Blood-thinning drugs to cut strokes

One in five of the patients admit­ted to hos­pi­tal with a stroke have a heart rhythm dis­or­der known as atri­al fib­ril­la­tion or AF.

The con­di­tion means that blood can pool in the heart, caus­ing clots to form. Peo­ple with AF are at five to six times greater risk of hav­ing a stroke which can often be fatal.

Although it can affect any­one, AF is more com­mon the old­er we get, affect­ing almost one in ten of the over-80s. Over­all, there are now more than one mil­lion peo­ple diag­nosed with AF and many more who are thought to have it, but are unaware that they do.

By 2050, experts say these fig­ures could dou­ble.

Trudie Lob­ban, founder and chief exec­u­tive of the AF Asso­ci­a­tion, says: “We know there are many peo­ple with AF who do not know they have it. In the first instance detec­tion can be as sim­ple as a pulse check.

“If you have AF and are at risk of an AF-relat­ed stroke, it is imper­a­tive you are assessed, and con­sid­ered for anti­co­ag­u­la­tion med­i­cine.

“We know that at least 7,100 AF-relat­ed strokes could be pre­vent­ed every year if peo­ple with AF were appro­pri­ate­ly treat­ed.

“It is crit­i­cal that greater aware­ness of AF and appro­pri­ate pre­scrib­ing of effec­tive ther­a­pies are NHS pri­or­i­ties – sav­ing lives while also reduc­ing cost to the NHS.”

The dan­ger from AF occurs when the atria – the upper cham­bers in the heart – beat irreg­u­lar­ly and the blood stag­nates caus­ing clots. When a clot forms, it can be pushed around the cir­cu­la­to­ry sys­tem and may get lodged in blood ves­sels in the brain, result­ing in a stroke.

A large num­ber of peo­ple diag­nosed with AF are known to be at risk of stroke, but they are not receiv­ing the anti­co­ag­u­la­tion they need, either because it isn’t offered to them or because it isn’t being used opti­mal­ly

For­tu­nate­ly, anti­co­ag­u­lants, often referred to as blood-thin­ning pills, can sig­nif­i­cant­ly reduce the risk of a stroke.

War­farin, for exam­ple, is an anti­co­ag­u­lant that has been used since the 1950s. It is cheap, effec­tive and well under­stood by doc­tors. But war­farin and oth­er, more recent­ly intro­duced, anti­co­ag­u­lant med­i­cines are not always used.

In August 2013, data from the Sen­tinel Stroke Nation­al Audit Pro­gramme showed only one in three of the patients with AF who had a stroke were on anti­co­ag­u­lants such as war­farin.

This may be because get­ting the dose of war­farin right is not a sim­ple process, and is com­pli­cat­ed by the fact that it inter­acts with cer­tain foods and alco­hol.

Care­ful mon­i­tor­ing is need­ed and patients must go reg­u­lar­ly to a spe­cial INR clin­ic to have a blood sam­ple tak­en that ensures their dosage is cor­rect.

Worse still, many AF patients are not pre­scribed anti­co­ag­u­la­tion ther­a­py at all and are instead giv­en aspirin. This may increase their risk of a bleed while doing lit­tle to reduce stroke risk.

Eve Knight, chief exec­u­tive and co-founder of the char­i­ty Anti­Co­ag­u­la­tion Europe, says: “There are a large num­ber of peo­ple diag­nosed with AF who are known to be at risk of stroke, but they are not receiv­ing the anti­co­ag­u­la­tion they need, either because it isn’t offered to them or because it isn’t being used opti­mal­ly.”

The good news is that major changes should soon alter how AF patients are treat­ed.

Exist­ing guide­lines from the Euro­pean Soci­ety of Car­di­ol­o­gy (ESC) will be bol­stered in the forth­com­ing updat­ed guide­lines from the UK’s Nation­al Insti­tute for Health and Care Excel­lence (NICE), which makes clear that anti­co­ag­u­la­tion is key.

The NICE guide­lines will also include anoth­er impor­tant change for patients.

Three med­i­cines that mark a sig­nif­i­cant inno­va­tion in anti­co­ag­u­la­tion for AF patients in more than half a cen­tu­ry are now being rec­om­mend­ed in the draft NICE guide­lines which will be finalised and pub­lished in June.

Known as nov­el oral anti­co­ag­u­lants or NOACs, these med­i­cines pro­vide a fixed dose with­out the need for anti­co­ag­u­la­tion mon­i­tor­ing and elim­i­nate the need to vis­it an INR clin­ic. Three NOACs are avail­able on the NHS and all of them are at least as good as war­farin in reduc­ing the risk of a stroke in AF patients.

While the ESC guide­lines make clear that there is insuf­fi­cient evi­dence to rec­om­mend one of these NOACs over anoth­er, they do point out that some patient char­ac­ter­is­tics, drug com­pli­ance, tol­er­a­bil­i­ty and cost may be impor­tant con­sid­er­a­tions in the choice of an agent.

In some parts of the UK, these more recent­ly intro­duced med­i­cines are already being embraced.

Craig Barr, a con­sul­tant car­di­ol­o­gist at the Dud­ley Group NHS Foun­da­tion Trust, says: “When we looked at the options avail­able and all of the data, we felt that nov­el anti­co­ag­u­lants, which don’t require con­stant blood tests, were the best option for the major­i­ty of our patients. We now have options in anti­co­ag­u­la­tion man­age­ment, where­as three years ago we didn’t. This means patients and doc­tors alike now have choice so that fac­tors, such as age, lifestyle and pref­er­ences, can be tak­en into account when con­sid­er­ing the treat­ment plan.”

