A new study suggests that eating lots of fish may increase the risk of atrial fibrillation in some people. However, according to the lead author, heavy fish eaters in the study are stil at less risk than others of sudden death from heart problems. Dr Anthony Aizer, an electrophysiologist at New York University Medical Center, says it is possible that omega-3 fatty acids may promote the development of atrial fibrillation in younger people but prevent it in older people who have other medical conditions.