Doc Talk

New blood thinners slightly safer, more convenient

They are as effective as warfarin and patients need not go for regular blood tests

One of my patients, Madam Tan, celebrated her 80th birthday a few weeks ago.

Her family doctor, whom she sees regularly for the management of her diabetes and hypertension, recently discovered that she had an irregular heart rhythm.

However, Madam Tan had no other symptoms, and her blood pressure and blood sugar levels were well controlled.

She is, in many ways, the perfect patient. She eats in moderation and maintains a healthy weight. She goes for walks regularly and monitors her blood pressure at home. She is also well read and aware of the medications she is taking and why.

Her family doctor had correctly diagnosed her with atrial fibrillation, which was confirmed on a repeat heart trace (electrocardiogram) when I saw her.

Atrial fibrillation is an irregular heart-beat problem that can increase your risk of stroke, heart failure and other heart-related complications.


ST ILLUSTRATION: ADAM LEE

A significant part of the research on Rivaroxaban was carried out in Singapore. We know that the benefit and safety of the drug are even more significant among elderly and Asian patients.

It is due to a short circuit in the wiring of the heart. This, in turn, is commonly caused by ageing and longstanding hypertension (high blood pressure).

It is less commonly caused by hormonal changes or genetic inheritance.

Atrial fibrillation is the most common heart-rhythm problem among Singaporeans of her age. As many as one in 20 has it.

Yet, more than a third of the patients with this condition are not even aware that they have this problem. While it is not directly life-threatening, it markedly increases their risk of a major stroke.

As a cardiologist, I will need to determine if such patients have an associated heart-valve problem and that their heart function has not been affected by this irregular rhythm.

Madam Tan's heart scan confirmed that her heart function was normal for her age, though she had a slightly dilated heart chamber (her left atrium, to be precise).

Blood tests showed that she had normal kidney and thyroid hormone function.

Her heart rhythm may be irregular but it is neither too fast nor too slow, as one of her current medications for hypertension had fortuitously helped to keep her heart rate under control.

Nevertheless, I needed to make sure her risk of a stroke was kept low. Many elderly patients have told me they are not fearful of death but, rather, of significant disability or pain.

Fortunately, the treatment to prevent strokes has undergone a major revolution in recent years.

Aspirin, which was first derived 100 years ago from an active ingredient found in the bark of the willow tree, is still a very good treatment for many types of strokes.

However, it will not protect one from a stroke that is caused by atrial fibrillation.

For that, the current standard of care is the use of warfarin, an excellent drug which was first extracted in the 1950s from sweet clover that had become mouldy.

However, its effectiveness is affected by diet, genetic factors and other medications. In addition, regular blood tests are required to adjust the dosage for safety and efficacy.

There is now a new class of medications called novel oral anticoagulants (NOAC). These have been shown to be as effective as warfarin and are slightly safer as there is less risk of serious bleeding.

Only patients with certain conditions, such as significant kidney problems or mechanical heart valves, should not use them.

With this new generation of blood thinners, there is no need to go for regular blood tests or to adjust the dosage.

I had a long discussion with Madam Tan and her family. She was concerned about her high risk of stroke and was keen to start treatment with warfarin.

She was, however, concerned about the frequent blood tests and visits needed to monitor the medication.

Her daughter, who usually accompanies her to the clinic, was concerned that she would have to take time off work and this might affect her job security.

Madam Tan also preferred a once-daily tablet as she might forget to take it in the afternoons.

I, therefore, recommended an NOAC drug. In her case, it was Rivaroxaban, sold under the Xarelto brand, and she needed to take it only once every morning.

A significant part of the research on Rivaroxaban was carried out in Singapore. We know that the benefit and safety of the drug are even more significant among elderly and Asian patients.

While the cost of this and other new-generation blood thinners is higher, Madam Tan and her family felt that the advantages outweighed the cost.

As she does not require very close monitoring, she can continue her regular follow-ups at the clinic near her home and continue to see her family doctor.

Madam Tan's case also shows the need for regular check-ups with your family doctor.

Research into new and better treatment for Singaporeans is crucial and I am very grateful to my patients who had volunteered for the research into this class of medications 10 years ago.

Although they did not benefit directly from their contribution, they have helped countless patients whom they will never meet, like Madam Tan.

•Dr Ong Hean Yee is a senior consultant cardiologist at Cardiac Solutions Medical Centre at Mount Elizabeth Novena Specialist Centre.

A version of this article appeared in the print edition of The Straits Times on February 28, 2017, with the headline 'New blood thinners slightly safer, more convenient'. Print Edition | Subscribe