Atrial Fibrillation
Clinical Snapshot
Atrial fibrillation (AF) is a supraventricular tachyarrhythmia characterized by uncoordinated atrial activation and, consequently, ineffective atrial contraction. On ECG this produces an irregularly irregular ventricular rhythm with no discrete, organized P waves. The 2020 CCS/CHRS guideline organizes management around three pillars applied to essentially every patient: (1) stroke prevention using the CHADS-65 algorithm, assessed and acted on independently of symptoms; (2) rate or rhythm control to relieve symptoms and prevent tachycardia-mediated cardiomyopathy; and (3) risk-factor modification (weight, blood pressure, sleep apnea, alcohol) to reduce AF burden and improve the success of rhythm-control therapy.[1] Atrial flutter is managed with the same stroke-prevention principles as AF and is not treated as a lower-risk arrhythmia for anticoagulation purposes. Stroke prevention is the dominant priority: an asymptomatic patient with a stroke-risk indication for anticoagulation still needs it, and a highly symptomatic patient does not get anticoagulation "instead of" rate/rhythm therapy — the two pillars are managed in parallel, not as alternatives.
Recognize the Condition
Typical presentation
Palpitations, an irregularly irregular pulse on manual palpation, fatigue, dyspnea, reduced exercise tolerance, and lightheadedness are typical. A substantial proportion of AF is entirely asymptomatic and found incidentally — on a routine pulse check, an ECG done for another reason, or a consumer wearable — so the absence of symptoms does not lower clinical priority once AF is confirmed; stroke risk is unrelated to symptom burden.
Classification by pattern (guides rhythm-control decisions, not stroke-prevention decisions)
Paroxysmal
Self-terminates, usually within 48 hours and by definition within 7 days.
Persistent
Continuous, lasting more than 7 days; requires cardioversion (electrical, pharmacologic, or spontaneous late conversion) to terminate.
Long-standing persistent
Continuous for more than 12 months, where a rhythm-control strategy is still being pursued.
Permanent
AF that the patient and clinician have jointly decided to accept, with no further attempts at rhythm control — a treatment decision, not a fixed electrical property.
Risk Factors
- Advancing age — the single strongest risk factor, and the basis of the age-65 threshold in the CHADS-65 algorithm.
- Hypertension.
- Structural or valvular heart disease, including prior myocardial infarction and heart failure.
- Hyperthyroidism.
- Obesity and obstructive sleep apnea — both independently increase AF risk and AF burden, and both are directly modifiable.
- Diabetes mellitus and chronic kidney disease.
- Excess alcohol intake, including acute binge intake ("holiday heart" presentation).
- Family history of AF.
- Post-cardiac-surgery state, and acute systemic illness or sepsis (secondary/reversible AF in this setting still needs the same stroke-risk assessment).
- Male sex.
Red Flags & Refer
Escalate or refer urgently for any of the following:
- Hemodynamic instability with rapid ventricular response (hypotension, pulmonary edema, ongoing chest pain, or altered mentation attributable to the arrhythmia) — needs emergency electrical cardioversion, not outpatient rate-control titration.
- Signs or symptoms of acute stroke or TIA — activate the emergency stroke pathway immediately; this can be the presenting event of previously undiagnosed AF.
- AF with ventricular pre-excitation (Wolff-Parkinson-White), suggested by an irregular wide-complex tachycardia — do not give an AV-nodal blocking agent (beta-blocker, non-dihydropyridine calcium channel blocker, digoxin, or adenosine); these can accelerate conduction down the accessory pathway and precipitate ventricular fibrillation. Manage with procainamide or electrical cardioversion and obtain expert/electrophysiology input.
- A mechanical heart valve or moderate-to-severe mitral stenosis (valvular AF) with a subtherapeutic INR, or any new AF in this population — this is a warfarin-only indication with a distinct, less forgiving risk profile.
- Ventricular rate that remains uncontrolled despite optimized first-line rate-control therapy — refer for rhythm-control assessment or AV-node ablation with pacemaker implantation rather than continuing to escalate rate-control drugs indefinitely.
