Zero to GP - GP Revision Podcast

Atrial Fibrillation - Essential GP Revision

• Thomas Watchman • Season 1 • Episode 14

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0:00 | 32:08
SPEAKER_01

Hi, this is Tom and welcome back to the Zero to GP podcast. In this episode, I'm going to be going through atrial fibrillation, covering all the key stuff you need to know as a GP and for your GP specialist exams. The format of this episode, as always, is I'll present cases and ask you questions. Your job is to come up with the answer and ideally say it out loud or write it down so you really commit to an answer, and then I'll go through the answer and the explanation. If you're a GP trainee and you're going to be doing your AKT at any point in the next, say, six or twelve months, check out the AKT revision resources from Zero2GP. That's the AKT revision book, which is really concise notes on all the key stuff you need to know for your GP exams. There's also the zero2gp.com website, which has flashcards, a question bank, and a fact trainer tool, which is a completely unique tool in the kind of GP exam preparation space. I don't think any other kind of um GP preparation resources are doing this, which is an ANCI-like tool where you can drill your knowledge on the key facts that you need for your GP exams and do spaced repetitions using this fact trainer tool. So check that out. There's currently a a three-day free trial, so you can try it without paying anything and see if you like it. And I'm going to be doing an AKT revision course, which is with me in person in London, face to face, in September this year. So check out the AKT revision course also. But for now, let's jump straight into this episode on atrial fibrillation. So our first case is a 65-year-old woman, and she presents with palpitations for a week. She says the last couple of this the last week, maybe a bit more, I've been having a funny feeling of fluttering in my chest. You feel her pulse, and she has an irregularly irregular pulse. So the first question is what are the two main differentials here when you feel an irregularly irregular pulse?

SPEAKER_00

The first one, of course, is atrial fibrillation.

SPEAKER_01

This whole video is about atrial fibrillation. So obviously that's going to be one of the differentials. The other one is ventricular ectopic beats. So we'll talk a bit more about that in a second. The second question is what ECG changes would you find with atrial fibrillation? So you're ancient ECG in this patient.

SPEAKER_00

What changes would suggest AF?

SPEAKER_01

The key things you're looking for in an ECG for atrial fibrillation are absent P waves. Part of the pathophysiology of atrial fibrillation is that the atria, the top two chambers of the heart, the right and left atria, are not beating in a coordinated fashion. Normally when these uh atria contract and beat normally, you get a P wave on the ECG. That's what the P wave represents. If they're just fluttering or sort of uh fibrillating, not really coordinated, you won't get any P waves because there's no coordinated electrical activity in the atria. The second thing on an ECG is you tend to get a narrow complex tachycardia. This means the QRS complex is narrow, which is normal. It's not a broad QRS complex. So you get a narrow complex, and the tachycardia just means the heart rate is fast, so over 100 beats per minute. So you get more than 100 beats per minute, and the QRS complexes are narrow. And the third thing you get is an irregularly irregular ventricular rhythm. This means if you look at the tops of the R waves on the ECG, uh right at the top, and you look across those peaks of the R wave, that they will be spaced irregularly, irregularly, if that makes sense. Um so you won't be able to see a pattern to the spacing between the R waves. Now you mentioned the other um the other differential of an irregularly irregular pulse, which is ventricular ectopic beats. These are seen on an ECG as random, weird-looking uh beats that come completely spontaneously within the ECG. So you might see a normal PQST uh kind of set of uh things to represent one heartbeat, and then you get this random uh ventricular beat that's just spaced in there without any uh any warning. It doesn't come after a P wave, it's just a random discharge within a ventricle, um, and it it can give an irregular, irregular pulse. Okay, so we've got the 65-year-old woman, she's diagnosed with atrial fibrillation based on this ECG. Her heart rate's 106 beats per minute, and you kind of assess her, and she's hemodynamically stable, she's otherwise well, you're not kind of worried that she needs admission immediately. The next question I have for you is what are the causes of atrial fibrillation?

