***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 —Atrial  fibrillation ( AF ) frequently complicates congestive heart failure ( CHF ) . However , the electrophysiological substrate for AF in humans with CHF remains unknown . We evaluated the electrophysiological and electroanatomic characteristics of the atria in patients with CHF . Methods and Results —Twenty-one patients ( aged 53.7±13.6 years ) with symptomatic CHF ( left ventricular ejection fraction 25.5±6.0 % ) and 21 age-matched controls were studied . The following were evaluated : effective refractory periods ( ERPs ) from the high and low lateral right atrium ( LRA ) , high septal right atrium , and distal coronary sinus ( CS ) ; conduction time along the CS and LRA ; corrected sinus node recovery times ; P-wave duration ; and conduction at the crista terminalis . In a subset , electroanatomic mapping was performed to determine atrial activation , regional conduction velocity , double potentials , fractionated electrograms , regional voltage , and areas of electrical silence .  Patients with CHF demonstrated an increase in atrial ERP with no change in the heterogeneity of refractoriness , an increase of atrial conduction time along the LRA and the CS , prolongation of the P-wave duration and corrected sinus node recovery times , and greater number and duration of double potentials along the crista terminalis . Electroanatomic mapping demonstrated regional conduction slowing with a greater number of electrograms with fractionation or double potentials , associated with areas of low voltage and electrical silence ( scar ) . Patients with CHF demonstrated an increased propensity for AF with single extrastimuli , and induced AF was more often sustained . Conclusions —Atrial remodeling due to CHF is characterized by structural changes , abnormalities of conduction , sinus node dysfunction , and increased refractoriness . These abnormalities may be responsible in part for the increased propensity for AF in CHF CONTEXT Patients with unstable angina/non-ST-segment elevation myocardial infa rct ion ( MI ) ( UA/NSTEMI ) present with a wide spectrum of risk for death and cardiac ischemic events . OBJECTIVE To develop a simple risk score that has broad applicability , is easily calculated at patient presentation , does not require a computer , and identifies patients with different responses to treatments for UA/NSTEMI . DESIGN , SETTING , AND PATIENTS Two phase 3 , international , r and omized , double-blind trials ( the Thrombolysis in Myocardial Infa rct ion [ TIMI ] 11B trial [ August 1996-March 1998 ] and the Efficacy and Safety of Subcutaneous Enoxaparin in Unstable Angina and Non-Q-Wave MI trial [ ESSENCE ; October 1994-May 1996 ] ) . A total of 1957 patients with UA/NSTEMI were assigned to receive unfractionated heparin ( test cohort )  and 1953 to receive enoxaparin in TIMI 11B ; 1564 and 1607 were assigned respectively in ESSENCE . The 3 validation cohorts were the unfractionated heparin group from ESSENCE and both enoxaparin groups . MAIN OUTCOME MEASURES The TIMI risk score was derived in the test cohort by selection of independent prognostic variables using multivariate logistic regression , assignment of value of 1 when a factor was present and 0 when it was absent , and summing the number of factors present to categorize patients into risk strata . Relative differences in response to therapeutic interventions were determined by comparing the slopes of the rates of events with increasing score in treatment groups and by testing for an interaction between risk score and treatment . Outcomes were TIMI risk score for developing at least 1 component of the primary end point ( all-cause mortality , new or recurrent MI , or severe recurrent ischemia requiring urgent revascularization ) through 14 days after r and omization . RESULTS The 7 TIMI risk score predictor variables were age 65 years or older , at least 3 risk factors for coronary artery disease , prior coronary stenosis of 50 % or more ,  ST-segment deviation on electrocardiogram at presentation  , at least 2 anginal events in prior 24 hours , use of aspirin in prior 7 days , and elevated serum cardiac markers . Event rates increased significantly as the TIMI risk score increased in the test cohort in TIMI 11B : 4.7 % for a score of 0/1 ; 8.3 % for 2 ; 13 . 