Most people have one or more abnormal heartbeats from time to time. Whether they come alone or in pairs, they are usually called ectopic beats or extra beats. Some people can have many thousands in 24 hours without feeling any discomfort, while others notice every single one.
What do ectopic beats feel like?
The feeling is often described as the heart skipping a beat, stopping for a moment or beating extra hard. The explanation is that an ectopic beat usually comes earlier than the next normal heartbeat would have. The following normal beat is then delayed, giving the heart more time to fill with blood. This beat becomes extra forceful because it pumps out a lot of blood.
Ectopic beats can come from both the atria and the ventricles. They are usually caused by heart cells that for various reasons are “irritable” and fire off a few extra impulses (increased automaticity).
Ectopic beats from the atria
Ectopic beats from the atria are normal, but can still cause discomfort in some people. For those who are bothered, a thorough examination and reassurance that this is not dangerous often helps. Sometimes that is not enough, and then it may be reasonable to try medication. Usually a beta blocker or a centrally acting calcium antagonist such as verapamil is tried. Although these rarely cause serious side effects, one should consider whether treatment is right, since the condition is benign to begin with. Flecainide is probably more effective than these at reducing symptoms, but carries a slightly increased risk of side effects in predisposed people. In my view it should only be used exceptionally for ectopic beats from the atria.
Now and then we receive referrals for ablation of ectopic beats from the atria. It is nevertheless very rarely done. Except in some special cases, it is difficult to locate the focus of the ectopic beats with current technology, so the chance of success is often limited. This must be weighed against the ever-present risk of complications from the procedure (see atrial fibrillation and atrial tachycardia). There will rarely be a reasonable balance between the chance of relieving symptoms and the risk of complications.
Ectopic beats from the ventricles (PVCs)
Ectopic beats from the ventricles are called premature ventricular contractions (PVCs) or ventricular extrasystoles. In theory they can come from any part of the ventricles, but some sites are more common than others. The most common location is the area in the right ventricle where blood is pumped out to the pulmonary artery (Right Ventricular Outflow Tract, RVOT). Slightly less common is the area just behind it, where blood is pumped from the left ventricle into the aorta (Left Ventricular Outflow Tract, LVOT).
Foci next to these areas are also not uncommon, for example from the top of the left ventricle or around the mitral valve. What ectopic beats from these areas have in common is that we usually find nothing else wrong when the heart is examined. They are then called idiopathic, which means “of unknown cause”.
The shape of the ectopic beats in the different leads shows where in the heart they come from.
Some people can have tens of thousands of ventricular ectopic beats per day without noticing them. They should nevertheless be followed up regularly at a hospital or by a cardiologist. Very frequent ventricular ectopic beats can over time reduce the pumping function of the heart and cause heart failure. If this is the case, or if the beats are troublesome, there may be reason to start treatment.
Treatment with medication
We usually try a beta blocker first. It is often effective, but can cause side effects. Another beta blocker can then be tried. Some are better tolerated than others, and there are individual differences. Some types of ectopic beats can be effectively stopped by verapamil. They are called verapamil-sensitive. We also sometimes try flecainide with good response.
Ablation
Some patients with ectopic beats are considered for ablation. This is easier if the referral contains the results of investigations at a hospital or by a cardiologist. Exercise ECG, long-term ECG, ultrasound of the heart and sometimes cardiac MRI can provide useful information. A 12-lead ECG showing the ectopic beats must be included with the referral. It gives valuable information about where the focus of the ectopic beats is located.
If we are reasonably confident that the focus is in the RVOT, the threshold for doing the procedure is lower than if we think it is in the left side of the heart. In that case we usually want more ectopic beats and a more stable number of them before we start, and it may be wise to try more aggressive medication first.
How it is done
If we believe the focus is in the RVOT, the right groin is anaesthetised and the veins are punctured, usually in three places. From here three catheters are passed up to the inside of the heart. Two are placed in specific positions, and the third is advanced to where blood is pumped from the right ventricle to the pulmonary artery. It is first used to create a three-dimensional model of the area in the computer.
If there are enough ectopic beats, we can use the best mapping method, an activation map. We then look for the site where the electrical signals causing the ectopic beats appear earliest. If we are lucky, we find a small area from which the signals spread outwards (centrifugal activation). If this area is ablated, the ectopic beats often disappear for good.
Unfortunately it is often not that simple. The ectopic beats may disappear before we have mapped well enough. We can then continue by pacing from the catheters and comparing the paced beats with the troublesome ectopic beats. This is called pace mapping. It is not as precise as an activation map and carries a higher risk of recurrence.
Ectopic beats from the left side of the heart
If the focus is in the left side of the heart, we must gain access there. This can be done by puncturing the wall between the right and left atrium and continuing to the left ventricle through the mitral valve. If the focus is where blood is pumped out into the aorta, the catheter must make several turns, which makes manoeuvring more difficult. It is often easier to puncture the artery in the groin (after good local anaesthesia) and follow the aorta up and, if needed, into the heart.
From the left side of the heart, large blood vessels lead directly to vital organs such as the brain. Both the equipment we introduce and the ablation itself can trigger blood clotting. To prevent clots, we give a blood thinner (heparin) directly into the bloodstream as soon as we are on this side. This gives effective protection, but increases the risk of bleeding. If that happens, the patient can become very unwell, but we have a large and capable team to help us. Lasting harm is rare, and the vast majority do well.
This is why we have a somewhat higher threshold for trying to ablate ectopic beats from the left than from the right side of the heart. The patient must be troubled by symptoms, and there should be many ectopic beats, preferably from a single focus. Previously we wanted the patient to have tried at least one potent antiarrhythmic drug before considering ablation. Under the international guidelines from 2022, this carries less weight.
Before and after
The patient should be well informed. The doctor at the hospital explains what is planned, but we also expect the referring doctor to have provided thorough information. That is an important reason why referrals usually come from specialist services.
The procedure usually lasts 3–5 hours, and many find it demanding. We relieve discomfort as best we can, with a doctor and nurse present and with sedatives and painkillers. But medicines have side effects, and if we give too much, the ectopic beats sometimes disappear, so that we cannot map well enough to attempt treatment.
After the procedure you usually have to stay in bed for 3 -4 hours. You can eat and drink as soon as you feel up to it, and are usually discharged the next day. A follow-up with the referring doctor after a few months is often appropriate.
Ectopic beats and heart rate monitors
Ectopic beats cause large jumps in the time between heartbeats. This disturbs measurements of heart rate variability (HRV) from watches and chest straps, and can give falsely high values. Read more under Pitfalls in HRV measurement.