Lone Atrial Fibrillation: Prophylactic Anti-arrhythmic Treatment

DOI: 10.1007/978-88-470-0636-2_3

ABSTRACT Atrial fibrillation is a common arrhythmia and the cause of substantial morbidity [1, 2]. Management strategies for its control are far from satisfactory [3]. Most importantly, whether by restoring sinus rhythm or by controlling ventricular rate, arrhythmic strategies bring with
them a proarrhythmic or arrhythmogenic risk [4]. In such cases, the basic arrhythmia may be aggravated or new and more devastating arrhythmia may be produced.

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    ABSTRACT: Five drugs currently constitute approximately 70% of the world market for antiarrhythmic medications. Since the publication of studies documenting that certain Class I drugs may increase mortality in high-risk postinfarction patients, basic science and clinical studies have focused on Class III antiarrhythmic drugs. However, drugs that prolong repolarization and cardiac refractoriness are sometimes associated with potentially lethal torsades de pointes. Amiodarone, a multichannel blocker, may be the exception to this observation, but it nevertheless fails to reduce total mortality compared with placebo in high-risk patients following myocardial infarction. However, Class III agents remain the focus of drug development efforts because they lack the negative hemodynamic effects, affect both atrial and ventricular tissue, and can be administered as either parenteral or oral preparations. Developers of newer antiarrhythmic agents have focused on identifying antiarrhythmic medications with the following characteristics: appropriate modification of the arrhythmia substrate, suppression of arrhythmia triggers, efficacy in pathologic tissues and states, positive rate dependency, appropriate pharmacokinetics, equally effective oral and parenteral formulations, similar efficacy in arrhythmias and their surrogates, few side effects, positive frequency blocking actions, and cardiac-selective ion channel blockade. New and investigational agents that more closely approach these goals include azimilide, dofetilide, dronedarone, ersentilide, ibutilide, tedisamil, and trecetilide. In the near future, medications will increasingly constitute only part of an antiarrhythmic strategy. Instead of monotherapy, they will often be used in conjunction with an implanted device. Combination therapy offers many potential advantages. Long-term goals of antiarrhythmic therapy include upstream approaches, such as identification of the biochemical intermediaries of the process and, eventually, of molecular and genetic lesions involved in arrhythmogenesis.
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    ABSTRACT: Direct current cardioversion of persistent atrial fibrillation is one of the most widely used and effective treatments for the restoration of sinus rhythm, but may be hampered by a low success rate and a high percentage of early recurrence. Pre-treatment with amiodarone or a glucose-insulin-potassium solution could improve the efficacy of electrical cardioversion by reversing the partially depolarized diastolic potential of the subsidiary pacemakers in atrial fibrillation. In a controlled randomized study, we assessed the effectiveness of electrical cardioversion in patients with persistent atrial fibrillation after pre-treatment with amiodarone or potassium infusion and the efficacy of amiodarone in maintaining sinus rhythm after electrical cardioversion. Ninety-two patients with persistent atrial fibrillation (>2 weeks duration) were prospectively randomized into three matched groups: A (n=31, oral amiodarone 400 mg. day(-1)1 month before and 200 mg. day(-1)2 months after cardioversion), B (n=31, 180 mg. day(-1)oral diltiazem 1 month before and 2 months after cardioversion and 80 mmol potassium, 50 UI insulin in 500 ml 30% glucose solution 24 h before cardioversion) and C (n=30, control patients, 180 mg. day(-1)oral diltiazem 1 month before and 2 months after cardioversion). Before cardioversion all patients were under 4 weeks effective oral anticoagulant therapy (warfarin). Before electrical cardioversion, the rate of spontaneous conversion to sinus rhythm was higher in group A (25%) than groups B (6%) or C (3%) (P<0.005). Electrical cardioversion was more successful in group A (88%) than groups B (56%) or C (65%) (P<0.05), while the electrical thresholds for effective cardioversion were lower in group B than the other groups (P<0.05). Twenty-four hours after cardioversion, the early recurrence of atrial fibrillation was similar in the three groups (P=ns), while at 2 months the recurrence rate was lower in group A (32%) than groups B (56%) or C (52%) (P<0.01). Pre-treatment with low-dose oral amiodarone, compared with oral diltiazem or glucose-insulin-potassium treatments, induces a significantly high percentage of instances of spontaneous conversion, increases electrical cardioversion efficacy and reduces atrial fibrillation recurrence.
    European Heart Journal 01/2000; 21(1):66-73. DOI:10.1053/euhj.1999.1734 · 14.72 Impact Factor