Representativeness of RELAX-AHF clinical trial population in acute heart failure.

BACKGROUND The Relaxin for the Treatment of Acute Heart Failure (RELAX-AHF) trial enrolled 1161 patients admitted to the hospital for acute heart failure (AHF) to evaluate the therapeutic efficacy of serelaxin, a recombinant form of human relaxin-2. We characterized how representative RELAX-AHF clinical trial enrollees were to those patients with AHF found in international registries. METHODS AND RESULTS We examined 196 770 AHF admissions from the Acute Decompensated Heart Failure National Registry-United States and Acute Decompensated Heart Failure National Registry-International registries. Patients were considered RELAX-AHF-type if they met the following criteria: discharge diagnosis of heart failure, systolic blood pressure >125 mm Hg, dyspnea at rest or with mild exertion, intravenous diuretic use, glomerular filtration rate of 30 to 75 mL/min per 1.73 m(2), hemoglobin >8 g/dL, and no use of intravenous inotropes or vasopressors. Baseline characteristics and treatments of RELAX-AHF-type and non-RELAX-AHF-type patients were compared. A Cox model was used to evaluate inpatient mortality. Among both Acute Decompensated Heart Failure National Registry-United States and Acute Decompensated Heart Failure National Registry-International registries, 20.7% (n=38 485) and 16.2% (n=1749) of patients met basic criteria for RELAX-AHF entry, respectively. These patients were more likely to be older, be women, have a previous history of hypertension, have preserved ejection fraction, and have better renal function. In-hospital mortality was lower in RELAX-AHF-type than in non-RELAX-AHF-type patients, even after multivariable adjustment (hazard ratio, 0.59; 95% confidence interval, 0.53-0.66; P<0.0001). CONCLUSIONS Patients potentially eligible for RELAX-AHF represent ≈2 in 10 patients with AHF in the United States, Latin America, or Asia-Pacific. These patients differ significantly from other hospitalized patients based on clinical characteristics and outcomes.