Methods: The patients are allocated to 3 months treatment with supplements of 2 g n-3 PUFAs or placebo (olive oil). The following data are registered at baseline and after 3 months treatment: Demographics and medical history, Standard ECG-12, blood pressure, blood samples, 48 hours ambulatory ECG Holter recordings, Intake of n-3 PUFAs (assessed by questionnaires and blood measurements).