Assessment & Diagnosis
Confirming the diagnosis
- 12-lead ECG showing an irregularly irregular RR interval with absent, discrete P waves and a chaotic fibrillatory baseline — this alone confirms AF.
- Extended rhythm monitoring (Holter, external event recorder, or implantable loop recorder) when paroxysmal AF is clinically suspected — palpitations, embolic stroke of undetermined source — but has not been captured on a resting ECG.
- Echocardiography to assess left atrial size, valvular disease (specifically to identify or exclude valvular AF), and left ventricular ejection fraction — LVEF directly determines which rate-control and rhythm-control drugs are appropriate.
- TSH, to identify hyperthyroidism as a reversible contributor.
- Electrolytes and renal function — both a baseline for DOAC dose selection and the reference point for the periodic renal monitoring every DOAC-treated patient needs.
Valvular vs. nonvalvular AF
Valvular AF — a mechanical heart valve, or moderate-to-severe mitral stenosis — is anticoagulated with warfarin only; DOACs were not studied and are not used in this population. All other AF is nonvalvular AF, where DOACs are preferred.[1]
Stroke risk stratification: the CHADS-65 algorithm
The CCS deliberately uses CHADS-65 rather than the internationally-recognized CHA2DS2-VASc score. It is a decision algorithm, not a points-based risk calculator: the presence of any CHADS2 risk factor is enough to trigger anticoagulation — there is no minimum total-score threshold to clear, unlike the classic warfarin-era CHADS2 ≥2 cutoff.[2]
| CHADS2 criterion | Points |
|---|---|
| Congestive heart failure (or LVEF ≤ 40%) | 1 |
| Hypertension | 1 |
| Age ≥ 75 years | 1 |
| Diabetes mellitus | 1 |
| Prior stroke, TIA, or systemic embolism | 2 |
Age ≥ 65 years, on its own, is sufficient to recommend anticoagulation regardless of the CHADS2 score. For a patient under 65, the presence of even one CHADS2 risk factor also warrants anticoagulation. Only a patient under 65 with zero CHADS2 risk factors falls outside the anticoagulation recommendation — for this group, most patients should receive no antithrombotic therapy for stroke prevention at all, not aspirin as a lesser alternative.[3]
Bleeding risk: HAS-BLED
| HAS-BLED criterion | Points |
|---|---|
| Hypertension (uncontrolled, systolic BP > 160 mmHg) | 1 |
| Abnormal renal function (dialysis, transplant, or creatinine > 200 µmol/L) | 1 |
| Abnormal liver function (cirrhosis, or bilirubin > 2x normal with AST/ALT/ALP > 3x normal) | 1 |
| Stroke (prior history) | 1 |
| Bleeding history or predisposition | 1 |
| Labile INR (time in therapeutic range < 60%, warfarin only) | 1 |
| Elderly (age > 65) | 1 |
| Drugs (concurrent antiplatelets/NSAIDs) or alcohol excess | 1 each, max 2 |
A score of ≥3 identifies a patient at meaningfully higher 1-year bleeding risk.[4] A high HAS-BLED score is a prompt to identify and correct modifiable bleeding-risk factors — it is not, on its own, a reason to withhold anticoagulation that the CHADS-65 algorithm otherwise indicates. Most of its components (blood pressure control, stopping unnecessary antiplatelets/NSAIDs, correcting anemia, limiting alcohol) are the same modifiable factors targeted by risk-factor-modification counselling.
Treatment Targets
- Prevent stroke and systemic embolism — the top priority, pursued independently of symptom burden.
- Control ventricular rate and/or restore and maintain sinus rhythm to relieve symptoms and prevent tachycardia-mediated cardiomyopathy.
- Modify reversible risk factors (weight, blood pressure, obstructive sleep apnea, alcohol) to reduce AF burden and improve the durability of rhythm-control therapy.
