BACKGROUND: Atrial fibrillation (AF) is the most common cause of embolic stroke. Although there is impressive risk reduction in stroke associated with warfarin therapy in clinical trials and guidelines on anticoagulation in AF, there are limited data on how well these goals are being met. This study aims to determine the adherence to guidelines on anticoagulant management among adult patients with AF at the Department of Internal Medicine Ward of the University of the Philippines - Philippine General Hospital (UP-PGH).
METHODS: This is a prospective study, which included patients aged 18 years and older with diagnosis of AF, which can be paroxysmal, persistent, long-standing or permanent. Upon admission, patients were interviewed and information like age, gender, duration of AF, co-morbid illnesses, and medical history were collected using a checklist. Risk factors for bleeding, use of antiplatelet/anticoagulant agents and International Normalized Ratio (INR) values were also determined.
RESULTS: There were 40 subjects included in the study, majority of which were female (77.5%) and in the 40-50 years age range (35%). There were 21 (52.5%) patients who had valvular AF and 19 (47.5%) who had non-valvular AF. Of those patients with valvular AF, 80.9% received warfarin. Of those patients with non-valvular AF, 94.7% were at moderate or high risk for thromboembolism, but only 47.4% of those patients received warfarin. We found that only a small percentage of patients (16%) had INR in the therapeutic range of 2.0-3.0. The majority of the patients had their INR in the sub-therapeutic ranges at 40% and 24% at INR values of 1.5-1.99 and 0-1.49 respectively. The majority of the patients on warfarin had INR monitoring ? 30 days, and these were patients already on chronic or long-term warfarin use. Those patients who had more frequent INR monitoring were those newly initiated on the treatment whose INR values where in the sub-therapeutic range.
CONCLUSION: The adherence of anticoagulant management among AF patients admitted at the Internal Medicine Wards of UP-PGH, to evidence-based clinical practice guidelines, was high at 80.9% for patients with valvular AF and was quite low at 47.4% for non-valvular AF patients. Patients were found to have low bleeding risks based on a HAS-BLED score and patients with moderate to high thromboembolic risk factors were more often prescribed with warfarin, although only a few patients achieved a therapeutic INR. A more frequent INR monitoring including a close follow-up with the patients should be performed to achieve target INR in most patients with AF. Moreover, we should not discount starting anticoagulation in patients with non-valvular AF who have moderate to high thromboembolic risk factors.