Char­i­ties such as the Stroke Asso­ci­a­tion say they hope that the new guide­lines for doc­tors, com­bined with a wider range of treat­ments, will lead to a reduc­tion in strokes.

Joe Korner, direc­tor of exter­nal affairs at the Stroke Asso­ci­a­tion, says: “We know that peo­ple with AF are five times more like­ly to have a stroke and that it’s linked to around 22,500 strokes in the UK each year. That’s why it’s vital that peo­ple with AF get the right treat­ment as soon as pos­si­ble. If the under­ly­ing con­di­tions of stroke, such as AF, are picked up at an ear­ly stage and peo­ple get the right treat­ment, they can reduce their risk of stroke which will save lives.”

ANTICOAGULATION

Q&A

Patients with atri­al fib­ril­la­tion should always ask their doc­tor about the best treat­ment to reduce their risk of stroke. Dr Khalid Khan, con­sul­tant car­di­ol­o­gist at Wrex­ham Maelor Hos­pi­tal, answers some com­mon ques­tions

Q: I’ve been diagnosed with AF, what is anticoagulation for?

A: The pur­pose of anti­co­ag­u­la­tion in AF is to reduce your chance of hav­ing a stroke. It achieves this by reduc­ing the risk of clot for­ma­tion in your heart that might then cause a stroke. We now have very good tools that can be used to esti­mate what your per­son­al risk of hav­ing a stroke is. The cal­cu­la­tion is based on known risk fac­tors for stroke, includ­ing your age, sex and med­ical his­to­ry, notably dia­betes, high blood pres­sure, heart dis­ease or a his­to­ry of pre­vi­ous stroke. Based on these results, your doc­tor can advise you on whether you need anti­co­ag­u­la­tion and, if so, which approach is most suit­able for you.

Q: What are the differences between the anticoagulants available?

A: War­farin has been used for many years and is cer­tain­ly effec­tive when used cor­rect­ly. Its down­side is that it can be hard to get the dose right for some patients as warfarin’s action varies between indi­vid­u­als, and it can inter­act with cer­tain foods and oth­er med­ica­tions. For this rea­son, you may need to go for reg­u­lar blood tests at a clin­ic. There are three alter­na­tive anti­co­ag­u­lants to war­farin, called rivarox­a­ban, apix­a­ban and dabi­ga­tran. These nov­el oral anti­co­ag­u­lants or NOACs are not affect­ed by food or oth­er drugs, so you do not need mon­i­tor­ing by reg­u­lar blood tests. In terms of their abil­i­ty to reduce your stroke risk, they are at least as good as war­farin, but some of the NOACs work dif­fer­ent­ly to oth­ers. Your doc­tor can advise.

More recent evi­dence and inter­na­tion­al guide­lines recog­nise that aspirin is much less effec­tive in pre­vent­ing stroke in atri­al fib­ril­la­tion

Q: I heard that the more recently introduced anticoagulants are more risky because they don’t have an antidote and so, if you start bleeding, it cannot be stopped, whereas warfarin has an antidote?

A: We have clear guide­lines and mea­sures that we can under­take to man­age bleed­ing when it does occur, what­ev­er a patient might be tak­ing, includ­ing for the more recent­ly intro­duced oral anti­co­ag­u­lants. The action of war­farin lasts for sev­er­al days and an injec­tion of vit­a­min K can reverse its effects, but this takes eight to twelve hours and is there­fore not a true anti­dote (which revers­es the effects imme­di­ate­ly). Com­pared with war­farin, the blood thin­ning effect of NOACs wears off much faster. It is reas­sur­ing that in all the stud­ies with the more recent­ly intro­duced oral anti­co­ag­u­lants, they had at least a com­pa­ra­ble safe­ty pro­file to war­farin in terms of over­all bleed­ing rates.

Q: My GP prescribed me aspirin as this follows current guidelines. Is this right?

A: Old­er guide­lines from 2006 sug­gest­ed that aspirin could be used in patients at low or medi­um risk of stroke. More recent evi­dence and inter­na­tion­al guide­lines recog­nise that aspirin is much less effec­tive in pre­vent­ing stroke in AF, and is no safer than an anti­co­ag­u­lant in terms of bleed­ing risk. Guide­lines due to be pub­lished by NICE in June are expect­ed to rec­om­mend anti­co­ag­u­la­tion for all patients who are thought to be at risk of stroke from AF.

Q: Does age affect how I should be treated for my AF?

A: As you get old­er, both your chance of hav­ing AF and your chance of hav­ing a stroke increase sig­nif­i­cant­ly. Old­er patients also have a some­what high­er bleed­ing risk with anti­co­ag­u­la­tion. How­ev­er, over­all, old­er patients are more like­ly to ben­e­fit from receiv­ing anti­co­ag­u­la­tion when com­pared to younger patients. The risks and ben­e­fits of treat­ment should be con­sid­ered for every indi­vid­ual to ensure the anti­co­ag­u­la­tion they receive is appro­pri­ate for them. Your own doc­tor, with knowl­edge of your med­ical his­to­ry, is in the best posi­tion to advise you of the most appro­pri­ate treat­ment.