approximately 30% of acute strokes occur in those 
 older than 80 years of age.6)9)24 ) however , elderly patients 
 tend to have high rates of poor outcomes and 
 in - hospital mortality.1)4)8)13)14)16)17)23)25)26)30 ) furthermore , family members of elderly patients are often reluctant to accept aggressive treatment . recently , prospective trials have shown the benefit of endovascular treatment ( evt ) for acute ischemic stroke.5)12)20)22)32 ) however , some trials included only patients aged 80 or less,20)32 ) and although trial inclusion criteria had no age limitation , a small proportion of elderly patients over 80 years were included.5)12)22 ) therefore , the evidence supporting that endovascular treatment can be actively recommended for elderly patients as for younger patients is not sufficient . to determine whether evt for acute ischemic stroke is also beneficial in acute ischemic stroke patients over 80 years of age who are candidates for evt , outcomes were compared between patients who underwent evt and those who did not , in terms of functional outcomes and rates of symptomatic hemorrhage , in - hospital morbidities , and mortality . this retrospective study was approved by our institutional review board . from a stroke registry ( january 2009-march 2014 ) at our institution , data was collected on patients matching the evt criteria for acute ischemic stroke of our institution : ( 1 ) time from onset < 8 hours , ( 2 ) major artery occlusion ( internal carotid artery , middle cerebral artery [ m1 and m2 ] , basilar artery , or vertebral artery ) , ( 3 ) diffusion - perfusion mismatch on mri ( > 120% difference between diffusion weighted imaging and time to peak map ) , ( 4 ) an initial national institute of health stroke scale [ nihss ] score of  5 , and ( 5 ) within time from onset of 4.5 hours , no clinical response to intravenous tpa , as described in previous studies.21)28 ) patients who had intracranial hemorrhage , large infarctions ( infarction size on diffusion mri  1/3 on middle cerebral artery territory ) , bleeding diathesis , or serious illnesses affecting life expectancy including malignancy were excluded . for 478 patients matching the evt criteria retrieved from the registry , additional criteria were applied : age > 80 years and a prestroke modified rankin scale ( mrs ) score of  2 . a total of 156 patients were selected as study subjects . to ensure agreement with the above mentioned criteria , the clinical and radiologic data of the patients were re - reviewed by two investigators ( k.h . and c.h.k . ) . the stroke mri protocol and the method of measuring diffusion - perfusion mismatch used have been previously described.18 ) at our institution , intravenous ( iv ) administration of tissue plasminogen activator ( tpa ) is considered , regardless of patient age , when indicated . accordingly , of the 156 study subjects , tpa was administered in 95 patients matching iv tpa indication , but none of them showed a clinical response . in the remaining 61 patients , iv tpa was not used , from passing its time window in 58 patients or from a previous history of intracranial hemorrhage in 3 patients . unlike iv tpa administration , evt for patients over 80 years of age was not actively recommended during the study period . information on risks and benefits of evt was provided to first - degree family members ( spouse , sons , and daughters ) and evt was performed when they agreed . because none of the patients were clearly conscious , they were unable to participate in this decision . of the 156 study subjects , family members of 100 ( 64.1% , non - evt group ) patients refused evt , thus they received standard medical treatment in the stroke unit in accordance with stroke guidelines.19 ) the remaining 56 ( 35.9% , evt group ) patients underwent evt according to agreement of family members . in line with our evt protocol , we primarily used clot retrieval using a penumbra reperfusion catheter ( penumbra , alameda , california ) or a solitaire fr stent ( ev3 , plymouth , minnesota ) . intra - arterial infusion of fibrinolytics was reserved for cases with a remaining small amount of thrombi or distal migrating emboli . technical details have been previously described.3)21)28 ) after evt , they were also managed according to the standard treatment guidelines in the stroke unit . basic demographic and clinical data ( past history , occlusion site , trial of org 10172 acute stroke treatment [ toast ] classification , time from onset , initial nihss score , iv tpa use , hemorrhage , in - hospital mortality , and mrs score [ prestroke , and at 3 and 12 months after stroke ] ) were retrieved from the stroke registry . according to the criteria proposed by the european cooperative acute stroke study ( ecass ) group,15 ) hemorrhage was classified as : hemorrhagic infarction type 1 ( hi-1 ) , hemorrhagic infarction type 2 ( hi-2 ) , parenchymal hematoma type 1 ( ph-1 ) , or parenchymal hematoma type 2 ( ph-2 ) . symptomatic hemorrhage was defined as one associated with a  4-point increase in nihss score or a 1-point deterioration in level of consciousness.11 ) the stroke registry was controlled by two stroke neurologists ( h.j.b . and m.k.h . ) . morbidities , including the need for endotracheal intubation , gastrointestinal bleeding , pneumonia , and urinary tract infection ( uti ) , were obtained by review of medical records ( s.p.b . and b.l . ) . patients were considered to have a hospital - acquired infection , when they had clinical , radiological , and laboratory findings compatible with infection and the organism was confirmed by culture . the angiographic outcomes of patients who underwent evt were reviewed and graded by two neurointerventionists ( g.h . and the effects of evt were determined using : ( 1 ) good functional outcome ( defined as a mrs score of 0 - 2 ) rates at 3 and 12 months after stroke , ( 2 ) symptomatic hemorrhage rates , ( 3 ) in - hospital morbidity rates ( endotracheal intubation , gastrointestinal bleeding , pneumonia , and uti ) , and ( 4 ) in - hospital mortality rates . statistical analysis was performed using stata ( version 13 , stata corp lp , college station , tx ) . the mann - whitney u test was used for bivariate analysis of continuous variables and the  or fisher 's exact test for bivariate analysis of nominal factors . the effects of evt were compared using binary logistic regression analysis , adjusted for confounders significantly associated with outcome after ischemic stroke : age ( < 85 or  85 years ) , time from onset ( < 4.5 or 4.5 - 8 hours ) , initial nihss score ( moderate , 5 - 14 or severe ,  15 ) , and prestroke mrs score ( 0 or 1 - 2 ) . " tpa use " was excluded from the logistic regression models , because of a lack of clinical response after tpa use in all cases and correlation with time from onset causing a multicollinearity problem . this retrospective study was approved by our institutional review board . from a stroke registry ( january 2009-march 2014 ) at our institution , data was collected on patients matching the evt criteria for acute ischemic stroke of our institution : ( 1 ) time from onset < 8 hours , ( 2 ) major artery occlusion ( internal carotid artery , middle cerebral artery [ m1 and m2 ] , basilar artery , or vertebral artery ) , ( 3 ) diffusion - perfusion mismatch on mri ( > 120% difference between diffusion weighted imaging and time to peak map ) , ( 4 ) an initial national institute of health stroke scale [ nihss ] score of  5 , and ( 5 ) within time from onset of 4.5 hours , no clinical response to intravenous tpa , as described in previous studies.21)28 ) patients who had intracranial hemorrhage , large infarctions ( infarction size on diffusion mri  1/3 on middle cerebral artery territory ) , bleeding diathesis , or serious illnesses affecting life expectancy including malignancy were excluded . for 478 patients matching the evt criteria retrieved from the registry , additional criteria were applied : age > 80 years and a prestroke modified rankin scale ( mrs ) score of  2 . a total of 156 patients were selected as study subjects . to ensure agreement with the above mentioned criteria , the clinical and radiologic data of the patients were re - reviewed by two investigators ( k.h . and c.h.k . ) . the stroke mri protocol and the method of measuring diffusion - perfusion mismatch used have been previously described.18 ) at our institution , intravenous ( iv ) administration of tissue plasminogen activator ( tpa ) is considered , regardless of patient age , when indicated . accordingly , of the 156 study subjects , tpa was administered in 95 patients matching iv tpa indication , but none of them showed a clinical response . in the remaining 61 patients , iv tpa was not used , from passing its time window in 58 patients or from a previous history of intracranial hemorrhage in 3 patients . unlike iv tpa administration , evt for patients over 80 years of age information on risks and benefits of evt was provided to first - degree family members ( spouse , sons , and daughters ) and evt was performed when they agreed . because none of the patients were clearly conscious , they were unable to participate in this decision . of the 156 study subjects , family members of 100 ( 64.1% , non - evt group ) patients refused evt , thus they received standard medical treatment in the stroke unit in accordance with stroke guidelines.19 ) the remaining 56 ( 35.9% , evt group ) patients underwent evt according to agreement of family members . in line with our evt