Severe respiratory failure and torsades de pointes induced by disopyramide in a patient with myasthenia gravis.

Class 1a anti-arrhythmic drugs are often used for the treatment of atrial fibrillation (AF), but it is not well known that myasthenia gravis (MG)-like symptoms can be generated by their anti-cholinergic effects. We had a patient with MG who developed symptomatic MG aggravation after AF treatment with disopyramide. Symptomatic MG aggravation was followed by Takotsubo-shaped cardiomyopathy, QT prolongation, and torsades de pointes. We suggest that the anti-cholinergic effects of disopyramide can induce MG crisis and should therefore be carefully considered when disopyramide is used to treat AF in patients with MG.