Antiarrhythmic Drugs Cheat Sheet

(Antiarrhythmics are the drugs that affect the action potential of cardiac cells and are used to treat arrhythmias and restore normal rate and rhythm.)

Antiarrhythmics affect the action potential of the cardiac cells by altering their automaticity, conductivity, or both. Because of this effect, antiarrhythmic drugs can also produce new arrhythmias—that is, they are proarrhythmic. Antiarrhythmics are used in emergency situations when the hemodynamics arising from the patient’s arrhythmia are severe and could potentially be fatal.



Most antiarrhythmics can aggravate existing arrhythmias or cause new ones. They also may produce CNS disturbances, such as dizziness or fatigue; GI problems, such as nausea, vomiting, or altered bowel elimination; hypersensitivity reactions; and hypotension. Some antiarrhythmics may worsen heart failure. Class II drugs may cause bronchoconstriction.

1: Amiodarone
Life-threatening recurrent ventricular fibrillation or recurrent hemodynamically unstable ventricular tachycardia unresponsive to adequate doses of other antiarrhythmics or when alternative drugs can’t be tolerated.

Effects result from blockade of potassium chloride leading to a prolongation of action potential
CNS: fatigue, malaise, tremor
CV: hypotension, bradycardia, arrhythmias, heart failure, heart block, sinus arrest
EENT: asymptomatic corneal microdeposits, visual disturbances
GI: nausea, vomiting
Hematologic: coagulation abnormalities
Hepatic: hepatic failure, hepatic dysfunction
Metabolic: hypothyroidism, hyperthyroidism
Respiratory: acute respiratory distress syndrome, severe pulmonary toxicity
Skin: photosensitivity, blue-gray skin

2: Flecainide acetate

Prevention of paroxysmal supraventricular tachycardia in patients without structural heart disease
Life-threatening ventricular arrhythmias.

A class IC antiarrhythmic that decreases excitability, conduction velocity, and automaticity by slowing atrial, AV node, His-Purkinje system, and intraventricular conduction; prolongs refractory periods in these tissues.
CNS: dizziness, headache, light-headedness
CV: new or worsened arrhythmias
EENT: blurred vision and other visual disturbances
GI: nausea, constipation, abdominal pain, vomiting, diarrhea
Respiratory: dyspnea

3: Lidocaine

Ventricular arrhythmias caused by MI, cardiac manipulation, or cardiac glycosides
A class IB antiarrhythmic that decreases the depolarization, automaticity, and excitability in the ventricles during the diastolic phase by direct action on the tissues, especially the Purkinje network.

CNS: confusion, tremor, stupor, restlessness, light-headedness, seizures, muscle twitching
CV: hypotension, bradycardia, new or worsened arrhythmias, cardiac arrest
EENT: tinnitus, blurred or double vision
Respiratory: respiratory depression and arrest
Other: anaphylaxis

Leave a Reply