This week, we continue our discussion on atrial fibrillation (Afib), the most common electrical conduction abnormality of the human heart.

It is proper that we devote enough attention to this heart rhythm abnormality given it’s ease of diagnosis and yet risk of significant complications and adverse outcome if undiagnosed and mismanaged. The risk of Afib is particularly significant for the elderly and those with longstanding poorly treated hypertension which is a common problem in our population.

How is Afib diagnosed?

Patients with atrial fibrillation can present with symptoms or it may be found incidentally. The most common symptom is that of palpitations which can be thought of as an awareness of an abnormal heartbeat. Patients can often describe that their heartbeat feels irregular. Other symptoms of atrial fibrillation may be related to the fact that the heart does not work efficiently when in this rhythm.

Patients may describe symptoms that may include shortness of breath, the inability to exercise normally or indeed may present with symptoms of overt congestive heart failure. Less common symptoms include dizziness and passing out or fainting. In some patients, atrial fibrillation does not manifest in any symptoms, and it is only discovered incidentally during an electrocardiogram (ECG), echocardiogram, or some other test where the cardiac rhythm is recorded. In fact, many blood-pressure monitors, or smart watches have the ability to recognise an irregular cardiac rhythm and notify the wearer resulting in them seeking medical attention.

From the point of view of the cardiologist, to diagnose atrial fibrillation, we need to see a recording of heart rhythm in which atrial fibrillation is documented. Unfortunately, the complaint of irregular heartbeats or palpitations is not sufficient as there are other heart rhythms that can result in these symptoms. If the patient is in atrial fibrillation all the time, “permanent or persistent atrial fibrillation”, a routine 12 lead electrocardiogram will suffice for diagnosis.

Patients, however, can have atrial fibrillation that is intermittent, “paroxysmal atrial fibrillation”. In this condition, atrial fibrillation comes and goes. The episodes can sometimes be quite brief (seconds to minutes) and long intervals of time may be present prior to the next episode (sometimes months to years). Diagnosis in these settings can be challenging and requires longer durations of monitoring. A Holter monitor allows for monitoring of the heart rhythm over 24 to 48 hours. Longer durations of monitoring can be done with loop recorders (up to 30 days) or implantable loop recorders. An implantable loop recorder is placed under the skin in the chest in a minor surgical procedure allowing monitoring of the heart rhythm over a period of 18 months to two years.

How do we evaluate and manage patients with atrial fibrillation?

As noted in our last article, atrial fibrillation is the result of changes in the structure of the atrial chambers. The causes of these changes are many and can be as simple as aging with the replacement of muscle tissue by scar tissue, or it may be as a result of heart disease. This is a process that often takes many years to evolve resulting in structural changes in the heart that affect electrical conduction in the heart.

Several research studies by investigators, including our team, have demonstrated that electrical conduction time across the upper chambers of the heart begin to slow down as these structural changes occur even before atrial fibrillation develops. These electrical conduction abnormalities tend to be more prominent in patients with hypertension, particularly the black hypertensives.

A diagnosis of atrial fibrillation thus requires that the heart be evaluated to see if any underlying heart disease is present along with evaluation for other miscellaneous conditions that can increase the risk for atrial fibrillation eg, overactivity of the thyroid gland. The testing that is done will depend on the patients age, risk factors and known cardiac disease, but ultrasound examination of the heart (echocardiography) and evaluation for coronary artery disease are commonly performed. Concurrent with evaluation of the heart, several other issues must be addressed. These include making sure that the heart rhythm is not too fast, decreasing the risk of stroke and deciding whether to try to maintain a normal rhythm.

Heart rate control is important in patients with atrial fibrillation.

Many patients with atrial fibrillation will have a heart rate that is inappropriately fast. This poses a problem in terms of patient symptoms, risk of damage to the muscle of the heart over long periods of time and a decrease in the efficiency of heart function. For most patients, the heart rate can be slowed down with medications. In a minority of patients, there is a need to do procedures to slow down the heart rhythm.

Atrial fibrillation puts you at risk for stroke

The most devastating complication of atrial fibrillation for most patients is the risk of stroke. In atrial fibrillation, there is a tendency for blood to clot in the left atrial chamber of the heart and for these clots to enter the bloodstream. Once there, they may travel to the brain and obstruct blood flow leading to stroke. The risk of stroke varies depending on several factors and may be low in a young person who has no other medical issues or may be as high as more than 20 per cent per year in patients with some types of mitral valve disease.

For patients who are at elevated risk of stroke, we use anticoagulant medications to “thin the blood” and make it less likely for clotting to take place in the heart. The use of these medications can reduce the stroke risk to that in the normal population but must be monitored closely to lower the risk of bleeding.

How important is it to maintain normal rhythm?

An important decision to be made in the patient with atrial fibrillation is whether to try to keep the patient in a normal rhythm or simply slow the heart rate. Some patients, particularly the elderly, will tolerate atrial fibrillation without symptoms and with a good quality of life. For these patients it may be enough to keep the heart rate slow and to give medications to prevent stroke. In other patients, symptoms may be bothersome or sometimes disabling. In these patients we attempt to keep the heart rhythm normal. The standard approach to this problem has been the use of medications to prevent heart rhythm abnormalities (anti-arrhythmic drugs).

Unfortunately, the success rate of this approach over the long term is somewhat poor. The best drug will maintain only about 40-50 per cent of the patients in a normal rhythm over five years. More recently, the use of procedures to alter the electrical properties of the heart, “Atrial fibrillation ablation”, have been shown to be superior with success rates of 70-80 per cent over five years in experienced hands.

Can we prevent AFIB, and how?

Given the strong role that age-related changes in atrial structure play in the genesis of atrial fibrillation, it is not likely that we can prevent atrial fibrillation in all patients, particularly the elderly. We can, however, do everything in our power to reduce the risk of heart disease that results in changes in the atria at younger ages. This would include lifestyle changes or medications to maintain a normal blood pressure and lower the risk of coronary artery disease. We have discussed these in previous articles but regular exercise, avoidance of weight gain, a heart healthy diet, avoiding smoking, the use of drugs or alcohol in excess are all important.

For patients who have been diagnosed with atrial fibrillation, recent data has suggested that losing weight, stopping smoking, treating sleep apnea and regular aerobic exercise can assist in decreasing the frequency of episodes of atrial fibrillation and potentially slowing progression.

Atrial fibrillation is the most common sustained abnormal heart rhythm and can result in significant complications for our patients, but diagnosis and appropriate therapy can allow most patients to live normal lives. If you think you may be at risk, please consult with your physician or a Cardiologist to assess your risk and provide guidance or treatment.

Dr Ernest Madu, MD, FACC, and Dr Paul Edwards, MD, FACC are Consultant Cardiologists at Heart Institute of the Caribbean (HIC) and HIC Heart Hospital

Dr Madu is a main TED Speaker whose TED talk has been translated into 19 languages, seen, and shared by more than 500,000 viewers. He has received the Distinguished Cardiologist Award, the highest award from the American College of Cardiology and has been named among the 100 most influential people in health care and among the 30 most influential in public health. Dr Madu is also a recipient of the Global Health Champion Award from the University of Pennsylvania. Dr Madu was past CEO of HIC and is currently the Chairman of IHS Holdings Ltd, an asset management company with interests in the USA, Africa, and the Caribbean.

Correspondence to info@caribbeanheart.com or call 876-906-2107.