Cardiovascular Critical Care I
II
β-Blockade
Ex.
Carvedilol (PO)
Labetalol (PO/IV)
Metoprolol (PO/IV)
Esmolol (IV)
N/A
or
↑
N/A
N/A
or
↓
Sinus bradycardia
AV block
Hypotension more likely with nonselective agents
Continuous infusions of esmolol or labetalol may contribute to
large amounts of fluid
Predominantly CYP2D6
N/A
III
Potassium channel
blockade
Dofetilide
(PO)
N/A
or
↑
N/A
or
↑
↑
Requires ECG monitoring for initiation, dose titration, reinitiation,
or introduction of new interacting agents
Requires renal dosing adjustments
Mg and K monitoring
Circulation 2024;149:e1−156.
CYP3A4
Trimethoprim, verapamil,
HCTZ, and many others
contraindicated
QT-prolonging drugs
↓
1–8
Ibutilide
(IV)
Only indicated for cardioversion of AF or enhancement of
electrical cardioversion
QT-prolonging drugs
↓
1–8
Sotalol
(PO/IV)
Requires renal dosing adjustments
Bradycardia
Mg and K monitoring
Circulation 2024;149:e1−156.
QT-prolonging drugs
↓
1–6
Amiodarone
(PO/IV)
Multi–channel-blocking properties
Monitor liver, thyroid, and pulmonary function tests
Average half-life 53 days; highly lipophilic; active metabolite
Bradycardia and hypotension
High protein binding
Inhibits CYP3A4, CYP2D6,
CYP2C9
Adjust warfarin and digoxin by
50%
↑
< 1
Dronedarone
(PO)
Multi–channel-blocking properties
Only approved for AF/flutter; less efficacious vs. amiodarone
Less potential for organ-system toxicity vs. amiodarone
Avoid in CHF, particularly NYHA class III/IV
Bradycardia
Liver function tests within first 6 mo of therapy
Inhibits CYP3A4, CYP2D6,
CYP2C9
< 1
IV
Calcium channel
blockade
Verapamil
(PO/IV)
↑
N/A
N/A
Hepatic dosing
Sinus bradycardia
Negative inotrope – avoid in patients with systolic heart failure
CYP3A4 (substrate and inhibitor)
N/A
Diltiazem
(PO/IV)
Decreased dosing in elderly patients and patients with hepatic
dysfunction
Bradycardia
Negative inotrope - avoid in patients with systolic heart failure
CYP3A4 (substrate and inhibitor)
N/A
Misc.
Others
Digoxin
(PO/IV)
↑
N/A
N/A
Alternative for rate control of AF/flutter; also used for systolic heart
failure
Decreased dosing in elderly and patients with kidney dysfunction
Loading dose may be given based on ideal body weight
Not dialyzable
Digoxin concentrations may be checked (AF/flutter: 0.8-2 ng/mL;
heart failure: 0.5-0.9 ng/mL)
Many interactions
Adenosine
(IV)
↑
Half-life < 10 s
Used for acute treatment of AV node reentrant tachycardias
Can help to distinguish atrial from ventricular arrhythmias
Magnesium
(IV)
↑
Used to treat Torsades and arrhythmias associated with
hypomagnesemia
Adjunctive treatment for atrial fibrillation with rapid ventricular
response to slow ventricular rate. Given with AV nodal blocking
agent
AF = atrial fibrillation; AV = atrioventricular; CHF = congestive heart failure; CNS = central nervous system; ECG = electrocardiogram; HCTZ = hydrochlorothiazide; IR = immediate release; IV = intravenous(ly); MI =
myocardial infarction; MOA = mechanism of action; NAPA = N-acetylprocainamide; N/A = not applicable; NYHA = New York Heart Association; PO = oral(ly); SR = sustained release; TdP = Torsades de pointes.
APPENDIX A – OVERVIEW OF ANTI-ARRHYTHMICS (continued)