[The best of arrhythmias in 1999].

Recent studies of atrial fibrillation, or rather "atrial fibrillations", have been based on focal atrial fibrillation which seems to be one of the commonest forms of paroxysmal atrial fibrillation. This observation led to the possibility of ablative therapy, usually near the pulmonary veins. Technological advances are awaited before a wider diffusion of this therapy becomes possible. In the field of defibrillation, the MUSTT study demonstrated the value of implantable defibrillators in the prevention of sudden death, in this trial in the case of asymptomatic high risk patients after myocardial infarction, with a decreased ejection fraction and non-sustained ventricular tachycardia. Two large scale randomised controlled trials (MERIT-HF and CIBIS II) have confirmed the value of betablockers in preventing sudden death, in patients with moderate or severe cardiac failure in association with classical treatment by diuretics, ACE inhibitors and digitalis. Similarly, for spironolactone, the RALES study showed a reduced incidence of sudden death in cardiac failure, as its physiopathological modes of action suggested. New techniques of three-dimensional mapping have confirmed their value. Finally, significant progress has been made in the field of genetics of cardiac arrhythmias, indicating that, in years to come, it will be possible to identify most of the genes responsible for conditions predisposing to arrhythmias.