To fast or not to fast—that is the question?

The use of periprocedural fasting to prevent complications such as pulmonary aspiration remains an important aspect of patient care for patient’s receiving general anaesthesia or greater than minimal sedation. American Society of Anaesthesiologists recommends fasting for elective procedures under general or moderate sedation for 6 hours and 2 hours for solid foods and clear liquids, respectively. However, this does not include those undergoing procedures with little sedation or local anaesthesia when risk of aspiration is reduced (1). Coronary procedures are most commonly performed under local anaesthesia and/or minimal sedation and fasting prior to these procedures remains commonplace despite a lack of robust evidence supporting this practice (2).

The rationale for a fasting strategy prior to coronary procedures is based on the observation that emesis was common with use of older ionic, high osmolar contrast agents coupled with reduced upper airway reflexes secondary to sedation. This was believed to produce a consequent risk of aspiration. Secondly, in the case of complications, fasting would reduce the risk of aspiration if there was a need for general anaesthesia and intubation. However, the complications of prolonged fasting are not to be understated. Studies have shown that prolonged pre-operative fasting can lead to patient dissatisfaction, pre-operative hypoglycemia, peri-operative hyperglycemia, dehydration, contrast-induced nephropathy, and may contribute to post-operative delirium (3,4). Therefore, there has been a significant push towards re-evaluating the need for pre-procedural fasting for patients undergoing cardiac procedures.

The TONIC trial is a single-centre, single-blind randomised control trial that aims to explore whether a non-fasting approach to elective or semi-urgent coronary procedures is non-inferior to a fasting approach, as is traditionally used (5). In this study of 739 patients, 697 procedures were elective while 42 semi-urgent and they consisted of 517 angiographies and 222 angioplasties, including complex and high-risk procedures. They analysed a composite primary endpoint of vasovagal event, hypoglycemia and nausea and/or vomiting while also analysing a composite secondary outcome of contrast-induced nephropathy and patient satisfaction. The authors found that a non-fasting strategy was non-inferior to a fasting strategy when it came to the primary outcome (8.2% non-fasting vs. 9.9% fasting). No significant difference was observed in the secondary endpoint, although patients in the non-fasting group felt less hungry and thirsty and most patients would choose a non-fasting strategy if they had to undergo the same procedure again. The results of this study suggest that a non-fasting approach to elective or semi-urgent coronary procedures is non-inferior to a fasting approach and may lead to greater patient satisfaction. This finding is congruent with other prospective trials including the similar and recently published SCOFF trial, which included 716 patients and found a non-fasting approach to be non-inferior to a fasting approach (primary outcome: 19.1% fasting vs. 12.0% non-fasting) (6-9).

TONIC adds further weight to previous retrospective studies that have demonstrated the adverse effects associated with fasting, as well as the exceedingly low risk of aspiration pneumonia and need for emergency intubation in elective and semi-urgent procedures (10,11). A study of cases done at a single centre in New Zealand that follows current fasting guidelines found no cases of aspiration over a 6-month period during which 1,030 cases were analysed. Nevertheless, a number of patients experienced hunger (47.1%), headache (11.6%), nausea (3.9%), vomiting (0.8%), vasovagal syncope (0.8%) as well as hyperglycemia (0.8%) and hypoglycemia (0.7%) (10). Cases of hyperglycemia and hypoglycemia are of particular concern for diabetic patients in whom medication provision can be complicated and is often mismanaged during times of fasting. A similar retrospective study performed at a UK institution where no patients are fasted pre-procedurally, found that there were no cases of aspiration or need for emergency intraprocedural endotracheal intubation in over 1,900 percutaneous coronary intervention (PCI) procedures performed over a 3-year period (11). These studies highlight that the perceived benefit and safety of preprocedural fasting may be lacking. So do the risks of fasting outweigh the perceived benefits? Are we doing more harm than good in taking this added ’safety’ measure?

In our opinion, one of the most important considerations when deciding whether to fast comes from the level of intraprocedural sedation required. As mentioned above, anaesthesiology guidelines recommend fasting prior to procedures requiring sedation due to impaired airway reflexes (1). The decision to use intraprocedural sedation for coronary procedures is largely institution and proceduralist dependant and this is certainly illustrated in the TONIC trial. Periprocedural sedation was only used for 155 patients [151 intravenous (IV) midazolam, 4 IV droperidol] out of the 739 included, while all other procedures were done under local anaesthesia (5). As per anaesthesiology guidelines, there is no need to fast for procedures done under local anaesthesia and therefore the use of a fasting strategy for patients undergoing elective or semi-urgent coronary procedures at institutions that sparingly use sedation is likely based on traditional practices and not guideline directed.

