Left atrial backward ejection in symptomatic hypertrophic cardiomyopathy--assessment by transthoracic and transesophageal Doppler echocardiography.

BACKGROUND: During atrial contraction, the left atrium produces both forward ejection to the left ventricle and backward ejection to pulmonary veins.
PURPOSE: To determine quantitatively left atrial ejection performance in symptomatic hypertrophic cardiomyopathy (HCM) patients by using left atrial systolic time intervals.
METHOD: Thirty-one patients with symptomatic HCM and sinus rhythm and 31 normal subjects were studied with transthoracic and transesophageal Doppler echocardiography. Left atrial pre-ejection period (APEP), corrected atrial pre-ejection period (APEPc), and the duration (AET) and the time velocity integral (IA) of the atrial contraction wave in transmitral flow were determined. The duration (PV-AET) and the time velocity integral (PV-IA) of reverse pulmonary venous flow during atrial contraction were also determined.
RESULTS: For normal subjects, significant correlations were found between APEP and electrocardiographic P wave duration (r = 0.78, p < 0.001), and between APEPc and left atrial forward ejection indices (AET: r = -0.42, p = 0.01, IA: r = -0.54, p < 0.05, respectively), but not between APEP and either of the two latter indices. These findings indicate that, for normal subjects, APEPc is a better index of left atrial systolic function than APEP. In contrast, for HCM patients, significant correlations were found between APEPc and left atrial backward ejection indices (PV-AET: r = -0.49; p < 0.005, PV-IA: r = -0.66; p < 0.001, respectively), but not between APEPc and left atrial forward ejection indices.
CONCLUSION: Augmentation of left atrial afterload may result in decreased left atrial forward ejection and increased left atrial backward ejection. Thus, both left atrial forward ejection and left atrial backward ejection must be considered in the assessment of left atrial ejection performance in patients with symptomatic HCM.