Quinidine: Is it a good drug or a bad drug?

Although quinidine, the oldest class I antiarrhythmic drug, has been available for several decades, recent reports have emphasized the possibility of dangerous side effects. Quinidine often successfully maintains sinus rhythm in patients with intermittent atrial fibrillation, suppresses sustained ventricular tachycardia in some patients, and minimally depresses left ventricular function. However, it can cause nonfatal and, occasionally, even fatal proarrhythmic complications. Therefore, it must be administered with caution in appropriately selected patients.