atrial fibrillation significantly increases with age in patients with heart failure , and the prevalence increases from < 10% in those with new york heart association ( nyha ) functional class i to almost 50% in those patients with nyha class iv [ 1 , 2 ] . it is estimated that two - thirds of patients with heart failure are over 65 years old and 4.5 times more likely to have atrial fibrillation in men and 5.9 times more likely in women . assessing systolic function in atrial fibrillation is especially important since both pharmacological and device - based therapies exist . however , due to the beat - to - beat variations in preload with atrial fibrillation , assessment of left ventricular systolic function is difficult . systolic function is most commonly assessed using the ejection fraction ( ef ) measured by angiographic , echocardiographic , or radionuclide methods with varying success as schemas continue to be developed to improve accuracy during atrial fibrillation [ 46 ] . in addition , invasive or imaging technologies such as cardiac magnetic resonance to quantify systolic function are expensive and not always readily available . beaverton , or ) records and algorithmically interprets simultaneous digital ecg and acoustic data by using the same array of electrodes used for a standard ecg . however , in the v3 and v4 positions , it employs dual sensors that acquire both ecg and sound data . measuring systolic time intervals and diastolic parameters produced by this technique include those to assess systolic function   including emat ( electrical mechanical activation time , q wave onset to the s1 interval ) , the presence of a third heart sound ( s3 ) , and sdi ( systolic dysfunction index , a combination of emat , s3 , qrs duration and qr interval ) . this diagnostic method is particularly appropriate in environments , where echocardiography or invasive assessment of lv function is not available   or when serial measurements are desired . the goal of the present paper was to evaluate the use of acoustic cardiography as a rapid , noninvasive method to assess lv systolic dysfunction ( lvsd ) in a population with atrial fibrillation that also underwent invasive diagnostic evaluation . we tested the hypothesis that acoustic cardiography could discriminate those patients with and without lv dysfunction independent of whether or not they also had atrial fibrillation . the local medical ethics committee approved the study .    after obtaining written informed consent from each patient short - acting diuretics were withheld on the morning of the catheterization but other cardiac drugs were administered as usual . all the subjects had measurement of left - ventricular ef and lv end - diastolic pressure ( lvedp ) .   left - ventricular maximum dp / dt ( i.e. , lv max(dp / dt ) ) was measured using a manometer - tipped catheter ( volcano inc . , parker , tx , usa ) in 108 patients and a fluid - filled catheter in the remaining 86 . lv max(dp / dt ) was calculated automatically ( schwarzer gmbh medical equipment , munich , germany ) in normally conducted beats . only recordings with a minimum of at least 4 normally conducted beats were used including in patients with atrial fibrillation . values of lv max(dp / dt ) of < 1600  mmhg / s were considered to be a marker of lvsd [ 1315 ] .   left ventricular ejection fraction measurements of right atrial , right ventricular and pulmonary artery systolic and wedge pressures were performed with multipurpose catheters . acoustic cardiography data were recorded immediately prior to cardiac catheterization with the patient in a supine position . this quantitative method provides parameters for assessing both systolic and diastolic lv function .   in the present study , we evaluated two systolic parameters  the electromechanical activation time ( emat ) and the systolic dysfunction index ( sdi ) . emat measures the time interval from the onset of the qrs complex to the point of maximum intensity of the first heart sound . therefore , emat indicates the amount of time required for the lv to generate sufficient force to close the mitral valve and reflects the velocity of force generated during systole . the sdi combines emat , qrs duration , qr interval and the strength of the third heart sound into one parameter ( sdi = transform ( qrs duration  qr interval  s3 strength  emat / rr interval ) ) . the sdi value undergoes a nonlinear transformation and is then reported as a value between 0 and 10 , where sdi > 5 indicates systolic dysfunction defined as ef < 50% , and sdi > 7.5 indicates ef < 35% and elevated filling pressure . the sdi was developed on separate learn and test sets of invasive cardiac catheterization data that provided both ef and lv end - diastolic pressure . the acoustic cardiographic parameters are calculated from a 10-second recording of data that typically involves averaging of measurements from 8 to 12 beats . data are presented as mean values and standard deviations with minimum and maximum values as ranges for continuous variables . we tested the null hypothesis for continuous data using the unpaired t - test for patients with and without atrial fibrillation and a priori chose alpha < 0.05 to indicate statistical significance . we also generated roc curves to determine the diagnostic sensitivities and specificities for lvsd and to calculate positive and negative likelihood ratios . unlike positive and negative predictive values , positive and negative likelihood ratios are independent of the prevalence of the abnormality in the population being tested . to avoid dividing by zero , we set the positive likelihood ratio equal to sensitivity in the cases in which specificity was 100% . the mean age of the 155 subjects without atrial fibrillation was 62.6  11.8 years ( range : 22 to 86 years ) , and 102 ( 66% ) of the subjects were men , whereas the mean age of the 39 patients with atrial fibrillation was 67.3  10.7 years ( range : 43 to 85 years ) and 32 ( 82% ) were men . one hundred three ( 66% ) of the subjects without atrial fibrillation had lvsd ( a lv max(dp / dt ) < 1600  mmhg / s ) , while 22 ( 56% ) of the subjects with atrial fibrillation had lvsd .   