[Atrial fibrillation and heart failure: a dangerous criminal conspiracy].

Atrial fibrillation (AF) and heart failure (HF) often coexist. Both associated with an altered prognosis, their coexistence is associated with a higher mortality. This dangerous criminal conspiracy is explained by common risk factors but also by a strong causative relationship. AF can be the cause of HF, especially by leading to a tachycardia-induced cardiomyopathy, either isolated or associated to an underlying heart disease. HF is a common cause of AF. It remains to be determined whether AF is an independent mortality risk factor or a simple marker of advanced HF, perhaps because available therapeutic tools are not enough successful to prevent AF.