MEDICAL MATTERS:New patient-friendly drugs to replace rat poison, writes MUIRIS HOUSTON
WITH MORE than 32,000 delegates, the Annual Congress of the European Society for Cardiology (ESC) is one of the biggest medical meetings in the world. This year it was held in a massive convention centre not far from Charles De Gaulle airport in Paris.
It’s always well worth a visit to catch up on the latest research on heart disease, stroke and other vascular diseases and this year was no exception.
One of the biggest topics at last month’s event was the link between stroke and a heart rhythm abnormality called atrial fibrillation. In this condition, clots are flicked off by the heart to the brain.
Atrial fibrillation is the most common heart rhythm condition, affecting about 1 per cent of the total population, rising to 10 per cent in people over the age of 80.
For years, the standard treatment for these patients was the drug warfarin (aka rat poison) which significantly reduces the risk of a stroke. But warfarin, the blood-thinning drug used to break up clots, is a notoriously fickle drug.
A person who slowly metabolises warfarin could quickly develop dangerous blood levels of the drug, causing severe bleeding. Because of this, it is standard practice to check the blood’s clotting ability on a regular basis in patients taking it.
And warfarin is one of the trickiest drugs when it comes to drug interactions, with the result that it can be rendered either ineffective or overly active in the body. Neither result is good for the patient.
Almost 10,000 people develop a stroke in the Republic each year. Some 30 per cent of these die within one year of having a stroke. And there are about 30,000 people who are stroke survivors, many of whom have a significant disability that affects their independence.
Atrial fibrillation increases the risk of stroke by a factor of five, so as these national figures suggest it is important for doctors to recognise and treat it. But because of warfarin’s risks and side effects, many patients decide against starting the drug.
I have seen quite a few people who have been advised by specialists to start warfarin because of their risk of stroke from atrial fibrillation but who refuse. As one 82 year old pointed out rather plaintively, “I’m in my 80s, I do not want to have to attend a warfarin clinic to have my blood checked every couple of weeks and I’m really worried about side effects.”
Research suggests about 50 per cent of patients with atrial fibrillation assessed as suitable for warfarin don’t take the drug because of a fear of side effects.
So the declaration by Prof Christoph Bode of the University of Freiburg at the ESC that “warfarin will be with us for a decade, but is nearing the end of its life” is a strong signal that alternative drugs that are at least as effective as warfarin are now available.
We heard about a number of trials of newer, more patient-friendly anticoagulants at the conference.
The Rocket AF trial compared the drug rivaroxaban with warfarin as an agent to prevent stroke from atrial fibrillation. The double blind randomised trial of more than 14,000 patients found rivaroxaban was as effective as warfarin while causing less fatal bleeding, in particular intra-cranial haemorrhage.
The once-daily tablet doesn’t require the same level of monitoring with frequent blood testing.
The RE-LY trial of a different anti-clotting agent, dabigatran, found it reduced the risk of stroke compared to patients taking warfarin, without increasing the risk of major bleeding.
And the Aristotle trial of a third drug, apixaban, in which 18,000 patients were followed up for more than 18 months showed that for every 1,000 patients treated with apixaban, some six strokes and eight deaths could be prevented. The drug was also safer than warfarin, causing 31 per cent less major bleeding.
The days of the use of rat poison to treat humans is drawing to a close while, with the advent of these three drugs, older patients in particular can look forward to a less challenging treatment to prevent the possibility of a life-changing stroke.