[Injectable and oral cibenzoline in the treatment of supraventricular tachycardia related to intranodal reentry or accessory atrioventricular conduction pathway].

Cibenzoline, a Vaughan-Williams Class I antiarrhythmic agent, was studied in 26 patients with orthodromic supraventricular tachycardia (SVT) by nodal reentry (n = 10) or an accessory pathway (AP) (n = 16). IV cibenzoline accelerated sinus rhythm, prolonged PR, AH, HV and QT, widened QRS and depressed or blocked anterograde and retrograde conduction in the accessory pathway, significantly, without significantly modifying conduction capacity in the AV node, nor atrial, nodal or ventricular refractory periods. It converted 6/10 of nodal reentries and 9/16 of reentries due to an AP, by a mean dose of 1 mg/kg, in 2 to 3 minutes, in 12 cases out of 16 by blocking retrograde conduction in the reentry circuit. It prevented reinduction of 12 of the 26 cases of SVT, significantly slowing the cycle of induced SVT in other patients. Oral cibenzoline (260 to 390 mg/day) prevented induced SVT in 11 cases out of 25 and spontaneous SVT in 14 cases out of 26, with a follow-up of 11 +/- 4 months (6 to 16), and this regardless of the reentry mechanisms. Intravenous cibenzoline was not associated with any clinical or hemodynamic intolerance but there was facilitation of episodes of SVT in one patient. Oral administration caused only one case of digestive intolerance, leading to lowering of the dose. Plasma levels showed no significant differences between successes and failures, for both the injection and oral formulations of cibenzoline, whether in terms of the conversion or prevention of episodes. Electrophysiological investigations had a 60% positive and 50% negative predictive value, a sensitivity of 64% and a specificity of 50%. Cibenzoline thus appears to be useful for the conversion and prevention of episodes, SVT, regardless of the reentry circuit, and seems justified, in view of its good safety/acceptability, as first line treatment in this diagnostic indication, measurement of plasma levels and electrophysiological investigations being of little apparent value in terms of guiding treatment and predicting its results.