Relationship Between Left Atrial Appendage Function and Plasma Concentration of Atrial Natriuretic Peptide

Background: It has been reported that the most intensely granuled cardiocytes secreting atrial natriuretic peptide (ANP) are located in the atrial appendages. Aims: To evaluate the mechanisms of ANP release in congestive heart failure. Methods and Results: The relationship between ANP and left atrial appendage (LAA) function was evaluated in 36 patients who underwent both transoesophageal echocardiography and cardiac catheterization. ANP level correlated positively with mean pulmonary capillary wedge pressure (mPCWP;r=0·75, P<0·0001), whereas it showed no significant correlation with the mean right atrial pressure. mPCWP correlated positively with the maximal LAA area (LAAa;r=0·79,P <0·0001) and negatively with the LAA ejection fraction during atrial contraction (LAA-EF;r=-0·61, P<0·0001) and peak late diastolic LAA emptying flow velocity (LAAF;r=-0·69, P<0·0001). ANP level correlated negatively with the LAA-EF (r=-0·56, P<0·001) and with LAAF (r=-0·61,P <0·0001). ANP level correlated more closely with the LAAa (r=0·79,P <0·0001) than with maximal LA volume (r=0·34, P<0·05). Multiple stepwise regression analysis selected LAAa as the only factor independently related to the plasma concentration of ANP (ANP=-22·4+28·6 LAAa, r=0·79,P <0·0001). Conclusions: We conclude that the factor most predictive for ANP in patients with left-sided cardiac dysfunction is distension of the LAA wall rather than elevation in the LA pressure or distension of the body of LA. This is consistent with the known distribution of ANP-secreting cardiocytes.