Millions of heart failure patients may be better off swapping their beta-blocker tablets for a pacemaker, according to heart specialists at Johns Hopkins University medical school.

They say patients with non-systolic heart failure may benefit more from pacemakers to speed up their heart rather than from continual, long-term use of beta blockers, drugs that slow it down.

Non-systolic heart failure is characterised by fairly normal function of the heart’s pumping action, when a person is at rest. This action falters, however, once daily physical activity begins, and the heart becomes increasingly unable to pump enough blood to energy-starved muscles.

Until now researchers had thought the problem was that these hearts were simply not able to relax properly, - a failure of their diastolic function.

The results of the latest study, which appear in the journal Circulation and are to be presented at the American Heart Association’s annual Scientific Sessions on November 15 in Dallas, Texas, suggest this is not the case, however.

Instead it appears that in patients with non-systolic heart failure, it is the failure of the heart to beat fast enough that causes symptoms. The researchers drew their conclusions after testing patients on an exercise test on a bike and comparing their performance with that of healthy patients.

Dr Barry Borlaug, the lead investigator and a cardiologist said: “This could dramatically change the way we initially treat patients with this kind of heart failure, because a cornerstone of current therapy is the use of beta blockers that slow down the heartbeat and decrease the strength of contraction.”

People with the more common, systolic form of the disease have a pumping function that is evenly depressed and weakened at all times. Beta blockers have been shown to effectively reduce the stress placed on the failing heart during physical activity.

However, in the US alone almost a quarter of a million people each year are diagnosed with non-systolic heart failure, and the numbers are rising due to an aging population and increasing life spans.

Global retail sales of beta-blockers for heart failure were $65 million in 2001 but this figure has risen sharply and Lehman Brothers have predicted that sales will peak in the billions of dollars in the US alone.

In a planned follow-up study next year, the Johns Hopkins scientists will directly compare the benefits of beta blockers with those of a pacemaker in 80 patients with non-systolic heart failure.

If the new study validates the current results, they predict that new practice guidelines on how beta blockers and pacemakers are used in this form of heart failure will follow – leading to a down-turn in the drugs' use.