Deriphylline (Theophylline) Should NOT Be Used to Treat Tachycardia—It Actually CAUSES Tachycardia
Intravenous deriphylline (theophylline/aminophylline) is contraindicated for treating tachycardia because theophylline itself is a well-established cause of tachyarrhythmias, particularly multifocal atrial tachycardia (MAT) and supraventricular tachycardia. 1, 2
Why Theophylline Causes—Rather Than Treats—Tachycardia
Theophylline as an Arrhythmogenic Agent
Theophylline therapy is explicitly listed as a common cause of multifocal atrial tachycardia in the 2015 ACC/AHA/HRS guidelines, alongside pulmonary disease, hypomagnesemia, and structural heart disease. 1
Discontinuation of theophylline resolves MAT in patients taking the drug—in a study of 16 patients with MAT on theophylline, the atrial rate fell and MAT resolved in all 16 patients after stopping the medication. 2
Rechallenge with aminophylline (IV theophylline) reproduces the arrhythmia—when 5 patients were given IV aminophylline after their MAT resolved, all 5 developed MAT with rapid ventricular response, even when serum levels were in the "therapeutic range" (10-20 mg/L). 2
Theophylline has a dose-dependent effect on atrial rate and ectopic activity, meaning higher doses worsen tachycardia. 2
Mechanism of Arrhythmogenesis
Theophylline antagonizes adenosine A1-receptors, which are critical for terminating supraventricular tachycardias—this is why adenosine (the first-line drug for SVT) may be ineffective in patients on theophylline. 3, 4
Theophylline toxicity can precipitate life-threatening SVT storms that are refractory to standard treatments including adenosine and electrical cardioversion, requiring mechanical circulatory support and hemodialysis to remove the drug. 4
Correct Management of Tachycardia
For Supraventricular Tachycardia (SVT)
Adenosine is the recommended first-line drug for acute treatment of hemodynamically stable SVT (150-200 mcg/kg rapid IV bolus), with a Class I recommendation. 1
IV beta-blockers, diltiazem, or verapamil are reasonable alternatives for acute SVT treatment in stable patients (Class IIa recommendation). 1
Immediate synchronized cardioversion is indicated for hemodynamically unstable patients. 1
For Multifocal Atrial Tachycardia (MAT)
First-line treatment is management of the underlying condition—if the patient is on theophylline, STOP IT. 1
IV metoprolol or verapamil can be useful for acute treatment of MAT (Class IIa recommendation), but only after addressing precipitating factors like theophylline. 1
IV magnesium may be helpful even in patients with normal magnesium levels. 1
For Ventricular Tachycardia (VT)
Immediate synchronized cardioversion for unstable VT with pulse. 5
IV amiodarone or lidocaine for stable VT—lidocaine 1-1.5 mg/kg bolus followed by infusion, or amiodarone 150 mg over 10 minutes. 6, 5
Critical Clinical Pitfall
If a patient presents with tachycardia and is taking theophylline/deriphylline, the drug is likely CAUSING the arrhythmia, not treating it. 1, 2 Check serum theophylline levels immediately and consider discontinuation. In severe theophylline toxicity with refractory tachyarrhythmias, propranolol and verapamil have been used successfully to control supraventricular tachycardia, and charcoal hemoperfusion or hemodialysis may be necessary. 4, 7