***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: Background — Clinical depression is associated with an increased risk for mortality in patients with a recent myocardial infa rct ion ( MI ) . Reduced heart rate variability ( HRV ) has been suggested as a possible explanation for this association . The purpose of this study was to determine if depression is associated with reduced HRV in patients with a recent MI . Methods and Results —Three hundred eighty acute MI patients with depression and 424 acute MI patients without depression were recruited . All underwent 24-hour ambulatory electrocardiographic monitoring after hospital discharge .  In univariate analyses , 4 indices of HRV were significantly lower in patients with depression than in patients without depression . Variables associated with HRV were then compared between patients with and without depression , and potential confounds were identified . These variables ( age , sex , diabetes , and present cigarette smoking ) were entered into an analysis of covariance model , followed by depression status . In the final model , all but one HRV index ( high-frequency power ) remained significantly lower in patients with depression than in patients without depression . Conclusions —We conclude that greater autonomic dysfunction , as reflected by decreased HRV , is a plausible mechanism linking depression to increased cardiac mortality in post-MI patients Background —Brachial artery endothelial function is impaired in individuals with atherosclerosis and coronary risk factors and improves with risk reduction therapy . However , the predictive value of brachial artery endothelial dysfunction for future cardiovascular events is unknown . Methods and Results —We preoperatively examined brachial artery vasodilation using ultrasound in 187 patients undergoing vascular surgery .  Patients were prospect ively followed for 30 days after surgery . Forty-five patients had a postoperative event , including cardiac death ( 3 ) , myocardial infa rct ion ( 12 ) , unstable angina/ischemic ventricular fibrillation ( 2 ) , stroke ( 3 ) , or elevated troponin I , reflecting myocardial necrosis ( 25 ) . Preoperative endothelium-dependent flow-mediated dilation was significantly lower in patients with an event ( 4.9±3.1 % ) than in those without an event ( 7.3±5%;P < 0.001 ) , whereas endothelium-independent vasodilation to nitroglycerin was similar in both groups . In a Cox proportional-hazards model , the independent predictors of events were age ( P = 0.001 ) , renal insufficiency ( P = 0.03 ) , noncarotid surgery ( P = 0.05 ) , and lower brachial artery flow-mediated dilation ( P = 0.007 ) . If troponin I elevation was not considered an event , low flow-mediated dilation remained an independent predictor of risk ( odds ratio 9.0 , 95 % CI 1.2 to 68;P = 0.03 ) . When a flow-mediated dilation cutpoint of 8.1 % was used , endothelial function had a sensitivity of 95 % , specificity of 37 % , and negative predictive value of 98 % for events . Conclusions —Impaired brachial artery endothelial function independently predicts postoperative cardiac events , which supports a role for endothelial dysfunction in the pathogenesis of cardiovascular disease . The strong negative predictive value of preserved endothelial function raises the possibility that assessment of brachial artery flow-mediated dilation will be useful in the management of patients undergoing vascular surgery BACKGROUND Hypertension has been linked to several psychological factors , including depression , but the relation between hypertension incidence and depressive symptoms has not been adequately examined . OBJECTIVE To determine if depressive symptoms independently predict hypertension incidence . DESIGN AND SETTING A prospect i ve , multicenter , epidemiological cohort of young adults ( aged 23 - 35 years at study entry ) from the general community without hypertension followed up for 5 years . SUBJECTS A sample of 3343 adults from 4 urban areas stratified for race ( black and white ) from the CARDIA ( Coronary Artery Risk Development in Young Adults ) study . MAIN OUTCOME MEASURE Hypertension incidence , which was defined as blood