Management notes

10% of the US population of 80 years of age and above suffer from atrial fibrillation. Sometimes atrial fibrillation is not noticed by the patient for a long time resulting in sufficient cardiac remodeling that establishing a sinus rhythm becomes very difficult. 

In this video talk, Dr. Syed discusses the definition, presentation, pathology, EKG, and salient points of management of the atrial fibrillation. Following aspects are discussed in detail:

1. Considerations for the treatment of the atrial fibrillation (AF.)
2. Cardioversion.
3. Anticoagulants and antiplatelets.
4. Antiarrhythmic.
5. Rate control.
6. Surgical approaches.

Considerations for Management

• Patient’s age and symptoms.
• Hemodynamic effects of the AF (LV function compromise, HF).
• Duration since the onset of the fibrillation.
  • <48 hours, unknown, >48 hours.
• Clinical stage of fibrillation.
  • Paroxysmal, persistent, permanent.
• Comorbidities.
• Risk of a cardiac incident.
• Risk of bleeding/stroke.
• Existing medication.

Electrical Cardioversion

• New onset AF associated with severe hypotension, pulmonary edema, and angina can be managed with electrical cardioversion. Usually, up to 48h of AF can be approached with cardioversion.
  • Assess the risk of stroke before cardioverting. (Use CHA2DS2-VASc score for assessment.)
    • Patients with prior embolic events, rheumatic mitral stenosis, hypertrophic cardiomyopathy with marked left atrial enlargement may not be cardioverted before careful consideration for the risk of stroke.
  • 200 Joule (sedation or anesthesia.)
    • Greater shock energy and different electrode placement may be tried if the shock fails to terminate AF.
    • If AF terminates and restarts then antiarrhythmic drugs (ibutilide) can be administered and then cardioversion attempted again.
• AF of unknown duration or greater than 48 hours must not be cardioverted. Following two choices are useful in such situations:
  • Give anticoagulants for 3 weeks before then cardiovert and then continue anticoagulants for at least 4 weeks after.
  • Perform transesophageal echocardiogram to detect a thrombus in the left atrial appendage. Cardiovert if there is no thrombus. Administer anticoagulants for at least 4 weeks after the cardioversion.
• Some patients may need continuous anticoagulation therapy instead of stopping after 4 weeks of cardioversion.

Medical Management

• Oral anticoagulants:
  • Vitamin K inhibitors.
  • Newer anticoagulants like:
    • Thrombin inhibitors (dabigatran.)
    • Factor Xa inhibitors (rivaroxaban, apixaban.)
  • Older anticoagulants like Warfarin are less used nowadays.
  • Immediate administration with Heparin is useful. This should give enough window of time to decide other therapies.
• Antiplatelet (Aspirin, Clopidogrel) have not shown efficacy for AF patients.
• Rate control:
  • Beta blockers.
  • Ca++ channel blockers. (Diltiazem, Verapamil.)
  • Na+/K+ ATPase inhibitor (Digoxin.) Especially when AV nodal blocking agent cannot be used.
• Rhythm Control (antiarrhythmic):
  • Class I
  • Class III

Anticoagulants/Stroke Prevention

• CHA2DS2-VASc score. (Indication of anticoagulants at a score of 2 or greater.)
  • Clinical Features:
    • CHF/LV Dysfunction: 1
    • HTN: 1
    • DM: 1
    • History of stroke, TIA or thromboembolism: 2
    • Vascular pathologies. History of MI, aortic atherosclerosis, PVD: 1
  • Age:
    • 65-74: 1
    • >= 75: 2
  • Sex:
    • Male: 0
    • Female: 1
• You can skip anticoagulants and antiplatelet, or administer Aspirin for a score of 0.
• Anticoagulants are administered at a score of 2 or higher, or to patients with prior history of stroke.
  • Anticoagulant may be considered even at a score of 1.
• Patients with rheumatic mitral stenosis or mechanical heart valves must receive vitamin K antagonists (Warfarin).
• Patients who have previously not received newer anticoagulants (Thrombin blocker and Factor Xa blockers) must get vitamin K antagonists as well.
• Keep in mind that 1% of the patients get intracranial hemorrhage or major bleeding that requires transfusion of fresh frozen plasma and vitamin K. (Monitoring is very important especially with the older anticoagulants.)
• Risk factors for bleeding are age >65-75 y, heart failure, anemia, excessive alcohol consumption, NSAID drugs usage, coronary stent patients on aspirin and a thienopyridine.
• Warfarin is superior to antiplatelet therapy.
  • It takes several days to achieve PT time/INR of greater than 2. Monitoring is needed. Hence newer anticoagulants are favored.
• Newer anticoagulants (dabigatran, rivaroxaban, and apixaban):
  • Shown marginal superiority over Warfarin (0.4%-0.7%.)
  • Promptly achieve the anticoagulant effect. Don’t need much dosage adjustment.
  • These are excreted by kidneys, hence severe renal failure patients cannot use these. Dose adjustment needed for modest renal failure.
  • •P-glycoprotein inducers and inhibitors also influence the excretion.
• Approach to the patient with paroxysmal AF and persistent AF is the same.
• Warfarin can be reversed by administering fresh frozen plasma and vitamin K.
• Reversing agents for the newer anticoagulants are lacking. However, they are excreted within 12 hours.
• Antiplatelet agents (aspirin, clopidogrel) are inferior to warfarin for stroke prevention in AF. Clopidogrel with aspirin is better than aspirin alone but have greater bleeding risk than aspirin alone.
• Chronic anticoagulants are contraindicated with patients with bleeding risks. In such patients, surgical removal of the left atrial appendage or catheter ablation is indicated.