At our institution, as well as many others, periprocedural sedation is frequently utilised in cases of coronary procedures. The subgroup analysis of the TONIC trial of patients who received moderate sedation included 155 patients showed non-inferiority for primary outcome in both per protocol and modified intention-to-treat analyses. However, there was a slightly higher incidence of the primary outcome in the non-fasting group in both analyses (+0.2% per protocol, +1.6% modified intention-to-treat), which highlights the potential role of fasting in this subgroup of patients. In contrast however, subgroup analysis of patient receiving sedation in the SCOFF trial favoured a non-fasting approach in these patients (absolute posterior difference −7.9%) (7). The difference in results is something to note and may need to be further evaluated in larger studies of patients receiving sedation to guide management in this cohort. Furthermore, mean fasting time in the non-fasting group was 3 hours with 22% having fasting times greater than 6 hours for food. The high crossover of patient from non-fasting to fasting groups may make interpretation of the results in both per-protocol and modified intention-to-treat analyses difficult. The authors conducted subgroup analyses to determine difference in outcomes in those who were truly fasted for less than 3 hours and greater than 3 hours and found no significant difference. However more detailed and extensive analysis of patients who received sedation and were truly fasted for less than 6 hours compared to those fasted for greater than 6 hours would be informative to centres where sedation is more commonly used such as ours. Furthermore, longer term impacts of pre-procedural fasting have not been evaluated by TONIC or other trials and may need to be investigated in studies with longer follow-up (5-9).

The evidence strongly supports the elimination of a routine fasting strategy prior to elective or semi-urgent coronary procedures, particularly those done under local anaesthesia. The TONIC trial demonstrates that perceived safety benefits of fasting are minimal and the harms of a fasting strategy may be more significant. Given this, routine fasting prior to coronary procedures should not be standard practice and the decision should be individualised to patients and their procedure. While not indicated for simple routine coronary interventions, fasting may be appropriate for patients undergoing procedures requiring higher sedation loads, such as complex PCI or even non-coronary procedures such as transcatheter aortic valve implantation and atrial fibrillation ablation. Institutions should re-evaluate their preprocedural fasting practices, incorporating the current guidelines and trial results with the aim of improving clinical practice, peri-procedural safety and patient satisfaction.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, AME Clinical Trials Review. The article has undergone external peer review.

Peer Review File: Available at https://actr.amegroups.com/article/view/10.21037/actr-24-160/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://actr.amegroups.com/article/view/10.21037/actr-24-160/coif). A.J.B. declares consulting fees from Abbott Vascular and speaker fees from Boston Scientific. The other authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Practice Guidelines for Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration: Application to Healthy Patients Undergoing Elective Procedures: An Updated Report by the American Society of Anesthesiologists Task Force on Preoperative Fasting and the Use of Pharmacologic Agents to Reduce the Risk of Pulmonary Aspiration. Anesthesiology 2017;126:376-93. [PubMed]
2. Naidu SS, Abbott JD, Bagai J, et al. SCAI expert consensus update on best practices in the cardiac catheterization laboratory: This statement was endorsed by the American College of Cardiology (ACC), the American Heart Association (AHA), and the Heart Rhythm Society (HRS) in April 2021. Catheter Cardiovasc Interv 2021;98:255-76. [PubMed]
3. Rüggeberg A, Meybohm P, Nickel EA. Preoperative fasting and the risk of pulmonary aspiration-a narrative review of historical concepts, physiological effects, and new perspectives. BJA Open 2024;10:100282. [PubMed]
4. Pimenta GP, de Aguilar-Nascimento JE. Prolonged preoperative fasting in elective surgical patients: why should we reduce it? Nutr Clin Pract 2014;29:22-8. [PubMed]
5. Boukantar M, Chiaroni PM, Gallet R, et al. A Randomized Controlled Trial of Nonfasting vs Fasting Before Interventional Coronary Procedures: The TONIC Trial. JACC Cardiovasc Interv 2024;17:1200-10. [PubMed]
6. Woods C, Wood M, Boylan A, et al. Fasting Versus a Heart-Healthy Diet Before Cardiac Catheterization: A Randomized Controlled Trial. Am J Crit Care 2024;33:29-33. [PubMed]
7. Ferreira D, Hardy J, Meere W, et al. Fasting vs. no fasting prior to catheterization laboratory procedures: the SCOFF trial. Eur Heart J 2024;45:4990-8. [Crossref] [PubMed]
8. Tamborrino PP, Papi L, Michelotti L, et al. Do We Need Fasting Prior to Coronary Angiography? The CORO-NF Randomized Pragmatic Study. Am J Med 2024;137:666-72. [PubMed]
9. Mishra A, Singh M, Kane M, et al. Strict versus no fasting prior to cardiac catheterization: a prospective evaluation of safety and clinical outcomes. Eur Heart J 2019;40:2811.
10. Bacus SB, Parsons J, Benatar J, et al. Fasting prior to cardiac catheterisation: a single-centre observational study. N Z Med J 2020;133:16-22. [PubMed]
11. Hamid T, Aleem Q, Lau Y, et al. Pre-procedural fasting for coronary interventions: is it time to change practice? Heart 2014;100:658-61. [PubMed]