A heart condition that affects one in 10 elderly people is costing society hundreds of millions of pounds each year, say experts.
Disturbances in heart rhythm can be dangerous
Atrial fibrillation is the most common form of heart rhythm disturbance - well over half a million UK people have it.
A study in the journal Heart says the cost of the problem to the NHS in 2000 was £459 million, with another £111 million spent in nursing homes.
The ageing population of the UK means that the cost is increasing, it says.
Atrial fibrillation happens when the pattern of electrical activity that normally drives the contraction of the heart muscle in a set rhythm in order to pump blood around the body goes wrong.
Patients experience a variety of symptoms, including a "flopping" sensation in the chest, often accompanied by shortness of breath, dizziness or fatigue.
Despite the common nature of the complaint, equally common conditions such as diabetes or heart failure are often treated more aggressively.
But atrial fibrillation raises the risk of death by between 40% and 90%, particularly increasing the chance of a stroke.
The latest figures compiled by University of Glasgow researchers suggests it consumes up to 1% of the total budget of the NHS.
A comparable figure for NHS spending on heart failure might be one billion pounds a year, and for angina £668 million.
The cost of hospital admissions, prescribed drugs and home care for elderly atrial fibrillation is rising fast - it has doubled since 1995.
Many patients with the condition need long-term blood-thinning therapy with warfarin, and regular blood tests to make sure they are on the right dose.
However, much of the cost to the NHS - and the physical damage to the patient - happens if atrial fibrillation leads on to a full stroke.
The researchers wrote: "We have shown that this insidious and deadly arrhythmia imposes a substantial economic as well as a health burden on the NHS in the UK.
"It is clear that atrial fibrillation costs are escalating rapidly and is worthy of the attention directed to heart failure when it became clear the latter was becoming a major public health problem."
Ellen Murray, from the University of Birmingham, is involved in large scale trials of screening for atrial fibrillation patients.
The idea is that by screening early, strokes can be prevented by timely treatment with warfarin or aspirin.
Her group is trying to work out the best way, and age, at which to start screening.
She said: "The national service framework from the goverment clearly says that GPs should be working to prevent strokes by treating atrial fibrillation.
"Screening is a good way of preventing strokes, and we are investigating the method we should use."