Early changes in sodium and water balances in patients with acute myocardial infarction: relationship to haemodynamics and creatine kinase.

Abstract

The changes in sodium and water balances during the first 4 days after an uncomplicated transmural myocardial infarction (MI) were determined in forty patients. The sodium balance was positive 4 days after MI in 80% of the patients but negative in 20%. Neither in anterior (n = 23) nor in inferior (n = 17) MI were rank correlations found between the haemodynamic parameters (cardiac index, mean arterial pressure, mean right atrial or pulmonary capillary pressures, right or left ventricular work indices) and sodium balance. However, the sodium balances correlated with the total creatine kinase (CK) release in anterior MI after 1 day (r = 0.60; P less than 0.002) and after 4 days (r = 0.65; P less than 0.001) but not in inferior MI. Furthermore, in anterior and inferior MI matched for their CK release, the sodium handling was different both after 1 day (-70 in anterior v. +44 mmol (24 h)-1 in inferior MI; P less than 0.001) and after 4 days (-36 v. +147 mmol (72 h)-1; P less than 0.01), a difference unexplained by differences in medical management or in sodium intake. Finally, sodium balance correlated with the changes in left ventricular stroke work index (LVSWI) observed during this period (r = 0.48, P less than 0.001), LVSWI being more stable when sodium balance was more positive. In conclusion, sodium balance after uncomplicated acute MI is related to MI location, to the size of anterior MI, and cannot be predicted from initial haemodynamics. Finally, the relation between LVSWI stability and positive sodium balance suggests that arbitrary sodium restrictions or diuretics might be deleterious to the haemodynamics after uncomplicated myocardial infarction.