2 % for 3 ; 19.9 % for 4 ; 26.2 % for 5 ; and 40.9 % for 6/7 ( P<.001 by chi(2 ) for trend ) . The pattern of increasing event rates with increasing TIMI risk score was confirmed in all 3 validation groups ( P<.001 ) . The slope of the increase in event rates with increasing numbers of risk factors was significantly lower in the enoxaparin groups in both TIMI 11B ( P = .01 ) and ESSENCE ( P = .03 ) and there was a significant interaction between TIMI risk score and treatment ( P = . 02 ) . CONCLUSIONS In patients with UA/NSTEMI , the TIMI risk score is a simple prognostication scheme that categorizes a patient 's risk of death and ischemic events and provides a basis for therapeutic decision making . JAMA . 2000;284:835 - Objective To develop a clinical risk prediction tool for estimating the cumulative six month risk of death and death or myocardial infa rct ion to facilitate triage and management of patients with acute coronary syndrome . Design Prospect i ve multinational observational study in which we used multivariable regression to develop a final predictive model , with prospect i ve and external validation . Setting Ninety four hospitals in 14 countries in Europe , North and South America , Australia , and New Zeal and . Population 43 810 patients ( 21 688 in derivation set ; 22 122 in validation set ) presenting with acute coronary syndrome with or without ST segment elevation enrolled in the global registry of acute coronary events ( GRACE ) study between April 1999 and September 2005 . Main outcome measures Death and myocardial infa rct ion . Results 1989 patients  died in hospital , 1466 died between discharge and six month follow-up , and 2793 sustained a new non-fatal myocardial infa rct ion . Nine factors independently predicted death and the combined end point of death or myocardial infa rct ion in the period from admission to six months after discharge : age , development ( or history ) of heart failure , peripheral vascular disease , systolic blood pressure , Killip class , initial serum creatinine concentration , elevated initial cardiac markers , cardiac arrest on admission , and ST segment deviation . The simplified model was robust , with prospect ively vali date d C-statistics of 0.81 for predicting death and 0.73 for death or myocardial infa rct ion from admission to six months after discharge . The external applicability of the model was vali date d in the data set from GUSTO IIb ( global use of strategies to open occluded coronary arteries ) . Conclusions This risk prediction tool uses readily identifiable variables to provide robust prediction of the cumulative six month risk of death or myocardial infa rct ion . It is a rapid and widely applicable method for assessing cardiovascular risk to complement clinical assessment and can guide patient triage and management across the spectrum of patients with acute coronary syndrome Background Although unstable coronary artery disease is the most common reason for admission to a coronary care unit , the long-term prognosis of patients with this diagnosis is unknown . This is particularly true for patients with diabetes mellitus , who are known to have a high morbidity and mortality after an acute myocardial infa rct ion . Methods and Results Prospect ively collected data from 6 different countries in the Organization to Assess Strategies for Ischemic Syndromes ( OASIS ) registry were analyzed to determine the 2-year prognosis of diabetic and nondiabetic patients who were hospitalized with unstable angina or non – Q-wave myocardial infa rct ion . Overall , 1718 of 8013 registry patients ( 21 % ) had diabetes . Diabetic patients had a higher rate of coronary bypass surgery  than nondiabetic patients ( 23 % versus 20 % , P < 0.001 ) but had similar rates of catheterization and angioplasty . Diabetes independently predicted mortality ( relative risk [ RR ] , 1.57 ; 95 % CI , 1.38 to 1.81;P < 0.001 ) , as well as cardiovascular death , new myocardial infa rct ion , stroke , and new congestive heart failure . Moreover , compared with their nondiabetic counterparts , women had a significantly higher risk than men ( RR , 1.98 ; 95 % CI , 1.60 to 2.44 ; and RR , 1.28 ; 95 % CI , 1.06 to 1.56 , respectively ) . Interestingly , diabetic patients without prior cardiovascular disease had the same event rates for all outcomes as nondiabetic patients with previous vascular disease . Conclusions Hospitalization for unstable angina or non – Q-wave myocardial