Initiation of Class IC antiarrhythmic medication and monitoring of the patient. Before medication with Class IC drugs is started it must be ensured by echocardiography that the heart is structurally healthy. Exercise stress test should always be performed if coronary artery disease cannot otherwise be definitely excluded. In selected cases, the exercise stress test can be performed after the pharmacotherapy has become stabilized, with the aim of identifying patients with susceptibility to proarrhythmia and patients who are so-called slow metabolizers. Source: Finnish Current Care Guideline 2017.