Abstract 18299: Are Omega-3 (Fish Oil) Supplements Proarrhythmic?
Data from clinical trials evaluating the benefits of fish oil (omega-3 polyunsaturated fatty acids, ω-3 PUFA) supplements on sudden cardiac death have been variable; some studies reported reduced cardiac mortality while others reported either no benefit or increased adverse events. An explanation for these variable results remains to be determined.
Methods: Post-MI dogs in which ventricular fibrillation could not be induced by acute ischemia during exercise (VF-) were assigned to ω-3 fatty acid ethyl esters (1–4 grams/day for 3 months, n=13) or matched corn oil supplements (n=11). Post-treatment, arrhythmia inducibility was re-evaluated with the exercise + ischemia test followed by left ventricular myocyte isolation. Perforated whole cell patch clamp recordings were used to elicit action potentials (T=35±0.5°C).
Results: The exercise + ischemia test failed to induce arrhythmias in any placebo treated animal. In marked contrast, this test provoked VF in 4 of 13 ω-3 PUFA treated dogs; in addition 1 dog died spontaneously during the treatment period (p<0.05 vs. placebo). There were no differences in the myocyte action potential duration at 90% repolarization (APD90) between the untreated VF- group and normal (non-infarcted) controls. All myocytes from ω-3 PUFA treated VF- animals exhibited a significantly longer APD90 (Figure). The longest APD90s were noted in myocytes from VF- dogs that developed arrhythmias after ω-3 PUFA treatment (VF-/+), significantly longer (P<0.05) than the APD90 of myocytes from untreated VF- or normal controls.
Conclusions: Chronic ω-3 PUFA treatment prolonged myocyte repolarization and increased inducible VF in a subset of post-MI dogs that were previously resistant to malignant arrhythmias. These data suggest that in the setting of a healed infarction and acute ischemia, ω-3 PUFAs could increase the risk for lethal arrhythmias as a consequence of these alterations in ventricular repolarization.
- © 2010 by American Heart Association, Inc.