Does digoxin efficacy differ by level of renal function, and how does GFR affect mortality in outpatients with systolic heart failure?
Renal dysfunction (eGFR <50) is strongly associated with increased mortality in stable systolic heart failure, but does not alter the efficacy of digoxin.
Renal dysfunction is a common complication for patients with heart failure, but its association with clinical outcomes has not been fully characterized. We evaluated the association of glomerular filtration rate (GFR) with heart failure survival and the effect of digoxin on heart failure outcomes across GFR strata. A secondary analysis from the Digitalis Intervention Group trial was conducted of 6800 outpatients with systolic heart failure. Renal function was categorized as estimated GFR (expressed in ml/min per 1.73 m(2)). All-cause mortality (mean, 3 yr) was inversely proportional to GFR (GFR >60, 31% mortality; GFR 30 to 60, 46% mortality; GFR 70 had a slightly lower mortality hazard (0.89; 95% CI, 0.78 to 1.00). Linear spline analyses confirmed that GFR = 50 was the appropriate risk threshold; above 50, GFR had no association with mortality, whereas below 50, mortality risk increased sharply with declining GFR (spline coefficient, P < 0.0001). Digoxin efficacy did not differ by level of GFR (P = 0.19 for interaction). Renal dysfunction is strongly associated with mortality in stable outpatients with heart failure, notably in patients with estimated GFR <50 ml/min per 1.73 m(2). The effect of digoxin did not differ by level of renal function.
Shlipak et al. (Sun,) studied this question.