***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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    Input: The reproducibility of a variety of Doppler indexes of diastolic function in an epidemiologic setting and in atrial fibrillation have not been reported . This study examined the reproducibility of left ventricular inflow in  subjects in sinus rhythm ( n = 80 ) and atrial fibrillation ( n = 12 ) , r and omly selected from the original cohort of the Framingham Heart Study . The following Doppler indexes were assessed for all subjects : peak and integral of early ( E ) diastolic inflow velocity , acceleration slope and time , deceleration slope and time , and pressure half-time . For subjects in sinus rhythm , the following parameters also were measured : the peak and integral of late ( A ) diastolic inflow velocity , ratios of peak velocities and integrals E/A , and atrial filling fraction . Intraobserver and interobserver variability were evaluated by statistical methods including Student 's t test of the systematic differences ( bias ) , percent bias , correlation coefficients , measurement precision , and percent precision . In subjects in sinus rhythm , although the interobserver bias was statistically significant for most of the parameters , it was < 10 % for all but 1 parameter ( acceleration time ) . For the peak and integral measures , the intra- and interobserver correlations were > or = 0.89 , with intra- and interobserver percent precision measures within 2.2 to 13.0 % of the corresponding mean values . The acceleration , deceleration and pressure half-time measures had somewhat lower correlations ( interobserver correlations ranging from 0.59 to 0.96 ) , with percent precision measures further from the corresponding means ( interobserver percent precision ranging from 10.1 to 19.5 % ) . ( ABSTRACT TRUNCATED AT 250 WORDS Background — There is a paucity of international data on the various types of atrial fibrillation ( AF ) outside the highly selected population s from r and omized trials . This study aim ed to describe patient characteristics , risk factors , comorbidities , symptoms , management strategy , and control of different types of AF in real-life practice . Methods and Results — Real-life global survey evaluating patients with atrial fibrillation ( RealiseAF ) was a contemporary , large-scale , cross-sectional international survey of patients with AF who had ≥1 episode in the past 12 months . Investigators were r and omly selected to avoid bias . Among 9816 eligible patients from 831 sites in 26 countries , 2606 ( 26.5 % ) had paroxysmal , 2341 ( 23.8 % ) had persistent , and 4869 ( 49.6 % ) had permanent AF . As AF progressed from paroxysmal to persistent and permanent forms , the prevalence of comorbidities , such as heart failure ( 32.9 % , 44.3 % , and 55.6 % ) , coronary artery disease ( 30.0 % , 32.9 % , and 34.3 % ) , cerebrovascular disease ( 11.7 % , 10.8 % , and 17.6 % ) , and valvular disease ( 16.7 % , 21.2 % , and 35.8 % ) , increased , and the prevalence of lone AF decreased . Similarly , there was an increase in mean CHADS2 [ cardiac failure , hypertension , age , diabetes , stroke ( doubled ) ] score ( 1.7 , 1.8 , and 2.2 ) , and more than half of patients ( 51.0 % , 56.7 % , and 67.3 % ) qualified for oral anticoagulants . Almost 90 % of patients received ≥1 antiarrhythmic drug , but > 60 % had European Heart Rhythm Association symptom scores from II to IV . Furthermore , 40.7 % of persistent and 49.8 % of permanent AF patients were still in AF with a heart rate > 80 beats per minute . Conclusions — This survey disclosed high cardiovascular risks and an unmet need in daily practice for patients with any type of AF , especially those with the permanent form BACKGROUND Doppler echocardiography is frequently used to predict filling pressures in normal sinus rhythm , but it is unknown whether it can be applied in sinus tachycardia , with merging of E and A velocities . Tissue Doppler imaging ( TDI ) can record the mitral annular velocity . The early diastolic velocity ( Ea ) behaves as a relative load-independent index of left ventricular relaxation , which corrects the influence of relaxation on the transmitral E velocity . METHODS AND RESULTS We evaluated 100 patients 64+/-12 years old with simultaneous Doppler and invasive hemodynamics . Mitral inflow was