Getting the right treatment can prevent heart attacks – here's how

Every year, more than 40,000 Australians die from heart disease. That’s almost a third of all deaths in Australia. Many more have a heart attack or stroke.

A study published today in the Medical Journal of Australia shows that we could be doing much more to prevent this from happening.

Patients who have already had a heart attack

Around 1.1 million Australian adults have had a heart attack, stroke or other kind of cardiovascular disease. Given their high risk of another event, almost all such patients should be taking both a blood pressure- and a cholesterol-lowering drug (a statin). Even if their blood pressure and cholesterol levels are normal, this has been shown to reduce their risk.

However, among such patients aged 45-74, only 45% were taking both drugs and in those over 75, only 49% were. Together, 558,000 people with known heart disease are estimated to not be taking both risk-lowering drugs.

The reasons may lie at different steps along the treatment pathway: doctors in hospital not commencing treatments before discharge, general practitioners not following up after discharge, or patients ceasing their medications. Even among patients with a problem with their heart such as a past heart attack or angina, only about 70% of patients continue taking blood pressure-lowering drugs and 65% continue taking statins.

People at high risk of heart disease

For people who have not had a heart attack, preventive treatment is more controversial. However, there is widespread agreement among health professionals that people who are at sufficiently high risk of heart disease should take both drugs.

Today’s MJA study shows many are not. In Australia, high risk is accepted as a 15% (or greater) risk of heart disease in the next five years. It is calculated from combining risk factors: age and gender, whether they smoke, whether they have diabetes, their blood pressure, and cholesterol levels.

Among those aged 45-74 in the high risk group, only 25% were taking both drugs and in those over 75, only 35% were. The total number of people at high risk of heart attack or stroke not taking the recommended treatments was 621,000.

This is surprising given everyone over the age of 45 (or 35 if you are Aboriginal or Torres Strait Islander) should have their blood pressure and cholesterol measured and a quantitative heart disease assessment recorded. But less than half have had this assessment completed.

If you know your blood pressure and cholesterol readings, you can check your own cardiovascular risk score here, and look at the effects different treatments will have on your own risk here.

When a risk calculator is not used, people who have a combination of risk factors that put them at high risk can easily be missed. Doctors (and patients) are more used to thinking about blood pressure or cholesterol levels individually. Doctors also find it difficult to explain the results from the risk calculator and the treatment options to patients.

In 2006, the Pharmaceutical Benefits Schedule criteria for statins were changed to make it easier to prescribe to patients at high risk, but the criteria are complicated and do not make it clear that all patients at high risk should be treated with a statin.

What about people at moderate risk?

The dividing line between high and low risk is not clear. The heart disease risk threshold for medication depends on where you live. It has been lowered to around 10% in the United Kingdom and about 7.5% in the United States, but without adequate input from patients about what they want.

Treatment of people at low risk may reduce the risk of heart disease, but the overall balance of harms and benefits can change.

A recent study used statins in people with a five-year risk of about 5%. Treating 1,000 people with daily medication prevented approximately three people dying of cardiovascular disease, four heart attacks and five strokes: a total of about 11 events. About nine people had increased muscle aches and pains. Is this a fair trade off? Some people will say yes and some will say no.

Cost is also an issue. Many statins are now off patent, but even at A$10 a month, the cost to prevent the 11 events is about A$700,000. Using a 5% threshold of risk would mean almost everyone over the age of 60 would be recommended to take both a statin and a blood pressure lowering drug.

In between the high-risk patients, where almost everyone agrees treatment is worthwhile, and very low risk patients, where treatment is not cost-effective and may even be harmful, some people may be willing to take the drugs and others will not.

For people at moderate risk, doctors need to find better ways to explain these risks and help patients come to their own decisions. This may include the use of decision-aid tools.

For those who already have had a heart attack, we need to find better ways to make sure they get appropriate preventive treatments to stop another one. This may include better reminder medication plans when patients are discharged from hospital, more tailored drug management from GPs and pharmacists, and SMS or phone-based reminders.

Jenny Doust is funded by an NHMRC Grant and has an NHMRC grant which includes research on the management of cardiovascular disease in general practice.

Paul Glasziou was a member of the LIPID trial management committee – a large RCT of pravastatin after myocardial infarction. He received no personal funding. He has an NHMRC grants which include examination of the use of estimating absolute cardiovascular risk.

Jenny Doust, Professor of Clinical Epidemiology, Bond University

Paul Glasziou, Professor of Medicine, Bond University

This article was originally published on The Conversation. Read the original article.