SPEAKER_00

Why might she have developed this?

SPEAKER_01

So there's quite a few possible causes of atrial fibrillation. And when you're assessing a new a patient presenting with new atrial fibrillation, you really need to assess what could be the cause here. Now it could be idiopathic. There might not be any clear underlying kind of secondary cause for the atrial fibrillation, but it's important to look for possible causes. And my mnemonic that I use is Smith, and this is followed by lifestyle uh factors. So Smith stands for S for sepsis. So look, do they have a big raging infection that could have triggered the atrial fibrillation? M is for mitral valve pathology. So if you have something like mitral stenosis or mitral regagitation, that can um set off atrial fibrillation. So obviously, you want to listen to the heart sounds and make sure the valves sound healthy. I is for ischemic heart disease. So if they've had a recent myocardial infarction or they've got angina, this can cause atrial fibrillation. So obviously, ask about chest pain and things like that. T is for thyrotoxicosis, so hyperthyroidism. So ask if they have any features like weight loss, uh obviously palpitation, sweating, that kind of thing, um, and consider checking a thyroid function test. H is for hypertension, so you want to check their blood pressure and see do they have a history of hypertension. And then lifestyle factors include alcohol, caffeine, and cocaine. So if somebody's taking loads of caffeine or they drink lots of alcohol, these things can set off atrial fibrillation. Okay, on to the next question, which is in this patient who's got new atrial fibrillation for the past week or so, which two drugs are you gonna start in this patient? So most well uh otherwise healthy patients will be started on two medications for um for atrial fibrillation. The first is bisoprolol, and the second is a doac, a type of anticoagulation. For example, a pixaban or riveroxaban. So my next question for you is what is the purpose of bisoprolol?

SPEAKER_00

Why are you gonna start bisoprolol in this patient?

SPEAKER_01

So the aim of starting bisoprool in this patient is to slow the resting heart rate down below 80 beats per minute. And this is called rate control. Most patients with atrial fibrillation, unless they have some unusual circumstances, which we'll talk about, are going to end up on rate control with beta blockers, particularly bisoprolol. So, why is this important? Well, let's have a look at normal atrial contraction. Um, normally with atrial contraction, there's coordinated contraction of the atria. And the purpose of atrial contraction is to squeeze blood out of the atria and fill up the ventricles. If the atria squeeze plenty of blood into the ventricles, then when the ventricles contract, there's lots of blood in there, and they can pump all that blood to the lungs or around the body. So that's what the atria normally do. In atrial fibrillation, you've got this chaotic uh fibrillation of the atria. So the blood is kind of just going round and round in circles, not really going in a coordinated fashion through to the ventricles. So the ventricles need to fill up by suction and gravity. They're not filling up by the atria contracting, they're filling up through suction and gravity. And this takes much longer to do than if the atria are efficiently pumping blood in. So what does this mean? This means the heart rate needs to slow down in order to give enough time for the ventricles to fill up so that the ventricles can squeeze plenty of blood into the lungs or the rest of the body. If the heart rate's going too fast, there's not enough time for the ventricles to fill up by suction and gravity from the atria. And so that there's a reduced cardiac output. There's less blood in the ventricles to squeeze out with each beat. So with rate control, you're slowing the heart rate down to give more time for the ventricles to fill, so you get a better or more blood pumped out through the to the lungs or around the body by the ventricles. Okay, next question is other than bisoprolol beats blockers, what other options do we have for rate control in atrial fibrillation?

SPEAKER_00

There's two other options.

SPEAKER_01

The first is a special type of calcium channel blocker, and the options of calcium channel blockers are deltazem and verapamil, and the other option we have is digoxin. So my next question is what's the main contraindication to calcium channel blockers for rate control in AF? When are you gonna avoid Diltiazem or verapamil?

SPEAKER_00

The most important contraindication to remember here is heart failure. The next question is when would digoxin be suitable?

