioventricular conduction system injuries and permanent pacemaker implantation .
the need of a new pacemaker was reported in partner study in similar rates after both tavi ( 5% and 6.4% ) and savr ( 6.4% and 7.2% ) , ( p = 0.44 , p = 0.69 , respectively ) , at one and two years , respectively . however ,
this complication was observed more commonly with corevalve implantations presumably because of its longer stent frame , self - expanding nature , or ovoid shape .
advancing age does not increase the risks for atrioventricular nodal block or permanent pacemaker ( figure 1). aki is another potential complication of tavi and is associated with an increase in post - procedure mortality .
pre - existing hypertension , chronic obstructive pulmonary disease , and blood transfusion predicted aki in one study .
surprisingly , neither the amount of intravenous contrast agent nor patient 's age , nor pre - procedure chronic kidney disease affected the risk of aki after tavi .
, , , paravalvular leak due to incorrect sizing or positioning of the prosthetic valve , or under - expansion of it , can result in aortic regurgitation .
this complication was more common in patients undergoing tavi than savr in the partner study ( 12.0% vs. 0.9% , p < 0.001 ) , but did not increase in very old patients when compared to younger patients. studies found that paravalvular leak is more prevalent with transfemoral approach and in patients received self - expandable valves . , valve leak should be followed closely and managed early because severe aortic regurgitation was found to be an independent predictor of mortality after tavi . based on the limited published studies , some of the expected complications after tavi are reported more in the oldest patients such as vascular injuries .
. however , very old patients may need closer monitoring to avoid further morbidities and mortality .
tavi offers a new treatment approach for tens of thousands of elderly patients with severe as , who otherwise would be treated medically with resultant poor outcomes . as transcatheter technology improves with second generation devices and operator experience increases , indications for tavi may expand to include patients with moderate surgical risk , especially those who are frail .
more studies to identify the indications and contraindications for specific prosthetic valves and methods of vascular access would help physicians tailor treatments to patients .
post - tavi morbidities and mortality are expected to decrease significantly with determination of the ideal anticoagulation treatment that can reduce the incidence of stroke without rising bleeding risk .
similarly , since paravalvular leak has a bad impact on survival of patients undergoing tavi , more efforts are made to predict this complication , such as using aortic valve calcium scoring . these efforts may result in better patients ' selection for tavi and decrease the expected mortality .
bioprosthetic valves are preferred for elderly patients undergoing savr , yet these tend to fail early , requiring re - operation .
mortality rates for re - operation are high , but theoretically may be lower with valve in valve implantation using the transcatheter technique .
many older adults with severe as are not candidates for savr because of high surgical risk , advanced age , frailty , or comorbidity conditions .
improvements in devices , technical expertise , and clinical experience , along with perioperative patient management may expand the use of tavi for elderly patients at lower surgical risk in the future .
more studies , however , are needed to explore a multiplicity of aspects of this treatment especially in very old patients .
 aortic valve stenosis ( as ) is common in the elderly . although surgical replacement of the valve has been the gold standard of management , many patients have been excluded from surgery because they were very old , frail , or had co - morbidities that increased operative risks . in the last decade , transcatheter aortic valve implantation ( tavi ) has emerged as a new treatment option suitable for these patients . 
 this article reviews the available literature on the role of tavi in elderly patients with severe aortic stenosis . 
 published studies showed that elderly individuals who underwent tavi experienced better in - hospital recovery , and similar short and mid - term mortality compared to those underwent surgical treatment of as . 
 however , long - term outcomes of tavi in elderly patients are still unknown . the available data in the literature on the effect of advanced age on clinical outcomes of tavi are limited , but the data that are available suggest that tavi is a beneficial and tolerable procedure in very old patients . some of the expected complications after 
 tavi are reported more in the oldest patients such as vascular injures . 
 other complications were comparable in tavi patients regardless of their age group . 
 however , very old patients may need closer monitoring to avoid further morbidities and mortality . 