By Morgan H. Randall, MD, FSCAI; Michael R. Massoomi, MD; and Louai Razzouk, MD, FSCAI

Introduction

The historic practice of requiring patients to remain nil per os (NPO) for medical procedures has traditionally been applied to those performed in the cardiac catheterization laboratory (CCL). As interventional cardiologists caring for a wide range of patients, we are motivated as a profession to maximize patient safety and minimize potential harms while maintaining efficiency in the dynamic CCL environment. The assumption that NPO requirements improve procedural outcomes has been challenged in recent years through no less than nine clinical trials, finding a lack of evidence to support this convention.^1,2 In this Tip of the Month, we focus on a patient-centered approach to NPO protocols through a brief review of the available evidence.

Risk of Aspiration

The rationale for limiting oral intake prior to procedures is to minimize gastric content, which would lead to lower rates of regurgitation and, by extension, pulmonary aspiration.³ However, the incidence of this outcome is extremely rare at 1.1/10,000 in nonselected cases.³ Of those aspiration events, it is estimated that 72% will result in death or permanent severe injury.³ Therefore, the expected incidence of major injury or death from perioperative aspiration is 0.79/10,000. It is overtly stated that the trial size needed to detect a difference in strategy makes such a study impractical. Anesthesia guidelines, by extension, also acknowledge that there are no clinical data to support this practice and that surrogate markers such as gastric volume or gastric emptying time have not been shown to determine event rates.³ For years, cardiology literature has indicated that there is no evidence to support this practice, especially as procedural materials and techniques have advanced.² In the most recent meta-analysis of cardiology-specific trials, the rates of aspiration are 3/1526 (19.7/10,000) in nonfasting patients compared to 1/1534 (6.5/10,000), a difference that is not statistically significant (RR, 2.14; 95% CI, 0.28 – 16.53, I² = 0%, X² P = .44).¹

Common Procedural Risks

While aspiration is rare, other procedural risks do exist related to NPO practices and are far more common. Events such as hypoglycemia, hyperglycemia, nausea/vomiting, contrast-induced nephropathy, and hypotension have all been evaluated. In sum, none of these outcomes has demonstrated a difference utilizing nonfasting protocols.¹ These studies are heterogenous in their composition, including elective coronary angiography, cardiac implantable electronic device procedures, transcatheter aortic valve replacement, and arrhythmia ablation.¹ The desired level of sedation similarly is varied, ranging from general anesthesia (rarely) to local anesthesia with light sedation.¹ Finally, it should be acknowledged that these trials have not specifically addressed suitability in patients receiving GLP-1 receptor antagonists, which are known to delay gastric emptying.

Table 1: Complication rates.

Note: Values expressed as events/10,000 procedures.

Advantages of Nonfasting Protocols

A consistently positive endpoint for all cardiac trials evaluating NPO interventions is an improvement in patient satisfaction.^1,4 While measures and methods have varied, there can be no doubt that this outcome favors limiting NPO restrictions. Furthermore, anesthesiology guidelines similarly find no difference when allowing carbohydrate-containing liquids two hours before a procedure.³ In fact, these guidelines cite 31 randomized controlled trials, among others, that report no aspiration events in either arm.³ It is therefore strongly recommended by the American Society of Anesthesiologists that healthy adults should drink carbohydrate-containing clear liquids until two hours before elective procedures.³ Another variable that is difficult to measure but felt to be relevant is that using more liberal NPO practices means that more patients will be “ready to go.” NPO requirements can lead to procedures being delayed by several hours or until the next day. In the SCOFF trial, fasting patients waited at least 10 hours longer than the nonfasting group.⁵ Given the dynamic nature of the CCL schedule, more lenient NPO practices may help reduce cases being “bumped” due to NPO requirements. It should be highlighted that exclusion criteria exist in each trial, requiring individualized decisions be made for each patient. Multidisciplinary discussions are advised to ensure best outcomes.

Conclusion

Removing NPO restrictions for CCL procedures has not been shown to affect clinical outcomes. While further studies are warranted, it may be reasonable to individualize such requirements using a patient-centered approach. Overall, liberalizing NPO status can lead to improved patient satisfaction and may improve CCL throughput and efficiency, all without increasing the risk of adverse outcomes. Shared decision-making acknowledging clinical outcomes, as well as patient preference, is likely to lead to best practices.

References

1. Bhat V, Kumar A, Georgy I, et al. Fasting Versus Non-fasting Protocols Before Cardiac Catheterization Procedures: A Meta-analysis of Clinical Trials. J Soc Cardiovasc Angiogr Interv. 2026 Jan 13;5(2):104161.
2. Bangalore S, Barsness GW, Dangas GD, et al. Evidence-Based Practices in the Cardiac Catheterization Laboratory: A Scientific Statement From the American Heart Association. Circulation 2021 Aug 3;144(5):e107–e119.
3. Joshi GP, Abdelmalak BB, Weigel WA, et al. 2023 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting: Carbohydrate-containing Clear Liquids with or without Protein, Chewing Gum, and Pediatric Fasting Duration—A Modular Update of the 2017 American Society of Anesthesiologists Practice Guidelines for Preoperative Fasting. Anesthesiology 2023 Feb 1;138(2):132–151.
4. Maqsood MH, Tamis-Holland JE, Mamas MA, et al. Fasting vs No Fasting Prior to Percutaneous Cardiovascular Procedures: A Meta-Analysis of Randomized Controlled Trials. JACC: Cardiovasc Interv. 2025 Mar 10;18(5):682–684.
5. Ferreira D, Hardy J, Meere W, et al. Fasting vs no fasting prior to catheterisation laboratory procedures: the SCOFF trial. Eur Heart J. 2024 Dec 16;45(47):4990-4998.