Acoustic cardiography augments prolonged QRS duration for detecting left ventricular dysfunction

Mobile Cardiac Acoustic Monitoring System to Evaluate Left Ventricular Systolic Function in Pacemaker Patients

The mobile cardiac acoustic monitoring system is a promising tool to enable detection and assist the diagnosis of left ventricular systolic dysfunction (LVSD). The objective of the study was to evaluate the diagnostic value of electromechanical activation time (EMAT), an important cardiac acoustic biomarker, in quantifying LVSD among left bundle branch pacing (LBBP) and right ventricular apical pacing (RVAP) patients using a mobile acoustic cardiography monitoring system. In this prospective single-center observational study, pacemaker-dependent patients were consecutively enrolled. EMAT, the time from the start of the pacing QRS wave to first heart sound (S1) peak; left ventricular systolic time (LVST), the time from S1 peak to S2 peak; and ECG were recorded simultaneously by the mobile cardiac acoustic monitoring system. LVEF was measured by echocardiography. A logistic regression model was applied to evaluate the association between EMAT and reduced EF (LVEF < 50%). A total of 105 pacemaker-dependent patients participated. The RVAP group (n = 58) displayed a significantly higher EMAT than the LBBP group (n = 47) (150.95 ± 19.46 vs. 108.23 ± 12.26 ms, p < 0.001). Pearson correlation analysis revealed a statistically significant negative correlation between EMAT and LVEF (p < 0.001). Survival analysis showed the sensitivity and specificity of detecting LVEF to be < 50% when EMAT ≥ 151 ms were 96.00% and 96.97% in the RVAP group. In LBBP patients, the sensitivity and specificity of using EMAT ≥ 110 ms as the cutoff value for the detection of LVEF < 50% were 75.00% and 100.00%. There was no significant difference in LVST with or without LVSD in the RVAP group (p = 0.823) and LBBP group (p = 0.086). Compared to LVST, EMAT was more helpful to identify LVSD in pacemaker-dependent patients. The cutoff point of EMAT for diagnosing LVEF < 50% differed regarding the pacing type. Therefore, the mobile cardiac acoustic monitoring system can be used to identify the progress of LVSD in pacemaker patients.

Changes in acoustic cardiographic parameters before and after hemodialysis are associated with overall and cardiovascular mortality in hemodialysis patients

Acoustic cardiography can provide simultaneous electrocardiography and acoustic cardiac data to assess the electronic and mechanical heart functions. The aim of this study was to assess whether changes in acoustic cardiographic parameters (ACPs) before and after hemodialysis (HD) are associated with overall and cardiovascular (CV) mortality in HD patients. A total of 162 HD patients was enrolled and ACPs were measured before and after HD, including left ventricular systolic time (LVST), systolic dysfunction index (SDI), third (S3) and fourth (S4) heart sounds, and electromechanical activation time (EMAT). During a follow-up of 2.9 years, 25 deaths occurred with 16 from CV causes. Multivariate analysis showed that high △SDI (per 1; hazard ratio [HR], 2.178; 95% confidence interval [CI], 1.189–3.990), high △EMAT (per 1%; HR, 2.218; 95% CI 1.382–3.559), and low △LVST (per 1 ms; HR, 0.947; 95% CI 0.912–0.984) were independently associated with increased overall mortality. In addition, high △EMAT (per 1%; HR, 2.141; 95% CI 1.117–4.102), and low △LVST (per 1 ms; HR, 0.777; 95% CI 0.637–0.949) were associated with increased CV mortality. In conclusion, the changes in ACPs before and after HD may be a useful clinical marker and stronger prognostic marker of overall and CV mortality than ACPs before HD.

Investigation of Acoustic Cardiographic Parameters before and after Hemodialysis

Patients with end-stage renal disease are at an increased risk of cardiovascular diseases and associated mortality. Acoustic cardiography is a technique in which cardiac acoustic data is synchronized with electric information to detect and characterize heart sounds and detect heart failure early. The aim of this study was to investigate acoustic cardiographic parameters before and after hemodialysis (HD) and their correlations with ankle-brachial index (ABI), brachial-ankle pulse wave velocity (baPWV), and ratio of brachial preejection period to ejection time (bPEP/bET) obtained from an ABI-form device in HD patients. This study enrolled 162 HD patients between October 2016 and April 2018. Demographic, medical, and laboratory data were collected. Acoustic cardiography was performed before and after HD to assess parameters including third heart sound (S3), fourth heart sound (S4), systolic dysfunction index (SDI), electromechanical activation time (EMAT), and left ventricular systolic time (LVST). The mean age of the enrolled patients was 60.4 ± 10.9 years, and 86 (53.1%) patients were male. S4 (p < 0.001) and LVST (p < 0.001) significantly decreased after HD, but EMAT (p < 0.001) increased. Multivariate forward linear regression analysis showed that EMAT/LVST before HD was negatively associated with albumin (unstandardized coefficient β = ‐0.076; p = 0.004) and ABI (unstandardized coefficient β = ‐0.115; p = 0.011) and positively associated with bPEP/bET (unstandardized coefficient β = 0.278; p = 0.003). Screening HD patients with acoustic cardiography may help to identify patients at a high risk of malnutrition, peripheral artery disease, and left ventricular systolic dysfunction.