SPEAKER_01

Dijoxin's only a suitable option for rate control in AF in sedentary patients. So you can't use it in patients who are active, young, you know, exercising and so on. The reason is that it's not effective in controlling the rate during exercise. It's only effective to control the rate in sedentary patients. The next question I have is what's the alternative to rate control? So for example, let's say you attempt rate control and you go through these medications and nothing is suitable, or um then they don't have effective control of symptoms despite rate control, what are the alternative options?

SPEAKER_00

Or what is the alternative option?

SPEAKER_01

The alternative to rate control is rhythm control. Most patients will be on rate control, but there are some specific scenarios where rhythm control is um what we're going to choose. So the options for rhythm control are cardioversion, and cardioversion is like a single event that takes the patient from atrial fibrillation back to normal sinus rhythm. And the options are for cardioversion either electrical, so they get an electrical shock with pads on the chest, and that sends them back to sinus rhythm, or you can use drugs to do it, for example phleconide. There's also drugs long-term which you can use for rhythm control, for example, sotolol or amiodorone. And then the final option is ablation procedures. So if this atrial fibrillation is caused by an accessory pathway in the atria, they can feed a catheter through the arterial system to the venous system to the atria and ablate that accessory pathway and put the patient back into sinus rhythm. So they're the options for rhythm control. Okay, so we've got this 75-year-old woman, she's diagnosed with atrial fibrillation, heart rate's 106, she's otherwise well. You said you're gonna prescribe, or we said we're gonna prescribe her a doac.

SPEAKER_00

What's the purpose of prescribing the doac? The doac is to reduce the risk of stroke.

SPEAKER_01

It's anticoagulation, meaning people talk about it thinning the blood. It's not technically accurate, it slows clotting in the blood. Um, but what what the aim is to reduce the risk of stroke. So why is this important in atrial fibrillation? Well, in atrial fibrillation, you've got chaotic fibrillating activity of the atria. Blood pulls, particularly in the left atrium, in something called the left atrial appendage, which is kind of like a pocket off the late left atrium. And the fact that blood's not moving fast and smoothly through the heart and collecting in the atria means a thrombus can form. So if a blood cot or thrombus forms in the left atrium, the next thing that will happen is it moves through to the left ventricle, then up to the aorta, through the carotid arteries, uh, travels up to the brain, and then blocks a cerebral artery, and this causes a stroke. So with anticoagulation, we're trying to prevent thrombus formation and reduce the risk of strokes. Next question I have is what scoring system would you use to determine the risk of an individual person having a stroke who has atrial fibrillation? If you want to, you could pause the video and list all the individual criteria for this scoring system.

SPEAKER_00

So the scoring system is the Chad's VASC score.

SPEAKER_01

So this is actually a mnemonic for remembering the factors, and you can score one point if you have any of these factors. So you add up the number of factors that apply to the individual patient. C is for congestive heart failure, H is for hypertension. A, the first A, which is A2, is for age above 75. And if they're above 75, this scores two points. D is for diabetes. S, which is S2, is for a previous stroke or TIA. And if they've had a previous stroke or TIA, they score two. V is for vascular disease, for example, peripheral arterial disease. A is for age between 65 and 74, they score one for that. And the final S is for sex, specifically if they're female. So the next question is what action would you take in terms of anticoagulation based on the Chad's vast score of an individual patient. If they score zero, they don't need any anticoagulation. So say you have a 50-year-old, otherwise fit and well, a male, a new AF, no need to prescribe anticoagulation. In fact, that applies to females as well. If they score one, you'd consider anticoagulation. So this is kind of a discussion and a consideration with the patient to decide should we start it or not. Females will automatically score one. So if a female scores one, you treat it as zero because they don't need anticoagulation. And then if they score two or more, then you offer anticoagulation. So all patients, two or more, should be offered anticoagulation. The next question is how do you calculate the risk of bleeding? So you're essentially thinning or reducing blood clotting in the patient's blood. That increases the risk of them having bleeds. For example, gastrointestinal bleeding, bleeding after cuts, nose bleeds, or even intracranial hemorrhage, things like that.

