Dronedarone in the prevention of atrial fibrillation. Safe use of dronedarone in the prevention of atrial fibrillation (AF) requires careful patient selection and regular follow-up. Before the treatment is started it must be ensured by echocardiography that the patient does not have heart failure. Furthermore, liver and renal function tests have to be checked. If plasma alanine aminotransferase (ALT) concentration is more than 3-fold the upper normal reference range limit, dronedarone must not be started. If ALT concentration during follow-up increases to at least 3-fold the upper normal limit, it must be controlled within 2 to 3 days. If the concentration is still increased, the drug is stopped. Dronedarone affects the renal function very little, but plasma creatinine concentration may increase because the drug competes with creatinine excretion in the kidneys. Plasma creatinine is determined before the treatment is started and one week after the start. If the concentration is increased, the test is repeated at 2 weeks from the start. Clinical assessment including ECG is performed at a frequency of at least every 6 months. Liver enzyme (ALT) concentrations are initially checked frequently: ALT concentration is determined at one week, at one month, then at 2, 3, 4, 5, 6, 9 and 12 months from the treatment start. Thereafter, the tests may be taken at longer intervals. If symptoms or findings suggesting heart failure or pulmonary dysfunction are detected during follow-up, echocardiography and/or pulmonary function test are performed without delay, and the medication is stopped if necessary. Dronedarone is contraindicated in permanent AF, and it is stopped if AF turns chronic during treatment. In practice, also the monitoring of INR values and digoxin concentrations has to be intensified after the initiation of dronedarone treatment. Source: Finnish Current Care Guideline 2017.