Doctors in this week's BMJ argue that new NICE guidelines on the use of digoxin, a drug used to slow heart rate in patients with irregular heart rhythm (atrial fibrillation), are inconsistent with the evidence.
Atrial fibrillation occurs when the electrical signals which keep the heart pumping, become disturbed. It is the most common heart rhythm problem especially in elderly people.
In June 2006, the UK National Institute for Health and Clinical Excellence (NICE) published new guidelines for control of heart rate in people with chronic atrial fibrillation. The guidelines depart from historical practice by recommending that instead of digoxin, two other types of drug (beta-blockers or calcium antagonists) should be the preferred initial treatment.
US guidelines also recommend the use of beta-blockers or calcium antagonists alone to control heart rate.
But two doctors at the Royal Hallamshire Hospital in Sheffield warn that it is safest to start treatment with digoxin first.
They reviewed 57 studies, including 25 randomised controlled trials, assessing digoxin, beta-blockers, calcium antagonists, and combinations for heart rate control in chronic atrial fibrillation.
They found little evidence that single treatment (monotherapy) with beta-blockers or calcium antagonists improves exercise tolerance compared with digoxin. On the contrary, there is clear evidence that when beta-blockers are used alone, exercise capacity may worsen, especially in people with a history of heart failure.
Similarly, little evidence exists that monotherapy with these drugs improves heart rate control at rest and during exercise compared with digoxin alone. Benefits on heart rate variability, together with improved exercise tolerance, have only been shown with the combination of digoxin and a beta-blocker or calcium antagonist, they say.
"We believe that the combination of digoxin and a beta-blocker or calcium antagonist should be recommended as first line management and we would emphasise that it is safest to start treatment with digoxin first," they conclude.