pressure higher than 160/95 mm Hg ( assessed on a single occasion ) or the use of prescribed antihypertensive medication . RESULTS Participants with high scores ( > or = 16 ) on the Center for Epidemiological Studies Depression ( CES-D ) Scale were at significant risk for hypertension incidence compared with those with low CES-D scores ( < or = 7 ; odds ratio , 2.10 ; 95 % confidence interval , 1.22 - 3.61 ) after adjustment for other hypertension risk factors ( eg , age , resting systolic blood pressure at the 5-year examination , physical activity , daily alcohol use , parental history of hypertension , education , presence of diabetes mellitus or heart disease , sex , and race ) in fixed logistic models . Those with intermediate depressive symptoms ( CES-D scores 8 - 15 ) were also at significant risk ( adjusted odds ratio , 1.78 ; 95 % confidence interval , 1.06 - 2.98 ) . These associations were significant in blacks alone but were not found in whites , who had a lower  hypertension incidence ( 29 [ 2 % ] of 1806 ) than blacks ( 89 [ 6 % ] of 1537 ) . CONCLUSIONS Depressive symptoms were predictive of later hypertension incidence in young adults , and young blacks with depressive symptoms were at high risk of developing hypertension Background —Endothelial dysfunction plays a key role in atherogenesis . We prospect ively investigated the impact of noninvasive measurement of endothelial function on cardiovascular risk in peripheral arterial disease ( PAD ) . The study was specially aim ed at assessing whether brachial artery flow-mediated dilation ( FMD ) added to the predictive value of  ankle-brachial pressure index  ( ABPI ) . Methods and Results —Of 131 patients monitored for a mean of 23±10 months , 18 had a coronary event , 12 a cerebrovascular event , and 9 a peripheral event .  The median FMD was lower in patients with an event than in those without ( 5.8 % versus 7.6 % , P < 0.05 ) , whereas vasodilation to nitroglycerin was similar in the two groups . The cardiovascular event rate was higher in patients with FMD below the median versus those with FMD above the median ( P < 0.001 by log-rank test ) . In a Cox proportion hazard model , independent predictors of events were FMD below the median ( P < 0.01 ) , ABPI below the median ( P < 0.01 ) , and previous stroke ( P < 0.02 ) . Similar results were obtained when peripheral events were excluded from the analysis . Below-median ABPI and FMD combined was more accurate in predicting risk ( relative risk [ RR ] 13.0 ; 95 % CI , 3.0 to 56.2 ; P < 0.01 ) than ABPI ( RR , 6.4 ; 95 % CI , 1.4 to 29.1 ; P < 0.02 ) and FMD ( RR , 4.8 ; 95 % CI , 1.1 to 23.3 ; P < 0.05 ) alone . Conclusions —A low brachial artery FMD is an independent predictor of cardiovascular risk in patients with PAD and adds to the prognostic value of ABPI , which is currently the most powerful prognostic indicator in PAD Background —Impaired endothelial function is a key event in the atherosclerosis process and predicts future cardiovascular events in subjects with and without coronary artery disease ( CAD ) . We performed the first prospect i ve study evaluating whether early measurement of brachial artery endothelium-dependent dilation ( flow-mediated dilation [ FMD ] ) after coronary stenting could predict occurrence of in-stent-restenosis . Methods and Results —The study population included 136 patients with single-vessel CAD undergoing percutaneous coronary intervention ( PCI ) with stenting and at least 6 months of follow-up . All patients underwent ultrasound detection of brachial artery reactivity 30 days after PCI ; FMD was investigated before and after 5 minutes of occlusion of the brachial artery , and nitroglycerin-mediated dilation was investigated before and after administration of sublingual nitrates .  