Prognostic Effect of the Dose of Loop Diuretic Over 5 Years in Chronic Heart Failure

Background: High diuretic doses in chronic heart failure (HF) are potentially deleterious. We assessed the effect of dynamic furosemide dose on all-cause mortality among HF ambulatory patients. Methods and Results: A cohort of 560 ambulatory patients from an outpatient clinic specialized in HF, with median age 70 years, 67% male, and 89% with moderate-severely reduced ejection fraction, was retrospectively followed for up to 5 years. Dynamic furosamide exposure was categorized as low (0-59 mg/d), medium (60-119 mg/d), high (120-159 mg/d), and very high (>= 160 mg/d). Extended Cox models were used to estimate the association between time-varying diuretic dose and mortality. A dose-dependent crude association between higher doses of furosemide and death (hazard ratio [HR] = 1.34, 95% confidence interval (CI): 1.06-2.16; HR = 2.09, 95% CI: 1.54-2.84, for high and very high dose, respectively) was totally explained by patients' characteristics and disease severity indicators (adjusted HR = 0.94, 95% CI: 0.63-1.38; HR = 1.10, 95% CI: 0.79-1.55, for high and very high dose, respectively). Conclusion: In this context, higher doses of diuretic did not impair survival, but rather indicated greater severity of the patient's condition.