Acute and chronic electrophysiological effects of pentisomide on the sinus and AV nodal function, noninvasive...

The acute and chronic electrophysiological effects on sinus function and AV nodal conduction of pentisomide (Pen), a new antiarrhythmic agent, were studied in ten patients with sick sinus syndrome (SSS) (group I) and in ten patients with normal sinus function (group II) using a permanent pacemaker with temporary pacing inhibition (Symbios 7005 Medtronic, Inc.). We measured noninvasively the corrected sinus node recovery time (CSNRT), the sino-atrial conduction time (SACT), according to Narula's method and the Wenckebach point before and after Pen administration, acutely and orally for 10 days. In group I intravenous injection (4 mg/kg) and oral administration (450 mg bid) of Pen significantly prolonged the CSNRT (+217% and +149%, respectively) and the SACT (+63% and +49%, respectively). In group II only the intravenous injection of Pen provoked a significant modification of CSNRT (+12%) and SACT (+14%). No modification in AV nodal conduction was noted in any patient. These results suggest that Pen must be used with caution in patients with sinus nodal dysfunction.