By Laura Cowen
Patients with atrial fibrillation (AF) and declining renal function are at increased risk of subsequent stroke or systemic embolism, major bleeding and death, US researchers report.
In addition, data from the ARISTOTLE (Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation) trial showed that although outcomes were better with apixaban than with warfarin, the rate of renal decline was similar in both treatment groups.
Ziad Hijazi (Uppsala Clinical Research Center, Sweden) and colleagues examined the rate of renal decline, and its effect on outcome, in 16,869 AF patients (mean age 70 years, 65% men) who took part in the prospective, randomised ARISTOLE trial comparing apixaban and warfarin.
They found that 13.6% had a clinically relevant annual decrease in estimated glomerular filtration rate (eGFR) of more than 20%, which was significantly associated with older age, low haematocrit level and the presence of heart failure, vascular disease and diabetes.
Change in renal function over time was not associated with treatment group, however.
During a median 1.8 years of follow-up, patients with worsening renal function had significantly higher rates of stroke or systemic embolism, ischaemic or unspecified stroke, major bleeding and mortality, compared with patients with no worsening, regardless of the baseline renal function.
And after accounting for potential confounders, the risks of stroke or systemic embolism, ischaemic or unspecified stroke, major bleeding and mortality were a significant 1.53, 1.56, 1.41 and 2.31 times higher, respectively, in patients with worsening renal function compared with those whose renal function was stable.
Overall, patients receiving apixaban had lower rates of stroke or systemic embolism and major bleeding compared with those receiving warfarin. While the difference was not statistically significant, it was consistent across all levels of renal function.
The researchers say it is "reassuring" that, in the vast majority of patients, renal function declined slowly over time. This implies that "in general, there is little need for close monitoring of renal function for dose adjustments of [non-vitamin K antagonist oral anticoagulants]", they write in JAMA Cardiology.
However, for the AF patients at risk of more rapid decline and those with initially poor renal function "more frequent monitoring of renal function when treated with oral anticoagulants" should be considered, they conclude.
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JAMA Cardiol 2016; Advance online publication