Occurrence
Atrial fibrillation is an arrhythmia that can occur once or twice in a lifetime under unfavorable circumstances as a symptom or consequence of other diseases (such as infections), electrolyte disturbances in the body, or alcohol abuse. But the arrhythmia can also be recurrent and then permanent. Atrial fibrillation occurs on average in 1-2% of the general population. With age, the risk of arrhythmias increases to 5% of people over 65 years of age and to over 10-15% – after 80 years of age. The incidence of atrial fibrillation is increasing with the aging of the population – by an average of 13% over the past two decades. In 2010, 21 million men and nearly 13 million women worldwide had atrial fibrillation. There are about 10 million patients with flicker in the European Union (out of 447 million), and there are 100-200 thousand new cases every year. This arrhythmia is the most common cause of hospitalization due to arrhythmias and, on average, it causes 7-10% of all urgent hospitalizations. The mean age of patients with atrial fibrillation is 75 years. In Poland, atrial fibrillation occurs in about 500-600 thousand. people. Unfortunately, arrhythmia has been shown to increase the risk of death: twice in women and 2 times in men. This is also because atrial fibrillation can be a symptom of an increase in advanced comorbidities (for more information, see https://www.dbamoserce.com/).
On the basis of its duration, we distinguish various forms of arrhythmia – fibrillation diagnosed for the first time, paroxysmal form – self-limiting or requiring moderation within 7 days, persistent form – lasting more than 7 days and long-term lasting for at least 1 year. The next stage is the consolidation of the arrhythmia – that is, permanent atrial fibrillation, occurring in 40-50% of patients, – accepted by the patient and the doctor. We recognize them when deviating from interventions aimed at restoring normal heart rhythm. In summary, the natural history of atrial fibrillation is characterized by a gradual increase in the frequency and duration of attacks. Initially, the arrhythmia becomes paroxysmal, then persistent, and finally, due to the inability to maintain the sinus rhythm, it is considered permanent. Often in the further course, due to the emerging impulse conduction disturbances from the atria to the ventricles, some patients will require the implantation of the pacing system. The problem is the growing socio-economic burden associated with the occurrence of arrhythmias.
The causes favoring the appearance of atrial fibrillation
In the last 20 years, great progress has been made in the diagnosis and treatment of atrial fibrillation. Undoubtedly, the main cause of this arrhythmia is arterial hypertension, especially under-treated and lasting longer – occurring in up to 75% of patients with atrial fibrillation. In Poland, arterial hypertension occurs in over 10 million people. Other causes of increased risk of this arrhythmia include old age, heart failure, congenital and acquired heart defects, changes in the heart in the course of chronic lung diseases, coronary artery disease, thyroid disease, obstructive sleep apnea, kidney failure, diabetes, cancer, mental (depression). As you can see, there are many potential causes. Genetic predisposition is also of great importance – this is indicated by more and more studies. However, there is a group of causes – risk factors that particularly facilitate the onset and recurrence of arrhythmias – that depend on us. You have to mention alcohol abuse, smoking, obesity, too intense but also insufficient physical effort (sedentary lifestyle), high exposure to chronic stress (more information on this subject can be found at https://www.dbamoserce.com/) .
Atrial fibrillation and thyroid disease
The results of observational studies of people over 60 years of age show that in patients with subclinical hyperthyroidism, the risk of developing atrial fibrillation may be up to 3 times higher compared to healthy people. Arrhythmia can occur in 10-20% of patients diagnosed with hyperthyroidism, more often in men. Its risk increases with age. It has been observed that after an average of 6 weeks of successful thyroid treatment, the heart rate returns to normal in most patients, but not in all of them in the later period.
What are the clinical symptoms of atrial fibrillation?
In 10-25% of cases, patients do not have symptoms of arrhythmia. For the rest, the symptoms may vary. Patients may report palpitations (40-50%), dyspnoea (30-40%), weakness (30-40%), chest pain, dizziness, fainting and / or fainting. In 15-30% of patients, symptoms significantly impair their functioning in everyday life. Heart rate is irregular in the presence of atrial fibrillation. Always confirm atrial fibrillation by ECG as there are other causes of irregular heartbeat such as supraventricular or ventricular premature accessory beats or atrial tachycardia with variable conduction of electrical impulses from the atria to the ventricles. Unfortunately, sometimes the first symptom of arrhythmia may be a stroke, heart failure or sudden cardiac death. The effects of long-term atrial fibrillation include increasing risk with age, risk of stroke, side effects of anticoagulants (bleeding), progressive heart failure, and cognitive impairment (for more information, see https://www.dbamoserce.com/).
Stroke
In Poland, there are an average of 70 strokes a year. Atrial fibrillation is the cause of about 20% of these, or one in 5-6 cases. They are five times more likely to have a stroke than the healthy population. The risk of stroke in this group of patients is assessed according to a scale taking into account additional risk factors such as old age, heart failure, hypertension, diabetes, previous stroke, concomitant cardiovascular disease, female gender. The more of these risk factors, the greater your risk of a stroke. The annual risk of stroke, depending on the presence of these risk factors, is 5-5%. The course and consequences of strokes in patients with atrial fibrillation are particularly severe due to the greater extent of brain tissue damage due to ischemia, and nearly half of them die after one year. Patients with asymptomatic (silent) arrhythmias are particularly prone to the occurrence of stroke, which is 20-25% of cases.
Why is this happening? During arrhythmias, there are unfavorable changes in the heart structures at the level of impulse conduction, secretion of hormones affecting the heart function and changes in the structure of the heart – enlargement of the dimensions of the heart cavities, left and right ventricular contractility disorders, dysfunction of the heart valves, which consequently can lead to heart failure. The amount of blood transfused by the heart is reduced by an average of 30%, which causes disturbances in the blood supply to the brain and other vital organs. Lack of effective atrial contraction causes blood to stagnate in the anatomical structure known as the left atrium appendage. This creates conditions for thrombus formation, which can cause ischemic strokes, accounting for 80% of patients with atrial fibrillation. Less common are haemorrhagic strokes – intracranial bleeding, which may be complications of anticoagulant therapy. Currently, we have 3 groups of anticoagulants used in the prevention of stroke. Older vitamin K antagonists require periodic blood clotting monitoring and dose adjustment. Non-vitamin K antagonists (NOACs), introduced a few years ago – in Europe since 2011, do not require clotting control and provide greater safety and effectiveness of treatment. In exceptional cases, heparin preparations can also be used.
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Author: Prof. dr hab. n. med. Rafał Dąbrowski
Cardiologist, internist
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