Syncope associated with documented paroxysmal atrioventricular block reproduced by adenosine 5' triphosphate injection.

Aims: We sought to investigate in patients with syncope the relationship between documented paroxysmal atrioventricular block (AVB) of unknown mechanism and AVB induced by adenosine triphosphate (ATP) injection.

Methods And Results: We selected patients >45 years free of structural heart disease with syncope related to paroxysmal AVB documented by Holter or in-hospital monitoring, but without any trigger suggestive of vasovagal origin and with normal baseline electrocardiogram. Adenosine triphosphate test was performed according to the usual protocol.