BACKGROUND: Atrial mechanical stunning is a form of tachycardia mediated atrial cardiomyopathy that manifests after reversion of persistent atrial arrhythmias to sinus rhythm.

OBJECTIVES: To examine if chronic omega-3 polyunsaturated fatty acid supplementation with fish oils can reverse atrial mechanical stunning.

METHODS: Patients undergoing reversion of persistent atrial fibrillation (AF) or atrial flutter (AFL) to sinus rhythm were randomised to a control group (n=26) or an omega-3 group (n=23). The latter were prescribed 6g/day of fish oil for ≥ 1 month prior to the procedure. Parameters of left atrial appendage function were compared immediately before and immediately after reversion.

RESULTS: After fish oil intake for a mean of 70 days, the following were noted favoring the omega-3 group amongst both, AF and AFL patients: (i) 2 fold higher serum omega-3 levels (P<.001) (ii) less mean fall in emptying velocity (eg. AF: 8% vs. 32%, P=.02) (iii) less mean fall in appendage emptying fraction (eg. AFL: 7% vs. 60%, P=.002) (iv) lower incidence of new or increased spontaneous echocardiographic contrast (eg. AF: 11% vs. 62.5%, P=.003) and (v) lower incidence of atrial mechanical stunning (eg. AFL: 20% vs. 100%, P=.001). Omega-3 intake was an independent negative predictor of stunning in a multivariable analysis (odd ratio 0.18, P=.02)

CONCLUSIONS: Chronic fish oil ingestion in humans attenuates atrial mechanical stunning after reversion of atrial arrhythmias to sinus rhythm. This suggests that fish oils may target or even reverse underling cellular and/or structural remodeling that occurs in response to persistent atrial arrhythmias.