Introduction and objective: We present two families with atrial fibrillation in 20 of 50 members, during three generations, with known cardiac rhythms, in order to communicate their infrequent existence and the most relevant clinical facts.
Method: Clinical situation, evolution, ECG and ECHO findings, treatments and complications related with the disease are investigated.
Results: The presence of atrial fibrillation in 20 members is demonstrated, although one of them was on sinus rhythm at the time of the study; 3 patients had left ventricular enlargement on the ECHO study; the clinical situation was good in all patients except two who died because of complications related to the arrythmia and a third patient that had a brain stroke. The patients received different treatments because they where controlled by different physicians; the possible lethal proarrythmic effect in such cases must be taken into account.
Conclusion: Familiar atrial fibrillation is a very infrequent arrythmia, usually well tolerated, that follows a dominant autosomic hereditary pattern. The use of antiagregants is advised because of the risk of embolism, or the use of anticoagulants in the presence of associated risk factors. Electric cardioversion has been show not be useful. The possible proarrythmic effect of some antiarrythmic agents, used in the control of cardiac frequency, must be taken into account.