SPEAKER_00

How are you going to calculate their risk of bleeding? You would use the orbit score.

SPEAKER_01

This calculates how uh how risky it is to give them anticoagulation. For the vast, vast majority of patients, having anticoagulation is less risky than not having it. So if you it for most patients, the benefits of anticoagulation outweigh the risks. So the risk of bleeding is lower than their risk of stroke, if that makes sense. The next, the final question I have on anticoagulation is let's say anticoagulation is completely unsuitable, say they have a high risk of bleeding, and it's not appropriate to give them anticoagulation. What other option would they have for reducing their risk of stroke in atrial fibrillation? The other is a procedure called a left atrial appendage occlusion. What does this mean? Well, remember I told you that the thrombus formation often occurs in something called the left atrial appendage, which is a little pocket off of the left atrium. Well, if blood is kind of collecting in this pocket and forming a thrombus, that's a problem. But there is a procedure where you can occlude that left atrial appendage to stop blood from sitting in the pocket and um and and forming a thrombus, and that's called a left atrial appendage occlusion, and that's also an option for reducing the risk of stroke. Okay, so we've got a 65-year-old woman, she diagnosed with atrial fibrillation, she's starting a pixaban and bisoprolol. We've got a plan. Next question is what are the baseline bloods that you're gonna organize for the epixaban, for the doac? So the answers are a full blood count, you want to make sure they're not anemic and their platelet count is okay, a renal profile to make sure their kidneys are working okay, liver function tests to make sure their liver's working okay, and a clotting screen to check that their clotting system is functioning normally. Next question is what's the key renal function tests? You can you can click renal profile when you're organizing the blood tests, but there is a specific renal function test that you need for monitoring DOAX.

SPEAKER_00

What is it? The answer is creatinine clearance.

SPEAKER_01

And this is one that's always flagged up in GP practices. The clinical pharmacist will say it's patients on a Pixaban, they haven't had a creatinine clearance for such a long time. We need to organize a creatinine clearance. And you look back and they've had loads of uh renal function blood tests but no one's organized a creatinine clearance. So this is the key one for doacs. Next question is how often are you going to measure the creatinine clearance in a patient who's taking a Pixaban or Riverox band or another doac. So for most people it's going to be an annual creatinine clearance. So if someone's 55 years old, otherwise healthy, an annual creatinine clearance is just fine. For frail patients or patients above 75 years of age, it's more frequently specifically four monthly. And then it's more frequently again if their creatinine clearance is less than 60 milliliters per minute. And there is a specific way you can calculate how often they need to have the creatinine clearance done and that's that the months per per interval so for example how many months between creatinine clearance events, you can calculate that by the creatinine clearance divided by 10. So for example if the creatinine clearance is 40 divide that by 10 is 4. So they need a four monthly creatinine clearance. For example if the creatinine clearance is 30 then they need a creatinine they need they need it checked every three months. 30 divided by 10 is three. Okay let's move on to a completely new case you've got a 45 year old man who presents with 12 hours of palpitations. He says before this I was completely fine and then for the last 12 hours I've had palpitations I felt you know a funny feeling in my chest. You arrange an ECG and he has atrial fibrillation on his ECG with a heart rate of 115 and you fully assess him and he's hemodynamically stable. So he's he's systemically well but he's got these palpitations. What's your initial management in this case so in this scenario slightly different to the first scenario we need to arrange a hospital admission or at the minimum get urgent specialist advice. So phone the cardiologist on call and ask them for advice the reason for this is that he has new onset within the past 48 hours. So if there's new onset of atrial fibrillation within the last 48 hours need to be looking at admission or at least urgent specialist advice.

SPEAKER_00

Why?

