Hypochloremia, Diuretic Resistance, and Outcome in Patients With Acute Heart Failure.

BACKGROUND Chloride plays a role in renal salt sensing, neurohormonal activation, and regulation of diuretic targets, and hypochloremia predicts mortality in acute heart failure (AHF). AHF therapies, such as diuretics, alter chloride homeostasis. We studied the association between (changes in) chloride levels and diuretic responsiveness, decongestion, and mortality in patients with AHF. METHODS AND RESULTS Patients hospitalized for AHF in the PROTECT trial (n=2033) with serum chloride levels within 24 hours of admission and 14 days later were studied (n=1960). Hypochloremia was defined as serum chloride <96 mEq/L. Mean baseline chloride was 100.8±5.0 mEq/L. Low baseline chloride was associated with high bicarbonate, poor diuretic response, less hemoconcentration, and worsening heart failure (all P<0.01). Newly developed hypochloremia at day 14 was common and associated with a decline in renal function and an increase in blood urea nitrogen (P<0.01). In multivariable analyses, chloride measured at day 14, but not baseline chloride, was strongly and independently associated with mortality through 180 days (hazard ratio per unit decrease: 1.07 [1.03-1.10]; P<0.001). In comparison, sodium was not significantly associated with mortality after multivariable adjustment at any time point. Hypochloremia at baseline that resolved was not associated with mortality (P=0.55), but new or persistent hypochloremia at day 14 was associated with increased mortality (hazard ratio: 3.11 [2.17-4.46]; P<0.001). CONCLUSIONS Low serum chloride at AHF hospital admission was strongly associated with impaired decongestion. New or persistent hypochloremia 14 days later was independently associated with reduced survival, whereas hypochloremia that resolved by day 14 was not. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00354458.