- Avoid iatrogenic harm: correct anticoagulant selection and renal/age/weight-adjusted dosing, avoidance of unnecessary periprocedural bridging, and avoidance of AV-nodal blocking agents in pre-excited AF.
Choose Initial Treatment
Age ≥ 65, or any CHADS2 risk factor at any age anticoagulate. For nonvalvular AF, a DOAC (apixaban, dabigatran, edoxaban, or rivaroxaban) is preferred over warfarin — comparable or superior stroke prevention, similar or lower major bleeding, a consistently lower intracranial hemorrhage rate, and no routine coagulation monitoring.[1]
Valvular AF — mechanical heart valve, or moderate-to-severe mitral stenosis use warfarin specifically (INR 2.0-3.0, or INR 2.5-3.5 for a mechanical mitral valve) — DOACs are not used in this population.
Age under 65 with zero CHADS2 risk factors most patients should receive no antithrombotic therapy for stroke prevention. Do not substitute ASA — it is not an acceptable lesser alternative to anticoagulation when anticoagulation is indicated, and offers negligible protection in AF.[2]
Initial default for most patients, especially those who are older or minimally symptomatic: rate control.
Consider rhythm control for patients who remain symptomatic despite adequate rate control, younger patients, first-detected AF, AF that is precipitating or worsening heart failure, or by patient preference. Catheter ablation is a reasonable first-line rhythm-control option in appropriately selected symptomatic patients — not only a fallback after drug failure.
Rate control drug selection
LVEF ≤ 40% an evidence-based beta-blocker — bisoprolol, carvedilol, or metoprolol.
LVEF > 40% a beta-blocker or a non-dihydropyridine calcium channel blocker (diltiazem or verapamil).
Target: average resting heart rate under 100 bpm while in AF (lenient rate control is an accepted, evidence-based target — strict control below 80 bpm is not required). Digoxin may be added when first-line therapy is insufficient, or used as monotherapy specifically in sedentary/inactive patients, since it does not control exertional heart rate.
Rhythm control drug selection
No structural or ischemic heart disease flecainide, propafenone, sotalol, dronedarone, or amiodarone are all options; amiodarone is typically reserved for refractory cases given its toxicity burden.
Coronary artery disease or significant structural heart disease avoid Class IC agents (flecainide, propafenone) — increased post-MI mortality risk; use sotalol, dronedarone, or amiodarone instead.
LVEF ≤ 40% / heart failure with reduced ejection fraction amiodarone is the only agent considered safe for rhythm control in this population.[2]
Non-Pharmacologic Treatment
- Risk-factor modification is its own treatment pillar, not an adjunct: weight loss toward a BMI under 27, blood pressure control, treatment of obstructive sleep apnea (CPAP), limiting alcohol intake, and regular exercise all reduce AF burden and improve the success of rhythm-control therapy.[1]
- Electrical cardioversion — for persistent AF, once the anticoagulation requirements below are met (at least 3 weeks of therapeutic anticoagulation beforehand, or a transesophageal echocardiogram excluding left atrial thrombus if earlier cardioversion is needed).
- Catheter ablation (pulmonary vein isolation) — a first-line rhythm-control option for appropriately selected symptomatic paroxysmal or persistent AF, and the standard next step after antiarrhythmic drug failure or intolerance.
- AV-node ablation with permanent pacemaker implantation — a last-resort rate-control option when pharmacologic rate control fails despite optimized therapy.
- Left atrial appendage occlusion (e.g., a Watchman-type device) — an alternative stroke-prevention strategy for patients at high stroke risk who have a genuine contraindication to long-term oral anticoagulation.
Special Populations
Pregnancy
AF in pregnancy is uncommon. Low-molecular-weight heparin or unfractionated heparin is preferred over both DOACs and warfarin for anticoagulation, since warfarin is teratogenic (particularly first trimester) and DOAC safety data in pregnancy are inadequate. For rate control, beta-blockers (e.g., metoprolol) are preferred. Avoid amiodarone in pregnancy given fetal thyroid toxicity, reserving it only for a life-threatening arrhythmia with no reasonable alternative.
