***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: The objective was to identify subgroups of patients with hypertension and atherosclerotic renal artery stenosis who may benefit from immediate intervention . In the DRASTIC study , patients with hypertension , significant atherosclerotic renal artery stenosis , and a normal or mildly impaired renal function were r and omized between immediate balloon angioplasty  ( PTRA ; n=56 ) and drug therapy followed by angioplasty after 3 months , if needed ( Med-PTRA ; n=50 ) . In this secondary analysis of the data , changes in the renal function and blood pressure after 1 year were studied by analysis of covariance in the following subgroups : patients with positive captopril – renin challenge test , abnormal captopril renogram , recently developed hypertension , bilateral stenosis , and severe stenosis . We found a benefit of immediate angioplasty only for patients with bilateral stenosis . Their creatinine clearance had decreased ( mean±s.d . : −4.2±13.5 ml/min ) in the Med-PTRA group , whereas it had improved substantially ( + 10.0±15.7 ml/min ) in the PTRA group ( P=0.02 ) . For patients with unilateral stenosis , the change in creatinine clearance did not differ between PTRA and Med-PTRA ( + 4.3±15.5 and + 1.3±12.5 ml/min , respectively ) . The patients with bilateral stenosis also seemed to benefit most from immediate intervention with regard to blood pressure control . None of the other subgroups had a clear benefit of immediate intervention regarding renal function or blood pressure control . In conclusion , intervention should not be postponed in patients with bilateral stenosis , even if renal function is normal . Other hypertensive patients with atherosclerotic renal artery disease could initially well be treated by aggressive multidrug therapy alone unless hypertension persists or renal function deteriorates Renal function and antihypertensive drug efficacy were determined in a prospect i ve , double-blind , multicenter study comparing enalapril plus hydrochlorothiazide with st and ard triple therapy ( hydrochlorothiazide , timolol , and hydralazine ) in 75 patients with documented renovascular hypertension . Both groups had significant mean decreases in systolic and diastolic blood pressures . Effective control of diastolic hypertension occurred in 96 percent of patients receiving enalapril compared with 82 percent of patients receiving the triple-drug regimen . Effective renal plasma flow was significantly increased by enalapril therapy . In contrast , the glomerular filtration rate had a bimodal response . In 80 percent of enalapril-treated patients , there was no significant change in the inulin clearance , although in 20 percent of patients ( 10 ) , there was a 28 percent decrease in the inulin clearance with a concomitant 12 percent increase in renal plasma flow . Seven of the 10 patients had unilateral renal artery stenosis , but in all 10 , it was high- grade stenosis ( more than 80 to 90 percent stenosis ) . Although a significant rise in the serum creatinine level occurred in one patient in association with diuretic therapy , volume repletion reversed this azotemia . No oliguric acute renal failure occurred in the enalapril-treated group . The cause of the decrease in glomerular filtration rate induced by enalapril plus hydrochlorothiazide in a minority of patients with renal artery stenosis appears to be quite complex . Although the abolishment of the autoregulation of glomerular filtration secondary to blockage of angiotensin II appears to be a primary cause , the roles of decreased arterial pressure , renal counterbalance , concurrent diuretic therapy , and other hemodynamic factors that may maintain glomerular ultrafiltration pressure must also be considered . The results of this study show that enalapril plus hydrochlorothiazide is effective in treating renovascular hypertension . Special care is needed for a small group of patients with renovascular hypertension in whom there is a decrease in the glomerular filtration rate with this therapy . This may identify a subset of patients with unilateral or bilateral high- grade renal artery stenosis in whom alternative therapy -- percutaneous angioplasty or surgical intervention -- may be considered ACUTE renal failure occasionally complicates therapy with the oral angiotensin-converting-enzyme inhibitor captopril.1 2 3 4 5 A variety of mechanisms have been postulated to