protocol , we primarily used clot retrieval using a penumbra reperfusion catheter ( penumbra , alameda , california ) or a solitaire fr stent ( ev3 , plymouth , minnesota ) . intra - arterial infusion of fibrinolytics was reserved for cases with a remaining small amount of thrombi or distal migrating emboli . technical details have been previously described.3)21)28 ) after evt , they were also managed according to the standard treatment guidelines in the stroke unit . basic demographic and clinical data ( past history , occlusion site , trial of org 10172 acute stroke treatment [ toast ] classification , time from onset , initial nihss score , iv tpa use , hemorrhage , in - hospital mortality , and mrs score [ prestroke , and at 3 and 12 months after stroke ] ) were retrieved from the stroke registry . according to the criteria proposed by the european cooperative acute stroke study ( ecass ) group,15 ) hemorrhage was classified as : hemorrhagic infarction type 1 ( hi-1 ) , hemorrhagic infarction type 2 ( hi-2 ) , parenchymal hematoma type 1 ( ph-1 ) , or parenchymal hematoma type 2 ( ph-2 ) . symptomatic hemorrhage was defined as one associated with a  4-point increase in nihss score or a 1-point deterioration in level of consciousness.11 ) the stroke registry was controlled by two stroke neurologists ( h.j.b . and m.k.h . ) . hospital morbidities , including the need for endotracheal intubation , gastrointestinal bleeding , pneumonia , and urinary tract infection ( uti ) , were obtained by review of medical records ( s.p.b . and b.l . ) . patients were considered to have a hospital - acquired infection , when they had clinical , radiological , and laboratory findings compatible with infection and the organism was confirmed by culture . the angiographic outcomes of patients who underwent evt were reviewed and graded by two neurointerventionists ( g.h . and the effects of evt were determined using : ( 1 ) good functional outcome ( defined as a mrs score of 0 - 2 ) rates at 3 and 12 months after stroke , ( 2 ) symptomatic hemorrhage rates , ( 3 ) in - hospital morbidity rates ( endotracheal intubation , gastrointestinal bleeding , pneumonia , and uti ) , and ( 4 ) in - hospital mortality rates . statistical analysis was performed using stata ( version 13 , stata corp lp , college station , tx ) . the mann - whitney u test was used for bivariate analysis of continuous variables and the  or fisher 's exact test for bivariate analysis of nominal factors . the effects of evt were compared using binary logistic regression analysis , adjusted for confounders significantly associated with outcome after ischemic stroke : age ( < 85 or  85 years ) , time from onset ( < 4.5 or 4.5 - 8 hours ) , initial nihss score ( moderate , 5 - 14 or severe ,  15 ) , and prestroke mrs score ( 0 or 1 - 2 ) . " tpa use " was excluded from the logistic regression models , because of a lack of clinical response after tpa use in all cases and correlation with time from onset causing a multicollinearity problem . basic demographic and clinical data were not significantly different in the evt and non - evt groups ( table 1 ) . in the evt group , successful recanalization ( tici grade  2b ) was achieved in 46 patients ( 82.1% ) . of these , 25 patients did not achieve good outcomes and thus , futile recanalization , defined as mrs  3 despite successful recanalization , was 54.3% . complications occurred in 3 ( 5.4% ) patients during evt : vessel rupture in 2 patients and intracranial artery dissection in 1 patient . of these , good outcomes were achieved in 2 patients at 3 and 12 months after stroke . recanalization failed in 1 patient with vessel rupture , whose outcome was poor ( mrs 5 at 3 and 12 months ) , although bleeding was stopped by temporary balloon occlusion . at 3 months after stroke , good functional outcomes were achieved in a greater portion of patients in the evt group than in the non - evt group ( 20 [ 35.7% ] vs. 11 [ 11.0% ] , adjusted odds ratio [ or ] 4.779 , 95% confidence interval [ ci ] 1.972 - 11.579 , p = 0.001 ; table 2 and fig . at 12 months follow - up , this trend continued and the good functional outcome rate was significantly higher in the evt group than in the non - evt groups ( 20 [ 35.7% ] versus 14 [ 14.0% ] , adjusted or 3.705 , 95% ci 1.574 - 8.722 , p = 0.003 ; fig . 1b ) . in the non - evt group , proportions of patients who were severely disabled or dead ( mrs score of 4 - 6 ) were over 80% and significantly higher than in the evt group at 3 months ( 83 [ 83.0% ] vs. 28 [ 50.0% ] , adjusted or 6.950 , 95% ci 2.844 - 16.985 , p < 0.001 ) and 12 months ( 82 [ 82% ] vs. 32 [ 57.1% ] , adjusted or 4.180 , 95% ci 1.837 - 9.510 , p = 0.001 ) after stroke ( fig . 