Limitations
This was a single center study with limited number of patients. Our
protocol did not go beyond 20 mcg/kg/min of dobutamine and does not
qualify as a high dose dobutamine study. Anesthesia was not uniformly
given with either general anesthesia or conscious sedation, which may
have had variable effects on the cardiac conduction. In addition,
anti-arrhythmic and/or rate control agents were not uniformly held
before the procedure as the decision was up to the electrophysiologist
based on the individual patient. Selection of patients was not
consecutive because it was not always feasible to perform the study
protocol due to time constraints. Moreover, we did not perform a VABCL
or VERP in 13 patients who underwent AF ablations given the length of
the procedure and the effect of ventricular pacing on the blood
pressure. There were other limited missing variables which the authors
deemed insignificant. Exclusion of patients due to time constraints
could possibly introduce bias and affect the study results, especially
if we excluded patients when procedures were long. Safety is always the
priority, and if patients were under anesthesia for a prolonged period,
we did not want to extend the procedure and place the patient at greater
risk. Therefore, the more complicated, sicker patients with more cardiac
substrate and longer procedure times (those patients undergoing atrial
fibrillation ablation) were either excluded or ventricular pacing was
not performed. Patients included in this study underwent
electrophysiologic testing for a variety of indications. The
heterogeneity of indications must be considered when interpreting
results.