MUNICH - Globally, more than 10% of patients with atrial fibrillation who present to the emergency department are dead within a year, an analysis of the RE-LY AF registry showed.
"And despite modern medical therapy, more than 4% of global Afib patients experience a stroke within 1 year," said Jeffrey Healey, MD, of McMaster University in Hamilton, Ontario, here at the European Society of Cardiology (ESC) meeting.
The mortality rate seems to be highly variable between different countries or regions, Healey noted.
For example, the crude mortality rate was highest in Africa (20%), South America (18%), and China (14%), but when adjusted for confounders, the African rate was equal to the North American rate (12%).
The adjusted factors were age, sex, heart failure, coronary artery disease, hypertension, diabetes, rheumatic heart disease, and reason for ED presentation, Healey reported
The regions in the registry are North America, South America, Western Europe, Eastern Europe, Middle East, Africa, India, China, and Southeast Asia. It includes 47 countries, 164 sites, and more than 15,000 patients. This was a 1-year analysis.
The median age for atrial fibrillation (Afib) patients presenting to the ED was around 70 except in the Middle East, Africa, and India where it dipped to around 60.
Of note, patients with a primary diagnosis of Afib at admittance were more likely to live compared with those who were admitted to the ED for other reasons.
In all regions, admittance with Afib as a primary diagnosis was in the minority, as most people were admitted for other reasons.
The disparity in mortality between primary and secondary Afib diagnosis was at least doubled in all regions including Africa (12% versus 22%), North America (4% versus 16%), South America (10% versus 26%), and the Middle East (4% versus 19%).
By far, the highest cause of death in those with Afib as a secondary diagnosis was heart failure (34%), followed by infection (12%), and stroke (9.5%). Respiratory failure, cancer, sudden death, and myocardial infarction (all below 9%, in descending order) rounded out the other causes of death, Healey pointed out.
Regionally, Eastern Europe, Africa, India, and China had the highest rates of heart failure mortality at about 41% when Afib was the secondary diagnosis. They also had the highest rate of death as a result of stroke, at approximately 55%.
All other regions fell below the 30% mark for heart failure death, with North America and Southeast Asia rounding out the bottom at a rate of about 8.5%.
Regarding stroke death, all other regions except the Middle East fell below the 30% mark, again with North America and Southeast Asia hovering at the lowest rate of around 22%.
Africa (8%), China (7%), and Southeast Asia (6.5%) had the highest crude stroke rates. When researchers adjusted for age, prior stroke/TIA, heart failure, hypertension, diabetes, and use of vitamin K antagonists, rates in China and Southeast Asia dropped close to the crude global average of 4%, while Africa dropped even further to about 3.7%, Healey reported.
He noted the use of warfarin and the importance of quality monitoring as a way to reduce the risk of stroke.
Interestingly, in India, about one-third of the patients in the registry have documented rheumatic heart disease (RHD), with probably more that are undocumented, Healey said.
This subgroup has a higher risk of stroke than those without RHD (adjusted 4.3% versus 2.5%).
Those with RHD tended to be younger (49 versus 66), women, have a low rate of coronary artery disease, and be on warfarin compared with those who don't have RHD.
When the CHADS2 score was 3 or less, the crude and adjusted stroke rates among those with and without RHD were similar, but when the CHADS2 was greater than 3, those with RHD had almost twice the risk of stroke as those without RHD.
"Globally, the CHADS2 score has a greater influence on stroke risk than the presence of rheumatic heart disease," Healey said.
He concluded that "most of the differences in stroke rate can be explained on the basis of regional differences in patient characteristics and the use of vitamin K antagonists."
In addition, "the RE-LY AF registry shows very large unmet medical needs and large opportunities for improvement by applying currently available modalities for diagnosis, risk stratification, and treatment of patients presenting with atrial fibrillation," he said.
Primary source: European Society of Cardiology
Source reference: Healey JS, et al "Global variations in the 1-year rates of death and stroke in patients presenting to the emergency department with atrial fibrillation: results from the RE-LY Registry" ESC 2012; Abstract.