Evaluation of left ventricular systolic function using synchronized analysis of heart sounds and the electrocardiogram

Background: Heart failure is a major health concern and often requires echocardiography to confirm the diagnosis. We introduce a new method that uses a wearable heart sound and electrocardiogram (ECG) device that can be used in the outpatient setting.

Objective: The purpose of this study was to determine the value of synchronized analysis of heart sounds and ECG in identifying patients with depressed left ventricular ejection fraction (dLVEF) <50%.

Methods: One hundred eighty-nine patients (76 with dLVEF; 113 with normal ejection fraction) were enrolled. All were admitted to the hospital because of dyspnea or chest discomfort. N-Terminal pro-B-type natriuretic peptide (NT-proBNP) was measured in all patients. LVEF was determined by echocardiography. Heart sound and ECG signals were simultaneously recorded using the wearable synchronized phonocardiogram and ECG device. Heart sound and ECG signals were automatically analyzed using wavelet analysis and utilized to determine electromechanical activation time (EMAT), EMAT/RR, S1-S2 time, and S1-S2/RR.

Results: EMAT in the dLVEF group was significantly higher than that in the control group (159.82 ± 83 ms vs 91.58 ± 28 ms). Pearson correlation test showed a negative correlation between EMAT and LVEF (r = -0.449; P <.001). Receiver operating characteristic curve analysis demonstrated that the sensitivity and specificity of EMAT ≥104 ms for the diagnosis of EF <50% were 92.1% and 92%, respectively. Patients with intermediate NT-proBNP values were identified as dLVEF by EMAT ≥104 ms, with sensitivity of 93.5% and specificity of 92.8%.

Conclusion: The heart sound and ECG signal index EMAT contributes to the diagnosis of EF <50% and is especially helpful in patients with an inconclusive NT-proBNP value.