Third of heart attack patients are misdiagnosed, research claims

Heart attack illustration

Almost a third of people in England and Wales are being given the wrong initial diagnosis after a heart attack, research suggests. We look behind the headlines.

Women were more likely to be affected, and are 50 per cent more likely than men to have an initial diagnosis different from their final diagnosis, The University of Leeds study found.

It looked at NHS data over nine years, which involved 243 NHS hospitals, and about 600,000 heart attack cases. Around one third, 198,534 patients, were initially misdiagnosed.

The two main types of heart attack are STEMI and NSTEMI. STEMI occurs when there’s a total blockage of one of the coronary arteries that supplies oxygenated blood to the heart muscle. NSTEMI, which is more common, is a partial blockage of one or more arteries. Both result in serious damage to the heart muscle.

This research found that women who had a final diagnosis of STEMI had a 59 per cent greater chance of a misdiagnosis compared with men. Women who had a final diagnosis of NSTEMI had a 41 per cent greater chance of a misdiagnosis when compared with men.

After a heart attack women are 50% more likely to be misdiagnosed initially

It estimated that, if heart attack patients were correctly diagnosed initially then – over the decade of study – over 250 deaths per year might have been prevented.

But the research is likely to underestimate the number of preventable deaths. The researchers excluded patients who died in hospital because they were unsure what treatments they had received, and the NHS data they used does not record data for all patients who have had a heart attack. Therefore, the numbers of preventable deaths is underestimated, suggesting even greater potential for improvement.

The research

The study looked at the initial diagnosis, when the patient arrived at hospital, and the final diagnosis, given when they were discharged.

Survival was reduced by up to one-fifth among heart attack patients who had a different initial diagnosis when they first came to hospital. Other factors that affected the survival rate could include delays to getting treatment, the availability of specialist hospital facilities, and staffing.

The researchers recommend that clinical staff perform a highly sensitive troponin test to reduce this misdiagnosis. Cardiac troponins are proteins which are released into the blood when heart muscle has been damaged, for example, during a heart attack.

The researchers recommend that clinical staff perform a highly sensitive troponin test to reduce this misdiagnosis

The test is associated with higher and earlier rates of diagnosis of NSTEMI, more frequent use of guideline-indicated care and better clinical outcomes, the researchers said.

A strength of the research is the fact that the study took into account a lot of variables that could have influenced the outcome of the research, to make sure they weren’t behind the findings, which makes the findings more valid. These variables included patients medical history, smoking status, blood pressure, and the medications that were prescribed at discharge.

The average age of a STEMI patient was 64.5 and a non-STEMI patient was 72.5. Nearly two-thirds (64.1%) were prior or current smokers, 48.8% had hypertension, and 33.3% hyperlipidaemia (abnormally high levels of lipids and/or lipoproteins in the blood). The average hospital stay was five days.

A limitation of the study is that, since the research looked at previously collected data, they relied on the accurate recording of the diagnoses. Moreover, there was no data on the specific clinical diagnosis under the category ‘other initial diagnoses’.

The BHF view

Dr Mike Knapton, Associate Medical Director at the British Heart Foundation, said: “Thanks to this study we now have a better understanding of the experiences of both men and women when they are diagnosed as having suffered a heart attack. 

More research is urgently needed into tests that will enable earlier, more accurate diagnosis of a heart attack, particularly in women

“It’s important to get the diagnosis right straight away, if the correct diagnosis is delayed this will in turn delay the treatment. Time is critical; for the best outcome patients need the correct treatment as quickly as possible.”

“However, this new study also highlights the current scale of the issue and confirms more research is urgently needed into tests that will enable earlier and more accurate diagnosis of a heart attack, particularly in women.”

The media coverage

The story was picked up widely, and was covered by the Daily Mail, Guardian, Telegraph and BBC news, amongst others.

Most news sites chose to focus on the difference in accurate diagnosis between men and women, however the Daily Mail headline was ‘Doctors are failing to spot thousands of heart attacks suffered by women every year, a major study warns today'.

This could be misleading as the research paper does not mention doctors in the text, and does not blame them. Instead it recognises the misdiagnosis and survival rates, and links other factors that affected the survival rate could be delays to getting treatment, the availability of specialist hospital facilities, and staffing.

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