The usefulness of esmolol in predicting the efficacy of treatment with an oral beta-adrenergic blocking agent was evaluated in 27 consecutive patients with neurocardiogenic syncope. Seventeen patients had a positive head-up tilt test response at baseline and 10 patients required intravenous isoproterenol for provocation of hypotension. All patients were then given a continuous esmolol infusion (500 μg/kg per min loading dose for 3 min followed by 300 μg/kg per min maintenance dose) and rechallenged with a head-up tilt test at baseline or with isoproterenol. Of the 17 patients with a positive baseline tilt test response, 11 continued to have a positive response to esmolol challenge. Sixteen patients (including all 10 patients with a positive tilt test response with isoproterenol) exhibited a negative response to upright tilt during esmolol infusion. Irrespective of their response to esmolol infusion, all patients had a follow-up tilt test with oral metoprolol after an interval of ≥5 half-lives of the drug. All 16 patients (100%) with a negative tilt test response during esmolol infusion had a negative tilt test response with oral metoprolol. Of the 11 patients with a positive tilt test response during esmolol infusion, 10 (90%) continued to have a positive response with oral metoprolol. It is concluded that in the electrophysiology laboratory, esmolol can accurately predict the outcome of a head-up tilt response to oral metoprolol. This information may be helpful in formulating a therapeutic strategy at the initial head-up tilt test in patients with neurocardiogenic syncope. © 1992.
Sra, J. S., Murthy, V. S., Jazayeri, M. R., Shen, Y. H., Troup, P. J., Avitall, B., & Akhtar, M. (1992). Use of intravenous esmolol to predict efficacy of oral beta-adrenergic blocker therapy in patients with neurocardiogenic syncope. Journal of the American College of Cardiology, 19(2), 402–408. https://doi.org/10.1016/0735-1097(92)90498-C