Antiarrhythmic Drugs (Vaughan Williams Classification) 

Class Ia

Uses: APB and VPB suppression, SVT and VT suppression, AF or atrial flutter, and VF suppression

DisopyramideDisopyramide

Anticholinergic effects (urinary retention, glaucoma, dry mouth, blurred vision, intestinal upset), hypoglycemia, torsades de pointes VT, negative inotropic effects

Use cautiously with impaired LV function or renal insufficiency

Adverse effects may contribute to nonadherence

Decrease infusion rate or dosage or stop medication if QRS interval widens excessively †

IV form not available in the United States

Procainamide*Procainamide*

Hypotension (with IV infusion), positive anti-nuclear antibody or drug-induced lupus, agranulocytosis, torsades de pointes VT

Sustained-release preparations available

Decrease infusion rate or dosage or stop medication if QRS interval widens excessively† or if QTc interval becomes prolonged

QuinidineQuinidine

GI symptoms, thrombocytopenia, liver function abnormalities, torsades de pointes VT

Decrease infusion rate or dosage or stop medication if QRS interval widens excessively† or if QTc interval becomes prolonged

Class Ib

Uses: Suppression of ventricular arrhythmias (VPB, VT, VF)

LidocaineLidocaine

Tremor, seizures, drowsiness, delirium, paresthesias with rapid administration; risk of bradyarrhythmias after acute myocardial infarction

Reduce dosage after first 24 hours

Extensive first-pass hepatic metabolism

MexiletineMexiletine

Nausea, vomiting, tremor, seizures

Oral slow-release and IV forms not available in the United States

Class Ic

Uses: APB and VPB suppression, SVT and VT suppression, AF or atrial flutter, and VF suppression

FlecainideFlecainide

Occasionally, blurred vision and paresthesias

Proarrhythmic with coexisting structural heart disease

Decrease dosage or stop medication if QRS interval widens

IV form not available in the United States

PropafenonePropafenone

Beta-blockade, possible worsening of reactive airway disease, GI upset

Pharmacokinetics are nonlinear; increases in dose should not exceed 50% of previous dose

Saturable first-pass metabolism

IV form not available in the United States

Class II (beta-blockers)

Uses: Supraventricular tachyarrhythmias (APB, ST, SVT, AF, atrial flutter) and ventricular arrhythmias (often in a supportive role)

AcebutololAcebutolol

For all beta-blockers: GI disturbances, insomnia, nightmares, lethargy, erectile dysfunction, possible AV block in patients with AV node dysfunction; worsening of reactive airway disease (worse with the "non-selective" beta-blockers, propranolol, nadolol, timolol)For all beta-blockers: GI disturbances, insomnia, nightmares, lethargy, erectile dysfunction, possible AV block in patients with AV node dysfunction; worsening of reactive airway disease (worse with the "non-selective" beta-blockers, propranolol, nadolol, timolol)

Relatively contraindicated in patients with bronchospastic airway disorders

AtenololAtenolol

BetaxololBetaxolol

BisoprololBisoprolol

CarvedilolCarvedilol

EsmololEsmolol

MetoprololMetoprolol

NadololNadolol

PropranololPropranolol

TimololTimolol

Class III (membrane-stabilizing drugs)

Uses: Any tachyarrhythmia except torsades de pointes VT

Amiodarone‡Amiodarone‡

Pulmonary toxicity, QTc prolongation; torsades de pointes VT; bradycardia; gray or blue discoloration of sun-exposed skin; hepatic abnormalities; peripheral neuropathy; corneal microdeposits, altered thyroid function; serum creatinine increase

Noncompetitive beta-blocking, calcium channel blocking, and sodium channel blocking effects, with a long delay in onset of action

Prolongs refractoriness more homogeneously than other QT-prolonging drugs, so torsades de pointe VT is less common

IV form can be used for rhythm conversion

Azimilide*

Torsades de pointes VT

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Bretylium*Bretylium*

Hypotension

Also has class II properties

Used to treat potentially lethal refractory ventricular tachyarrhythmias (intractable VT, recurrent VF)

DofetilideDofetilide

Torsades de pointes VT

Contraindicated with prolonged QTc or decreased GFR

DronedaroneDronedarone

QTc prolongation, torsades de pointes VT, bradycardia, GI upset, hepatotoxicity, serum creatinine increase

Modified amiodarone molecule with shorter half-life, smaller volume of distribution, fewer adverse effects, and poorer efficacy

Should not be used with history of heart failure or with permanent AF

IbutilideIbutilide

Torsades de pointes VT

Used to terminate AF and atrial flutter

SotalolSotalol

Similar to class II; possible depressed left ventricular function and torsades de pointes VT

Clinically available formulations also have beta blocking (class II) activity

Avoid with renal insufficiency

Vernakalant

Hypotension (especially with heart failure)

Bradyarrhythmias (especially with concomitant beta-blockade)

Used to terminate recent-onset AF

Not available in the United States

Class IV (calcium channel blockers)

Uses: Termination of SVT and slowing of rapid AF or atrial flutter

DiltiazemDiltiazem

May precipitate VF in patients with VT, negative inotropy

IV form is used to slow ventricular response rate to AF or atrial flutter

VerapamilVerapamil

May precipitate of VF in patients with VT, negative inotropy

IV form is used to terminate narrow-complex tachycardias involving the AV node

Other antiarrhythmics

AdenosineAdenosine

Dyspnea, chest discomfort, and flushing, bronchospasm

Slows or blocks AV nodal conduction

Extremely short duration of action

Contraindications include asthma and high-grade heart block

Dipyridamole potentiates effects

DigoxinDigoxin

GI symptoms; multiple arrhythmias (VPBs, VT, APBs, atrial tachycardia, second-degree or third-degree AV block, or combinations)

Contraindicated with ventricular pre-excitation (manifest Wolff-Parkinson-White syndrome) because digoxin shortens refractory periods of the accessory connection; if AF occurs, ventricular response may be excessive and life-threatening