Chronic Rate Control

• Usual goal is resting heart rate of <80 bpm and <100 bpm with light exertion (walking).
  • Note: if rate control is difficult then up to 110 bpm resting heart rate is acceptable provided symptoms are tolerable and ventricular function is normal.
• Rate control is important to alleviate symptoms and prevent ventricular damage due to chronic tachycardia.
• Rate control is important to also reduce the pace of or to prevent cardiac remodeling.
• Beta blockers, calcium channel blockers, and digoxin are used. Sometimes in combination.
• Rate control is incorrect if the patient experiences exertion related symptoms.
• If rate control fails with medications then catheter ablation is indicated. Sometimes AV Junction is ablated with a pace maker to manage ventricular rate. Sometimes there may be dyssynchronous ventricular rate for which biventricular pacing will be indicated.

Rhythm Control

• Rhythm control strategy includes the decision to administer antiarrhythmic or catheter ablation.
• Patient’s preference in light of risk and benefits is the guiding principle.
• Usually, the strategy is selected for following patients:
  • Symptomatic paroxysmal AF.
  • First episode of symptomatic persistent AF.
  • AF with difficult rate control i.e. patients that have structural changes.
  • AF compromising ventricular function.
  • AF aggravating heart failure.
• AV-nodal blocking agents are used.
• B-Adrenergic blockers and calcium channel blockers are used.
• These drugs help maintain sinus rhythm, improve symptoms, and have a low-risk profile. These drugs, however, have low efficacy to prevent AF episodes.
• Class I Na+ channel blockers (flecainide, propafenone, disopyramide) can be used if there is no significant structural heart change.
  • These have negative inotropic and proarrhythmic effect. Cannot be used in patients with coronary artery disease or patients with heart failure.
• Class III (sotalol and dofetilide) can be given to the patients with coronary artery disease.
  • 3% patients can develop prolonged QT and induce torsades des pointes.
  • Dofetilide should only be administered in a hospital with ECG monitors. Many physicians take the same approach with sotalol.
  • Amiodarone maintains sinus rhythm better in two-thirds of the patients.
    • It is also used after the open heart surgery to prevent a sudden onset of AF. 2g given over 2 days.
    • p-glycoprotein inhibitor.
    • Contraindicated in patients with heart block or SA node dysfunction. (Due to its class IV like behavior.)

Surgical Approach

• In patients with long standing AF (usually > 1 year) enough structural changes occur to the atrial tissue that reentrant circuits become permanent. In such patients, cardioversion will fail. If patient’s symptoms are disrupting their quality of life with permanent reentry circuits then catheter ablation is used.
• Catheter ablation can be done in two ways:
  • Usually, the tissue around the pulmonary veins is ablated trapping the reentrant signals in these areas.
  • If the restructuring is extensive, then a maze like path is formed in the atrial tissue that guides the impulse travel and prevents re-entry.
• In rare cases, catheter ablation can cause cardiac tamponade, stroke, esophageal injury, SA node injury requiring a pacemaker, and death.

Disclaimer

• All information contained in and produced by the drbeen corp., is provided for educational purposes only. This information should not be used for the diagnosis or treatment of any health problem or disease.
• THIS INFORMATION IS NOT INTENDED TO REPLACE CLINICAL JUDGMENT OR GUIDE INDIVIDUAL PATIENT CARE IN ANY MANNER.