Breastfeeding
Warfarin is compatible with breastfeeding. DOAC data in lactation are limited — use warfarin or heparin instead of a DOAC when anticoagulation is needed during breastfeeding.
Renal impairment / chronic kidney disease
Renal function is both a dosing input and a monitoring requirement — assess at baseline and at least annually (more often, roughly every CrCl/10 months, if CrCl is under 60 mL/min) in every anticoagulated patient.[2] By CKD stage: eGFR >30 mL/min — apply the CHADS-65 algorithm as usual, with DOAC renal dose adjustment per the table above; eGFR 15-29 mL/min — a weak recommendation to continue anticoagulation, individualized (apixaban has the most outcome data of the DOACs in this range; warfarin remains an option); eGFR under 15 mL/min or dialysis — routine anticoagulation is not recommended given the lack of demonstrated net benefit in trials.
Elderly and frail patients
Age ≥65 is itself sufficient to recommend anticoagulation under CHADS-65 — advanced age or frailty is not, on its own, a reason to withhold it. DOACs are preferred over warfarin in this group given the consistently lower intracranial hemorrhage risk. Fall risk is not by itself a contraindication to anticoagulation — the stroke-prevention benefit outweighs the bleeding risk from falls in the great majority of patients who would otherwise qualify.
Obesity
Standard DOAC dosing is appropriate up to a BMI of about 40 or weight of about 120 kg. Beyond that, evidence is limited — warfarin, or drug-level testing if a DOAC is used, are reasonable alternatives.
Hepatic impairment
Avoid anticoagulation in advanced cirrhosis with significant coagulopathy (Child-Pugh C). Where anticoagulation is still needed in milder impairment, warfarin with closer INR monitoring is generally preferred over a DOAC given limited DOAC hepatic-impairment data.
Concurrent coronary artery disease
Stable CAD, more than 12 months from the last event or PCI: anticoagulant monotherapy — do not add an antiplatelet routinely. Recent ACS or PCI, under 12 months: a dual pathway of anticoagulant plus clopidogrel (the preferred P2Y12 inhibitor in this combination) is favoured over triple therapy; adding ASA (triple therapy) is reserved for up to 1 month in patients with high ischemic-risk features (e.g., stent thrombosis risk, complex PCI, diabetes, reduced ejection fraction).[2]
Perioperative / periprocedural anticoagulation
For an elective procedure in a DOAC-treated patient: low bleeding-risk procedure — hold the DOAC for 1 day before and 1 day after; high bleeding-risk procedure — hold for 2 days before and after. Dabigatran with CrCl 30-50 mL/min needs a longer hold given renal clearance — 2 days for a low-risk procedure, 4 days for a high-risk procedure.[5] Routine LMWH bridging is not needed for most DOAC-treated patients undergoing an elective procedure — this is a deliberate departure from the older warfarin-bridging paradigm. For warfarin: hold for approximately 5 days before the procedure, confirm the INR has normalized, and resume once hemostasis is adequate; reserve LMWH bridging for individualized high-thromboembolic-risk patients (a mechanical valve, or a stroke/TIA within the last 3 months) rather than applying it routinely.
Monitoring & Follow-Up
- Renal function at baseline and at least annually for every anticoagulated patient (more frequently if CrCl is under 60 mL/min) — this directly determines whether a DOAC dose needs adjustment.
- INR every 4-12 weeks for warfarin, more often if labile or time-in-therapeutic-range is poor; consider point-of-care/self-testing where available.
- Reassess stroke risk (CHADS-65) and bleeding risk (HAS-BLED) periodically, not just at diagnosis — turning 65, a new diagnosis of hypertension or diabetes, or an intervening bleeding event all change the recommendation.
- Adherence checks — up to 30% of patients are not fully adherent to their anticoagulant, a preventable driver of both stroke and, with erratic dosing, bleeding.[2] Pharmacists are well positioned to improve this through counselling, regimen simplification, reminder tools, and affordability review.
