Mitral valve prolapse, arrhythmias and sudden death.

Some of the classical concepts of mitral valve prolapse (MVP) should be rev iewed in the light of recent publications. It is a condition, according to strict echocardiographic criteria excluding near physiological abnormalitie s, which affects 2 to 3% of the adult population in the industrialised worl d. Only repetitive atrial arrhythmias and complex ventricular arrhythmias are more common in this condition than in control groups, the differences being more pronounced in cases of mitral regurgitation. The risk of syncope or s udden death is 0.1% per year, hardly any different to that of the rest of t he general adult population (0.2%). However, this risk may attain 0.9 to 2% in cases with mitral regurgitation. The causes of sudden death are unclear (haemodynamic. neurohumoral, arrhythmic, etc...), although there is eviden ce in favour of malignant Ventricular arrhythmias. Detailed clinical, elect rophysiological, isotopic and anatomopathological studies have raised doubt s as to the direct responsibility of the vascular malformation (or its even tual consequences on the atrial and ventricular chambers) in this mode of f atal outcome. On the other hand, localised or diffuse myocardial disease is often observed, usually a- or pauci-symptomatic, associated with MVP, the responsibility of which is more plausible. Therefore, the physician should adopt a flexible attitude towards these pat ients, reassuring those with benign symptoms at low risk and following up o r actively treating the rarer malignant forms (especially familial, syncopa l with mitral regurgitation and/or severe arrhythmias).