Discussion
Catheter ablation has become the first-line therapy for the treatment of
AF.2 During the procedure, pain may result from
catheter insertion or the ablation delivery itself.9Moreover, it is usually a quite lengthy procedure requiring the patient
to lie perfectly still to avoid complications and technical difficulties
such as EAM shifts or acquisition errors. Therefore, GA or deep sedation
are generally recommended, usually at the operator’s preference. In
recent years, deep sedation has showed to be a very viable alternative
to GA, reaching a similar efficacy level and being characterized by a
lower rate of potential drawbacks (less phrenic nerve or esophageal
injury, lower need for inotropic drugs during the procedure, presence of
patient’s feedback, etc.).10-11 Moreover, GA has
higher costs and requires more planning and organization in the
operating room.
Regarding deep sedation, many protocols have been tested over the
years.3-5
Benzodiazepines such as midazolam have been used in repeated boluses.
However, they lack a proper analgesic effect, and their main
disadvantage is the waxing and waning level of sedation/consciousness
which can jeopardize the success and the safety of the ablation
procedure. To maintain a longer and steadier level of sedation, propofol
has been used, especially through a continuous
infusion.4,12 For AF ablation, propofol has been
tested against a combination of midazolam and fentanyl by Tang et
al.13 and showed to be associated with an increased
risk of persistent oxygen desaturation reflecting in lower catheter
stability due to airway obstruction, despite achieving a deeper level of
sedation. Furthermore, hypotension is a common side effect of propofol,
mainly due to a reduction in systemic vascular resistance and a negative
inotropic effect. This is why anesthesia support or back-up is usually
necessary when propofol is used. In two large observational prospective
studies, propofol has been used as the drug of choice for sedation for
AF ablation without anesthesiologist supervision.4,16Hypoxia and hypotension were present in a percentage ranging from 1.5 to
2.3% in one study,16 whereas 15.6% of patients in
the other study required switching from propofol to midazolam due to
persistent hypotension or respiratory depression.4
In our center, we historically performed AF ablation procedures with
propofol and anesthesiologist supervision. In the first part of the year
2020, before COVID-19 breakthrough, all procedures were performed using
propofol and we had a 13% of either persistent hypotension or
respiratory depression, which luckily resolved without the need for
intubation or advanced life support maneuvers. After the pandemic
arrival, we were forced to manage AF ablation patients without the
anesthesiology team, which was redeployed in order to deal with the
COVID-19 emergency.
Dexmedetomidine was seen as a viable alternative to propofol.
Dexmedetomidine is a selective alpha2-adrenoreceptor agonist
characterized by anxiolytic, sedative and analgesic effects with minimal
risk of respiratory depression,15-18 therefore easier
to be managed by electrophysiologists. It has been safely used in
combination with other drugs to achieve deep
sedation.19-22 In the management of sedation for AF
ablation, dexmedetomidine has been evaluated in two randomized
controlled trials. The first one randomized dexmedetomidine and
remifentanil versus midazolam and remifentanil.23Dexmedetomidine was associated with a deeper level of sedation but a
lower incidence of respiratory depression; there was a non-significant
trend towards a higher rate of hypotension and transient bradycardia.
The second trial compared dexmedetomidine to thiamylal, a barbiturate,
reporting fewer body movements and apneic events and a similar incidence
of bradycardia and hypotension.24
To our knowledge, our study is the first comparison between
dexmedetomidine and propofol in patients undergoing AF ablation. Despite
not reaching statistical significance, likely due to the small sample
size of our population, we observed a trend in favor of dexmedetomidine
in terms of less hypotensive and hypoxic episodes. On the other hand,
dexmedetomidine was characterized by a slightly higher number of
bradycardia episodes compared to propofol (2 versus 0). They both
happened during ablation of the ganglionated plexi in the left atrium
and promptly resolved with pacing from the catheters inside the heart.
Procedural time did not statistically differ between the two groups.
Complete PVI was successfully achieved in every patient, there were no
procedure-related complications and every patient fully recovered from
deep sedation.