Besides convenience, inhaled therapy for atrial fibrillation (AF) offers several advantages to the patient, including allowing for quick action at the first signs of symptoms, a rapid delivery to the heart and response, and less side effects due to a lower drug dose and shorter duration of action. Beta-adrenergic blocking agents are used to treat supraventricular and ventricular tachycardias, and are indicated for control of ventricular rate in patients with paroxysmal, persistent, or permanent AF. In the February issue, Dr. Richard L. Verrier and team assessed the utility of intratracheal instillation of the cardioselective beta blocker metoprolol in managing AF, using the Yorkshire pig model of AF resulting from infusion of acetylcholine followed by atrial burst pacing. These investigators report that delivery of metoprolol via this pulmonary route was effective in reducing ventricular rate during AF and accelerating the conversion to normal sinus rhythm. Theirs is the first study to demonstrate that intratracheal delivery of a cardioselective beta blocker is effective for controlling AF. The application of this strategy with a nebulizer could accelerate translation of this finding to the clinic or real life setting.
