One in ten patients presenting to an emergency department with atrial fibrillation in developed countries will die within a year, most often from heart failure, a new study has found.

The situation is worse for those with less access to sophisticated medical care. The one-year mortality rates are 17% in South American and 20% in Africa.

Heart failure accounted for 30% of deaths, followed by other cardiovascular causes (about 25%). Stroke was the cause of 8% of deaths.

Stroke, whether fatal or non-fatal, occurred in the following year in 4% of patients. It was more common in patients for whom was a secondary diagnosis in the ED compared to those who were presenting primarily because of AF symptoms.

The findings were based on the RE-LY Atrial Fibrillation Registry, sponsored by Boehringer Ingelheim, which enrolled 15,400 patients between 2007 and 2011 in 47 countries.

Outcomes in North America, western Europe and Australia were used as the reference standard, for comparison with seven other regions ranging from South America to sub-Saharan Africa, China, India and Southeast Asia.

“Atrial fibrillation is a leading cause of morbidity and mortality worldwide,” the researchers wrote in The Lancet.

“However, most understanding of AF is based on findings from clinical trials and observational studies done in North America and western Europe, which exclude patients with secondary atrial fibrillation.

“Both of these factors might lead to an underestimation of the morbidity and mortality associated with AF.”

About 13% of patients required hospital admission for heart failure in the year following their emergency department presentation with AF, further highlighting the importance of heart failure in the pathway of disease.

Inadequate blood pressure control and insufficient use of anticoagulation emerged as common problems.

“Because hypertension is present in more than two-thirds of patients with AF worldwide, it is disappointing that the rate of control of hypertension is less than 20% globally and even lower in low-income and middle-income countries,” the research team wrote.

“Blood pressure control is particularly important, since antihypertensive treatment prevents both stroke and heart failure.

“There are opportunities to improve outcomes in most countries by fuller use of proven therapies, such as oral anticoagulation, and pharmacotherapies for hypertension and heart failure.”