The first CSANZ and National Heart Foundation of Australia guidelines for atrial fibrillation (AF) have introduced a ‘sexless’ version of the CHA2DS2-VASc score for predicting stroke risk.
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.
“It depends entirely on the clinical context, but if the patient presents and is haemodynamically or symptomatically compromised, then obviously you deal with the arrhythmia in the most appropriate fashion either with rate control or rhythm control. But then once they have been stabilised, very commonly you have a patient who will sit in AF, the rate will be controlled, their heart failure will be controlled and the decision you need to make is whether you are going to just control their rate or take a position of trying to revert them back to sinus rhythm.”
“And that is an important decision, primarily driven by quality of life and whether the patients are suffering symptomatically from being in AF. If you have done as much as you can to optimise them and they are symptomatic, then you would opt for a rhythm control strategy.”
The guidelines highlight the role of beta blockers and non-dihydropyridine calcium antagonists for rate control, flecainide for rhythm control provided the heart is structurally normal, and other drugs like sotalol and amioderone in specific contexts.
“And we also provide a contemporary context for when to start thinking about ablation, which can either be surgical or percutaneous.”
Professor Brieger says the application of integrated, patient-centred and multidisciplinary care has quite a priority in the guidelines.
“We advocate the use of e-health tools and resources wherever they are available; that there needs to be a feedback loop so patients are followed up and reassessed regularly, and we focus on strategies to ensure compliance with medications.”
He also emphasises it is critical that patients are monitored as they get older and accumulate risk factors.
“As the patient gets older they may fall into a category where anticoagulants would be considered whereas they might not have originally. That needs to be kept in mind. They might develop vascular disease and that then increases their risk of stroke also.”
“Certainly there are comorbidities that are challenging in managing these patients and one of them is renal impairment. The new anticoagulants have to be used cautiously in patients with renal impairment. There are dose modifications if they have mild-moderate renal impairment and if their renal function deteriorates further the drugs need to be stopped and warfarin substituted.”
In his concluding remarks, Professor Brieger notes that the AF guidelines have also included some suggestions regarding future research questions.
“I think it’s fair to say there are some recommendations that are probably still controversial primarily because there isn’t enough data to adequately inform them.”
“One of the big areas emerging is that as we put more long-term devices in more patients and we have better capacity to monitor patients with devices for other reasons, we are detecting AF with increasing frequency.”
“One of the decisions we need to face is: what is the threshold for anticoagulants in patients with incidental device-detected AF?”
“Another area that is always controversial and continues to be is looking at patients who develop AF in the context of some other illness and recover from the AF. Is their risk the same as patients who present de novo with AF? Our current recommendations suggest they should be treated in the same way, even though the data we have suggests their risk is probably slightly lower.”
“There are some sub-groups of patients where we are making these blanket recommendations but we would really like to be more informed as to whether these treatments are necessary or not in the long term.”