Atrial fibrillation

Welcome to the Australian Prescriber Podcast. Australian Prescriber, independent, peer-reviewed and free.

I'm Dr Ashlea Broomfield, your host for this episode. It's a pleasure to be speaking to Rajeev Kumar Pathak, who is an associate professor of cardiology at the Australian National University in Canberra. Thank you so much for joining us.

Thank you, Ashlea. Good afternoon, everyone.

You've written an article called Atrial Fibrillation: An Update. What's changed?

Look, we have had some really exciting changes recently, most importantly, the new anticoagulant drugs, which have come through. We had warfarin for decades. They had their own limitations. Now we have got newer and better drugs, which can be given and has less interference with the lifestyle of the patients. Then we have, from rate and rhythm control strategies' perspective, the new drugs, the new procedures in catheter ablations, which have come through. And, finally, the recognition of the fact that atrial fibrillation is almost an end-organ damage because of the cardiac risk factors. Management of these cardiac risk factors are essential in overall management of atrial fibrillation, and something we all should be thinking and addressing.

So new drugs, new ablation technology, the recognition that we should be treating people holistically, which is also a really useful thing as a GP to hear. You know, one disease model is it's all about the rest of the patient as well. That's always exciting. The other thing that I noticed is there's now recommendation to screen for atrial fibrillation and we often do that in general practice when we're checking the blood pressure, we'll have a feel of the pulse. But there's a recommendation now to do screening via ECG in general practice, so how often should we be doing that?

We see lots of patients with cryptogenic stroke or ESUS patients, that means embolic stroke of unknown origin. There's been multiple studies which have shown that atrial fibrillation is one of the commonest cause for this type of strokes.

Now the only way we will be able to try and prevent these strokes if we screen these patients regularly, that is, how much is enough? Unfortunately, it's difficult to know. But at least checking their pulse or doing ECGs at the time of their regular visits, at least have an ECG once a year, so that we can see if we can pick up things and overall education of the healthcare professionals and our patients, empowering them so that they can look for signs and symptoms and seek help at the right time, I think, will improve the overall care of the patient.

It's often quite a common thing for people to come in and potentially have symptoms of atrial fibrillation, which might be palpitations or shortness of breath or some intermittent chest pain or other kind of odd physical symptoms. In those circumstances when you can identify an acute response, we will often look for doing rhythm control. If we're screening patients more regularly and they may have asymptomatic atrial fibrillation, how do we differentiate between what type of AF that they have and whether they're a candidate for rhythm control or not?

The best way is if the patients are symptomatic, then it is easy to identify those patients. The biggest problem has been when the patients have atrial fibrillation and they're asymptomatic. Those are the patients who get stroke without any prior warning.

Now those patients, the only way we will be able to pick up if we do a regular screening and, as we discussed, doing an ECG, checking their pulse is important, educating patients to know their pulse and trying to have that as a community program. Know your pulse will be something very important.

Now once these patients get identified and we know that they have atrial fibrillation or we have picked up in our clinic setting, one thing for sure is important is anticoagulation in these patients. Now if their CHA₂DS₂-VASc score is two and above or one, but have some other additional associated factors, a discussion about anticoagulation is very important. If there is no contraindication, they should be started on anticoagulation.

Then comes rate and rhythm control strategy discussion. If they're asymptomatic, but they are tachycardic, a proper assessment doing a Holter monitor to see their atrial fibrillation burden. If they're going tachycardic or persistent tachycardic with a heart rate above 100 those patients, for sure, require some type of management even if they're not symptomatic at the moment, even if it means starting with some beta blockers to control the rate or calcium channel blockers. If the Holter shows that the burden is quite significant, starting them on antiarrhythmic medication to reduce the burden is very appropriate.

Finally, as we discussed, addressing the cardiac risk factors, weight, blood pressure, screening for diabetes, screening for sleep apnoea, all of them become very important, even in patients with asymptomatic atrial fibrillation.

So in the asymptomatic patient, you're more likely to implement a trial of rhythm control if their arrhythmic burden is higher on the Holter monitor?

Yes, correct. You know, sometimes, and this we have seen in our clinical practice, our population and our patients regress to mean they do not realise that their quality of life and their exercise tolerance is reduced because of atrial fibrillation burden. They blame their age, their lack of fitness, rather than the physical factor or the pathological factor they have. If you maintain the sinus rhythm, suddenly the quality of life is improved and you hear them saying that, "What I used to think was my age is actually my disease." So a trial to try to maintain sinus rhythm in these patients is not inappropriate.

Now that doesn't mean they should go for a catheter ablation. But if they have a high burden of atrial fibrillation, you see them flipping in and out, putting them on antiarrhythmic medication to reduce the burden and try to keep them in sinus rhythm is a good strategy. We all know if they get here, so you have atrial fibrillation, the likelihood of disease progression is greater and, therefore, maintaining sinus rhythm has a big value in these patients.

Clearly you have to balance between other factors such as them getting bradycardic or becoming dizzy. But if they can tolerate, it is a good idea to try and put them on rhythm control strategies.

When we're considering someone for anticoagulation, you mentioned previously the CHA₂DS₂-VASc score. I noticed in your article that the Australian CHA₂DS₂-VASc score is now a sexless score with a different score profile. Can you talk about that a little bit?

I think this was really important changes and I'm really glad that we have now got that incorporated into guidelines. Just female by itself when the CHA₂DS₂-VASc score came through, the female gender became significant in the statistics and that whs added into the CHA₂DS₂-VASc score.

