Image copyright fstop123/Getty

Breast implants make it trickier to run tests that can help spot a possible heart attack, a cardiologist has said.

Dr Sok-Sithikun Bun, from Monaco, did a small trial, with 48 women, and found electrocardiogram (ECG) tests, which measure the electrical activity of the heart, were often unreliable because the breast implants "got in the way".

Dr Bun is presenting his findings at a conference in Austria.

Having a pre-implant ECG for doctors to refer to would help, he said.

"We do not want to frighten patients, but it may be wise to have an ECG before a breast implant operation," Dr Bun said.

"The ECG can be kept on file and used for comparison if the patient ever needs another ECG."

Image copyright Mutlu Kurtbas/Getty Image caption Other tests are needed alongside ECGs to confirm or rule out a possible heart attack

Doctors use ECGs to help them diagnose the cause of chest pain.

Small sticky patches, called electrodes, are put on the patient's arms, legs and chest and connected by wires to the ECG machine, which picks up and records the electrical signals, which can then be printed on to paper.

Faulty readings

Image copyright KLAUS GULDBRANDSEN/SCIENCE PHOTO LIBRARY Image caption The type of implants most commonly used in the UK are silicone gel

The women in the ECG trial were in their early 30s to late 40s and healthy, with no known heart problems - 28 of them had implants, 20 did not.

Two independent heart experts, who had never met the participants and did not know whether or not they had had implants, interpreted the women's ECG results.

More than a third of the scans from the implant group were interpreted as "abnormal" by these experts.

But the women were given a clear bill of health with other heart checks.

"We think the abnormal ECG recordings were false readings due to the implants," said Dr Bun.

"We have two hypotheses. It might be the composition of the implant that acts like a barrier for the electrical signals coming from the heart.

"Or, it may be a slightly different position of the ECG [chest] electrodes due to the breast implants."

The danger was that ECG readings would be confusing for doctors and get in the way of them reaching a speedy diagnosis, said Dr Bun.

"Doctors could mistakenly conclude that a patient with breast implants has a manifestation of coronary artery disease if they believe in the false ECG findings," he said.

It is not clear if the size of the implant matters.

Dr Mike Knapton, from the British Heart Foundation, said the findings would apply to the significant number of women who have had breast implants, either following treatment for breast cancer or as a cosmetic procedure.

"These findings will help those reading an ECG to avoid the risk of a false diagnosis and any unnecessary follow-up tests or treatment."