in the population without atrial fibrillation , the lv max(dp / dt ) was 1474  479  mmhg / s ( range : 480 to 2928  mmhg / s ) and 1589  534  mmhg / s ( range : 648 to 2832  mmhg / s ) in the group with atrial fibrillation . table 1 shows that the subjects with lvsd had significantly lower mean values of ef , larger end - diastolic and end - systolic volumes , and greater mean values of emat and the systolic dysfunction index . heart rate was significantly higher and emat longer in the populations with atrial fibrillation independent of whether there was lvsd or not . figure 1 shows the means and 95% confidence intervals of emat , the systolic dysfunction index and ef . in both the patients with and without atrial fibrillation , emat and the systolic dysfunction index discriminate between the presence versus the absence of lvsd , as does the ejection fraction . figure 1 also reveals that emat is higher in patients with atrial fibrillation compared to those in sinus rhythm both with and without lvsd suggesting that atrial fibrillation alone impairs lv contractility . the roc curves in figure 2 reveal that emat and sdi are similar in performance for the groups with and without atrial fibrillation . table 2 shows sensitivities , specificities and the likelihood ratios for emat , sdi , and ef at common thresholds to detect lv systolic dysfunction in groups with and without atrial fibrillation . note the similar performances for emat and sdi independent of the presence of atrial fibrillation . specificities were high for all populations for emat and sdi , with moderate sensitivities ( ranging from 30 to 64 ) . echocardiography measures several systolic parameters but the beat - to - beat variations in preload with atrial fibrillation make accuracy difficult . a study by gosselink   found that varying left ventricular performance during atrial fibrillation is determined by cycle length - dependent contractile mechanisms including postextrasystolic potentiation and mechanical restitution , but that beat - to - beat changes in preload consistent with the starling mechanism are diminished after long and short preceding intervals . another study using simultaneous biplane views of the left ventricle concludes that systolic function can be accurately assessed in atrial fibrillation by averaging 2 beats with equal subsequent cycle lengths greater than 500  ms . dubrey   found that in atrial fibrillation the average number of beats required to determine cardiac output using doppler measurements was approximately 13 beats ( ranging 4 to 17 beats ) or three times that required in sinus rhythm . therefore , the time required and skill necessary to perform echocardiographic examinations in patients with atrial fibrillation are quite high . cardiac magnetic resonance imaging ( cmri ) has superior interobserver and intraobserver variability than echocardiography and is the preferred technique by some clinicians for volume and ejection fraction estimation in heart failure patients due to its three - dimensional technique for nonsymmetric ventricles and excellent image quality . but recent literature is mixed on its routine use in the management of atrial fibrillation for evaluation of systolic function . in a recent review of cardiovascular imaging in atrial fibrillation , wazni et al . recommend the use of cmri for precise visualization of left atrial and pulmonary vein anatomy   but recommend echocardiography for clinical management . the acoustic cardiography method is a rapid and inexpensive test and does not have the above limitations inherent in echocardiography or cardiac magnetic resonance imaging . the procedure needed to obtain emat and sdi requires no more time , effort , or technical skill than that needed for recording a standard 12-lead ecg , and the analysis of the data is fully automated . this averaging of values over multiple cardiac cycles improves their performance by minimizing the effect of varying preceding rr intervals as demonstrated for systolic time intervals over 30 years ago [ 23 , 24 ] . in the present paper , we defined left ventricular systolic dysfunction as lv max(dp / dt ) < 1600 , a threshold value similar to that used by other investigators [ 1315 ] . left - ventricular maximum dp / dt is sensitive to changes in contractility and is affected to a lesser extent by both preload and afterload [ 25 , 26 ] . left ventricular max(dp / dt ) may be delayed and may follow the opening of the aortic valve in patients with severe lvsd or with marked vasodilatation with very low aortic diastolic pressures . its sensitivity to preload is greater in ventricles with enhanced