Education And Debate


BMJ 1995; 311 doi: (Published 16 December 1995) Cite this as: BMJ 1995;311:1631
  1. Gregory Y H Lip,
  2. Robert D S Watson,
  3. Shyam P Singh

    One of the most important principles of using antiarrhythmic drugs for controlling any arrhythmia is to treat only patients who are symptomatic, have malignant arrhythmias (such as ventricular fibrillation), or are haemodynamically compromised (for example, with hypotension or heart failure). If a patient has only mild and infrequent symptoms, treatment with antiarrhythmic drugs should be avoided. This strategy is justified by evidence of substantial morbidity associated with such treatment and worsened long term prognosis, particularly if class I agents are used. Many antiarrhythmic drugs also depress cardiac function and may precipitate heart failure, and most can aggravate or cause an arrhythmia (arrhythmogenesis or proarrhythmic effect).

    Vaughan-Williams classification of antiarrhythmic drugs

    • Class I--Membrane-stabilising agents (fast sodium channel blockers) Class Ia--Blockssodium channel and delays repolarisation, increasing duration of action potential (for example, quinidine, disopyramide, procainamide)

      Class Ib--Blocks sodium channel and accelerates repolarisation, decreasing duration of action potential (for example, lignocaine, phenytoin)

      Class Ic--Blocks sodium channel, with little effect on repolarisation (for example, flecainide, propafenone)

    • Class II--£ Adrenoceptor blockers

      For example, atenolol, metoprolol

    • Class III--Drugs increasing duration of action potential

      For example, amiodarone, bretylium, sotalol (also has class II activity)

    • Class IV--Calcium channel blockers

      For example, verapamil, diltiazem

    Antiarrhythmic drugs can be used for rate control of chronic atrial fibrillation, cardioversionof atrial fibrillation to sinus rhythm, maintenance of sinus rhythm after cardioversion, and control of symptoms (including as a prophylaxis in paroxysmal atrial fibrillation). Antithrombotic prophylaxis with warfarin or aspirin should also be given. Prescribing habits for atrial fibrillation,however, vary greatly, perhaps reflecting uncertainty about what the best drug is and a lack of scientific evidence from controlled trials.

    An approach to drug management of atrial fibrillation Paroxysmal atrial fibrillation

    • Consider drugs for prevention of paroxysms and maintenance of sinus rhythm

    • Consider treatment with antithrombotic drugs Chronic atrial fibrillation

    • What is the objective of management? Consider cardioversion to sinus rhythm or heartrate control

      Cardioversion: Is the patient taking anticoagulants? …

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