***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: PURPOSE Although early death from perioperative myocardial infa rct ion ( PMI ) after vascular surgery is well established , long-term outcome in patients surviving PMI is unknown . This prospect i ve study was design ed to determine cardiac outcome and survival rates in patients with symptomatic and asymptomatic nonfatal PMI associated with peripheral vascular surgery . METHODS During a 36-month period for 1989 to 1992 , all patients undergoing vascular surgery at our institution were monitored for PMI with serial creatine kinase and myocardial b and isoenzymes and electrocardiography . PMIs were classified as symptomatic ( associated with chest pain , arrhythmia , congestive heart failure , or hypotension ) or asymptomatic ( electrocardiographic changes and /or elevated creatine kinase and myocardial b and isoenzymes ) . Patients with PMI were then prospect ively monitored and compared for late survival , with control patients undergoing vascular surgery without PMI during the same interval . RESULTS During the study period 1561 major peripheral vascular procedures were performed . There were 47 PMIs ( 3.0 % ) . Eleven ( 0.7 % ) PMIs were fatal , 31 were nonfatal , and five other patients with PMI died during operation of non-heart-related causes . Eight of 31 patients with nonfatal PMI had a " chemical PMI " with creatine kinase and myocardial b and isoenzyme elevation as the sole indicator of PMI . During follow-up ( mean 27.7 months ) , there was a higher incidence of both subsequent myocardial infa rct ion and coronary artery revascularization among the patients with nonfatal PMI compared with control subjects ( p < 0.05 ) ; however , survival for patients with nonfatal PMI at 1 and 4 years ( 80 % and 51 % ) did not differ from that of control patients ( 90 % and 60 % ) ( p > 0.05 ) . Patients with " chemical PMI " had similar patterns of subsequent myocardial infa rct ion and coronary intervention as control patients . CONCLUSIONS Patients surviving nonfatal PMI after peripheral vascular surgery have a higher incidence of subsequent adverse cardiac events and coronary artery revascularization than patients undergoing vascular surgery without PMI , but they have similar survival rates at 1 and 4 years . Patients in the enzyme-only PMI group have a similar outcome compared with control subjects suggesting that a perioperative " chemical MI " may not be a significant clinical event This article describes the patient population and operative management of 666 patients with nonruptured aneurysms of the abdominal aorta . Statistical significance of variables was determined by the chi-square test and logistic regression analysis . There were no statistically significant differences ( p greater than 0.05 ) in mortality rate for abdominal aortic aneurysm ( AAA ) on the basis of indication for surgery ( asymptomatic , 3.9 % ; asymptomatic but with evidence of enlargement , 4.9 % ; and symptomatic , 7.2 % ) or the urgency of operation ( elective operation , 4.5 % ; and urgent operation , 7.1 % ) . Characteristics of the 72 participating surgeons did not influence the operative mortality rate . A family history of AAA was documented in 6.1 % of cases and was more common if the patient was female ( p = 0.03 ) and less than 65 years of age ( p = 0.04 ) . Patients without clinical evidence of coronary artery disease had a 0.8 % mortality rate from cardiac disease compared with 6.2 % if any stigmata of coronary disease were present . Prior aortocoronary bypass surgery did not reduce the incidence of postoperative cardiac events or operative mortality rate . Patients having " routine " angiography did not have a less complicated operative course , fewer thrombotic complications , or lower mortality rate than those not having it . Those patients with an inflammatory AAA ( 4.5 % ) did not have a significantly higher incidence of pain .  