What drug is most likely to restore sinus rhythm in a patient with atrial fibrillation and a ventricular rate of 130 beats/min?

The drug that is most likely to restore sinus rhythm in a patient with atrial fibrillation and a ventricular rate of 130 beats/min is adenosine. Adenosine works by temporarily blocking the atrioventricular (AV) node, which can interrupt the reentrant circuits that contribute to atrial fibrillation. This action can sometimes restore normal sinus rhythm quickly, especially when atrial fibrillation involves a rapid ventricular response.

In situations of acute atrial fibrillation where rapid ventricular rates are present, adenosine can effectively terminate the arrhythmia in patients, especially if there is an underlying aspect of reentrant tachycardia. It is a rapidly acting agent that provides a quick clinical response, making it an ideal choice for acute management.

The other options, while useful in the setting of atrial fibrillation, have different mechanisms and likely take longer to restore sinus rhythm. Beta-blockers like bisoprolol and esmolol are primarily used to control the heart rate rather than directly convert to sinus rhythm. Flecainide, as a class IC antiarrhythmic agent, may convert atrial fibrillation to sinus rhythm but requires careful consideration of the patient's structural heart disease status and might not act as rapidly as