What is Atrial Stunning?
MELBOURNE, AUSTRALIA. Cardioversion and radiofrequency catheter ablation are often followed by a phenomenon known as atrial stunning. This condition involves a transient mechanical dysfunction of the left atrium and left atrial appendage (LAA) and is associated with an increased risk of post-procedure ischemic stroke, failure of improvement in cardiac output, decreased exercise tolerance, and an increased risk of arrhythmia recurrence. The degree of stunning can be measured with transesophageal echocardiography (TEE) and involves comparison of LAA emptying velocity (LAAEV), LAA emptying fraction (LAAEF), and the extent of the development of new or increased spontaneous echocardiographic contrast (SEC) after the procedure. SEC is defined as the appearance of swirling clouds of echodensity on the TEE.
Fish Oil Supplementation Reduced Extent of Atrial Stunning in Patients
A group of researchers at the University of Melbourne report that supplementation with fish oil for at least 30 days prior to cardioversion or catheter ablation markedly reduces the extent of post-procedure atrial stunning. Their trial involved 49 patients scheduled for cardioversion of persistent atrial fibrillation (34 patients) or ablation of atrial flutter (15 patients). Only 18% had underlying heart disease, so 82% had lone AF or flutter. The patients were divided into a control group (26 patients) and a fish oil group in which 23 patients received 6 grams/day of natural fish oil [providing 1080 mg/day of eicosapentaenoic acid (EPA) and 720 mg/day of docosahexaenoic acid (DHA)] for a minimum of 30 days prior to their procedure. Due to scheduling problems fish oil supplementation was actually done for an average (mean) of 70 days. The researchers observed the following differences in LAAEV, LAAEF, SEC, and degree of atrial mechanical stunning when comparing results obtained immediately before the procedure with those obtained immediately after.
* New or increased presence of SEC
The researchers conclude that fish oil supplementation for a minimum of 30 days prior to procedures aimed at restoring sinus rhythm is highly effective in preventing post-procedure atrial mechanical stunning (82% reduction in risk). They speculate that reversion to sinus rhythm leads to an acute calcium deficiency implicated in a loss of contractile function. Fish oil is known to modulate L-type calcium channels to reduce fluctuations of concentration in heart cells.
Kumar, S, Sparks, PB, et al. Effects of chronic omega-3 polyunsaturated fatty acid supplementation on human atrial mechanical function after reversion of atrial arrhythmias to sinus rhythm. Heart Rhythm, Vol. 8, May 2011, pp. 643-49