classified into 3 patterns : complete merging of E and A velocities ( pattern A ) , discernible velocities with A dominance ( B ) , or E dominance ( C ) . The Doppler data were analyzed at the mitral valve tips for E , acceleration and deceleration times of E , and isovolumic relaxation time . In patterns B and C , the A velocity , E/A ratio , and atrial filling fraction were derived . Pulmonary venous flow velocities were also measured , and TDI was used to acquire Ea and Aa . Weak significant relations were observed between pulmonary capillary wedge pressure ( PCWP ) and sole parameters of mitral flow , pulmonary venous flow , and annular measurements . These were better for patterns A and C. E/Ea ratio had the strongest relation to PCWP [ r=0.86 , PCWP=1.55 + 1.47(E/Ea ) ] , irrespective of the pattern and ejection fraction . This equation was tested prospect ively in 20 patients with sinus tachycardia . A strong relation was observed between catheter and Doppler PCWP ( r=0.91 ) , with a mean difference of 0.4+/-2.8 mm Hg . CONCLUSIONS The ratio of transmitral E velocity to Ea can be used to estimate PCWP with reasonable accuracy in sinus tachycardia , even with complete merging of E and A velocities Background —Conventional Doppler measurements have limitations in the prediction of left atrial pressure ( LAP ) in patients with mitral valve disease ( MVD ) , given the confounding effect of valve area , left ventricular ( LV ) relaxation , and stiffness . However , the time interval between the onset of early diastolic mitral inflow velocity ( E ) and annular early diastolic velocity ( Ea ) by tissue Doppler imaging ( TDI ) , TE−Ea , which is well related to the time constant of LV relaxation ( & tgr ; ) in canine and clinical studies , is not subject to these variables . We therefore undertook this study to test its usefulness in a patient population . Methods and Results —Two-dimensional Doppler and TDI echocardiography were performed simultaneously with right-heart catheterization in 51 consecutive patients ( mean±SD age , 64±11 years ) with MVD : 35 with moderately severe to severe mitral regurgitation ( MR ) and 16 with moderate to severe mitral stenosis ( MS ) . Among several Doppler measurements , only the mitral E/A ratio , isovolumetric relaxation time ( IVRT ) , and pulmonary venous Ar duration had significant relations with mean pulmonary capillary wedge pressure ( PCWP ) . The ratio of IVRT to TE−Ea ( for MR , r=−0.92 ; for MS , r=−0.88 ; both P<0.001 ) and the ratio of IVRT to & tgr ; ( for MR , r=−0.74 ; for MS , r=−0.85 ; both P<0.001 ) had the best correlations with PCWP . In 54 repeat studies , including those performed after MV repair or replacement , these ratios tracked well the changes in PCWP and readily identified changes in mean PCWP by ≥5 mm Hg . A similar correlation was noted in 13 patients with atrial fibrillation ( r=−0.92 , P<0.01 ) and in a prospect i ve group of 14 patients with MR ( r=−0.93 , P<0.001 ) . Conclusions —The ratio of IVRT to TE−Ea or to & tgr ; can be readily applied for estimating mean PCWP in patients with MVD and can track changes in PCWP after valve surgery BACKGROUND It is traditionally difficult to estimate left ventricular ( LV ) systolic function in atrial fibrillation ( AF ) . The aim of this study was to vali date the use of an index beat , the beat after the nearly equal preceding ( RR1 ) and pre-preceding ( RR2 ) intervals , for the measurement of LV peak longitudinal systolic strain ( PLSS ) . The difference between RR1 and RR2 intervals of the index beat must be < 60 msec . LV PLSS measured from the index beat ( PLSSindex ) was compared with LV PLSS measured from the conventional but time-consuming method of averaging multiple cardiac cycles ( PLSSavg ) . METHODS Ninety-eight patients with persistent or permanent AF and resting ventricular rates ≤ 105 beats/min were prospect ively included .  