Computerized acoustic cardiographic electromechanical activation time correlates with invasive and echocardiographic parameters of left ventricular contractility.

Background: Electromechanical 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.
Methods: A 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 >or= 0.15 was prospectively defined as abnormal.
Results: An 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/m(2) vs 71.0 +/- 35.8 mL/m(2), P = .011), end-diastolic volume index (61.2 +/- 29.8 mL/m(2) vs 100.3 +/- 40.8 mL/m(2), 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).
Conclusions: An 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.