A ‘sexless’ version of the CHA2DS2-VASc score for predicting stroke risk is a key feature of the first Australian guidelines for atrial fibrillation (AF) introduced by the National Heart Foundation and CSANZ.
The guidelines, launched this week at the CSANZ 2018 conference in Brisbane, maintain the importance of stroke risk stratification in people with AF but with the “CHA2DS2-VA” score – minus the female sex category component (Sc).
According to lead author Professor David Brieger, the CHA2DS2-VASc has a strong evidence base, but guidelines have encouraged a cumbersome practice of selecting different CHA2DS2-VASc thresholds for males and females when recommending anticoagulation.
“We believe that it is valuable but one of the minor irritations with that score is that it includes female sex as a variable when deciding whether to anticoagulate or not,” he tells the limbic.
“So if you have more than one risk factor regardless of your sex, you should be anticoagulated. If you have one risk factor regardless of your sex, you may or may not be anticoagulated. If you have no risk factors regardless of sex, you don’t need to be anticoagulated.”
“In any event, it turns out that sex doesn’t add anything to this risk schema because we are focusing on the lower risk end of the cohort. It only adds predictive value when you are getting into the high-risk population who are all anticoagulated anyway.”
Professor Brieger, from Concord Repatriation General Hospital and the University of Sydney, says the Australian guidelines suggest prioritising novel oral anticoagulants over warfarin as per international guidelines.
“And we provide some updated data on managing patients who require both anticoagulants and antiplatelet therapy that is based on some RCTs that emerged subsequent to the international guidelines,” he adds.
Professor Brieger says the new guidelines are important because of the prevalence of AF, the significant morbidity and mortality associated with the condition, and the substantial variation in management.
“And in addition to that the landscape changes so rapidly that a lot of the latest developments were not included in some of these international guidelines.”
“These guidelines are shorter than the international ones and easier to navigate. The medications that we address are of course the ones that are available locally so there isn’t a lot of extraneous information that is not relevant to us.”
“Quite a lot of what emerges in guidelines is based on local expert opinion because there isn’t a lot of data and we are fortunate to have a lot of expertise in this country and a lot of people who work in this environment and can make recommendations that are germane.”
He also notes that the guidelines recommend that screening for AF should be opportunistic in patients over the age of 65.
“We are not advocating anything more aggressive than that.”
“In the prevention space, in addition to traditional risk factors for AF such as excessive alcohol intake and hypertension, we also pay attention to some of the newer risk factors like obstructive sleep apnoea, obesity and lack of exercise.”
Management of the arrhythmia
According to Professor Brieger another key aspect of the guidelines is the importance of first determining whether the initial management strategy is going to be one of rate control or rhythm control.