Heparin administration ( 84.8 % ) did not reduce the complications of graft thrombosis , " trash , " distal thrombosis , and /or amputation . The 6.8 % of patients requiring suprarenal aortic cross-clamping had a higher incidence of postoperative renal dysfunction ( p = 0.02 ) and intraoperative blood loss ( p less than 0.001 ) , but cardiac events were not more frequent . When the aortic cross-clamping time was prolonged ( more than 70 minutes ) , the requirement for crystalloid fluid administration increased ( p less than 0.001 ) and postoperative myocardial infa rct ion was more common ( p = 0.004 ) . After ligation of the left renal vein in 7.9 % , renal damage or dialysis was more frequent ( p = 0.01 ) . Patients having an intra-abdominal graft ( tube , 38.5 % and biiliac , 30.7 % ) had fewer wound infections ( p = 0.02 ) and graft thromboses ( p less than 0.001 ) than the patients with a femoral anastomosis . When the internal iliac artery flow was interrupted bilaterally ( 12 % ) , diarrhea ( p = 0.03 ) and ischemic colitis ( p = 0.03 ) were more frequent complications . Reimplantation of the inferior mesenteric artery was carried out in 4.8 % . After renal artery bypass in 2.1 % , the mortality rate was not increased , but the incidence of transient renal dysfunction was increased ( p = 0.03 ) . ( ABSTRACT TRUNCATED AT 400 WORDS Physicians must make decisions about screening patients for abdominal aortic aneurysms ( AAAs ) , monitoring or referring for surgery patients with AAAs of various sizes , and assessing patients with symptoms that may be related to AAAs . This review article analyzes the evidence for each scenario . The effectiveness and cost-effectiveness of screening for AAA is based on results from four r and omized controlled trials . A cost-effectiveness analysis using a Markov model showed that ultrasound screening of white men beginning at age 65 is both effective and cost-effective in preventing AAA-related death . Such screening would have a small but real impact over a 20-year period in these men . For patients with a known AAA — which is often detected incidentally — the evidence clearly suggests periodic ultrasound surveillance for those with small AAAs ( 3.0–3.9 cm in diameter ) and elective surgical repair for those with large AAAs ( = 5.5 cm ) . Two recent r and omized controlled trials have shown that early surgical repair confers no survival benefit compared with periodic surveillance for patients with intermediate-sized AAAs ( 4.0–5.5 cm in diameter ) , so those patients can also be monitored . Some centers choose to increase the frequency of monitoring to every 3 to 6 months when the AAA reaches 5.0 cm . Factors to consider in assessing symptomatic patients include the high risk of life-threatening conditions , the potential increased risk of death or poor outcome with delay in diagnosis , the limitations of ultrasound in identifying whether symptoms are due to known or suspected AAA , and the timely availability of computed tomography or other imaging tests . If available , computed tomography is preferred in patients with recent or severe symptoms , since it is better at detecting retroperitoneal hemorrhage and other complications and in providing preoperative definition of the anatomy CONTEXT Among patients with abdominal aortic aneurysm ( AAA ) who have high operative risk , repair is usually deferred until the AAA reaches a diameter at which rupture risk is thought to outweigh operative risk , but few data exist on rupture risk of large AAA . OBJECTIVE To determine the incidence of rupture in patients with large AAA . DESIGN AND SETTING Prospect i ve cohort study in 47 Veterans Affairs medical centers . PATIENTS Veterans ( n = 198 ) with AAA of at least 5.5 cm for whom elective AAA repair was not planned because of medical contraindication or patient refusal . Patients were enrolled between April 1995 and April 2000 and followed up through July 2000 ( mean , 1.52 years ) . MAIN OUTCOME MEASURE Incidence of AAA rupture by strata of initial and attained diameter . RESULTS Outcome ascertainment was complete for all patients . There were 112 deaths ( 57 % ) and the autopsy rate was 46 % . Forty-five patients had probable AAA rupture . The 1-year incidence of probable rupture by initial AAA diameter was 9.4 % for AAA of 5.5 to 5.9 cm , 10.2 % for AAA of 6.0 to 6.9 cm ( 19.1 % for the subgroup of 6.5 - 6.9 cm ) , and 32.5 % for AAA of 7.0 cm or more . Much of the increased risk of rupture associated with initial AAA diameters of 6.5 - 7.9 cm was related to the likelihood that the AAA diameter would reach 8.0 cm during follow-up , after which 25.7 % ruptured within 6 months . CONCLUSION The rupture rate is substantial in high-operative-risk patients with AAA of at least 5.5 cm in diameter and increases with larger