A Mendelian-randomization study provides strong evidence that high blood pressure contributes to atrial fibrillation (AF), which means AF could be preventable, the researchers say. "To that end, clinicians should encourage and prioritize blood pressure control in patients at high risk for incident atrial fibrillation as an effective strategy to reduce this common arrhythmia and its complications, which include stroke, heart failure, dementia, and depression," Dr. Georgios Georgiopoulos of King's College London, in the U.K., and the National and Kapodistrian University of Athens, in Greece, told Reuters Health by email. While several observational studies have shown a strong relationship between BP and the risk of AF, their design could be susceptible to systematic biases that cannot support a causal link, Dr. Georgiopoulos said. The new study used genetic data and Mendelian-randomization analysis, "which minimizes the likelihood of reverse causality (i.e., that atrial fibrillation causes high blood pressure) or that other traits linked with atrial fibrillation (confounders) are responsible since alleles are randomly assorted at conception, ensuring a balanced distribution of unmeasured confounders," he explained. The researchers retrieved genetic variants associated with BP traits contained in the International Consortium of Blood Pressure-Genome Wide Association Studies (GWAS). From 901 reported variants, 894 were assessed in a dedicated GWAS of AF genetics, including more than one million people of European ancestry, of whom 60,620 had AF and 970,216 did not. In their Mendelian randomization analysis, the team found that elevated BP was significantly associated with an increased risk of AF. Specifically, increases of 1 mm Hg in systolic blood pressure, diastolic blood pressure and pulse pressure were associated with 1.8%, 2.6% and 1.4% relative increases in the risk of AF, respectively, the researchers report in the European Journal of Preventive Cardiology. "The results provide strong evidence of a causal relationship between blood pressure and atrial fibrillation. In addition, our study showed that the relationship was not driven by other conditions including coronary-artery disease and obesity," Dr. Georgiopoulos told Reuters Health. He said "further research is warranted to understand the details of the relationship between blood pressure and atrial fibrillation as well as to evaluate the possible beneficial effect of various classes of antihypertensive treatment on the future risk of this arrhythmia." Dr. Alon Gitig, director of cardiology at Mount Sinai Doctors-Westchester in New York, said the results "confirm previous observational studies and suggest that the link between blood pressure and atrial fibrillation is not simply that they both cluster with other risk factors for poor cardiovascular health, but rather that chronic exposure of the heart to elevated blood pressure leads to mechanical and electrical changes that, over time, promote arrhythmia generation." Therefore, he told Reuters Health by email, "if we can aim for perfection in blood pressure targets, through combined use of lifestyle interventions and judicious choice of medications, we can likely reduce the burden of atrial fibrillation, which causes frequent health care system utilization and chronic symptoms that impact quality of life for many patients." Dr. Gitig was not involved in the study. The study had no commercial funding and the authors have no relevant disclosures. —Megan Brooks Source
