AF-B-STEP

Atrial fibrillation (AF) describes an irregular heart rhythm that arises when the heart’s regular pacemaker is replaced by fast and recurrent chaotic activity in the atria (the upper chambers of the heart). AF can cause severe symptoms including palpitations, fatigue, chest pain, shortness of breath, and difficulties exercising. What’s more, patients with AF face an increased risk of stroke and heart failure. AF affects a third of the over-55s, and it accounts for 2-3% of total health care costs in Europe and the US.

Today, AF is diagnosed in a binary fashion – you either have it or you don’t – and treatments are selected based on this binary distinction. However, we know that the burden of the disease varies immensely from one patient to another. In some patients, AF episodes are brief and rare; in others, they are frequent; and some people are in atrial fibrillation all the time. Recent data suggest that the risk of stroke and heart failure increases when more time is spent in atrial fibrillation, i.e. when the atrial fibrillation burden is higher. Meanwhile the increasing ability of implanted devices and consumer electronics to detect short and rare episodes of AF means the proportion of patients with low-burden AF is rising. We currently lack a way of quantifying a patient’s atrial fibrillation burden, and this makes it hard to determine which patients are at greatest risk of stroke, heart failure, or poor quality of life. Meanwhile data from implanted and wearable devices could help health care professionals and others to quantify atrial fibrillation burden, but these data are currently not reported in a standardised way, making comparisons across devices challenging.

The goal of AF-B-STEP is to define and quantify AF burden and its impact on health outcomes such as heart failure, stroke, patient-reported outcomes, and heart and brain function. The project also aims to set out standards for AF burden reporting by cardiac implanted electronics devices and consumer wearables. The hope is that this will trigger a step change in the diagnosis and care of people living with AF.

One of the first tasks of the AF-B-STEP team will be to combine and integrate existing data on AF burden and health outcomes, including cardiovascular events (stroke, heart failure), patient-reported outcomes, quality of life, and cardiac and cognitive functions. Fifteen partners from academia and industry are providing data sets to the project.

The project will use this, large, harmonised dataset to define the distribution of AF burden. By linking AF burden information to outcomes, the project will determine the influence of AF burden on outcomes including stroke, heart failure, cardiovascular death, patient-reported outcomes and quality of life, and heart and brain function. In parallel, the consortium will define standards for AF burden reporting for cardiac implanted electronic devices and for intermittent rhythm monitors such as ECG patches and consumer wearables, directly involving project partners who manufacture these devices.

The project aims to define three broad AF burden categories: low (not requiring further tests or treatment at this point in time); intermediate (further tests needed to refine diagnosis and decide on treatment) and high (an AF burden that justifies starting anticoagulation and rhythm control treatment). The AF burden categories will be validated by analysing the results of clinical trials of AF treatments. Finally, the work aims to develop and validate ECG, imaging, and blood markers that can identify patients with a low, intermediate, or high AF burden.

The project outputs will help physicians and patients alike to diagnose, monitor and treat AF. The project expects that its innovations will ultimately help to measurably reduce stroke and heart failure. Meanwhile people with a low AF burden will be spared from undergoing unnecessary treatments. The project will generate evidence that may lead to updated treatment guidelines that incorporate AF burden into treatment decisions.

Information on the links between AF burden and health outcomes plus standards for AF burden measurement could also simplify the assessment of new AF treatments. AF-B-STEP will engage with regulators to explore a possible role of AF burden in the regulatory assessment of new treatments.

Finally, by standardising the way medical and m-health devices report AF burden, the project will boost the competitiveness of Europe’s cardiac implanted devices and consumer m-health industries.