Challenges of stroke prevention in patients with atrial fibrillation in clinical practice

Direct oral anticoagulants: key considerations for use to prevent stroke in patients with nonvalvular atrial fibrillation

Atrial fibrillation (AF) is the most common cardiac arrhythmia worldwide. Strokes that occur as a complication of AF are usually more severe and associated with a higher disability or morbidity and mortality rate compared with non-AF-related strokes. The risk of stroke in AF is dependent on several risk factors; AF itself acts as an independent risk factor for stroke. The combination of effective anticoagulation therapy, risk stratification (based on stroke risk scores, such as CHADS₂ and CHA₂DS₂-VASc), and recommendations provided by guidelines is essential for decreasing the risk of stroke in patients with AF. Although effective in preventing the occurrence of stroke, vitamin K antagonists (VKAs; eg, warfarin) are associated with several limitations. Therefore, direct oral anticoagulants, such as apixaban, dabigatran etexilate, edoxaban, and rivaroxaban, have emerged as an alternative to the VKAs for stroke prevention in patients with nonvalvular AF. Compared with the VKAs, these agents have more favorable pharmacological characteristics and, unlike the VKAs, they are given at fixed doses without the need for routine coagulation monitoring. It remains important that physicians use these direct oral anticoagulants responsibly to ensure optimal safety and effectiveness. This article provides an overview of the existing data on the direct oral anticoagulants, focusing on management protocols for aiding physicians to optimize anticoagulant therapy in patients with nonvalvular AF, particularly in special patient populations (eg, those with renal impairment) and other specific clinical situations.

Cost-effectiveness of dabigatran for stroke prevention in non-valvular atrial fibrillation in Spain

INTRODUCTION AND OBJECTIVES

Assessment of the cost-effectiveness of dabigatran for the prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation in Spain, from the perspective of the National Health System.

METHODS

Adaptation of a Markov chain model that simulates the natural history of the disease over the lifetime of a cohort of 10,000 patients with non-valvular atrial fibrillation. Model comparators were warfarin in a first scenario, and a real world prescribing pattern in a second scenario, in which 60% of the patients were treated with vitamin K antagonists, 30% with acetylsalicylic acid, and 10% received no treatment. Deterministic and probabilistic sensitivity analyses were performed.

RESULTS

Dabigatran reduced the occurrence of clinical events in both scenarios, providing gains in quantity and quality of life. The incremental cost-effectiveness ratio for dabigatran compared to warfarin was 17,581 euros/quality-adjusted life year gained and 14,118 euros/quality-adjusted life year gained when compared to the real world prescribing pattern. Efficiency in subgroups was demonstrated. When the social costs were incorporated into the analysis, dabigatran was found to be a dominant strategy (ie, more effective and less costly). The model proved to be robust.

CONCLUSIONS

From the perspective of the Spanish National Health System, dabigatran is an efficient strategy for the prevention of stroke in patients with non-valvular atrial fibrillation compared to warfarin and to the real-world prescribing pattern; incremental cost-effectiveness ratios were below the 30,000 euros/quality-adjusted life year threshold in both scenarios. Dabigatran would also be a dominant strategy from the societal perspective, providing society with a more effective therapy at a lower cost compared to the other 2 alternatives. Full English text available from:www.revespcardiol.org.

A study of elderly adults taking warfarin admitted with prolonged international normalized ratio: a community hospital's experience

OBJECTIVES

To assess bleeding complications and outcome of individuals receiving oral anticoagulants who were admitted to the hospital with an international normalized ratio (INR) greater than 4 by comparing them according to age (≤ 80, >80).

DESIGN

Retrospective cohort study.

SETTING

Community hospital.

PARTICIPANTS

All individuals (N = 253) admitted to the Department of Internal Medicine over a period of 4 years with an INR greater than 4: Group I, aged 80 and younger (n = 127); Group II, older than 80 (n = 126). Data included bleeding complications, survival, and quality of INR control before admission and up to 48 months after admission.

RESULTS

Atrial fibrillation was the most common indication for warfarin therapy. Its incidence was higher in the older group (88% vs 73%, P = .004). More elderly participants lived in nursing homes (23% vs 9.4%. P = .004) or received in-home assistance (38.9% vs 20.5%, P = .002). There was no difference in INR upon admission, duration of warfarin treatment, or frequency of INR tests before admission. The incidence of bleeding events was 18.1% in Group I and 12.7% in Group II (P = .30). Major bleeding events occurred in 1.6% of Group I and none of Group II (P = .50). During follow-up after the first admission, the incidence of INR greater than 4 was higher in Group II (87.3% vs 70%, P = .02), without a difference in the number of additional admissions or bleeding events.

CONCLUSION

Primary care physicians can safely maintain warfarin treatment in elderly adults, even in those with a history of hospitalization for high INR, using frequent INR measurements.