A recent Cochrane review of 8 randomized trials with a total of 9598 patients concluded that adjusted-dose warfarin reduces stroke and other major vascular events in patients with nonvalvular AF by about one third, compared with antiplatelet therapy alone.23
Warfarin or aspirin? Tools to help you decide
The risk of stroke varies considerably among patients with AF, depending on age and history of thromboembolic events, among other risk factors. What’s more, anticoagulation therapy carries an inherent risk of increased bleeding, making its use a complicated decision. A validated stroke risk stratification scheme like the CHADS2 can help.24 (See “Warfarin or aspirin? An anticoagulation risk tool”.)
The ACC/AHA/ESC guidelines recommend an alternate means of determining when anticoagulation is needed. The recommended risk stratification scheme divides risk factors for stroke into 3 categories:
- weak/less validated (female gender, age 65-74 years, coronary artery disease, thyrotoxicosis)
- moderate (≥75 years of age, hypertension, heart failure, LV ejection fraction ≤35%, diabetes mellitus)
- high (previous stroke, TIA, or embolism; mitral stenosis, prosthetic heart valve).
The guidelines recommend warfarin therapy for any patient with any high-risk factor or 2 or more moderate-risk factors; aspirin therapy for patients with no moderate- or high-risk factors; and aspirin or warfarin for patients with 1 moderate-risk factor.1
When conventional therapy fails
For patients who do not respond to conventional therapy, other options, including radiofrequency catheter ablation and pacemakers, may be effective in controlling symptoms and improving quality of life. In a recent RCT of 70 patients 18 to 75 years of age who experienced monthly symptomatic episodes of AF, the recurrence rate at the end of the 12-month follow-up was 13% after pulmonary vein isolation with radiofrequency ablation compared with 63% after treatment with antiarrhythmic drugs (P<.001). The rate of hospitalization was also significantly lower in the radiofrequency ablation group: 9% compared with 54% in the antiarrhythmia group (P<.001).25 Another option to consider for patients who require cardiac surgery for other reasons is left atrial appendage (LAA) occlusion or ligation at the time of surgery. This may prevent cardiac embolization, because the vast majority of thrombi in nonvalvular AF involve the LAA.
Correspondence
Shobha Rao, MD, University of Texas Southwestern Family Medicine Residency Program, 6263 Harry Hines Blvd., Clinical 1 Building, Dallas, TX 75390; shobha.rao@utsouthwestern.edu.