Results from the ONTARGET study, the world’s largest cardiovascular study in high risk patients, has shown that combination treatment with commonly used blood-pressure lowering drugs, ARBs and ACE-inhibitors, does not provide extra protective benefit for patients at high risk heart disease, stroke, and heart failure. In fact, the treatment increases the risks of dizziness, blackouts and kidney problems.

The findings were announced today by Australian researchers from The George Institute for International Health and the Baker Heart Research Institute at the American Congress of Cardiology in Chicago, coinciding with publication in the New England Journal of Medicine.

The landmark study compared the effectiveness of two types of anti-hypertensive drug treatments: the ACE-inhibitor (angiotensin-coverting enzyme inhibitor) ramipril, and the ARB (angiotensin receptor blocker), telmisartan. The study had two aims, to determine whether telmisartan was equivalent to ramipril, and that the combined treatment was superior to ramipril alone, in the prevention of cardiovascular death, myocardial infarction, stroke, or hospitalisation for heart failure in people at high-risk of cardiovascular disease on the basis of being aged over 55 years and having a history of heart attack, angina, stroke, peripheral vascular disease, or diabetes with complications.

Global co-chair of the study, Professor Craig Anderson from The George Institute said today, "Separately, ACE inhibitors and ARBs have shown benefits and to effectively lower blood pressure. The combination of ARBs and ACE inhibitors was therefore thought to provide extra benefit over using the therapies individually. However, this study has shown that this is not the case, with no extra benefits of combining ACE-inhibitors with ARBs in people with cardiovascular disease. This has been further underlined by apparent side-effects such as increased dizziness and blackouts from lower blood pressure, and an increase in kidney problems, including the need for dialysis."

A total of 25 620 patients with an average age of 66 were recruited from 41 countries across the world to take part in the randomised controlled trial and followed up for over four years, providing an exceptional amount of data. According to Professor Garry Jennings from the Baker Heart Research Institute and Australian National Leader of the study, "The study has established the benefits of an ARB as a suitable alternative to an ACE inhibitor for the prevention of cardiovascular events, but there is no additional advantage from combining ARBs and ACE-inhibitors. Such combination treatment cannot be recommended as part of routine care in the management of high risk patients with cardiovascular disease or diabetes."

Cardiovascular disease is a major global healthcare problem accounting for 40-50 per cent of all deaths in industrialised countries and about 25 per cent in other countries. Cardiovascular disease, which includes heart attack, stroke, congestive heart failure and sudden death, causes major health problems and much distress for many people, families and health care systems around the world. Research has shown that that several different types of drugs used for the treatment of high blood pressure can prevent cardiovascular disease, but there is uncertainty over the ability of one type of drug to be more effective than another or, if a combination of two different types of drugs, is more effective at reducing risk of cardiovascular events.

The risk of coronary heart disease is significantly reduced by commonly used drugs that lower blood pressure, including ACE-inhibitors and ARBs. Both have shown to improve health by preventing cardiovascular complications in high-risk patients, while ACE-inhibitors may cause an irritable cough in about 10 per cent of patients. According to authors, ARBs are now readily available and allow effective lowering of blood pressure without the side effects associated with ACE-inhibitors.

The results of ONTARGET, incorporated into guidelines, will provide important recommendations about the options for treatment in patients with cardiovascular disease. The benefits of ARBs are being evaluated in additional placebo-controlled trials that are expected to be known later in 2008.