Blood test for heart attacks ‘inaccurate’

THOUSANDS of patients may be being wrongly diagnosed with heart attacks in NHS hospitals because of a flawed test.

A blood test for troponin – a protein released into the blood during a heart attack – is widely used in A&E departments to check whether someone has suffered an attack.

But a study of 20,000 patients suggests around one in 20 have abnormally high troponin levels even though there is nothing wrong with their hearts.

Cardiologists now fear many patients are being misdiagnosed and unnecessarily undergoing invasive surgery as a result.

NHS guidelines recommend some heart attack patients undergo a procedure to widen an artery almost immediately so as to improve their chances of survival.

Around 190,000 have a heart attack in the UK each year. Current guidelines recommend troponin tests to help identify or exclude a heart attack.

The study, published in the British Medical Journal, found slightly more than 5 per cent of the patients had a troponin level greater than 40 ng/L – considered to be an indicator of heart attack. However, most were being treated for other issues, and had no obvious signs of a heart attack.

Professor Nick Curzen, who led the study at University Hospital Southampton, said doctors needed to interpret troponin levels carefully to avoid misdiagnosis and inappropriate treatment. And Professor Sir Nilesh Samani, of the British Heart Foundation, said: ‘As this study emphasises, a positive test should not always be interpreted as being due to heart attack.’