By Rebecca Jenkins
In moderately obese or underweight patients with atrial fibrillation (AF), the different non-vitamin K antagonist oral anticoagulants (NOACs) appear to be similarly safe and effective, European experts say.
The advice is one of several recommendations in an updated European Heart Rhythm Association practical guide to NOACs for stroke prevention in AF, which supplements existing clinical guidelines.
It has become more complicated for clinicians to identify the correct dose of NOAC, the authors wrote in the European Heart Journal, with several agents available in different doses for varying indications (including DVT prevention). The tested standard dose should be used wherever possible, they said, but patient age, weight, renal function, co-medications and other comorbidities would influence the choice.
Trials for the factor Xa inhibitors edoxaban and apixaban used specific dose-reduction criteria including body weight ‘possibly making those drugs the preferred choice’ for patients weighing less than 60 kg, the authors wrote.
Apixaban is available in Australia, as well as another factor Xa inhibitor rivaroxaban and the direct thrombin inhibitor dabigatran.
The authors noted that there were limited data on NOACs in patients with a body weight above 120 kg or below 50 kg, in which case vitamin K antagonists should be considered.
Associate Professor John Amerena, Director of the Geelong Cardiology Research Unit, welcomed the instructive nature of the guidance, noting it covered elderly patients, those with renal dysfunction and patients needing surgery, as well as those with low or high body weight.
‘In low body weight patients, it’s really important to do the formal evaluation of the creatinine clearance with the Cockcroft-Gault Equation as the eGFR may overestimate true renal function,’ he said. ‘We would generally be recommending using the lower dose of the agent if they meet the dose-reduction criteria.’
Australian data showed a marked increase in prescriptions of NOACs between 2010 and 2016, Professor Amerena said.
‘As time goes on, from a cardiac perspective, I think the only reason warfarin will be used is in the patients not eligible for NOACs – so those with valvular heart disease (prosthetic mechanical valves and moderate-severe mitral stenosis) and renal failure as well as in uncommon haematological conditions,’ he told Cardiology Today.
Eur Heart J 2018; doi: 10.1093/eurheartj/ehy136.