Atrial fibrillation (AFib) is an irregular and often rapid heart rhythm that can increase the risk of stroke, heart failure, and other complications. In critical care, healthcare providers work to control the heart rate, restore normal sinus rhythm when feasible, and administer treatments to prevent complications like blood clots. The treatment of AFib in this setting typically involves heart rate reducing agents that allow the patient to convert to sinus rhythm. Close monitoring and specialized interventions are integral to managing atrial fibrillation effectively.
Atrial Fibrillation
Postoperative Atrial Fibrillation
Postoperative Atrial Fibrillation
Role of Adrenergic (Sympathetic) Stress in Atrial Fibrillation (AF)
Sympathetic nervous system activation via adrenergic neurotransmitters plays a significant role in the development and perpetuation of AFib, particularly during periods of high physical or emotional stress.1
Release of catecholamines as part of the fight or flight response, affects cardiac automaticity, atria ectopy, and heterogeneity of atria conduction.2
Catecholamines bind β-adrenergic receptors (β-ARs) on cardiomyocytes triggering a signaling cascade that results in an increase in heart rate and conduction velocity along with an increase in force of contraction and speed of relaxation.1-3
Adrenergic stimulation contributes to the mechanism of reentry—where an electrical impulse circles continuously rather than following a normal path—by affecting electrical conduction and excitability within the atria. As such, it can enhance the variability of electrophysiological properties across the atrial tissue.2
Excessive β-AR stimulation is associated with electrophysiological abnormalities, sometimes leading to serious disturbances in cardiac rhythm, particularly in the setting of underlying cardiovascular disease.3,4
Postoperative Atrial Fibrillation (POAF)
Postoperative atrial fibrillation (POAF) affects nearly 40% of patients and is associated with longer hospitalization stays, and increased mortality, heart failure, stroke, and healthcare costs.3
POAF is a manifestation of numerous factors. The release of systemic and local inflammatory cytokines, which can change electrical properties of atrial tissue.1,2,4
Surgical stress, anesthetic stress pain, hypotension, pain and anxiety can lead to a surge in catecholamines, which can trigger abnormal electrical firing in the atria.4
Surgery is frequently associated with blood loss and fluid shift, anemia, hypovolemia or hypervolemia and electrolyte disturbance, which can trigger POAF.3
In cardiac surgery, heart muscle may experience temporary ischemia and subsequent reperfusion injury, which can cause oxidative stress and transient pro-arrhythmic effects on atrial tissue.1-3
Importance of Blunting of Adrenergic Stimulation in POAF
β-blockers (e.g., Metoprolol, Bisoprolol, Atenolol, Carvedilol, Esmolol) are the cornerstone of POAF management, generally considered first-line therapy for rate control and are recommended by guidelines.4,5
β -blockers slow conduction of electrical signals through the atrioventricular (AV) node, thereby reducing the number of impulses that reach the ventricles and slow the heart rate.5
These drugs are particularly effective in reducing AFib incidence in high-adrenergic states, as in patients after cardiac surgery.1
Some β-blockers with class III antiarrhythmic properties are also used to maintain sinus rhythm after electrical or chemical cardioversion.5
References:
- Grandi E, Ripplinger CM. Antiarrhythmic mechanisms of beta blocker therapy. Pharmacol Res. 2019 Aug;146:104274. doi: 10.1016/j.phrs.2019.104274.Epub 2019 May 14. PMID: 31100336; PMCID: PMC6679787.
- Carnagarin R, et al. Sympathetic Nervous System Activation and Its Modulation: Role in Atrial Fibrillation. Front Neurosci 2019; 12-2018. doi.org/10.3389/fnins.2018.01058
- Shah, S.; Chahil, V.; Battisha, A.; et al. Postoperative Atrial Fibrillation: A Review. Biomedicines 2024, 12, 1968.
- Muehlschlegel JD, Burrage PS, Ngai JY, et al.. Society of Cardiovascular Anesthesiologists/European Association of Cardiothoracic Anaesthetists Practice Advisory for the Management of Perioperative Atrial Fibrillation in Patients Undergoing Cardiac Surgery. Anesth Analg. 2019 Jan;128(1):33-42. doi:10.1213/ANE.0000000000003865. PMID: 30550473.
- Van Gelder Isabelle C, Michiel Rienstra, Karina V Bunting, et al. Scientific Document Group , 2024 ESC Guidelines for the management of atrial fibrillation developed in collaboration with the EuropeanAssociation for Cardio-Thoracic Surgery (EACTS): Developed by the task force for the management of atrial fibrillation of the European Society ofCardiology (ESC), with the special contribution of the European Heart Rhythm Association (EHRA) of the ESC. Endorsed by the European StrokeOrganisation (ESO), European Heart Journal, Volume 45, Issue 36, 21 September 2024, Pages 3314–3414.
- Diaconu CC, Marcu DR, Bratu OG, Stanescu AMA, Gheorghe G, Hlescu AA, Mischianu DLD, Manea M. Beta-blockers in Cardiovascular Therapy: AReview. J Mind Med Sci. 2019; 6(2): 216-223. DOI: 10.22543/7674.62.P216223