account for captopril- OBJECTIVE The objective of our study was to evaluate the safety of CO(2 ) and gadodiamide angiography for diagnosing and percutaneously treating renal artery stenosis in patients with chronic renal insufficiency and presumed ischemic nephropathy . SUBJECTS AND METHODS One hundred forty-six consecutive patients with chronic renal insufficiency ( serum creatinine > 1.5 mg/dL ) were examined for renal artery stenosis using CO(2 ) and gadodiamide as the angiographic contrast agents . If renal artery stenosis was detected , percutaneous balloon angioplasty with or without stenting was performed . In patients for whom 48-hr creatinine levels were available , we performed an analysis to determine the incidence of contrast-involved nephropathy ( increase in serum creatinine of 0.5 mg/dL at 48 hr without identifiable cause ) . Major complications were reported up to 1 week , and mortality was reported up to 30 days after the procedure . RESULTS Ninety-five patients had serum creatinine levels available at 48 hr . An increase in creatinine of greater than 0.5 mg/dL at 48 hr occurred in three patients ( 3.2 % ) , presumably caused by CO(2 ) , by gadodiamide , or by both . Neither diabetes nor the degree of preexisting chronic renal insufficiency was a predictor of worsening renal function 48 hr after the procedure . The volumes of CO(2 ) and gadodiamide used for diagnostic studies alone versus the volume used for interventional studies was not significantly different ( for CO(2 ) , p = 0.09 ; for gadodiamide , p = 0.30 ) . Eleven major complications occurred in eight patients ( 5.5 % ) . Two deaths ( 1.4 % ) occurred within 30 days . One death was due to cholesterol embolization and the other was not believed to be related to the procedure . CONCLUSION Angiography and percutaneous treatment of renal artery stenosis in patients with chronic renal insufficiency and suspected ischemic nephropathy can be performed relatively safely using CO(2 ) and gadodiamide as angiographic contrast agents without an increased risk of complications . Contrast-induced nephropathy potentially occurred in 3.2 % of patients . Neither the degree of underlying renal insufficiency nor diabetes was a risk factor for predicting a greater likelihood of renal function worsening at 48 hr of follow-up . The volumes of CO(2 ) and gadodiamide used in this study did not result in an increased risk of contrast-involved nephropathy Data for the effects on blood pressure of renal artery balloon angioplasty are mostly from uncontrolled studies . The aim of this study was to document the efficacy and safety of angioplasty for lowering blood pressure in patients with atherosclerotic renal artery stenosis . Patients were r and omly assigned antihypertensive drug treatment ( control group , n = 26 ) or angioplasty ( n = 23 ) . Twenty-four-hour ambulatory blood pressure , the primary end point , was measured at baseline and at termination . Termination took place 6 months after r and omization or earlier in patients who developed refractory hypertension . In those allocated angioplasty , antihypertensive treatment was discontinued after the procedure but was subsequently resumed if hypertension persisted . Secondary end points were the treatment score and the incidence of complications . Two patients in the control group and 6 in the angioplasty group suffered procedural complications ( relative risk , 3.4 ; 95 % confidence interval , 0.8 to 15.1 ) . Early termination was required for refractory hypertension in 7 patients in the control group . Antihypertensive treatment was resumed in 17 patients in the angioplasty group . Mean ambulatory blood pressure at termination did not differ between control ( 141+/-15/84+/-11 mm Hg ) and angioplasty ( 140+/-15/81+/-9 mm Hg ) groups . Angioplasty reduced by 60 % the probability of having a treatment score of 2 or more at termination ( relative risk , 0.4 ; 95 % confidence interval , 0.2 to 0.7 ) . There was 1 case of dissection with segmental renal infa rct ion and 3 of restenosis in the angioplasty group . No patient suffered renal artery thrombosis . In unilateral atherosclerotic renal artery stenosis , angioplasty is a drug-sparing procedure that involves some morbidity . Previous uncontrolled and unblinded assessment s of angioplasty overestimated its potential for lowering blood pressure PURPOSE To compare the results of balloon percutaneous transluminal renal angioplasty ( PTRA ) and stent placement in atherosclerotic ostial , proximal , and isolated truncal stenoses . MATERIAL S AND METHODS Between January 1994 and April 1998 the authors prospect ively followed up 163 consecutive patients with 200 atherosclerotic renal arterial lesions after primary PTRA or primary stent placement . Duplex ultrasonography was performed 1 day and 3 , 6 , and 12 months later . RESULTS The primary 12-month PTRA patency rates were 34 % ( 21 of 33 atherosclerotic lesions ) for ostial stenoses , 65 % ( 20 of 60 ) for proximal stenoses , and 83 % ( five of 30 ) for truncal stenoses ( chi(2 ) value , 15.63 ; P < .001 ) . The corresponding stent patency rates were 80 % ( four of 21 ) , 72 % ( nine of 34 ) , and 66 % ( five of nine ) , respectively ( chi(2 ) value , 4.11 ; not significant ) . Significant stent-related reduction in risk of restenosis was limited to the ostial stenoses ( P = .002 ) . CONCLUSION Renal arterial stent placement considerably improves patency in ostial stenoses , but compared with the technically successful PTRA , it does not significantly improve primary patency in proximal and isolated truncal renal arterial stenoses The purpose s of this study were to determine the prevalence of angiographically significant renal artery stenosis in a patient population referred for diagnostic cardiac catheterization  and to develop a model that predicts the highest-risk subset of patients who have significant renal artery narrowing . A prospect i ve validation cohort study was undertaken in a referral-based university hospital . After left ventriculography , abdominal aortography was performed to screen for the presence of renal artery disease . A convenience sample of 1,302 of 1,651 consecutive patients undergoing diagnostic cardiac catheterization  were enrolled in the study . Of the 1,302 abdominal aortograms performed , 1,235 ( 95 % ) were deemed of adequate quality for the evaluation of renal artery anatomy . Renal artery disease was identified in 30 % of the patients . Insignificant renal artery stenosis was found in 187 ( 15 % ) and significant ( greater than or equal to 50 % diameter narrowing ) stenosis was found in 188 ( 15 % ) . Significant unilateral disease was present in 11 % , and bilateral disease was present in 4 % . By univariable and multivariable logistic regression analysis , the association of both clinical ly and catheterization-derived variables with renal artery disease was assessed . Multivariable predictors included age , severity of coronary artery disease , congestive heart failure , female gender , and peripheral vascular disease . Hypertension was not an associated variable . These data reveal the previously undetected high prevalence of renal artery disease in patients undergoing cardiac catheterization  and provide clinical and angiographic features that assist in predicting its presence Purpose : To determine pretreatment variables that may predict 1-year clinical outcome of stent placement for renal artery stenosis . Methods : In a prospect i ve study , 40 consecutive patients ( 29 men ; mean age 60 ± 9.1 years ) with angiographically proven atherosclerotic renal artery stenosis were treated with stent placement because of drug resistant hypertension ( n=14 ) , renal function impairment ( n=14 ) , or both ( n=12 ) .  Clinical success at 1 year was defined as a decrease of diastolic blood pressure ≥10 mmHg or a decrease in serum creatinine ≥20 % , depending on the indication for treatment . Regression analysis was performed using anatomical parameters from angiography and intravascular ultrasound , estimates of renal blood flow from renal scintigraphy , and single-kidney renal function measurements . Results : Patients treated for hypertension had better outcome than those treated for renal function impairment , with clinical success rates of 85 % and 35 % , respectively . Preserved renal function , with low serum creatinine and high 2-kidney glomerular filtration rate at baseline , was associated with clinical success in the entire patient group at follow-up ( p=0.0 
    Output:
    
Some evidence suggested similar kidney outcomes but better blood pressure outcomes with angioplasty , particularly in patients with bilateral renal disease .
Weak evidence suggested no large differences in mortality or cardiovascular events between medical and revascularization treatments .
No evidence directly compared adverse event rates between treatments .