Hyponatremia associated with reduced survival in patients with severe chronic heart failure

Survival over time in patients with severe chronic heart failure and a left ventricular ejection fraction less than 30% who, at study entry, had either a normal plasma sodium concentration (greater than 137 mEq/L, solid line) or hyponatremia (plasma sodium less than or equal to 137 mEq/L, dashed line). Survival was significantly reduced in the patients with hyponatremia. The survival rate was very low (approximately 15% at 12 months) in those with a baseline plasma sodium concentration less than or equal to 130 mEq/L.