engleski

Prospective evaluation of infrahisal second-degree AV block induced by atrial pacing in the presence of chronic bundle branch block and syncope

The value of nonfunctional infrahisal second- degree atrioventricular (AV) block induced by incremental atrial pacing was prospectively examined in 192 patients with chronic bundle branch block (BBB) and syncope. We compared 174 (91%) patients with normal response to atrial pacing (Group I) to 18 (9%) patients with atrial induced nonfunctional infrahisal second-degree AV block (Group II). Patients in group I had higher incidence of organic heart disease, ventricular tachycardia induction, and retrograde ventriculoatrial conduction (P<0.001, P<0.05, P<0.01, respectively), while patients in group II had higher incidence of primary conduction disease and prolonged H-V intervals (P<0.001, P<0.01, P<0.001). During mean follow-up period of 65+-34 months for group I, and 68+-35 months for group II, a development of spontaneous second- or third- degree AV blok was higher in group II (14/18, 78%), than in group I (15/174, 9%)(P<0.001). The site of AV block was infrahisal in all patients in group II, and in 10 of 15 patients in group I. Because of the prophylactic pacing in all patients in group II, the incidence of sudden death was similar among the two groups, but patients in group I had higher incidence of cardiac death (P<0.05). Conclusion: In patients with BBB and syncope, a nonfunctional infrahisal AV blokc induced by incremental pacing identified patients with particulary high risk of development of spontanous infrahisal AV blokc- Therefore, permanent cardiac pacing is absolutely indicated in these patients.

infrahisal AV block ; atrial pacing ; bundle branch block ; syncope

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