Professor Ronan Collins
Clinical lead for Stroke, Co-Director of Atrial Fibrillation Clinic Tallaght Hospital, Dublin
Atrial fibrillation is a leading cause of stroke. Unfortunately, many people have no symptoms — so we all need to be more aware of it and the treatment options available to us.
The good news is that we are all living longer, says Professor Ronan Collins, national clinical lead for stroke and co-director of atrial fibrillation clinic and at Tallaght Hospital, Dublin. The challenging news is that, as we age, our chances of developing age-related diseases and disorders increases. One of these age-related conditions is atrial fibrillation (AF), a heart rhythm irregularity that shouldn’t be ignored as it is a major risk factor for stroke.
“Atrial fibrillation is the commonest rhythm disorder affecting the heart,” explains Professor Collins. “Around 5% of people over the age of 60 have it, and around 10% over the age of 75 have it. As populations age, we will see an increase in the numbers of AF cases.”
The heart is both a mixer and a pump for our blood. In AF, the atria — the ‘mixer’ and upper chamber of the heart — is affected by rhythm abnormality and no longer mixes blood effectively. “There is then a possibility that clots can form” says Dr Collins. “If these clots form and fall out of the mixer into the ventricle (‘pump’ and lower chamber) they can be pumped around the body and may jam in a small blood vessel, obstructing blood flow. As one of the first major blood vessels leaving the system travel to the brain, the clot formed in AF causes frequently interrupts blood flow to the brain, causing stroke; occasionally such clots may travel to affect circulation to limbs, gut and other organs such as kidney, causing significant damage.”
Sometimes, atrial fibrillation has no symptoms
People with AF may have few, or even no symptoms, making diagnosis complicated. “Occasionally, if the rhythm irregularity quickens, it may be felt as a palpitation or fluttering feeling in the chest,” says Professor Collins.
“This may be associated with breathlessness or even chest pain, or a feeling of light headedness and fatigue. At least half of all cases come and go intermittently, often referred to as paroxysmal atrial fibrillation.” Worryingly, however, the first and only symptom can be a when stroke occurs; which is why those with AF are usually prescribed blood thinners for life.
The higher your BMI and blood pressure, the harder your heart has to work
People who develop hypertension (high blood pressure) in younger life are also at an increased risk of developing AF. “Sustained hypertension results in the heart muscle becoming stronger and thicker,” says Professor Collins. “But this means the atria have to work harder, becoming larger and widening under stress, and this is often the first step to developing AF.”
Controlling blood pressure is therefore important, as is maintaining an ideal body weight, because the higher your body mass index, the harder your heart has to work, the stiffer the heart muscle becomes and the greater strain put on the atrium (‘the mixer’).
The higher a BMI, the harder the heart must work
People who develop hypertension (high blood pressure) in younger life are also at an increased risk of developing AF. “Sustained hypertension results in the heart muscle becoming stronger and thicker,” says Dr Collins. “But this means the atria have to work harder, becoming larger and widening under stress.”
Controlling blood pressure is therefore important, as is maintaining an ideal body weight, because the higher your body mass index, the harder your heart has to work.
Newer anticoagulants reduce haemorrhage risk
There are a number of treatment options for AF patients, both to restore the rhythm of the heart and prevent the major complications such as stroke. These include Direct Current Cardioversion, which administers a brief electric shock to get the heart back into a regular rhythm; a more invasive procedure called an ‘ablation’ where a catheter is placed into the atrium of the heart, to detect and then ablate or neutralise the area of abnormal electrical activity causing the irregular rhythm. However, the chances of direct current cardioversion or an ablation working or leading to sustained normal rhythm with age and certain other factors.
Drugs known as anti-arrhythmics are often used to maintain the normal rhythm once restored or regulate the rate so that the AF doesn’t go too fast causing symptoms. This often leads to better pump function and the patient feeling better. B-Blockers are one example of such drugs. Perhaps the most important drugs in AF, are agents known as anticoagulants which are used to prevent the major risk of AF, i.e. clot formation and stroke. Older anti-coagulants such as warfarin, tended to produce variable levels of blood thinning at various times in individual patients requiring very regular monitoring. They had many interactions with diet and drugs and as such were not ideal for the population most in need of protection in AF, i.e. older people. “Newer anticoagulants are more reliable,” says Professor Collins and are the drugs of choice recommended by the major professional bodies.
“More crucially, the newer drugs are safer in terms of reducing the risk of bleeding to the brain. When it comes to prescribing anticoagulants, most clinicians follow guidelines from the European Society of Cardiology (ESC), which advises on the threshold of risk and agents of choice to prevent stroke In AF. ESC firmly recommends the use of newer agents, sometimes referred to as Non-Vitamin K Oral Anti Coagulants (NOACS). As clinicians, it is vital to explain to patients the range of AF treatment options and the risks of stroke and bleeding they present in a language patients can relate too”.