Interview conducted by April Cashin-Garbutt, BA Hons (Cantab)
Please could you explain what cardiac arrhythmias are?
Cardiac arrhythmias are disturbances of the heartbeat. The heart can either go too slowly, which might make people collapse or exhausted; or too quickly.
We can fix slow heartbeats essentially across the board with pacemakers. Rapid heartbeats come with a broader range of implications and some causes cannot be fully resolved at the moment. They can have all sorts of impacts on people’s health. Rapid heartbeats (tachycardias/fibrillations) can shorten lives and so there is a tremendous opportunity to develop better treatments.
Are there many different types of cardiac arrhythmia?
If we focus on the rapid heartbeats, there are two main categories that are unresolved. One is atrial fibrillation, which is an irregular rhythm of the upper chambers of the heart. The other is ventricular fibrillation, which is a rapid uncontrolled rhythm of the lower chambers of the heart.
With ventricular fibrillation, if an individual suffers this rhythm and it is not resolved within a 4 minute window, then the person dies. With atrial fibrillation, if that is not properly managed then the main consequence to the patient is the risk of a stroke.
How many people are cardiac arrhythmias thought to affect? Is this number on the rise?
Cardiac arrhythmias are more or less universal: if you ask people 'if in the last year have you had any disruption in your heartbeat?', about a quarter would tell you they’ve felt some extra beats, sustained beats or something unusual.
In terms of having big impacts, if you are 40 years of age, the chance of having atrial fibrillation in your life time is about 1 in 4. Looking at ventricular fibrillation (VF), about 70,000 people drop dead each year in the UK of VF and in the US, we think it is about 400,000 people.
How much is known about the causes of cardiac arrhythmias?
I think in general terms you could categorize them into people who have got known pre-existing heart disease and those who do not. In the former category there is an increased risk of cardiac arrhythmias across the board. For example, if you’ve got coronary heart disease, or if you’ve got a heart muscle disease or a disease causing heart failure, you will have an increased risk of an arrhythmia.
The other category of people is the group with no pre-existing history of heart disease. In those patients, when arrhythmias occur there may be a higher chance of a primary genetic influence. When you investigate those people, you may find that they have evidence of structural heart disease, but in some people you may find there is no change in the structure of the heart, there is no evidence of coronary heart disease, the arrhythmia simply occurred of itself. The approach to this group varies and may require simple reassurance in the majority. Only a small but important minority will have a cause with potentially significant and risky implications.
How are cardiac arrhythmias diagnosed?
To my mind, arrhythmia diagnosis and management has got many aspects of a more traditional approach to medicine: you go along to your doctor and tell him your history, your story. He will do a simple examination, which may not involve all that much, as at the time you visit, you may not be experiencing the symptoms.
The doctor will probably do an electrocardiogram that might indicate that you have a heart issue but it might be normal. Then, the doctor might do some recordings of the heartbeat by placing an ECG monitor on which you wear for 24 hours to try and capture one of these events.
These are the ways in which cardiac arrhythmias are diagnosed. I think the thing to emphasize is much of what the cause is might come from the history – that is from the correct interpretation of your responses when the doctor asks you about your symptoms.
How are cardiac arrhythmias treated?
There are a range of treatments. In our field there are three basic categories of treatment and I think this sort of breakdown might also apply to many other branches of medicine:
One is to use drug treatment – the problem with arrhythmias is that the drugs are not terribly good because they were developed years ago when we didn’t have a clear idea of mechanisms. Even though they can be effective in some patients, they often have side effects and potentially significant other toxicity issues attached.
The second category is that of ablation – this has caused a lot of interest and excitement because people having an ablation may be cured of an arrhythmia. There are not many things in cardiology that can provide a cure, but for certain forms of arrhythmia, just through the application of a quick, simple ablation procedure a cure can be obtained.
The third category of treatment is that of device therapy. That includes pacemakers for slow heartbeats and defibrillators for rapid heartbeats that may put an individual's life at risk.
How do you think the future of cardiac arrhythmia treatment will develop?
The point that we strongly emphasized in the Lancet series is that we need to know more about mechanisms. We need to understand more about why people get arrhythmias. Then we need to look at the basis of that arrhythmia using the fully panoply of modern biology, using genetics, genomics, using a systems approach that may encompass computerized models, animal models and stem-cell based models.
Using model systems we will be able to work out more about the mechanisms. In addition, if we have systems that model arrhythmias then we can add things like drugs to see if we can 'rescue' the situation, to see if we can correct the rhythm in the model. Then if we can apply that in patients we might find that it makes the rhythm better. If it makes them better without much in the way of side effects, then it might provide a new treatment.
Where can readers find more information?
They can access the Lancet series here: http://www.thelancet.com/series/cardiac-arrhythmias
They can find out more information from the Atrial Fibrillation association: http://www.atrialfibrillation.org.uk/
And from the Arrhythmia alliance: http://www.arrhythmiaalliance.org.uk/
About Dr Andrew Grace
Dr. Andrew Grace’s main specialty is Cardiology with sub-specialties in Atrial fibrillation, Cardiac Electrophysiology, implantation of pacemakers and defibrillators and Catheter ablation of cardiac arrhythmias. He trained in medicine at St Thomas’ Hospital in London completing his Ph.D. in Cambridge with post-doctoral studies as a Fulbright Scholar at the University of California.
Dr. Grace runs a large, productive group at the University of Cambridge and has a track record of publishing high quality research. His work is widely known and respected and he is regularly invited to participate in national and international research initiatives. His research has lead to tests for the prediction of arrhythmias.
He has also been centrally involved in the development of novel devices, catheters and drugs all of which are predicted to have substantial impacts on the treatment of arrhythmias. Dr. Grace has developed one of the largest clinical practices in cardiac arrhythmia management in the United Kingdom and specialises in catheter ablation techniques particularly for atrial fibrillation.
Dr. Grace is currently Consultant Cardiologist at Papworth Hospital NHS Foundation Trust, Honorary Consultant Cardiologist at Addenbrooke's Hospital, and Research Group Head in the Department of Biochemistry, University of Cambridge.
He is also a Fellow of the Royal College of Physicians, a Fellow of the American College of Cardiology, a Fellow of the European Society of Cardiology, Adjunct Professor of Medicine at Xi'an Jiaotong University, Peoples Republic of China, a Royal Air Force Civil Consultant in Cardiac Electrophysiology and a member of the Government’s Expert Advisory Group on Human Medicines
Dr. Grace lives in central Cambridge with his wife and four children.