- Reassess ventricular rate control and rhythm-control symptom burden at routine follow-up; escalate rather than simply re-reassuring if targets are not being met.
Common Errors to Avoid
- Using ASA, alone, for AF stroke prevention when anticoagulation is indicated — it is not an acceptable lesser alternative and provides only marginal protection.
- Prescribing a DOAC to a patient with a mechanical heart valve or moderate-to-severe mitral stenosis — this is a warfarin-only indication; DOACs were not studied and are contraindicated here.
- Missing the renal, age, or weight dose-reduction criteria for a DOAC — both over- and under-dosing are common and each carries real consequences (bleeding vs. inadequate stroke protection).
- Giving an AV-nodal blocking agent (beta-blocker, non-dihydropyridine CCB, digoxin, or adenosine) to a patient with pre-excited AF (Wolff-Parkinson-White) — this can accelerate accessory-pathway conduction and precipitate ventricular fibrillation.
- Using flecainide or propafenone in a patient with coronary artery disease or significant structural heart disease.
- Stopping anticoagulation prematurely after cardioversion because sinus rhythm was restored — the minimum 4-week post-cardioversion anticoagulation requirement is independent of the rhythm outcome.
- Cardioverting a patient without at least 3 weeks of therapeutic anticoagulation beforehand (or a transesophageal echocardiogram excluding thrombus) when AF duration is over 48 hours or unknown.
- Routine LMWH bridging for an elective procedure in a DOAC-treated patient — unnecessary in most cases and increases bleeding without a stroke-prevention benefit.
- Missing that edoxaban should generally be avoided in patients with CrCl over 95 mL/min, where efficacy versus warfarin was reduced in the pivotal trial.[6]
- Treating digoxin as a first-line or monotherapy rate-control agent in an active, ambulatory patient — it does not control exertional heart rate.
Clinical Decision Algorithm
Drug Tables
How to use this table: Doses are adult doses for nonvalvular atrial fibrillation stroke prevention and rate/rhythm control, and require patient-specific confirmation, including renal/hepatic adjustment. Select any drug name to open its complete Pharmasist Drug Database page.
Direct oral anticoagulants (DOACs) — preferred over warfarin for nonvalvular AF
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Apixaban | Standard: 5 mg PO BID. Reduced: 2.5 mg PO BID if ≥2 of: age ≥80y, weight ≤60 kg, serum creatinine ≥133 µmol/L (1.5 mg/dL). | Bleeding, bruising | Avoid combined strong CYP3A4 and P-gp inhibitors (e.g., ketoconazole, ritonavir) unless dose-adjusted per monograph; avoid strong dual inducers (e.g., rifampin, phenytoin). | DOAC of choice per CCS. No routine coagulation monitoring needed. More outcome data than the other DOACs in significant renal impairment.[7] |
| Rivaroxaban | Standard: 20 mg PO once daily with the evening meal. Reduced: 15 mg PO once daily with food if CrCl 30-49 mL/min. Use with caution, limited data, if CrCl 15-29 mL/min. | Bleeding, GI upset | Avoid combined strong CYP3A4 and P-gp inhibitors/inducers. | Take with food — absorption is reduced in the fasted state. Not recommended if CrCl is under 15 mL/min.[8] |
| Dabigatran | Standard: 150 mg PO BID. Reduced: 110 mg PO BID if age ≥80y, or age 75-79y plus an additional bleeding-risk factor (e.g., CrCl 30-50 mL/min, concomitant P-gp inhibitor, high bleeding risk). | Dyspepsia, bleeding | P-gp substrate — avoid initiating concurrently with verapamil (separate dosing by at least 2 hours if the combination is needed); avoid strong P-gp inhibitors in renal impairment. | Only DOAC with a widely available specific reversal agent (idarucizumab). Contraindicated if CrCl is under 30 mL/min. Do not open, chew, or crush the capsule.[5] |