Clinical in-stent restenosis was demonstrated in 20 patients ( 15 % ) , whereas 116 patients ( 85 % ) remained free of signs or symptoms of recurrent ischemia . FMD was significantly impaired in patients with restenosis versus those without restenosis ( percent diameter variation 4.6±5.8 % versus 9.5±6.6 % , P=0.002 ) ; moreover , 4 % of patients with FMD ≥7 % ( median value ) developed in-stent restenosis versus 28 % of those with FMD < 7 % ( P=0.0001 ) . On multivariate analysis , FMD was the strongest predictor of restenosis ( OR 4.5 , 95 % CI 2.4 to 12.0 ) ; conversely , nitroglycerin-mediated dilation did not independently predict the risk of restenosis ( OR 2.4 , 95 % CI 0.8 to 6.3 ) . Conclusions —This is the first prospect i ve study indicating that impaired FMD independently predicts occurrence of in-stent restenosis in patients undergoing PCI . Early evaluation of endothelial function after stenting may represent a useful screening tool to stratify patients according to future risk of restenosis Objective — Reactive hyperemia is the compensatory increase in blood flow that occurs after a period of tissue ischemia , and this response is blunted in patients with cardiovascular risk factors . The predictive value of reactive hyperemia for cardiovascular events in patients with atherosclerosis and the relative importance of reactive hyperemia compared with other measures of vascular function have not been previously studied . Methods and Results — We prospect ively measured reactive hyperemia and brachial artery flow-mediated dilation by ultrasound in 267 patients with peripheral arterial disease referred for vascular surgery ( age 66±11 years , 26 % female ) . Median follow-up was 309 days ( range 1 to 730 days ) . Fifty patients ( 19 % ) had an event , including cardiac death ( 15 ) , myocardial infa rct ion ( 18 ) , unstable angina ( 8) , congestive heart failure ( 6 ) , and nonhemorrhagic stroke ( 3 ) . Patients with an event were older and had lower hyperemic flow velocity ( 75±39 versus 95±50 cm/s , P=0.009 ) . Patients with an event also had lower flow-mediated dilation ( 4.5±3.0 versus 6.9±4.6 % , P<0.001 ) , and when these 2 measures of vascular function were included in the same Cox proportional hazards model , lower hyperemic flow ( OR 2.7 , 95 % CI 1.2 to 5.9 , P=0.018 ) and lower flow-mediated dilation ( OR 4.2 , 95 % CI : 1.8 to 9.8 , P=0.001 ) both predicted cardiovascular events while adjusting for other risk factors . Conclusions — Thus , lower reactive hyperemia is associated with increased cardiovascular risk in patients with peripheral arterial disease . Furthermore , flow-mediated dilation and reactive hyperemia incrementally relate to cardiovascular risk , although impaired flow-mediated dilation was the stronger predictor in this population . These findings further support the clinical relevance of vascular function measured in the microvasculature and conduit arteries in the upper extremity BACKGROUND Depression is a risk factor for the development of coronary heart disease but the relationship between coronary endothelial dysfunction and depression is not yet known . This study investigated whether depressive symptomatology is associated with coronary endothelial dysfunction in patients without coronary artery disease ( CAD ) . METHODS AND RESULTS Incremental acetylcholine ( Ach ; 20 , 50 and 100 microg/min ) and nitrate ( 200 microg/min ) were infused into the left coronary ostium of 52 patients ( male 30 , 51.8 years ) with depressive symptoms as indicated by a Beck Depression Inventory ( BDI ) score of > or=10 and a Hamilton Depression Rating Scale ( HAM-D17 ) of > or=7 but without overt CAD or any vasoactive medications .  Vascular responses to each drug were measured quantitatively at the mid-segments of the left anterior descending artery ( LAD ) and compared to those of 103 matched control subjects ( male 64 , 51.3 years ) with angiographically normal looking LAD and as estimated by BDI < 10 and HAM-D17 < 7 . Patients in the depressive group showed significant vasoconstriction compared with patients in the non-depressive group ( p=0.017 , 0.090 , 0.004 respectively ) . However , endothelium-independent vasodilatation to nitrates did not differ significantly between the two groups ( p=0.461 ) . No differences in risk factors were found between the two groups . CONCLUSIONS Depressive mood is associated with coronary endothelial dysfunction in patients without 
    Output:
    
Diverse studies support the inverse correlation between depressed mood and endothelial function , as measured by FMD .