RELATION OF LEFT ATRIAL VOLUME AND SYSTOLIC FUNCTION TO THE HORMONAL RESPONSE IN IDIOPATHIC DILATED CARDIOMYOPATHY

We studied the relation of left atrial mechanical function to the horm onal response in 14 patients with idiopathic dilated cardiomyopathy. L eft atrial volumes were echocardiagraphically measured at mitral valve opening (maximal), at onset of atrial systole (onset of the P wave of the electrocardiogram) and at mitral valve closure (minimal) from the apical 2- and 4-chamber views using the biplane area-length method. L eft atrial systolic function was assessed with the left atrial active emptying fraction ([volume at onset of atrial systole-minimal]/[volume at onset of atrial systole]). Plasma renin activity, aldosterone and atrial natriuretic peptide plasma levels were determined using commerc ially available kits. Left atrial maximal volume was directly, and lef t atrial active emptying fraction was inversely related to plasma reni n activity (r = 0.60, P = 0.02 and r = -0.59, P = 0.026, respectively) , aldosterone (r = 0.61, P = 0.02 and r = -0.53, P = 0.048) and atrial natriuretic factor (r = 0.79, P = 0.0009 and r = -0.62, P = 0.01) pla sma levels. Thus, increased left atrial size and depressed left atrial contractile performance are associated with increased hormonal respon se in idiopathic dilated cardiomyopathy.