7 [ 12.5% ] versus 29 [ 29.0% ] , adjusted or 0.262 , 95% ci 0.098 - 0.703 , p = 0.008 ) and uti ( 9 [ 16.1% ] versus 34 [ 34.0% ] , adjusted or 0.256 , 95% ci 0.099 - 0.657 , p = 0.005 ) were significantly less frequent in the evt group during admission ( table 2 ) . hemorrhage occurred in 40 ( 25.6% ) patients , including 8 ( 5.1% ) with symptomatic hemorrhage during admission . although hemorrhage types ( hi , 6 [ 10.7% ] vs. 11 [ 11.0% ] ; ph , 9 [ 16.1% ] vs. 14 [ 14.0% ] , p = 0.941 ) were similar in the two groups , symptomatic hemorrhage rates were significantly higher in the evt group ( 6 [ 10.7% ] vs. 2 [ 2.0% ] , adjusted or 6.859 , 95% ci 1.139 - 41.317 , p = 0.036 ) . in - hospital mortality rate did not differ significantly between the evt and non - evt groups ( 7 [ 12.5% ] vs. 8 [ 8.0% ] , adjusted or 1.380 , 95% ci 0.408 - 4.664 , p = 0.604 ) . the present study shows that evt for acute ischemic stroke was associated with good functional outcomes at 3 and 12 months after stroke in patients over 80 years of age who were candidates for evt . it also reduced rates of in - hospital morbidities , such as hospital - acquired infections . although symptomatic hemorrhage occurred more frequently after evt , overall functional outcome of elderly patients treated by evt was still better and in - hospital mortality rate was not higher than that of patients not treated with evt . our results indicate that the benefit of evt for acute ischemic stroke is maintained even in patients over 80 years of age . therefore , elderly patients should not be simply excluded from evt candidates because of their age . this is consistent with subgroup analysis of recent prospective trials reporting that no significant interaction was detected between the benefit of evt and age.5)12 ) in addition to functional outcomes , in - hospital morbidities were also evaluated as a primary outcome of evt , because these often lead to unfavorable or fatal outcome in elderly patients.8)13 ) we found that pneumonia and uti developed more frequently in the non - evt group . poor clinical condition in patients with acute ischemic stroke is associated with these in - hospital morbidities and , in turn , their developments are predictors for unfavorable outcome and mortality.2)7)10)27)29)31)33)34)35)36 ) therefore , these findings suggest that a better clinical condition achieved by evt would reduce in - hospital morbidities , contributing to a more favorable outcome in evt groups . especially in elderly patients with acute ischemic stroke , symptomatic hemorrhage is frequent and associated with high rates of in - hospital mortality and poor outcome.1)4)8)13)14)16)17)23)25)26)30 ) in the current study , however , in - hospital mortality rates were not different between the two study groups . in addition , more than 80% of patients not treated by evt were severely disabled or dead ( mrs score of 4 - 6 ) due to acute stroke or its sequelae at 3 and 12 months after stroke , thus this proportion was found to be much higher than that of the evt group . therefore , these results indicate that the benefit of evt overweighs the risk of symptomatic hemorrhage after evt . in practice , we frequently encounter elderly patients with acute ischemic stroke , but no consensus has been reached on this issue . although our results do not provide definite evidence obtained from a well - designed randomized study , we believe that they could provide some useful information for physicians and patients , until sufficient data become available these include its retrospective nature , single center experience , and its relatively small cohort . in addition , selection bias is likely to have been introduced by involving family members in the treatment decision - making process , and the general management afforded to both evt and non - evt groups may have been less than aggressive due to considerations of patient age . nevertheless , the general management guidelines followed were identical for the evt and non - evt groups and all patients were managed without abandoning treatment , because only patients whose family - members agree on treatment for stroke are permitted to be referred to our tertiary referral hospital . the present study demonstrated that evt improved functional outcomes at 3 and 12 months after stroke in patients over 80 years of age with acute ischemic stroke who were candidates for evt . these results indicate that the benefit of evt for acute ischemic stroke is maintained in elderly patients . in these patients , symptomatic hemorrhage occurred more frequently after evt , but the benefit of evt overweighs the risk of symptomatic hemorrhage , considering the high rate of poor outcomes in patients who did not undergo evt . accordingly , our findings suggest that evt can be considered in elderly patients , if indicated .