In a population consisting of 45 subjects (15 patients with mitral stenosis, 15 patients with heart failure, and 15 normal subjects), the left atrial (LA) pressure-area relation was assessed and the correlations between LA stroke work, LA kinetic energy, and LA ejection force were studied. The area of the counterclockwise A loop expressing the LA external work was measured. LA kinetic energy was obtained from the formula: 1/2 x stroke volume x 1.06 x v2, where v = transmitral Doppler A velocity. An excellent correlation was found between LA stroke work index and LA kinetic energy when data from all patients were plotted together (r = 0.95, p <0.001). The Pearson's correlation similarity coefficient between LA ejection force and kinetic energy as well as between LA ejection force and stroke work index was r = 0.54 (p <0.001). The r value of 0.54 was significantly lower than r = 0.95 (p <0.03). LA kinetic energy extends the use of transmitral flow Doppler data to include assessment of LA work. LA work can be obtained noninvasively with a high degree of accuracy.