infa rct ion predicts a high 2-year morbidity and mortality ; this is especially evident for patients with diabetes . Diabetic patients with no previous cardiovascular disease have the same long-term morbidity and mortality as nondiabetic patients with established cardiovascular disease after hospitalization for unstable coronary artery disease BACKGROUND Appropriate treatment policies should include an accurate estimate of a patient 's baseline risk . Risk modeling to date has been underutilized in patients with acute coronary syndromes without persistent ST-segment elevation . METHODS AND RESULTS We analyzed the relation between baseline characteristics and the 30-day incidence of death and the composite of death or myocardial (re)infa rct ion in 9461 patients with acute coronary syndromes without persistent ST-segment elevation enrolled in the PURSUIT trial [ Platelet glycoprotein IIb/IIIa in Unstable angina : Receptor Suppression Using Integrilin ( eptifibatide ) Therapy ] . Variables examined included demographics , history , hemodynamic condition , and symptom duration . Risk models were created with multivariable logistic regression and vali date d by bootstrapping techniques . There was a 3.6 % mortality rate and 11.4 % infa rct ion rate by 30 days . More than 20 significant predictors for mortality and for the composite end point were identified . The most important baseline determinants of death were age ( adjusted chi(2)=95 ) , heart rate ( chi(2)=32 ) , systolic blood pressure ( chi(2)=20 ) , ST-segment depression ( chi(2)=20 ) , signs of heart failure ( chi(2)=18 ) , and cardiac enzymes ( chi(2)=15 ) . Determinants of mortality were generally also predictive of death or myocardial (re)infa rct ion . Differences were observed , however , in the relative prognostic importance of predictive variables for mortality alone or the composite end point ; for example , sex was a more important determinant of the composite end point ( chi(2)=21 ) than of death alone ( chi(2)=10 ) . The accuracy of the prediction of the composite end point was less than that of mortality ( C-index 0.67 versus 0.81 ) . CONCLUSIONS The occurrence of adverse events after presentation with acute coronary syndromes is affected by multiple factors . These factors should be considered in the clinical decision-making process Background Acute coronary syndrome ( ACS ) patients have a wide spectrum of risks for subsequent cardiovascular events and death . However , there is no simple , convenience scoring system to identify risk of adverse outcomes . We investigated whether CHADS2 and CHA2DS2-VASc scores were useful tools to assess the risk for adverse events among ACS patients . Methods This observational prospect i ve study was conducted at 39 hospitals . Totally 3,183 patients with ACS were enrolled , and CHADS2 and CHA2DS2-VASc scores were calculated . The primary endpoint was occurrence of adverse event , including subsequent myocardial infa rct ion , stroke , or death , within 1 year of discharge . Results CHADS2 and CHA2DS2-VASc scores were significant predictors of adverse events in separate multivariate regression analyses . A Kaplan-Meier analysis of CHADS2 and CHA2DS2-VASc scores of ≥2 showed a higher rate of adverse events as compared with scores of < 2 ( P<0.001;log-rank test ) . CHA2DS2-VASc score was better than CHADS2 score in predicting subsequent adverse events ; the area under the receiver operating characteristic curve increased from 0.66 to 0.70 ( p<0.001 ) . Patients with CHADS2 scores of 0 or 1 were further classified according to CHA2DS2-VASc score , using a cutoff value of 2 . The rate of adverse events significantly differed between those with a score of < 2 and those with a score of ≥2 ( 4.1 % vs.10.7 % , P<0.001 ) . Conclusions CHADS2 and CHA2DS2-VASc scores were useful predictors of subsequent adverse events in ACS patients Chronic hypertension is a well established risk factor for the development of cardiovascular disease ; however , its prognostic significance after a non-ST-segment elevation acute coronary syndrome remains to be established . Data from 15,414 patients included in six r and omized Thrombolysis in Myocardial Infa rct ion ( TIMI ) trials ( TIM 
    Output:
    
CHADS2 score can predict mortality in patients with CAD .
However , higher CHADS2 score is associated with increased incidence of stroke/TIA only in patients without AF