Management of Paroxysmal Tachycardia with Metoprolol

Introduction to Metoprolol Dosage

The maximum daily dose of metoprolol XR for paroxysmal tachycardia is 400 mg once daily, according to the American Heart Association guidelines 1
The initial dose of metoprolol succinate (XR/extended-release) should be 50 mg once daily, with gradual increases based on clinical response 1
For acute management of paroxysmal tachycardia episodes, IV metoprolol can be administered at 5 mg over 1-2 minutes, repeated every 5 minutes to a maximum of 15 mg, as recommended by the American College of Cardiology 2

Metoprolol is a beta-1 selective adrenergic receptor blocker that reduces the effects of circulating catecholamines, heart rate, and AV node conduction, and decreases blood pressure, acting as a negative inotrope 2

Metoprolol has demonstrated effectiveness in stable, narrow-complex tachycardias uncontrolled by adenosine or vagal maneuvers, control of ventricular rate in atrial fibrillation or flutter, and certain forms of polymorphic VT, according to the European Society of Cardiology 2

Metoprolol should be avoided in patients with AV block greater than first degree or SA node dysfunction (without pacemaker), decompensated systolic heart failure, hypotension, reactive airway disease/asthma, and pre-excited atrial fibrillation or flutter, as recommended by the American Heart Association 1, 2
When using metoprolol for paroxysmal tachycardia, monitor for hypotension, bradycardia, precipitation or worsening of heart failure, and bronchospasm in susceptible patients, according to the American College of Cardiology 1, 2

Abrupt withdrawal of metoprolol can lead to rebound tachycardia and worsening of symptoms, and should be avoided, as warned by the European Heart Journal 3
Inadequate initial dosing, failure to recognize pre-excitation, overlooking comorbidities, and drug interactions can also lead to adverse effects, and should be carefully managed, according to the American Heart Association 1