ECGs of 861 patients in whom PS related to an atrioventricular accessory pathway (AP) was identified at electrophysiological study (EPS), were studied.
The most frequent unusual presentation (9.6%) was the PS presenting with a normal or near normal ECG, noted preferentially for left lateral AP and rarely for posteroseptal or right lateral location. More exceptional (0.1%) was the presence of a long PR interval, which did not exclude a rapid conduction over AP. The association of a complete AV block with symptomatic tachycardias was exceptional (0.3%) and was shown related to a rapid conduction over AP after isoproterenol. Most of the presented patients were at high-risk at EPS.
The diagnosis of PS is not always evident and symptoms should draw attention to minor abnormalities and lead to enlarge indications of EPS, only means to confirm or not PS.