Now we realise that just being the female, there is a small risk because of the estrogen and the other hormones which you have. But most of these patients by the time they have atrial fibrillation are more than 55, 60 years old. In those subset of patients, the risk of clot is similar to the risk which we see in men. I think just being a female was not really that clinically relevant a factor in that age. Because, otherwise, anyone who was more than 65, if she was a female, suddenly became a CHA₂DS₂-VAS cscore of two and should be on a lifelong anticoagulation and then it was becoming a real clinical problem. I think now with the sex gone, both male and female will be seen as a similar subset of patients.

However, the CHA₂DS₂-VASc score is just a rough guide. It's a good guide, but then there are other novel factors we should also kept in mind, such as obesity, sleep apnoea, duration of these risk factors such as diabetes, severity of these risk factors, such as hypertension and diabetes and, similarly, if the young female with estrogen, I think they are prothrombotic and that should be accounted for.

So in atrial fibrillation management we are seeing holistic medicine and gender equality. I think both of those two are really good signs.

Absolutely. We need to treat the patient, rather than treat the disease only.

When we're looking at therapies for risk factors for atrial fibrillation, which ones are associated with improved stroke outcomes?

Look, the stroke incidence is so low that the studies which have looked into this, we have never been able to show one intervention which has led to a reduction in stroke. The reason is very simple. It's very difficult to show an effect when the incidence of a problem itself is low.

However, I think if we reduce the overall burden of atrial fibrillation and in our study such as LEGACY study and the CARDIO-FIT study, we have looked at the effect of risk factor management and we are seeing a dramatic reduction in the burden of atrial fibrillation. It's only natural to think if you have reduced the burden of atrial fibrillation, it only makes sense that overall risk of stroke in those patients should go down.

In the article you mentioned that anticoagulation reduces the relative risk of stroke by about 70%, which I thought it was quite a significant number. When we're talking about stroke as a low-incidence disease, what does that mean in real terms when we look at a 70% reduction?

The real risk of stroke is anywhere between 1% to 2% to 10% and depends on the CHA₂DS₂-VASc score, of course. Therefore, if you take anticoagulation, if your risk is, say 10%, because your CHA₂DS₂-VASc score is high, if you take anticoagulation, your risk will be 2% to 3%, rather than 10%. So that's the 70% reduction of risk of stroke.

Is that per year, the 1% to 2% to 10% per year?

Annualised risk, yes.

I've also noticed in my practice that direct anticoagulants are much more common, as you said in the article. When they first came on the market, there was a lot of worry about them in relation to the inability to reverse if someone was presenting with bleeding issues or needed surgery. Now they've been on the market for so long and are recommended over warfarin, unless in special circumstances where they cannot be used, also which you've outlined in your article. What is the kind of general feeling now about the safety of direct anticoagulants?

I agree. When the new drug came, we took that into our practice slowly, which was quite the right thing. With the years of experience, we have found these drugs to be extremely safe. There are conditions in which we will not use them, and those are patients with severe renal impairment and a creatinine clearance of either less than 15 for apixaban and rivaroxaban, and less than 30 for dabigatran. There are concerns regarding lack of availability of reversible agent, which is not a case of dabigatran. Now we have a reversal agent, which is available. For apixaban and rivaroxaban, they are work in progress.

On the subject of bleeding, if someone has a high HAS-BLED score, does that mean that they can't have anticoagulation?

The balance is between the CHA₂DS₂-VASc score and the HAS-BLED score. If you have a slightly higher HAS-BLED score, but your CHA₂DS₂-VASc score is very high, so say like five or six, in those patients, you will have a discussion to say that your risk of stroke is significantly greater and you'll have some risk of bleeding.

Now HAS-BLED score has the factors such as hypertension. So having a high HAS-BLED score because your blood pressure is more than 160, rather than not giving them anticoagulation, I would advise to get a better blood pressure control.

Now if you have a GI bleed because of gastric ulcers, management of GI bleed should be done, rather than stopping these patients from anticoagulation.

Those things should be addressed in most cases, rather than should be a reason for us not to put these patients on anticoagulation in the long term.

My last question is when would we consider a referral to an electrophysiologist to consider a catheter ablation?

The guidelines at the moment are that you need to fail rhythm control strategy or you're intolerant to rhythm control strategies. So if you have a patient who is on anti-arrhythmic medications, such as flecainide or sotalol, and they continue to have atrial fibrillation, you consider putting them on amiodarone, but amiodarone has terrible side effects in long term. Those patients should definitely be sent for catheter ablation for atrial fibrillation.

Patients who are taking these medications and they can't tolerate them because of the side effects, clearly those patients should again be referred for catheter ablation. These are for paroxysmal atrial fibrillation.

For patients with persistent atrial fibrillation, it's a subset where a careful discussion should be with the patient about the quality of life, how it is affected by the atrial fibrillation and if they are tolerating anti-arrhythmic medications or not.

Is there anything you wanted to add before I close up?

Like I keep telling the same thing again and again, here is the end-organ damage because of the cardiac risk factors the patients have.

There are two subsets of patients in our community we see. They are patients with no risk factors. They are lean with no risk factors. They have atrial fibrillation. Those patients, if we manage their atrial fibrillation with rhythm control strategies and if it's unsuccessful doing catheter ablation, the results are fantastic, up to 90% success for arrhythmia-free survival.

If they have cardiac risk factors, we should manage those risk factors and only do catheter ablation in these patients if they continue to have breakthrough arrhythmias. And I think holistic management is extremely important.

Awesome. That's unfortunately all the time we've got for this episode. Thanks for joining us today, Rajeev.

Thank you very much.

The views of the hosts and guests on the podcast are their own, and may not represent Australian Prescriber or NPS MedicineWise. I'm Ashlea Broomfield, and thanks for joining us on the Australian Prescriber Podcast.