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Stroke Risk in AF Patients Frequently Underestimated


December 06, 2015

New research showed that primary care physicians failed to properly predict stroke or bleeding risk in a majority of their atrial fibrillation (AF) patients and mismanaged anticoagulation levels of patients on warfarin.

The real-world study involved 4,670 Canadian adults with a median age of 77 years and a history of AF — 3 to 10 years since diagnosis — who were treated by 474 primary care physicians. The physicians rated 864 (18.5%) patients at low risk of stroke, 1,606 (34.4%) at intermediate risk, and 1,523 (32.6%) patients at high risk. The median CHADS2 score they assigned was 2 and the median CHA2DS2-VASc score was 4, noted the study.

According to the study, the physicians used a formal stroke risk assessment tool for only half of the patients. Notably, 65% of the 864 patients rated at low risk of stroke were confirmed to be truly low risk by their CHADS2 scores. That showed physicians underestimated stroke risk in 35% of patients. Additionally, only 6.7% of patients rated at low stroke risk had CHA2DS2-VASc scores of 0, which suggested the physicians underestimated the risk of stroke in 94% of patients.

Although physicians assessed bleeding risk in 75% of patients, they used a formal tool to do so only about 25% of the time. Accordingly, the physicians’ predictions of bleeding risk agreed with HAS-BLED scores in only 22% to 64% of cases. A little more than one-third of patients had their bleeding risk overestimated or underestimated, which could have led to over- or under-coagulation, noted the study.

The physicians still prescribed antiplatelet therapy or warfarin to 96% of patients, reported the researchers. A little more than half of patients had a TTR of less than 70%. The researchers said those findings indicated room for improvement in managing anticoagulation therapy in AF patients.

“Anticoagulation in patients at risk for stroke is an important intervention to reduce the risk of this potentially devastating complication,” said lead investigator Dr. Shaun Goodman, of the Canadian Heart Research Centre and a cardiologist at St Michael’s Hospital in Toronto. He pointed out that the Canadian Cardiovascular Society (CCS) AF Guidelines recommend that all patients with AF should be stratified using a predictive index for the risks of stroke and bleeding, and that most patients should receive antithrombotic therapy.

“However, despite these recommendations, the uptake of these evidence-based therapies was suboptimal,” he commented. “Among those who did receive anticoagulation with warfarin, as many as 4 in 10 patients spent less time in the therapeutic range we know is optimal to reduce the risk of stroke.”

The study was published online in the Canadian Journal of Cardiology.

It did not receive direct support from the industry.

 

—Dan Cook

 

Reference:

1. Angaran P, Dorian P, Tan MK, et al. The risk stratification and stroke prevention therapy care gap in Canadian atrial fibrillation patients. Can J Cardiol. 2015 Oct 14. [Epub ahead of print]

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