Primary Care Doctors Aren't Following Guidelines, Leading to Sub-optimal Treatment of Atrial Fibrillation

A study in the Canadian Journal of Cardiology suggests that gaps in knowledge among primary care physicians are leading to less than optimal treatment for atrial fibrillation patients, many of whom are improperly assessed for stroke and bleeding risks. Further, the researchers note significant instances of under- and over-prescribing (as well as incorrect dosing) of oral anticoagulation therapy.

Patients with atrial fibrillation (AF) have an increased risk for stroke and are often prescribed oral anticoagulation (OAC) therapy. OAC therapy can prevent disastrous strokes, but at the expense of increased bleeding risks. Striking the balance between the benefits and potential risks isn’t an exact science, but there are well-established guidelines to assess the risk of stroke and bleeding in AF patients to determine whether OAC is needed.

This study, however, shows that primary care physicians, key players in the early diagnosis and treatment of AF, are either not familiar enough with the guidelines to implement them properly or are not aware of them in the majority of cases studied.

The study, one component of the national Facilitating REview and EDucation to OptiMize stroke prevention in Atrial Fibrillation (FREEDOM AF) knowledge translation program, collected data on 4,280 patients (≥18 years without a significant heart valve disorder) from 438 general practitioners undertaking an ethics-approved chart audit describing characteristics, AF and medical history, antithrombotic treatment, and estimated risk, from February to April 2011.

Prior history included: stroke (11%), transient ischemic attack (13%), systemic embolism (2%), hypertension (75%), heart failure (20%), and diabetes (27%).

The study authors observed that physicians were unable to give an estimate of stroke and bleeding risk in 15% and 25% of their AF patients, respectively; when such estimates were provided, they were based on a predictive stroke and bleeding risk index in only 50% and 25% of patients, respectively. Furthermore, there is apparent underestimation of especially stroke but also bleeding risk in a substantial number of patients.

Despite the relatively high use of antithrombotic therapy, the estimated day-to-day anticoagulation INR target was achieved in only half of current warfarin-treated patients. Although antithrombotic therapy with warfarin was prescribed for 90% of the patients, 44% of patients were not receiving a proper dosage for over 70% of the time.

“Among those who did receive anticoagulation with warfarin, as many as four in 10 patients spent less time in the therapeutic range we know is optimal to reduce the risk of stroke,” the study authors noted.

Limitations of the study include the fact that the patients were already being treated with OAC at a significantly greater rate than would be expected in a general AF population, so the results might not be generalizable. The review also predates the release of newer OAC drugs such as apixaban, dabigatran, and rivaroxaban, which have different risk-benefit profiles and are now prescribed more frequently than warfarin.