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.
Efstratiadis
Stilianos
S
Division of Cardiology, Department of Medicine, University of Utah, Salt Lake City, Utah 84132-2401, USA.
Michaels
Andrew D
AD
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001011:Aorta / Q000503:physiopathology; D016279:Atrial Function, Left / Q000502:physiology; D002037:Bundle-Branch Block / Q000503:physiopathology; D006328:Cardiac Catheterization; D002306:Cardiac Volume / Q000502:physiology; D015331:Cohort Studies; D015150:Echocardiography, Doppler / Q000379:methods*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006347:Heart Sounds / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology*; D010701:Phonocardiography / Q000379:methods*; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure / Q000502:physiology