Computerized Acoustic Cardiographic Electromechanical Activation Time Correlates With Invasive and Echocardiographic Parameters of Left Ventricular Contractility

BackgroundElectromechanical activation time (EMAT) is a systolic time interval defined as the time from Q-wave onset to the peak first heart sound. We assessed the correlation between systolic dysfunction and EMAT calculated using computerized acoustic cardiography.MethodsA total of 25 patients with heart failure contemporaneously underwent echocardiography, left-sided heart catheterization, and acoustic cardiography. Invasive pressure–volume hemodynamics included peak isovolumetric left ventricular (LV) pressure at the end-diastolic volume, end-diastolic pressure, dyssynchrony, and maximal +dP/dT. An EMAT/(R to R interval) (%EMAT) interval ≥ 0.15 was prospectively defined as abnormal.ResultsAn abnormal %EMAT correlated with a lower LV ejection fraction (50.9% ± 18.6% with normal EMAT vs 32.0% ± 10.9% with abnormal EMAT, P = .015), end-systolic elastance (3.07 ± 1.56 mm Hg/mL vs 1.43 ± 0.83 mm Hg/mL, P = .018), and peak isovolumetric LV pressure at the end-diastolic volume (317 ± 90 mm Hg vs 222 ± 67 mm Hg, P = .015). An abnormal %EMAT was associated with a higher end-systolic volume index (33.6 ± 29.3 mL/m2 vs 71.0 ± 35.8 mL/m2, P = .011), end-diastolic volume index (61.2 ± 29.8 mL/m2 vs 100.3 ± 40.8 mL/m2, P = .012), and dyssynchrony (26.1% ± 6.0% vs 31.5% ± 3.5%, P = .028). There was no difference in end-diastolic pressure (20.3 ± 7.9 mm Hg vs 21.4 ± 12.3 mm Hg, P = .78).ConclusionsAn abnormal %EMAT was strongly associated with impaired LV contractility but had no association with LV filling pressures. This noninvasive, simple, point-of-care diagnostic test has potential applications when echocardiography cannot be obtained in a timely fashion to assess systolic function.