New Blood Test Reveals Risk of Atrial Fibrillation and Stroke

New research suggests that a simple blood test could identify people with a genetic predisposition towards atrial fibrillation (AF) and justify prophylactic treatment to cost-effectively prevent strokes.

A study team from Lund University in Sweden worked with several other research groups around the world to find a dozen genetic variants that put people at risk for AF. Then, the Swedish team used data from a community health cohort to measure the potential benefits of testing everyone for those variants.

Team members, who published their findings in the journal Stroke, used Cox models to adjust for established AF risk factors before assessing how well their AF genetic risk score (AF-GRS) predicted both incident AF and ischemic stroke among 27,471 participants in the Malmö Diet and Cancer Study.

During a follow-up period that averaged more than 14 years, 2,160 people experienced AF for the first time and 1,495 suffered their first ischemic stroke. Participants in the top AF-GRS quintile were at increased risk for incident AF (hazard ratio [HR], 2.00; 95% confidence interval [CI], 1.73—2.31; P=2.7×10–21) and ischemic stroke (HR, 1.23; 95% CI, 1.04–1.46; P=0.02) when compared with the bottom quintile.

Using AF-GRS along with established AF risk factors improved both discrimination and reclassification (P<0.0001 for both).

“An AF-GRS can identify (the) 20% of individuals who are at ≈2-fold increased risk for incident AF and at 23% increased risk for ischemic stroke,” the study authors wrote. “Targeting diagnostic or therapeutic interventions to this subset may prove clinically useful.”

Team members also measured the AF-GRS for patients who were already diagnosed with AF when the cohort was formed, and they found that patients with high scores were 70% to 80% more likely to suffer a stroke during the follow-up period than patients who had AF but none of the genetic variants in question.

Olle Melander, a Professor of Internal Medicine at Lund University who was one of the paper’s co-authors, says the connection between high AF-GRS and eventual stroke could help doctors determine which of their AF patients should receive lifelong treatment with anticoagulants such as warfarin and which would derive little benefit from such drugs.

Moreover, Melander said in a news release that, “In patients who are suspected of having temporary but recurrent episodes of atrial fibrillation, or in people with high blood pressure, it can be important for doctors to look at their genetic predisposition using a blood test…We also consider that more widespread treatment of high blood pressure may be justified in those with a high genetic risk of atrial fibrillation.”

In all, the study authors believe their work suggests that nearly everyone should undergo a simple blood test that would identify the genes in question.

“One in five people have a genetic weakness that means they have twice as high a risk of developing atrial fibrillation as those with a low genetic risk,” Melander said. “This genetic risk is therefore one of the strongest risk factors for atrial fibrillation that we know of in people without overt cardiac disease. It increases the risk as much as high blood pressure, for example.”