Site-Specific Effects of Dobutamine on Cardiac Conduction and Refractoriness
Authors: Goldner Bruce , Ismail Haisam , Gabriels James , Chang David , Donnelly Joseph , Kim Beom Soo , Epstein Laurence , Hentz Roland , Fishbein Joanna , Kowalski Marcin 
Published: August 2022

Background: Isoproterenol, a non-specific beta agonist, is
commonly used during electrophysiology studies (EPS). However, with the
significant increase in the price of isoproterenol in 2015 and the
increasing number of catheter ablations performed, the cost implications
cannot be ignored. Dobutamine is a less expensive synthetic compound
developed from isoproterenol with a similar mechanism to enhance cardiac
conduction and shorten refractoriness, thus making it a feasible
substitute with a lower cost. However, the use of dobutamine for EPS has
not been well-reported in the literature. Objective: To
determine the site-specific effects of various doses of dobutamine on
cardiac conduction and refractoriness and assess its safety during EPS.
Methods: From February 2020 to October 2020, 40 non-consecutive
patients scheduled for elective EPS, supraventricular tachycardia,
atrial fibrillation, and premature ventricular contraction ablations at
a single center were consented and prospectively enrolled to assess the
effect of dobutamine on the cardiac conduction system. At the end of
each ablation procedure, measures of cardiac conduction and
refractoriness were recorded at baseline and with incremental doses of
dobutamine at 5, 10, 15, and 20 mcg/kg/min. For the primary analysis,
the change per dose of dobutamine from baseline to each dosing level of
dobutamine received by the patients, comparing atrioventricular node
block cycle length (AVNBCL), ventricular atrial block cycle length
(VABCL) and sinus cycle length (SCL), was tested using mixed-effect
regression. For the secondary analysis, dobutamine dose level was tested
for association with relative changes from baseline of each
electrophysiologic parameter (SCL, AVNBCL, VABCL, atrioventricular node
effective refractory period (AVNERP), AH, QRS, QT, atrial effective
refractory period (AERP), ventricular effective refractory period
(VERP), using mixed-effect regression. Changes in systolic and diastolic
blood pressures were also assessed. The Holm-Bonferroni method was used
to adjust for multiple testing. Results: For the primary
analysis there was no statistically significant change of AVNBCL and
VABCL relative to SCL from baseline to each dose level of dobutamine.
The SCL, AVNBCL, VABCL, AVNERP, AERP, VERP and the AH, and QT intervals
all demonstrated a statistically significant decrease from baseline to
at least one dose level with incremental dobutamine dosing. Two patients
(5%) developed hypotension during the study and one patient (2.5%)
received a vasopressor. Two patients (5%) had induced arrhythmias but
otherwise no major adverse events were noted. Conclusion: In
this study, there was no statistically significant change of AVNBCL and
VABCL relative to SCL from baseline to any dose level of dobutamine. As
expected, the AH and QT intervals, and the VABCL, VERP, AERP and AVNERP
all significantly decreased from baseline to at least one dose level
with an escalation in dobutamine dose. Dobutamine was well-tolerated and
safe to use during EPS.