***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 
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    ***EXAMPLES*** 
    Input: Objective To investigate the associations of diastolic blood pressure ( DBP ) and systolic blood pressure ( SBP ) with the risk of coronary heart disease , sudden cardiac and all-cause death in elderly men . Design A cohort study . Setting The Dutch town of Zutphen . Subjects Eight hundred and eighty-five r and omly selected men , aged 64 - 84 years . Main outcome measures Relative risks adjusted for age , body mass index , total and high-density lipoprotein cholesterol , cigarette smoking , alcohol consumption , use of blood pressure-lowering medications without a specific indication for hypertension , and the physician who measured the blood pressure . Results Neither DBP nor SBP was associated significantly with the incidence of a first coronary heart disease event and no clear associations were observed with mortality from coronary heart disease . However , positive associations with sudden cardiac death were observed . The adjusted relative risk for men with definite isolated systolic hypertension was 9.20 . The risk of dying from coronary heart disease not recorded additionally as sudden death was highest in men at the lower end of the DBP and SBP distributions and in men using antihypertensives . DBP and SBP were positively associated with all-cause mortality when possible comorbidity at the time of the blood pressure measurement was accounted for . Overall , the highest risk for all endpoints was observed in men on antihypertensive medication , who formed a distinct group with a clustering of cardiovascular risk factors . Conclusion Elevated DBP and SBP , and especially isolated systolic hypertension , are important predictors of sudden cardiac death in elderly men . The highest risk of nonsudden coronary heart disease mortality was found at the lower end of the blood pressure distributions and among men on antihypertensive medication Summary Background The associations of blood pressure with the different manifestations of incident cardiovascular disease in a contemporary population have not been compared . In this study , we aim ed to analyse the associations of blood pressure with 12 different presentations of cardiovascular disease . Methods We used  linked electronic health records from 1997 to 2010 in the CALIBER ( CArdiovascular research using LInked Bespoke studies and Electronic health Records ) programme to assemble a cohort of 1·25 million patients , 30 years of age or older and initially free from cardiovascular disease , a fifth of whom received blood pressure-lowering treatments . We studied the heterogeneity in the age-specific associations of clinical ly measured blood pressure with 12 acute and chronic cardiovascular diseases , and estimated the lifetime risks ( up to 95 years of age ) and cardiovascular disease-free life-years lost adjusted for other risk factors at index ages 30 , 60 , and 80 years . This study is registered at Clinical Trials.gov , number NCT01164371 . Findings During 5·2 years median follow-up , we recorded 83 098 initial cardiovascular disease presentations . In each age group , the lowest risk for cardiovascular disease was in people with systolic blood pressure of 90–114 mm Hg and diastolic blood pressure of 60–74 mm Hg , with no evidence of a J-shaped increased risk at lower blood pressures . The effect of high blood pressure varied by cardiovascular disease endpoint , from strongly positive to no effect . Associations with high systolic blood pressure were strongest for intracerebral haemorrhage ( hazard ratio 1·44 [ 95 % CI 1·32–1·58 ] ) , subarachnoid haemorrhage ( 1·43 [ 1·25–1·63 ] ) , and stable angina ( 1·41 [ 1·36–1·46 ] ) , and weakest for abdominal aortic aneurysm ( 1·08 [ 1·00–1·17 ] ) . Compared with diastolic blood pressure , raised systolic blood pressure had a greater effect on angina , myocardial infa rct ion , and peripheral arterial disease , whereas raised diastolic blood pressure had a greater effect on abdominal aortic aneurysm than did raised systolic pressure . Pulse pressure associations were inverse for abdominal aortic aneurysm ( HR per 10 mm Hg 0·91 [ 95 % CI 0·86–0·98 ] ) and strongest for peripheral arterial disease ( 1·23 [ 1·20–1·27 ] ) . People with  hypertension ( blood pressure ≥140/90 mm Hg or those receiving blood pressure-lowering