INCREASED PLASMA ATRIAL-NATRIURETIC-PEPTIDE LEVELS AFTER HEART-TRANSPLANT - RELATION TO VENTRICULAR EXPRESSION AND SEVERITY OF REJECTION

To determine whether elevated plasma atrial natriuretic peptide (ANP) levels observed after cardiac transplant are related to ventricular AN P expression and/or the severity of rejection, 59 ambulatory patients with cardiac transplant underwent hemodynamic evaluation, endomyocardi al biopsy, and plasma ANP sampling. Forty-two of the 59 patients had r ight ventricular (RV) biopsy specimens immunohistochemically stained f or the presence of ANP. Plasma ANP levels were elevated (p < 0.0001) i n transplant patients (172 +/- 12 pg/ml) compared to normal subjects ( 36 +/- 4 pg/ml). Sixty-four percent of transplant patients showed stai nable RV ANP on endomyocardial biopsy. There was no significant differ ence in plasma ANP levels between patients with or without RV ANP. The degree of RV staining did not correlate with plasma ANP levels, degre e of rejection, mean atrial or systemic pressures, or specific immunos uppressive regimen. Plasma ANP levels were higher in patients with mod erate or severe rejection (237 +/- 17 pg/ml) compared to patients with mild or no rejection (163 +/- 12 pg/ml; p 0.03), but there was signif icant overlap of values. These data suggest that ventricular ANP secre tion may account for some of the increase in plasma ANP levels in card iac transplant patients. However, increased plasma ANP levels in some transplant patients who have no RV ANP and the lack of correlation bet ween the amount of stainable RV ANP and plasma ANP levels suggest that other mechanisms are also likely responsible for plasma ANP elevation s in this setting.