Managing chronic atrial fibrillation: a Markov decision analysis comparing warfarin, quinidine, and low-dose amiodarone

* Objective: To compare the relative risks and benefits of several clinical strategies for managing patients with chronic atrial fibrillation. * Design: Five recent randomized controlled trials of warfarin in atrial fibrillation, 6 randomized controlled trials of quinidine, and 13 longitudinal studies of low-dose amiodarone were used. A MEDLINE search was also done (1966 to present). * Measurements: A Markov decision analysis model was used to assess outcomes in large, hypothetical cohorts of patients with atrial fibrillation followed from 65 to 70 years of age within four clinical strategies: 1) no treatment; 2) warfarin; 3) electrical cardioversion followed by quinidine to maintain normal sinus rhythm; and 4) electrical cardioversion followed by low-dose amiodarone. * Results: In this hypothetical cohort, fewer patients had disabling events with amiodarone (1.4%) than with quinidine (1.8%), warfarin (2.6%), or no treatment (7.4%). Amiodarone appeared to be associated with the lowest 5-year mortality (13.6%) when compared with warfarin (14.4%), quinidine (15.2%), and no treatment (18.2%). In terms of quality-adjusted life-years, amiodarone had the highest expected value (4.75 years), followed by warfarin (4.72 years), quinidine (4.68 years), and no treatment (4.55 years). Amiodarone remained the preferred strategy using the most plausible scenarios of risks associated with atrial fibrillation. Choices among warfarin, quinidine, and no treatment depended on estimates of bleeding rates with warfarin, stroke rates after discontinuing warfarin, quinidine-related mortality, and the quality of life with warfarin. * Conclusion: Cardioversion followed by low-dose amiodarone to maintain normal sinus rhythm appears to be a relatively safe and effective treatment for patients with chronic atrial fibrillation.
Cardioversion and low-dose amiodarone may be an effective treatment for chronic atrial fibrillation. Atrial fibrillation is the rapid, random contraction of individual fibers of the heart muscle causing an irregular, rapid heart beat. Cardioversion is used to restore the normal rhythm of the heart by electrical shock. Researchers applied a decision analysis model to a hypothetical set of patients based on the patients of 24 studies. They evaluated the efficacy of no treatment, warfarin, cardioversion followed by quinidine and cardioversion followed by low-dose amiodarone. Among the hypothetical patients, 1.4% had disabling cardiac events with amiodarone, compared to 1.8% with quinidine, 2.6% with warfarin and 7.4% with no treatment. Amiodarone was also associated with the lowest five-year mortality rate (13.6%) and the highest expected value for quality-adjusted life years (4.75 years) when compared to the other treatments.