drugs ) had a lifetime risk of overall cardiovascular disease at 30 years of age of 63·3 % ( 95 % CI 62·9–63·8 ) compared with 46·1 % ( 45·5–46·8 ) for those with normal blood pressure , and developed cardiovascular disease 5·0 years earlier ( 95 % CI 4·8–5·2 ) . Stable and unstable angina accounted for most ( 43 % ) of the cardiovascular disease-free years of life lost associated with hypertension from index age 30 years , whereas heart failure and stable angina accounted for the largest proportion ( 19 % each ) of years of life lost from index age 80 years . Interpretation The widely held assumptions that blood pressure has strong associations with the occurrence of all cardiovascular diseases across a wide age range , and that diastolic and systolic associations are concordant , are not supported by the findings of this high-resolution study . Despite modern treatments , the lifetime burden of hypertension is substantial . These findings emphasise the need for new  blood pressure-lowering strategies , and will help to inform the design of r and omised trials to assess them . Funding Medical Research Council , National Institute for Health Research , and Wellcome Trust Sudden cardiac death ( SCD ) generally refers to an unexpected death from a cardiovascular cause in a person with or without preexisting heart disease . The specificity of this definition varies depending on whether the event was witnessed ; however , most studies include cases that are associated with a witnessed collapse , death occurring within 1 hour of an acute change in clinical status , or an unexpected death that occurred within the previous 24 hours.1–3 Further , sudden cardiac arrest describes SCD cases with resuscitation records or aborted SCD cases in which the individual survived the cardiac arrest . The incidence of SCD in the United States ranges between 180 000 and 450 000 cases annually.4 These estimates vary owing to differences in SCD definitions and surveillance methods for case ascertainment.4,5 In recent prospect i ve studies using multiple sources in the United States,6,7 Netherl and s,8 Irel and , 9 and China,10 SCD rates range from 50 to 100 per 100 000 in the general population .3 Despite the need for multiple sources of surveillance to provide a more accurate estimate of SCD incidence , it is clear that the overall burden in the population remains high . Although improvements in primary and secondary prevention have result ed in substantial declines in overall coronary heart disease ( CHD ) mortality over the past 30 years,11,12 SCD rates specifically have declined to a lesser extent.13–16 SCD still accounts for > 50 % of all CHD deaths and 15 % to 20 % of all deaths.17,18 For some segments of the population , rates are not decreasing19 and may actually be increasing.14,19 As a result , SCD prevention represents a major opportunity to further reduce mortality from CHD . Despite major advances in cardiopulmonary resuscitation20 and postresuscitation care , survival Background Left ventricular ( LV ) diameter is routinely measured on the echocardiogram but has not been jointly evaluated with the ejection fraction ( EF ) for risk stratification of sudden cardiac death ( SCD ) . Methods and Results From a large ongoing community‐based study of SCD ( The Oregon Sudden Unexpected Death Study ; population ≈1 million ) , SCD cases were compared with geographic controls . LVEF and LV diameter , measured using the LV internal dimension in diastole ( categorized as normal , mild , moderate , or severe dilatation using American Society of Echocardiography definitions ) were assessed from echocardiograms prior but unrelated to the SCD event . Cases ( n=418 ; 69.5±13.8 years ) , compared with controls ( n=329 ; 67.7±11.9 years ) , more commonly had severe LV dysfunction ( EF ≤35 % ; 30.5 % versus 18.8 % ; P<0.01 ) and larger LV diameter ( 52.2±10.5 mm versus 49.7±7.9 mm ; P<0.01 ) . Moderate or severe LV dilatation ( 16.3 % versus 8.2 % ; P=0.001 ) and severe LV dilatation ( 8.1 % versus 2.1 % ; P<0.001 ) were significantly more frequent in cases . In multivariable analysis , severe LV dilatation was an independent predictor of SCD ( odds ratio 2.5 [ 95 % CI 1.03 to 5.9 ] ; P=0.04 ) . In addition , subjects with both EF ≤35 % and severe LV dilatation had higher odds for SCD compared with those with low EF only ( odds ratio 3.8 [ 95 % CI 1.5 to 10.2 ] for both versus 