The research showed that the AI approach could take account of different underlying health conditions for each patient, as well as the interactions of these conditions to isolate response to beta-blocker therapy. This worked in patients with normal heart rhythm, where doctors would normally expect beta-blockers to reduce the risk of death, as well as in patients with AF where previous work has found a lack of effectiveness. In normal heart rhythm, a cluster of patients was identified with reduced benefit from beta-blockers (combination of older age, less severe symptoms and lower heart rate than average). Conversely in patients with AF, the research found a cluster of patients who had a substantial reduction in death with beta-blockers (from 15% to 9% in younger patients with lower rates of prior heart attack but similar heart function to the average AF patient).