RLN2 and atrial fibrillation: The fact that the recombinant form of relaxin-2, known as serelaxin, was shown to be safe in acute heart failure (AHF) patients in the phase III clinical trial RELAXin in Acute Heart Failure (RELAX-AHF) constitutes an additional advantage and encourages the possible use of this hormone as a therapeutic strategy for AF10,11, since 53% of the participants had a previous clinical history with AF, 41% presented AF during the course of the clinical trial, and serelaxin treatment was associated with a slight decrease in AF incidence10–12.