Tiny devices help detect 'silent' heart rhythm problems, aid stroke management

Remote video URL
Dr Seow Swee Chong, senior consultant at the National University Heart Centre's Department of Cardiology, demonstrating the insertion of a Insertable Cardiac Monitor on a piece of dummy skin.

SINGAPORE - At around 8.30am one November morning in 2016, Mr Ng Kok Seng's heart stopped beating for six seconds but the retiree, then 62, did not notice, and carried on with his daily activities.

He found out only after a tiny device implanted in his chest, known as an Insertable Cardiac Monitor (ICM) alerted a team at the National University Health System (NUHS), which called him and told him to go for an emergency consultation. The device was inserted after Mr Ng suffered a stroke the month before.

Mr Ng learnt he had atrial fibrillation, a common heart rhythm disorder which causes the organ to beat much faster than usual - over 300 beats per minute, up from the usual 60 to 80.

Dr Seow Swee Chong, senior consultant at the National University Heart Centre's Department of Cardiology, who treated Mr Ng, said on Monday (Oct 21) that his experience is common among patients with atrial fibrillation.

"Around 80 to 90 per cent of our patients who have atrial fibrillation don't have any symptoms," he said.

He noted that Mr Ng's heart had stopped for about six seconds, not long enough for him to notice. He said: "Typically you would need to have a pause (in heartbeat) of about 10 seconds or longer before you faint... You need to deprive the brain of oxygen for long enough before you lose consciousness."

Dr Pipin Kojodjojo, another senior consultant at the Department of Cardiology, estimated that around 50,000 Singaporeans have the condition, although the actual figures could be higher.

Dr Seow Swee Chong (left) with his patient Mr Ng Kok Seng. The Insertable Cardiac Monitor was implanted inside Mr Ng 3 years ago and it detected atrial fibrillation two weeks after the implantation. ST PHOTO: KELVIN CHNG

It is a chronic and progressive disease, which means that with time, it will recur more frequently until the heart is unable to beat regularly again. It affects around 15 to 20 per cent of those over the age of 80.

Those who have certain conditions including obesity, hypertension and obstructive sleep apnoea are also at higher risk of the disease, which is responsible for about one quarter of all strokes. Atrial fibrillation-related strokes are also typically more disabling, said Dr Pipin.

He added that Singapore has seen a significant increase in the proportion of stroke patients with atrial fibrillation - 20.6 per cent in 2016, up from 16 per cent in 2007.

Citing the growing number of patients requiring treatment for the condition here, he said: "It's really a major healthcare issue for us, and even more so in future."

Typically, atrial fibrillation is diagnosed using an electrocardiogram (ECG). However, Dr Pipin said there are problems with this method.

First, as a majority of patients with the disease do not have symptoms, they are unaware of their condition and do not get checked.

And secondly, the ECG will appear abnormal only if atrial fibrillation occurs during the test.

"Atrial fibrillation can come and go... if you just had a checkup yesterday, it doesn't mean you can't have (the condition) today," said Dr Pipin.

So in 2015, the Heart Rhythm and Stroke teams at the National University Hospital and National University Heart Centre conducted a study to find a better way to detect atrial fibrillation.

A total of 205 patients like Mr Ng, who had strokes with no known cause, were implanted with ICMs.

The device is roughly the length of a AAA battery, but flatter, and takes around three minutes to be inserted into a patient under local anaesthesia.

The device is injected to the left of the patient's breast bone just before they are discharged.

ICMs, which have a battery life of about three years, record and analyse patients' heart rhythms throughout the day.

In the event of a heart rhythm disturbance, a team at NUHS is alerted.

Once the condition is detected, appropriate treatment can be done to reduce the risk of stroke.

Atrial fibrillation was detected in about 12 per cent of the patients who had ICMs inserted, whose condition may have otherwise been missed.

The study also found that ICMs are more than seven times more effective than traditional methods in detecting atrial fibrillation with no symptoms.

Dr Seow said that accurate diagnosis is important, as without a diagnosis of atrial fibrillation, stroke patients are typically discharged on weaker blood thinners such as aspirin.

However, such medication is ineffective to prevent strokes caused by atrial fibrillation, which requires specific blood thinners called oral anticoagulants.

Patients whose atrial fibrillation is undetected are thus at higher risk of getting a second stroke.

Dr Seow noted that all the patients in the study who had their condition detected were given such medication and have not been hit by a second stroke.

In Mr Ng's case, after his ICM alerted Dr Seow that he had an abnormal heart rhythm, he had a pacemaker inserted and was given anticoagulants.

The retiree said: "Because of the ICM, the atrial fibrillation was detected... It saved me."

Patients who do not have any abnormalities detected will not have to visit the hospital to have their heart rhythm monitored, saving valuable time and resources, said Dr Seow.

Given its success, Ng Teng Fong General Hospital will also be introducing ICMs to detect atrial fibrillation in patients with unexplained stroke. This will start in December.

Bukit Batok AF-Clinic patient So Teng Hung (left) under the care of Advance Practice Nurse Liau Wei Fong. ST PHOTO: KELVIN CHNG

In order to better facilitate the management of atrial fibrillation, NUHS will also be expanding the operating hours of its nurse-led clinic for the condition at Bukit Batok Polyclinic.

The clinic helps such patients monitor their blood pressure and sugar levels, and educates them on managing their weight, diet and lifestyle habits.

It serves to reduce the burden on Singapore's hospital system, and also gives patients a one-stop location to visit to manage their atrial fibrillation and related conditions, reducing cost and time.

Patients will also benefit from longer consultation sessions with Advanced Practice Nurses - around 20 minutes. This is more than what they would usually get with a doctor.

Retiree So Teng Hung learnt he had atrial fibrillation while hooked up to an ECG machine.

The 83-year-old, who has been attending the clinic for 11 months, said: "When you go to see a doctor, most of the time you feel very nervous, but when you see nurses, you feel at ease, and you can ask them a lot of questions regarding your condition, and they give a lot of good advice.

"I really appreciate what they have done."

Join ST's Telegram channel and get the latest breaking news delivered to you.