| Edoxaban | Standard: 60 mg PO once daily. Reduced: 30 mg PO once daily if CrCl 30-50 mL/min, weight ≤60 kg, or a concomitant strong P-gp inhibitor (e.g., verapamil, quinidine, dronedarone). | Bleeding, rash | Strong P-gp inhibitors increase levels — use the reduced dose. | Avoid if CrCl exceeds 95 mL/min — reduced efficacy versus warfarin in the pivotal trial at very high creatinine clearance. Not recommended if CrCl is under 30 mL/min or on dialysis.[6] |
Vitamin K antagonist
Mandatory (not optional) for valvular AF — a mechanical heart valve or moderate-to-severe mitral stenosis. Also the fallback anticoagulant when DOACs cannot be used, e.g., severe renal impairment or dialysis.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Warfarin | Individualized, titrated to INR 2.0-3.0 (nonvalvular AF) or INR 2.5-3.5 (mechanical mitral valve). | Bleeding, rare skin necrosis, teratogenic | Extensive — CYP2C9/VKORC1-mediated interactions with innumerable drugs (including amiodarone, which substantially increases INR), foods, and herbal products. | Requires regular INR monitoring, dose titration, and dietary vitamin K consistency counselling. |
Rate control — beta-blockers
Preferred class for rate control at any left ventricular ejection fraction; specific evidence-based agents in LVEF ≤40%.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Metoprolol | Tartrate: 25-100 mg PO BID. Succinate (extended-release): 50-200 mg PO once daily. IV (acute rate control): 2.5-5 mg IV over 2 minutes, may repeat every 5 minutes to 3 doses. | Bradycardia, hypotension, fatigue, bronchospasm | Additive bradycardia with diltiazem, verapamil, or digoxin. | Titrate to a resting heart rate under 100 bpm. |
| Bisoprolol | 2.5-10 mg PO once daily. | Bradycardia, hypotension, fatigue | Additive bradycardia with diltiazem, verapamil, or digoxin. | Evidence-based option specifically in LVEF ≤40%; once-daily dosing may aid adherence. |
Rate control — non-dihydropyridine calcium channel blockers
Use only if LVEF is greater than 40% — negative inotropy can worsen heart failure with reduced ejection fraction.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Diltiazem | Extended-release: 120-360 mg PO once daily, started low and titrated. IV (acute): 0.25 mg/kg bolus over 2 minutes, then infusion. | Hypotension, bradycardia, peripheral edema, constipation, worsening heart failure | Additive bradycardia with beta-blockers or digoxin; CYP3A4 substrate/inhibitor — raises levels of many co-administered drugs. | Avoid in LVEF ≤40% / heart failure with reduced ejection fraction. |
| Verapamil | Sustained-release: 120-360 mg PO once daily. | Hypotension, bradycardia, constipation, worsening heart failure | Additive bradycardia with beta-blockers or digoxin; P-gp/CYP3A4 interactions (e.g., raises dabigatran levels — avoid concurrent initiation). | Avoid in LVEF ≤40% / heart failure with reduced ejection fraction. |
Rate control — cardiac glycoside
Add-on when first-line therapy is insufficient, or monotherapy specifically in sedentary/inactive patients — it does not control exertional heart rate.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Digoxin | Loading (if needed): 0.25 mg PO/IV every 6 hours, up to 3 doses in 24 hours (maximum 1.5 mg/24h). Maintenance: 0.125-0.25 mg PO once daily; reduce to 0.0625-0.125 mg once daily in renal impairment, the elderly, or low body weight. | Nausea, visual disturbance, arrhythmia — narrow therapeutic index | Amiodarone, verapamil, and dronedarone raise digoxin levels significantly (reduce digoxin dose by up to 50% when combined); hypokalemia and hypomagnesemia increase toxicity risk. | Not appropriate as monotherapy in an active, ambulatory patient. Monitor renal function and electrolytes. |
Rhythm control — antiarrhythmics
Agent choice is dictated by the presence of coronary artery disease or reduced ejection fraction, not by patient preference alone.