diameter PURPOSE We present extended follow-up findings of the Kingston prospect i ve sizing program for patients with abdominal aortic aneurysm ( AAA ) smaller than 5.0 cm in diameter , with gender-specific analysis . METHODS From 1976 to 2001 , 895 patients ( 688 men , 207 women ) with AAA smaller than 5.0 cm were entered , regardless of fitness , in a prospect i ve sizing program in which computed tomography scans were obtained every 6 months . Operations were performed in fit patients with an increase in AAA size to 5 cm ( n = 190 ) , AAA expansion greater than 0.5 cm in 6 months ( n = 27 ) , or for other reasons ( n = 33 ) . Follow-up continued until AAA rupture , surgery , death , or removal from the program . RESULTS No AAA smaller than 5.0 cm ruptured during prospect i ve follow-up . There was a statistically significant increase in expansion rate relative to size at entry , with the highest mean expansion rate of 0.52 cm/y for AAA 4.5 to 4.9 cm in diameter . There was no significant difference in AAA expansion rate between men and women . The frequency of surgery was inversely related to age at entry , but was positively related to AAA size at entry , with patients with AAA 4.5 to 4.9 cm at entry 6.8 times more likely ( 95 % confidence interval , 4.3 - 10.7 ) to undergo surgery than those with AAA 3.0 to 3.4 cm at entry . Women were older than men at entry , and age at entry in those undergoing surgery was significantly greater in women . CONCLUSIONS The study confirms the results of the United Kingdom Small Aneurysm Trial and the Aneurysm Detection and Management Study , that is , that risk for rupture is extremely unlikely with AAA smaller than 5.0 cm , which enables safe follow-up surveillance programs in both men and women with AAA smaller than 5.0 cm Gloucestershire 's screening project shows the potential benefits of a national programme and how it could be run Every year about 6000 men die from a ruptured abdominal aortic aneurysm in Engl and and Wales.1 Although this represents only about 2 % of all deaths in men , the condition is largely preventable . It is also a disease that seems to be increasingly prevalent , at least in Scotl and , despite the fact that deaths from other atherosclerotic conditions are reducing.2 This article explores the requirements for a national aortic screening programme , using as a model the Gloucestershire aneurysm screening project , which has been running for 13 years.3 Ultrasound screening for abdominal aortic aneurysms fulfils all the criteria for a population screening programme,4 5although only in men.6 The recent multicentre aneurysm screening study found that screening reduced the mortality from aneurysm disease in men by 42 % after four years of follow up ; it is expected , with further study , to show a small but significant decrease in the population mortality.7 The study also showed that  screening is as cost effective as other current screening programmes , at a cost of £ 28 000 for each added year of life.8 ! [ ] [ 1 ] Ruptured abdominal aortic aneurysm is largely preventable Credit : GCa/SPL This information builds on data from previous smaller r and omised studies , 9–11 and has encouraged debate about the value of a national screening programme for aortic aneurysms.12 13 The National Screening Committee in the United Kingdom is currently assessing the evidence before making any recommendation .14 Our experience in Gloucestershire shows how a screening programme could work . Screening for abdominal aortic aneurysm was introduced in Gloucestershire in September 1990 . All men reaching the age of 65 who are registered with general practice s in the county are offered an ultrasound scan of … [ 1 ] : Background and Purpose — Very few studies have provided information regarding long-term prognosis after stroke . We aim ed to determine the absolute and relative survival over 10 years among patients with first-ever stroke from a population -based study in Perth , Western Australia . Methods — For a 12-month period beginning February 1989 , all individuals with a suspected acute stroke or transient ischemic attack who were resident in a geographically defined and representative region of Perth , Western Australia , were 
    Output:
    
Our results support the economic viability of a national screening program for men reaching 65 years of age in Canada .