contractility , but is reduced in lvsd . nevertheless , reduced lv max(dp / dt ) is clinically important because of its association with a poor prognosis [ 2830 ] . emat also reflects the rate of left ventricular pressure development since it measures the time required to close the mitral valve . emat is similar to lv max(dp / dt ) in that it is influenced by preload via the starling mechanism invoked by left - ventricular filling pressure . however , emat is not affected by afterload resulting from changing systemic vascular resistance or aortic valvular obstruction . in this way , emat can be a robust measurement in atrial fibrillation even with other concurrent disease conditions . the systolic dysfunction index combines emat with qrs duration , the qr interval , and the strength of the third heart sound . it was developed to provide good detection of systolic dysfunction at values above 5.0 , and above 7.5 detects systolic dysfunction with elevated filling pressures . as a continuous variable sdi can provide a means to track changes in systolic function and filling pressures . diminished lv max(dp / dt ) is a well - established and accurate marker of lv systolic dysfunction . the present study has shown that acoustic cardiographic parameters discriminate well between normal versus low values of lv max(dp / dt ) in patients with atrial fibrillation . however , it would be useful to know if these parameters also identify patients who are at increased risk of adverse clinical outcomes . nonacute heart failure patients ( n = 128 ) were studied using acoustic cardiography and echocardiography ( personal communication , m. zuber ) . they were followed for 27.1  14.8 months and all heart failure events and all - cause deaths were recorded ( 24 events total ) . echocardiographic and acoustic cardiographic measurements were evaluated for sensitivity at 90% specificity and the corresponding odds ratios . echocardiographic parameters had lower sensitivity ( t deceleration time 26% at 180  ms ; ef 17% at 45% ; e / e   ratio 18% at 15 ; e / a 25% at 1.8 ) than the acoustic cardiographic parameters ( emat 38% at 120  ms ; sdi 45% at 5.0 ) . the echocardiographic measurements also had lower odds ratios ( ranging from 0.4 for t deceleration time to 2.2 for e / e ratio ) than acoustic cardiographic parameters ( ranging from 5.9 for emat to 7.5 for sdi ) . this study would indicate that both emat and sdi have superior prognostic value over the traditional echocardiographic measurements . in another study of patients hospitalized for acute heart failure ( n = 45 ) , acoustic cardiographic recordings were taken within 24 hours of admission , before discharge and 2 weeks after discharge . predischarge and 2-week postdischarge % emat ( defined as emat divided by the r - r interval ) was significantly associated with adverse post - discharge events , with or without adjustment for age , gender , left ventricular ef , e / e by doppler echocardiography , and serum n - terminal probrain natriuretic peptide . we conclude that acoustic cardiography detects left ventricular systolic dysfunction in patients with atrial fibrillation . this is particularly important when repeat assessment is desired and in situations where invasive ( cardiac catheterization ) or noninvasive ( echocardiographic or cardiac magnetic resonance imaging ) assessment of lv function is not feasible or readily available . although it is similar to older methods used to obtain systolic time intervals , acoustic cardiography is a relatively new method of quantifying cardiac function and has limited routine use . there was not a control group of healthy subjects due to the fact that this was an invasive cardiac catheterization study . not all the recordings of left ventricular dp / dt were performed with manometer - tipped catheters . left ventricular ejection fraction although short - acting diuretics were withheld on the morning of the catheterization , the subjects varied with respect to the types and dosages of other cardiac drugs that they were receiving . since beta adrenergic blockers , vasodilators , ace inhibitors and other cardiac drugs influence ventricular performance , this pharmacological variability may have affected our results .
objectives . assessment of left ventricular ( lv ) systolic function in patients with atrial fibrillation can be difficult . 
 acoustic cardiography provides several parameters for quantifying lv systolic function . 
 we evaluated the ability of acoustic cardiography to detect lv systolic dysfunction in patients with and without atrial fibrillation . 
 design . 
 we studied 194 patients who underwent acoustic cardiography and cardiac catheterization including measurement of angiographic ejection fraction ( ef ) and maximum lv dp / dt . 
 lv systolic dysfunction was defined as lv maximum dp / dt < 1600  mmhg / s . 
 acoustic cardiographic parameters included electromechanical activation time ( emat ) and the systolic dysfunction index ( sdi ) . results . 
 acoustic cardiography detected systolic dysfunction with high specificity and moderate sensitivity with similar performance to ef ( sensitivity / specificity without afib : emat 30/96 , sdi 40/90 , ef at 35% 30/96 ; sensitivity / specificity with afib : emat 64/82 , sdi 59/100 , ef at 35% 45/82 ) . conclusions . 
 acoustic cardiography can be used for diagnosis of lv systolic dysfunction in atrial fibrillation .