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.