| Drug | Dosage | Adverse effects | Drug interactions | Comments |
|---|---|---|---|---|
| Flecainide | 50-150 mg PO BID; pill-in-the-pocket 200-300 mg single oral dose for selected paroxysmal AF (first dose given under monitored conditions, with a concurrent AV-nodal blocking agent). | Proarrhythmia, dizziness, visual disturbance | CYP2D6 substrate — levels affected by CYP2D6 inhibitors. | Contraindicated in coronary artery disease or significant structural heart disease — increased post-MI mortality. Needs a concurrent AV-nodal blocker to prevent 1:1 conduction if atrial flutter develops. |
| Propafenone | 150-300 mg PO TID (immediate-release), or 225-425 mg PO BID (extended-release); pill-in-the-pocket 450-600 mg single oral dose. | Proarrhythmia, dizziness, metallic taste | CYP2D6 substrate; additive AV-nodal effects with beta-blockers. | Same coronary artery disease / structural heart disease contraindication as flecainide. |
| Sotalol | 80-160 mg PO BID, renally adjusted; initiate under ECG/QTc monitoring. | QT prolongation, torsades de pointes, bradycardia | Avoid combining with other QT-prolonging drugs. | An option in structurally normal or ischemic heart disease. Requires baseline and follow-up QTc monitoring; renal clearance means dose/frequency reduction in renal impairment. |
| Dronedarone | 400 mg PO BID with food. | GI upset, rare hepatotoxicity, QT prolongation | CYP3A4 substrate/inhibitor — increases digoxin and dabigatran levels. | Contraindicated in permanent AF and in NYHA class III-IV or recently decompensated heart failure — an increased mortality signal was seen in this population. |
| Amiodarone | Loading: 400-600 mg PO daily (divided) for 2-4 weeks. Maintenance: 100-200 mg PO once daily. | Thyroid dysfunction, pulmonary fibrosis, hepatotoxicity, corneal microdeposits, photosensitivity, bradycardia | Potent CYP3A4/2C9/P-gp inhibitor — significantly increases warfarin (reduce dose ~30-50%), digoxin (reduce dose ~50%), and dabigatran levels. | The only rhythm-control agent considered safe in LVEF ≤40%/HFrEF. Requires baseline and periodic TSH, liver function tests, and monitoring for extracardiac toxicity. |
References
- The 2020 Canadian Cardiovascular Society/Canadian Heart Rhythm Society Comprehensive Guidelines for the Management of Atrial Fibrillation — Canadian Journal of Cardiology, Canadian Cardiovascular Society/Canadian Heart Rhythm Society (Andrade JG, Aguilar M, Atzema C, et al.). Can J Cardiol 2020;36(12):1847-1948
- The 2020 CCS atrial fibrillation guidelines for pharmacists: Top 10 takeaways — Canadian Pharmacists Journal (LeBlanc K, MacGillivray J, Carroccia A, Macle L, Andrade JG). Can Pharm J 2022;155(2):73-82
- Guidelines: Atrial Fibrillation — Practical Guide — Canadian Cardiovascular Society. CCS Atrial Fibrillation Practical Guide
- A novel user-friendly score (HAS-BLED) to assess 1-year risk of major bleeding in patients with atrial fibrillation: the Euro Heart Survey — Chest (Pisters R, Lane DA, Nieuwlaat R, de Vos CB, Crijns HJGM, Lip GYH). Chest 2010;138(5):1093-1100
- Dabigatran (Pradaxa) — Clinical Guide — Thrombosis Canada. Thrombosis Canada Clinical Guide
- LIXIANA (edoxaban) Product Monograph — Servier Canada Inc.. Health Canada Product Monograph
- APIXABAN Product Monograph — Health Canada Drug Product Database. Health Canada Product Monograph
- XARELTO (rivaroxaban) Product Monograph — Health Canada Drug Product Database. Health Canada Product Monograph
Professional reference only. Apply clinical judgment and verify patient-specific decisions against current authoritative guidance and product information.