OBJECTIVETo evaluate the prognostic significance of hyponatremia in patients with AMI.

METHODSThe study population consisted of 670 patients with AMI in coronary care unit in our hospital from January 2003 to December 2004. The patients were designed into three groups according to serum sodium concentration within twenty four to forty eight hours following the onset of AMI: Group A. Na(+) > or = 135 mmol/L; Group B. Na(+) 120-135 mmol/L; Group C. Na(+) < or = 120 mmol/L. The data of myocardial enzymes, myocardial infarction size, heart function and inhospital mortality were analyzed retrospectively.

RESULTS1. The inhospital mortality of each group: group A was 7.6% (17/225), group B was 8.1% (34/421), group C was 33.3% (8/24). The difference between group C and group B or group A was significant. The P value was little than 0.05. 2. Activities of serum creatine phosphatase kinase and serum creatine phosphatase kinase isoenzymes and myocardial infarction sizes in each group were different (P < 0.05). 3. 59 cases of all died and 611 cases of all recovered in duration of hospital stay. Serum sodium concentrations of the recovered group were (133.00 +/- 5.25) mmol/L, and that of the died group were (122.00 +/- 7.25) mmol/L (P < 0.01). 4. In a multivariate logistic regression analysis, hyponatremia was associated with 30-day mortality in patients with AMI. In analysis of the association between the degree of hyponatremia and outcome, we observed that the risk of 30-day mortality increased with the severity of hyponatremia.

CONCLUSIONHyponatremia may be one of the important markers that predict a worse prognosis in patients with AMI.