The case for inpatient initiation of antiarrhythmic therapy

Progress toward the development of a safe and effective agent for treating reentrant cardiac arrhythmias: synthesis and evaluation of ibutilide analogues with enhanced metabolic stability and diminished proarrhythmic potential

A series of ibutilide analogues with fluorine substituents on the heptyl side chain was prepared and evaluated for class III antiarrhythmic activity, metabolic stability, and proarrhythmic potential. It was found that fluorine substituents stabilized the side chain to metabolic oxidation. Many of the compounds also retained the ability to increase the refractoriness of cardiac tissue at both slow and fast pacing rates. The potential for producing polymorphic ventricular tachycardia in the rabbit model was dependent on the chirality of the benzylic carbon. The S-enantiomers generally had less proarrhythmic activity than the corresponding racemates. One compound from this series (45E, trecetilide fumarate) had excellent antiarrhythmic activity and metabolic stability and was devoid of proarrhythmic activity in the rabbit model. It was chosen for further development.

Rhythm or rate control in atrial fibrillation--Pharmacological Intervention in Atrial Fibrillation (PIAF): a randomised trial

BACKGROUND

Atrial fibrillation is the most commonly encountered sustained cardiac arrhythmia. Restoration and maintenance of sinus rhythm is believed by many physicians to be superior to rate control only. However, there are no prospective data that compare both therapeutic strategies.

METHODS

The Pharmacological Intervention in Atrial Fibrillation (PIAF) trial was a randomised trial in 252 patients with atrial fibrillation of between 7 days and 360 days duration, which compared rate (group A, 125 patients) with rhythm control (group B, 127 patients). In group A, diltiazem was used as first-line therapy and amiodarone was used in group B. The primary study endpoint was improvement in symptoms related to atrial fibrillation.

FINDINGS

Over the entire observation period of 1 year, a similar proportion of patients reported improvement in symptoms in both groups (76 responders at 12 months in group A vs 70 responders in group B, p=0.317). Amiodarone administration resulted in pharmacological restoration of sinus rhythm in 23% of patients. Walking distance in a 6 min walk test was better in group B compared with group A, but assessment of quality of life showed no differences between groups. The incidence of hospital admission was higher in group B (87 [69%] out of 127 vs 30 [24%] out of 125 in group A, p=0.001). Adverse drug effects more frequently led to a change in therapy in group B (31 [25%] patients compared with 17 [14%] in group A, p=0.036).

INTERPRETATION

With respect to symptomatic improvement in patients with atrial fibrillation, the therapeutic strategies of rate versus rhythm control yielded similar clinical results overall. However, exercise tolerance is better with rhythm control, although hospital admission is more frequent. These data may serve as a basis to select therapy in individual patients.

Cost effectiveness of therapies for atrial fibrillation. A review

Atrial fibrillation is the most common supraventricular tachyarrhythmia encountered in clinical practice, affecting over 5% of persons over the age of 65 years. A common pathophysiological mechanism for arrhythmia development is atrial distention and fibrosis induced by hypertension, coronary artery disease or ventricular dysfunction. Less frequently, atrial fibrillation is caused by mitral stenosis or other provocative factors such as thyrotoxicosis, pericarditis or alcohol intoxication. Depending on the extent of associated cardiovascular disease, atrial fibrillation may produce haemodynamic compromise, or symptoms such as palpitations, fatigue, chest pain or dyspnoea. Arrhythmia-induced atrial stasis can precipitate clot formation and the potential for subsequent thromboembolism. Comprehensive management of atrial fibrillation requires a multifaceted approach directed at controlling symptoms, protecting the patient from ischaemic stroke or peripheral embolism and possible conversion to or maintenance of sinus rhythm. Numerous randomised trials have demonstrated the efficacy of warfarin--and less so aspirin (acetylsalicylic acid)--in reducing the risk of embolic events. Furthermore, therapeutic strategies exist that can favourably modify symptoms by restoring and maintaining sinus rhythm with cardioversion and antiarrhythmic prophylaxis. However, the risks and benefits of various treatments is highly dependent on patient-specific features, emphasising the need for an individualised approach. This article reviews the findings of cost-effectiveness studies published over the past decade that have evaluated different components of treatment strategies for atrial fibrillation. These studies demonstrate the economic attractiveness of acute management options, long term warfarin prophylaxis, telemetry-guided initiation of antiarrhythmic therapy, approaches to restore and maintain sinus rhythm, and the potential role of transoesophageal echocardiographic screening for atrial thrombus prior to pharmacological or electrical cardioversion. Further, we discuss the merits and limitations of the cost-effectiveness analyses in the context of overall treatment strategies. Finally, we identify areas that will require additional research to achieve the goal of effective and economically efficient management of atrial fibrillation.