A method is provided, including identifying that a subject is at risk of suffering from atrial fibrillation (AF). Responsively to the identifying, a risk of an occurrence of an episode of the AF is reduced by coupling an electrode device to a site of a subject containing parasympathetic nervous tissue； driving, by a control unit, the electrode device to apply an electrical current to the site not responsively to any physiological parameters sensed by any device directly or indirectly coupled to the control unit； and configuring the current to stimulate autonomic nervous tissue in the site. Other embodiments are also described.