1.7 [ 95 % CI 1.2 to 2.5 ] for low EF only ) , suggesting that severe LV dilatation additively increased SCD risk . Conclusion LV diameter may contribute to risk stratification for SCD independent of the LVEF . This readily available echocardiographic measure warrants further prospect i ve evaluation Background —There are few data regarding the determinants of sudden cardiac death ( SCD ) in women , primarily because of their markedly lower rate of SCD compared with men . Nonetheless , existing data , although sparse , suggest possible gender differences in risk factors for SCD . Methods and Results —In this prospect i ve cohort of 121 701 women aged 30 to 55 years at baseline , SCD was defined as death within 1 hour of symptom onset . From 1976 to 1998 , 244 SCDs were identified . Although the risk of SCD increased markedly with age , the percentage of cardiac deaths that were sudden decreased . Most ( 69 % ) women who suffered a SCD had no history of cardiac disease before their death . However , almost all of the women who died suddenly ( 94 % ) had reported at least 1 coronary heart disease risk factor . Smoking , hypertension , and diabetes conferred markedly elevated ( 2.5- to 4.0-fold ) risk of SCD , similar to that conferred by a history of nonfatal myocardial infa rct ion ( relative risk , 4.1 ; 95 % confidence interval , 2.9 to 6.7 ) . Family history of myocardial infa rct ion before age 60 years and obesity were associated with moderate ( 1.6-fold ) elevations in risk . With regard to mechanism , 88 % of SCDs were classified as arrhythmic . In 76 % of these , the first rhythm documented was ventricular tachycardia or ventricular fibrillation . Conclusions —These prospect i ve data suggest that , as in men , coronary heart disease risk factors predict risk of SCD in women and that SCD is usually an arrhythmic death . Therefore , prevention of atherosclerosis or ventricular arrhythmias may reduce the incidence of SCD in women BACKGROUND Risk factors specific to sudden cardiac death ( SCD ) , ie , death within 1 hour after onset of symptoms , have been poorly identified , although recent findings from the present study incriminate heavy drinking and elevated heart rate . This paper examines the relations between a wide range of established and potential risk factors for ischemic heart disease ( IHD ) and SCD to identify independent risk factors for SCD and factors that might particularly or specifically relate to SCD . METHODS AND RESULTS We present a prospect i ve study of a cohort that was drawn from general practice s in 24 British towns of 7735 middle-aged men who were followed up for 8 years . During 8 years of follow-up , the men experienced 488 major IHD events ( nonfatal and fatal ) , of which 117 ( 24 % ) were classified as SCD . Age , preexisting IHD , arrhythmia , systolic blood pressure , blood cholesterol , elevated heart rate ( > or = 90 beats per minute ) , physical activity ( all , P < .05 ) , and , to a lesser extent , smoking ( P = .06 ) , HDL cholesterol ( P < .07 ) , and elevated hematocrit ( > or = 46 % , P < .09 ) emerged as independent risk factors for SCD after adjustment for a wide range of factors . Diabetes was not found to be associated with SCD , and forced expiratory volume in 1 second , body mass index , white blood cell count , and antihypertensive drugs were not associated with risk of SCD after adjustment . When examined in relation to non-sudden IHD deaths and nonfatal myocardial infa rct ion , elevated heart rate , heavy drinking , and arrhythmia emerged as factors that appear to be specific or particular to SCD . These three factors and age and blood cholesterol were associated with an increased risk of SCD in men both with and without preexisting IHD .  Physical activity , systolic blood pressure , and current smoking were associated with SCD only in men without preexisting IHD . HDL cholesterol and hematocrit were strong predictors of SCD only in men with preexisting IHD . CONCLUSIONS Three risk factors appear to be specific or particular to the risk of SCD , and these and other risk factors operate differently in patients with versus those without preexisting IHD . These findings have implication s for the causes and prevention 
    Output:
    
A nonlinear relationship was suggested between SBP and SCD .
This meta- analysis found an increased risk of SCD with hypertension diagnosis and increasing SBP .