Use of acoustic cardiography immediately following electrical cardioversion to predict relapse of atrial fibrillation

Predicting atrial fibrillation (AF) recurrence after successful electrical cardioversion (ECV) is difficult. The main aim of this study was to investigate whether acoustic cardiography (AUDICOR® 200) immediately post-ECV might provide indices for AF relapse following cardioversion. Acoustic cardiography parameters included Electromechanical Activation Time (EMAT), Left Ventricular Systolic Time (LVST), QRS duration, heart rate and third heart sound intensity (S3 Strength). We analysed data from 140 patients who underwent successful cardioversion and in whom AUDICOR results and echocardiographic measurements immediately after (baseline) ECV were available. Patients were prospectively followed-up at 4-6 weeks, 3 and 12 months post-ECV, and sinus rhythm maintenance was evaluated using acoustic cardiography and Holter electrocardiography. The effect of each baseline AUDICOR parameter on the hazard of AF relapse was investigated using Cox proportional hazards (PH) models. Fifty patients (35.7%) had AF relapse. Of all the AUDICOR parameters, only S3 Strength exhibited consistent predictive value. Increasing S3 Strength increased the hazard of relapse in a univariable Cox PH model (HR=2.52, p=0.003), and in two multivariable Cox PH model constructions (Model 1 excluded heart rate and Model II excluded EMAT/RR, LVST and LVST/RR) both of which included the parameters as continuous variables (Model I: HR=1.15, p=0.042; Model II: HR=1.14, p=0.045) or the parameters dichotomized according to suggested cut-points (Model I: HR=2.5, p=0.007; Model II: HR=2.09, p=0.031). In conclusion, this study suggests that acoustic cardiography may be a simple inexpensive and quantitative bedside method to assist in prediction of AF recurrence after ECV.

Systolic time intervals combined with Valsalva maneuver for the diagnosis of left ventricular dysfunction in COPD exacerbations

Background

The goal of this study was to determine the value of systolic time intervals and their change during Valsalva maneuver (VM) in the diagnosis of left ventricular dysfunction (LVD) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Methods

We included 166 patients admitted to the emergency department for AECOPD. Measurement of systolic time intervals included electromechanical activation time (EMAT), left ventricular ejection time (LVET), and EMAT/LVET ratio. These were performed at baseline and during the first strain phase of the VM using a computerized phonoelectrocardiographic method. The diagnosis of LVD was determined on the basis of clinical examination, echocardiography, and brain natriuretic peptide. The values of systolic time intervals were compared between patients with and without LVD; their diagnostic performance was assessed using the area under receiver operating characteristic (ROC) curve.

Results

Patients with LVD (n=95) had a significantly higher EMAT and lower LVET and EMAT/LVET ratio compared to patients without LVD (n=71); the area under ROC curve was 0.79, 0.88, and 0.90, respectively, for EMAT, LVET, and EMAT/LVET ratio. All baseline systolic time intervals changed significantly during VM in patients without LVD but they did not change in patients with LVD. The area under ROC curve increased to 0.84 and 0.93, respectively, for EMAT and EMAT/LVET ratio but did not change for LVET.

Conclusion

Simple and noninvasive measurements of systolic time intervals combined with VM could be helpful to detect or rule out LVD in patients admitted to the emergency room for COPD excacerbation. The EMAT/LVET ratio seems to have the best diagnostic value.

Impact of preload changes on positive and negative left ventricular dP/dt and systolic time intervals: preload changes on left ventricular function

AIM/OBJECTIVES

Previous work has shown that the electromechanical activation time (EMAT) is prolonged in patients with abnormally low left ventricular (LV) dP/dt. In the present study, we investigated whether EMAT was responsive to rapid changes in LV systolic function induced by abrupt increases in LV preload.

METHODS AND RESULTS

A total of 116 patients were assessed before and after LV angiography with a bolus injection of 40 mL of non-ionic contrast dye. Left ventricular end-diastolic pressure (LVEDP) increased from 18 ± 7 mmHg to 20 ± 8 mmHg (P < 0.01). In patients with a baseline dP/dt < 1500 mmHg/sec, dP/dt increased from 1098 ± 213 mmHg/sec to 1146 ±306 mmHg/sec (P=0.02) and EMAT decreased from 106 ± 29 ms to 103 ±18 ms (P=0.02). In patients with a baseline dP/dt > 1500 mmHg/sec, dP/dt decreased from 1894 ± 368 mmHg/sec to 1762 ± 403 mmHg/sec (P=0.01) and EMAT increased from 88 ± 13 ms to 93 ± 16 ms (P=0.02). Changes in negative dP/dt were similar to changes in dP/dt.

CONCLUSION

Electromechanical activation time is a non-invasively measured parameter that allows accurate and rapid detection of changes in LV contractility.

