Cardiac Dysfunction, Congestion and Loop Diuretics: their Relationship to Prognosis in Heart Failure

Background: Diuretics are the mainstay of treatment for congestion but concerns exist that they adversely affect prognosis. We explored whether the relationship between loop diuretic use and outcome is explained by the underlying severity of congestion amongst patients referred with suspected heart failure. Method and Results: Of 1190 patients, 712 had a left ventricular ejection fraction (LVEF) ≤50 %, 267 had LVEF >50 % with raised plasma NTproBNP (>400 ng/L) and 211 had LVEF >50 % with NTproBNP ≤400 ng/L; respectively, 72 %, 68 % and 37 % of these groups were treated with loop diuretics including 28 %, 29 % and 10 % in doses ≥80 mg furosemide equivalent/day. Compared to patients with cardiac dysfunction (either LVEF ≤50 % or NT-proBNP >400 ng/L) but not taking a loop diuretic, those taking a loop diuretic were older and had more clinical evidence of congestion, renal dysfunction, anaemia and hyponatraemia. During a median follow-up of 934 (IQR: 513–1425) days, 450 patients were hospitalized for HF or died. Patients prescribed loop diuretics had a worse outcome. However, in multi-variable models, clinical, echocardiographic (inferior vena cava diameter), and biochemical (NTproBNP) measures of congestion were strongly associated with an adverse outcome but not the use, or dose, of loop diuretics. Conclusions: Prescription of loop diuretics identifies patients with more advanced features of heart failure and congestion, which may account for their worse prognosis. Further research is needed to clarify the relationship between loop diuretic agents and outcome; imaging and biochemical measures of congestion might be better guides to diuretic dose than symptoms or clinical signs

Clinical relevance of serum electrolytes in dogs and cats with acute heart failure: A retrospective study

Background: Hypochloremia is a strong negative prognostic factor in humans with congestive heart failure (CHF), but the implications of electrolyte abnormalities in small animals with acute CHF are unclear. Objectives: To document electrolyte abnormalities present upon admission of small animals with acute CHF, and to assess the relationship between electrolyte concentrations and diuretic dose, duration of hospitalization and survival time. Animals: Forty-six dogs and 34 cats with first onset of acute CHF. Methods: Retrospective study. The associations between electrolyte concentrations and diuretic doses were evaluated with Spearman rank correlation coefficients. Relationship with duration of hospitalization and survival were assessed by simple linear regression and Cox proportional hazard regression, respectively. Results: The most commonly encountered electrolyte anomaly was hypochloremia observed in 24% (9/46 dogs and 10/34 cats) of cases. In dogs only, a significant negative correlation was identified between serum chloride concentrations at admission (median 113 mmol/L [97-125]) and furosemide doses both at discharge (median 5.2 mg/kg/day [1.72-9.57]; r = 0.59; P < .001) and at end-stage heart failure (median 4.7 mg/kg/day [2.02-7.28]; r = 0.62; P = .005). No significant hazard ratios were found for duration of hospitalization nor survival time for any of the electrolyte concentrations. Conclusions and Clinical Importance: The observed association between serum chloride concentrations and diuretic doses suggests that hypochloremia could serve as a marker of disease severity and therapeutic response in dogs with acute CHF