SPEAKER_01

Why is this important here is that there's an option of doing cardioversion so immediately kind of getting his heart back to sinus rhythm and the options are electrical cardioversion so he has uh electrical cardioversion some pads on his chest they shock his heart and it goes back to sinus rhythm or the other option is pharmacological so amiodrone or phleconide to bring his heart back to normal sinus rhythm. That's if he presents within 48 hours. Another scenario where you're going to be arranging admission is if the patient's hemodynamically unstable, they have new um new evidence of heart failure or there's some kind of underlying cause like chest pain or an infection. So let's say this patient goes into hospital and they say yeah we need to do cardioversion we we think that's a good idea. So it's planned but it's delayed because of you know a busy ward and so on. It's delayed for more than 48 hours after the onset of atrial fibrillation so they say okay you can go home and we'll do cardioversion as an outpatient my question for you here is what are going to be the what what what will be the key management considerations in this patient who's having he's got new AF and he's going to have cardioversion as an outpatient next few weeks or so the key things here are going to be that he needs anticoagulation based on his ChadSbass score so he may not need it but he needs to calculate his score and he's going to need anticoagulation for at least sorry he will need anticoagulation for at least three weeks before he has outpatient cardioversion. The reason for this is that during the 48 hours or so since the onset of AF, he may have developed a thrombus in the left atrium or the left atrial appendage. And so if you cardiovert him, that will then shoot that thrombus into the ventricles up to the brain and cause a stroke. So he needs anticoagulation for at least three weeks to kind of ensure that he doesn't have a thrombus there when they come to cardiovert him. So cardioversion is either within 48 hours or delay it for more than three weeks at least three weeks and have anticoagulation in the interim. He's also going to need interim rate control for example with a beta blocker bisoplow. Okay let's move on to our final case on atrial fibrillation this is a 70 year old man and he comes with intermittent palpitations. So he says I get these episodes that last say 12, 24, 48 hours where my heart feels like it's beating irregularly and then it just goes back to normal. And he's been having these for a while he also has a smartwatch let's say he's got an Apple watch and that has been flagging up and telling him he's got atrial fibrillation. So he says I probably shouldn't get I probably should get this checked out so I've turned up here today. You do an ECG on the day and it shows sinus rhythm.

SPEAKER_00

My first question in this case is what's your suspected diagnosis here.

SPEAKER_01

In this case you're suspecting paroxysmal atrial fibrillation paroxysmal atrial fibrillation describes when patients have episodes of AF that could last like minutes, hours, days and then they go in intermittently into sinus rhythm between these episodes. Next question is how are you going to diagnose this important thing here is you need to capture these episodes of atrial fibrillation on an ECG on a on a rhythm strip. So the options are to arrange an ambulatory ECG for example 24 hour ECG or an event recorder that sits on his chest for longer and picks up events when he has episodes of atrial fibrillation this usually requires referral to cardiology or the arrhythmia clinic and they'll organize their stuff. So let's say he's diagnosed with paroxysmal AF and he's under the cardiology services what specialist option is available if he's having infrequent episodes of paroxysmal AF There's an option called a pill in the pocket strategy. It doesn't literally mean there's a pill in the pocket but the idea is he carries around pills specifically a medication called fleconide and then if you know it depends on the patient whether they're able to identify the symptoms they're otherwise well they don't have any structural heart disease and so on. But if he if he develops symptoms and he's confident it's a new episode of atrial fibrillation he can take the fleconide and that should kind of cardiovert him back to sinus rhythm and he'll be okay from then on. And then let's say it happens again a few weeks later he can do the same thing. So this is a pill in the pocket approach. And the final question I have is what additional consideration do we need for this 70 year old man who's got paroxysmal atrial fibrillation so the final consideration is anticoagulation. Again this depends on the Chad's VAS score. So even with paroxysmal atrial fibrillation patients still need to be assessed for whether they need anticoagulation to reduce the risk of stroke so thanks for listening to this episode on atrial fibrillation hopefully it was super helpful for you and remember if you're sitting your AKT exam anytime in the next six or twelve months think about the resources which is the AKT revision book then there's the zero to gp.com website and the AKT revision course coming up in September in London. And I hope to see you in the next episode which will be in about a week's time