LV PLSSindex and LV PLSSavg were obtained from two-dimensional speckle-tracking echocardiography . RESULTS LV PLSSindex had a highly significant correlation with LV PLSSavg ( r = 0.970 , P < .001 ) . Bl and -Altman analysis showed only small bias of 0.01 % , and the 95 % limits of agreement were + 1.64 % to -1.62 % . Compared with those with lower risk scores of stroke indicated by CHADS(2 ) scores < 2 or CHA(2)DS(2)-VASc scores < 2 , patients with higher risk scores of stroke indicated by CHADS(2 ) scores ≥ 2 or CHA(2)DS(2)-VASc scores ≥ 2 had lower PLSSavg and PLSSindex ( P ≤ .012 ) . CONCLUSIONS LV PLSSindex was a good alternative to LV PLSSavg in patients with AF . Use of the index beat to measure LV longitudinal systolic strain in patients with AF was as accurate as the time-consuming method of averaging multiple cardiac cycles Single-beat determination of left ventricular systolic function at a beat with equal subsequent cardiac cycles has been proposed as an accurate method in atrial fibrillation . However , there has still been substantial variability between the values calculated from beats with equal subsequent cycles . Therefore , some refinement on the single-beat method is needed . In 100 patients with atrial fibrillation , Doppler aortic flow time-velocity integral was determined for at least 20 consecutive cardiac cycles . The values at beats with equal subsequent cardiac cycles were chosen and compared with the average values over all cardiac cycles . The values at beats with cycle lengths shorter than 500 milliseconds were usually far below the average values over all cardiac cycles . Bl and -Altman agreement analysis revealed improved accuracy by gradually narrowing the range of the limits of agreement when 2 or 3 beats with equal subsequent cycles and cycle lengths longer than 500 milliseconds were used for evaluation OBJECTIVES We sought to obtain a noninvasive estimation of mean pulmonary wedge pressure ( MPWP ) in patients with chronic atrial fibrillation ( AF ) . BACKGROUND It has previously been demonstrated that MPWP can be reliably estimated from Doppler indexes of mitral and pulmonary venous flow ( PVF ) in patients with sinus rhythm . Doppler estimation of MPWP has not been vali date d in patients with AF . METHODS MPWP was correlated with variables of mitral and pulmonary venous flow velocity as assessed by Doppler transthoracic echocardiography in 35 consecutive patients . The derived algorithm was prospect ively tested in 23 additional patients . RESULTS In all patients the mitral flow pattern showed only a diastolic forward component . A significant but relatively weak correlation ( r = -0.50 ) was observed between MPWP and mitral deceleration time . In 12 ( 34 % ) of 35 patients , the pulmonary vein flow tracing demonstrated only a diastolic forward component ; a diastolic and late systolic forward flow was noted in the remaining 23 patients ( 66 % ) . A strong negative correlation was observed between MPWP and the normalized duration of the diastolic flow ( r = -0.80 ) and its initial deceleration slope time ( r = -0.91 ) . Deceleration time > 220 ms predicted MPWP < or = 12 mm Hg with 100 % sensitivity and 100 % specificity . When estimating MPWP by using the equation MPWP = -94.261 PVF deceleration time -9.831 Interval QRS to onset of diastolic PVF -16.337 Duration of PVF + 44.261 , the measured and predicted MPWP closely agreed with a mean difference of -0.85 mm Hg . The 95 % confidence limits were 4.8 and -6.1 mm Hg . CONCLUSIONS In patients with chronic AF , MPWP can be estimated from transthoracic Doppler study of PVF velocity signals Although exercise intolerance is a major symptom of patients with atrial fibrillation ( AF ) , the factors limiting these patients ' exercise capacity remains uncertain . This study evaluated the correlation of clinical and echocardiographic parameters with exercise capacity of patients with AF . In all , 73 patients ( 61 men and 12 women ; mean age 61 years ) with chronic AF were included in this study . Those patients with primary valvular diseases were excluded .  St and ard 2-dimensional and Doppler echocardiography was performed , and we averaged 10 consecutive measurements of each variable . Patients then underwent a symptom-limited treadmill exercise testing . We also measured patients ' plasma levels of B-type natriuretic peptide before exercise testing . Of all clinical and echocardiographic parameters we assessed , age ( r = -0.45 , P = .006 ) , ratio of early mitral inflow 
    Output:
    
Cardiac cycle length and equivalence were more important than the number of beats averaged .
Conclusion With careful selection of appropriate cardiac cycles , echocardiography is a valid tool to identify diastolic dysfunction in AF , and E/e ' is an independent marker of clinical status and adverse prognosis .