Estimation of left ventricular function using a novel acoustic-based device

BACKGROUND

We examined the feasibility of estimating left ventricular ejection fraction (LVEF) by a novel acoustic-based device [vibration response imaging (VRI); Deep Breeze].

METHODS

One hundred and forty-one subjects (117 patients and 24 healthy volunteers; age 55 ± 15 years, 82% men) were examined by both VRI and echocardiography. LVEF was determined by echocardiography (echo-LVEF) using the biplane Simpson's method. Low-frequency acoustic signals (10-70 Hz) were recorded by VRI from the left posterior thorax by a matrix of 36 microphones during 8 s of breath holding, and an electrocardiogram was recorded simultaneously. The acoustic signals were processed digitally, and an algorithm designed to estimate LVEF was developed (VRI-LVEF), based on a combination of multiple acoustic (systolic and diastolic acoustic signals, beat-to-beat variability of acoustic signals and propagation of acoustic signals throughout the matrix), electrocardiographic and clinical parameters.

RESULTS

Mean echo-LVEF was 51 ± 15% (range, 11-76%). Echo-LVEF was reduced (< 50%) in 55 subjects (39%) and severely reduced (< 35%) in 28 subjects (20%). VRI-LVEF calculated by a multivariate algorithm correlated significantly with echo-LVEF (R(2) = 0·59; P < 0·001). VRI-LVEF accurately predicted the presence of reduced (< 50%) or severely reduced (< 35%) echo-LVEF, with sensitivities of 84% and 82%, specificities of 86% and 91%, positive predictive values of 79% and 70% and negative predictive values of 89% and 95%, respectively.

CONCLUSIONS

LVEF can be estimated using a novel acoustic-based device. This device may assist in triage of patients according to LVEF prior to definitive assessment of LVEF by echocardiography.

Aspects of left ventricular morphology outperform left ventricular mass for prediction of QRS duration

BACKGROUND

The knowledge of the case-specific normal QRS duration in each individual is needed when determining the onset, severity and progression of the heart disease. However, large interindividual variability even of the normal QRS duration exists. The aims of the study were to develop a model for prediction of normal QRS complex duration and to test it on healthy individuals.

METHODS

The study population of healthy adult volunteers was divided into a sample for development of a prediction model (n = 63) and a testing sample (n = 30). Magnetic resonance imaging data were used to assess anatomical characteristics of the left ventricle: the angle between papillary muscles (PM(A)), the length of the left ventricle (LV(L)) and left ventricular mass (LV(M)). Twelve-lead electrocardiogram (ECG) was used for measurement of the QRS duration. Multiple linear regression analysis was used to develop a prediction model to estimate the QRS duration. The accuracy of the prediction model was assessed by comparing predicted with measured QRS duration in the test set.

RESULTS

The angle between PM(A) and the length of the LV(L) were statistically significant predictors of QRS duration. Correlation between QRS duration and PM(A) and LV(L) was r = 0.57, P = 0.0001 and r = 0.45, P = 0.0002, respectively. The final model for prediction of the QRS was: QRS(Predicted)= 97 + (0.35 x LV(L)) - (0.45 x PM(A)). The predicted and real QRS duration differed with median 1 ms.

CONCLUSIONS

The model for prediction of QRS duration opens the ability to predict case-specific normal QRS duration. This knowledge can have clinical importance, when determining the normality on case-specific basis.

Acoustic cardiography to improve detection of coronary artery disease with stress testing

AIM

To assess if performance of 12-lead exercise tolerance testing (ETT) can be improved by simultaneous acoustic cardiography and to compare the diagnostic performances of electrocardiography (ECG) during ETT and acoustic cardiography for detection or exclusion of angiographically proven coronary artery disease (CAD).

METHODS

We conducted an explorative study with retrospective data analysis using a convenience sample of consecutive patients (n = 59, mean age: 62 years) from an outpatient clinic in Switzerland, who were referred for ETT by their general practitioner on suspicion of CAD, and in whom, coronary angiography was carried out. Measurements included sensitivity, specificity, likelihood ratios and receiver operating characteristic curves. A standard, symptom-limited, 12-lead ECG exercise tolerance test was performed by independent persons with simultaneous acoustic cardiography and subsequent cardiac angiography for determination of significant CAD.

RESULTS

Thirty-four of the 59 adult subjects (58%) had a final diagnosis of CAD by angiography, and in 25 subjects, CAD was excluded by angiography. Sensitivity/specificity of ST segment depression in the group was 29%/92%, whereas the most powerful acoustic cardiographic parameter was the strength of the fourth heart sound (S4), with corresponding sensitivity/specificity of 53%/92%. The disjunctive combination of the S4 and ST depression had sensitivity/specificity of 68%/84%.

CONCLUSION

In this preliminary pilot study, the use of acoustic cardiography alone during ETT or disjunctively with ST depression has been shown to be a simple and convenient method for the detection of CAD, which was superior to ST depression on the standardized ECG.