Plasma sodium and mortality risk in patients with myocardial infarction and a low LVEF
Article first published online: 6 MAY 2011
© 2011 The Authors. European Journal of Clinical Investigation © 2011 Stichting European Society for Clinical Investigation Journal Foundation
European Journal of Clinical Investigation
Volume 41, Issue 11, pages 1237–1244, November 2011
How to Cite
Schou, M., Valeur, N., Torp-Pedersen, C., Gustafsson, F. and Køber, L. (2011), Plasma sodium and mortality risk in patients with myocardial infarction and a low LVEF. European Journal of Clinical Investigation, 41: 1237–1244. doi: 10.1111/j.1365-2362.2011.02532.x
- Issue published online: 10 OCT 2011
- Article first published online: 6 MAY 2011
- Received 26 November 2010; accepted 28 March 2011
- left ventricular systolic dysfunction;
- mortality risk;
- myocardial infarction;
- plasma sodium
Eur J Clin Invest 2011; 41 (11): 1237–1244
Background Hyponatremia is a known prognostic factor for mortality in patients with heart failure but has not been extensively studied in patients with myocardial infarction (MI). This study was, therefore, designed to evaluate whether plasma sodium and hyponatremia (< 135 mM) are associated with mortality risk in patients with MI.
Materials and methods In retrospective analyses using data from the Trandolapril Cardiac Evaluation (TRACE) study – a randomized, double-blind, placebo-controlled trial of trandolapril in 1749 patients with MI and left ventricular ejection fraction (LVEF) ≤ 35%– associations between plasma sodium or hyponatremia and more than 15-year mortality risk were evaluated in multivariate Cox proportional hazard models including traditional clinical confounders before and after additional adjustment for renal function, use of diuretics or both.
Results During the extended follow-up time, 1462 patients died. Both hyponatremia [Hazard ratio: 1·30 (95% CI: 1·13–1·50), P < 0·001] and plasma sodium [Hazard Ratiopro mM increase in P-Na: 0·98 (95% CI: 0·96–0·99), P = 0·004] were associated with mortality risk, and the adjusted parameter estimates were not affected by additional adjustment for renal function, use of diuretics or both.
Conclusions Hyponatremia and plasma concentrations of sodium are associated with long-term mortality risk in patients with MI complicated by left ventricular systolic dysfunction. Importantly, these associations are independent of renal function and use of diuretics. Whether the associations between plasma sodium or hyponatremia and long-term mortality risk reflect a causation or merely the severity of the underlying cardiac disease remains to be clarified.