I hope you’ve had a good week. It’s certainly a busy time of year for many people, myself included. In addition to Christmas, December brings both my children’s birthdays so added complexity! It’s enough to bring on palpitations!
I think this is week 3 now on the subject of palpitations, and whilst they are very common, I’m conscious they won’t apply to everyone. I thought therefore I would make this the last post for the current series on the subject (there will be plenty more time to add to this topic on the members site later) before pivoting next week to something new.
As a result therefore, I wanted to write about atrial fibrillation today, as it’s arguably the heart rhythm I get asked about most. AF for short, is very common, affecting about 6% of people in their late 60s, increasing with age to 20% by age 80. It is more common in men, and more common with any other heart disease, such as heart attacks, heart failure or inherited heart conditions. There are some other common risk factors, such as thyroid disease, alcohol, smoking and high blood pressure. It’s also very common in lifelong endurance athletes, and I would not be at all surprised if I get it in the future!
One of the main reason doctors worry about AF is the associated risk of a stroke. That risk is there, because of a small structure called the left atrial appendage. If a patient gets AF, this ear-shaped structure has the unfortunate ability to form a blood clot within it, which if it detaches, can move to the brain and cause a stroke. I use the analogy of a slow moving stream getting silted up – if the blood is not being cleared effectively because the heart is fibrillating, it is much more likely to form a clot in the appendage.
The risk is related to several features – a patient’s age, the presence of high blood pressure, structural heart problems such a heart failure, diabetes, a previous stroke, vascular disease, and gender. Doctors then use a scoring system to calculate the stroke risk, and this in turn informs the recommendation for a blood thinner. In years gone by we might have used aspirin on occasion, and commonly warfarin, but almost universally now we use drugs called DOACs (apixaban, edoxaban, rivaroxaban and dabigatran). This bring the stroke risk right down, but do increase the risk of bleeding. Your doctor will talk you though this if needed.
AF is an irregularity of the heartbeat. It typically originates in the pulmonary veins, which join the heart and lungs together. For some reason, they generate additional electrical signals which spread from the veins to the rest of the heart. The sino-atrial node (remember this from the anatomy diagram?) does not fire as it should, but the rest of the conduction system tissue in the ventricles works normally.
AF can come and go (we call this paroxysmal AF), but over time tends to become persistent, and then permanent. The investigations Cardiologists use are the same as for other arrhythmias, and so I will not go through them again here.
Treatment
The key question here is what are the patient’s symptoms. It often amazes me that two patients with the same heart rhythm problem can be so differently affected. Some have no symptoms whatsoever, some have really quite disabling symptoms, and everything in between. If a patient has few or no symptoms, it may simply be that stroke risk reduction with a blood thinner is all that is needed. For patients with symptoms that occur only infrequently, we have the option of ‘pill in the pocket’ treatment, where they can take a larger than normal dose of a heart rhythm drug on and as and when basis. For patients who have regular symptoms, regular medication is often needed.
Medication
The commonest drugs used are beta-blockers, rate-slowing calcium channel blockers, digoxin, flecainide and amiodarone. It is a huge topic to cover these in detail so will leave this also for another time, and I will add to the drugs section of the members area in due course.
Ablation
For those that either do not tolerate or do not wish to take medication, there may be the option of ablation. This is an interventional procedure, often under general anaesthetic, where a small tube called a catheter is advanced to the heart via the vein in the groin. A needle is used to make a hole from the right to the left side of the heart, and ablation energy (either heat or cold) is applied where the pulmonary veins join the left atrium. This has the effect of blocking future electrical signals from the veins spreading to the rest of the heart. Success rates vary on a number of factors, including the presence of structural heart disease, age, how long AF has been present for, and indeed the operator. Sometimes a second procedure is needed also.
Pacemakers
In a subset of patients, they have both very fast and very slow heart rhythms. In this case, we may take the approach of putting in a pacemaker to treat the slow ones, then either using drugs, or a very different kind of ablation (simpler – AV node ablation) to treat the fast ones.
I’m very conscious that whilst I try to keep things succinct, this post has rather ran on! I hope you have found it enjoyable and interesting, and look out for this month’s AMA and research blog up on the website today.