Atrial fibrillation in intensive care units

Abstract

Summary Atrial fibrillation (AF) is an abnormal irregular heart rhythm whereby electrical signals are generated apparently randomly throughout the atria. It is the most common of all cardiac arrhythmias. The occurrence of AF has been poorly studied in general intensive care units (ICUs), but extensively studied in the postoperative period, when it is a cause of admission to surgical ICUs (S-ICUs) or can delay patient transfer from S-ICUs. The most frequently identified risk factors are increased age, valvular heart disease, atrial enlargement, preoperative atrial arrhythmias, and chronic lung diseases. Ischaemic heart disease is probably the most common cause of AF, followed by hypertension, rheumatic heart disease, thyrotoxicosis, cardiomyopathy, mitral valve disease, haemochromatosis and infection (e.g. pneumonia or systemic sepsis). The onset of AF or faster rates of chronic AF may be precipitated by acid–base disturbances, electrolyte abnormalities (in particular, hypokalaemia or hypomagnesaemia), hypovolaemia, myocardial ischaemia, and surgical manipulation in the thorax. Postoperative AF resolves spontaneously in most patients, but can recur. Two main therapeutic strategies can be adopted in perioperative AF: rhythm control and rate control. The former is based on electrical or pharmacological treatment, while the latter is only pharmacological. No clear superiority has been pointed out by comparative studies, but the choice is influenced by clinical conditions. Rhythm control strategy should be chosen in the presence of contraindications to anticoagulation, which is indicated if spontaneous conversion to sinus rhythm does not occur within 48h.