Left atrial dysfunction in left ventricular restrictive physiology

Doppler mitral inflow at atrial systole is reduced in patients with dilated cardiomyopathy and restrictive left ventricular (LV) filling. However, loss of left atrial (LA) systole may worsen heart failure. To test the hypothesis that LA function may not be adequately described by Doppler flow in patients with restrictive filling, we measured LA area changes using echocardiographic automated boundary detection (ABD). In 20 patients with dilated cardiomyopathy (ejection fraction <40%), 10 with restrictive (peak E/A > 1.2, E deceleration time <150 ms) and 10 age-matched with non restrictive LV filling, and in 20 control subjects, we used ABD (4-chamber view) to measure: maximum and minimum LA areas (cm²); their difference as LA filling; LA systolic emptying area change (area at ECG P wave-minimum); LA systolic emptying normalized by filling (systolic area change/filling x 100, %). We also measured Doppler mitral LV atrial filling fraction (A integral/total integral x 100, %). In patients with LV restrictive physiology, LA areas were larger and LA filling smaller. LA systolic emptying was reduced, but when normalized to LA filling it was not different from that of the other two groups. Atrial filling fraction was increased in non restrictive and reduced in restrictive patients. In conclusion, in restrictive dilated cardiomyopathy the left atrium is larger and fills less than in patients without restrictive physiology. Though LA systolic emptying is also reduced, it may still account for as much as half of the total LA change in dimension, the difference compared to the reduced LV atrial filling fraction being that Doppler includes the LV conduit filling volume. Compared to Doppler flow analysis, ABD provides a more detailed definition of LA dysfunction in patients with dilated cardiomyopathy and restrictive physiology.