Safety of short-term aspirin discontinuation before colonoscopy in patients on chronic aspirin therapy: a retrospective cohort study

Authors

Abstract

Aim Current guidelines recommend continuation of aspirin during low-risk endoscopic procedures; however, aspirin is still frequently interrupted in routine practice. The aim of our study was to evaluate real-world adherence to guideline-concordant aspirin management and its associated clinical outcomes in routine practice.
Methods We conducted a retrospective observational study at a tertiary cardiology center, dividing patients into two groups: those who temporarily discontinued aspirin 3–5 days pre-procedure and those who maintained ongoing therapy. The study’s primary endpoints included short-term and one-year outcomes of gastrointestinal (GI) bleeding, major adverse cardiovascular events (MACE), and all-cause mortality.
Results Among 5,643 elective outpatient colonoscopies performed during the study period, a total of 1,069 patients were included in the analysis (aspirin discontinued: n = 712; aspirin continued: n = 357) Within 30 days after colonoscopy, gastrointestinal bleeding occurred in 13 of 712 patients (1.8%) who discontinued aspirin and in 9 of 357 patients (2.5%) who continued aspirin (absolute risk difference +0.8%; number needed to harm = 125), with no additional bleeding events during one-year follow-up. Myocardial infarction was observed in 9 patients (1.3%) in the discontinuation group and 4 patients (1.1%) in the continuation group, while all-cause mortality was identical in both groups (0.8%), and no ischemic stroke or unstable angina occurred.
Conclusion In this real-world observational cohort, no differences were observed in clinically documented cardiovascular or gastrointestinal bleeding events between aspirin continuation and short-term interruption strategies, although the low event rates and retrospective design preclude definitive conclusions.

Keywords

Introduction

Periprocedural management of aspirin in patients undergoing non-cardiac procedures represents a critical cardiovascular safety issue rather than a purely procedural concern. Large international cohort studies have demonstrated that myocardial injury after non-cardiac surgery (MINS) is common, frequently asymptomatic, and independently associated with increased short-term mortality, even in the absence of clinically overt myocardial infarction.^1,2 Furthermore, clinical practice increasingly relies on high-sensitivity cardiac troponin assays to detect subclinical myocardial injury and stratify perioperative cardiovascular risk across a broad range of settings, including emergency and procedural contexts.³
Surgical and procedural stress is accompanied by a well-described prothrombotic state characterized by increased platelet aggregability, endothelial dysfunction, and plaque instability.⁴ Aspirin, through irreversible inhibition of platelet cyclooxygenase-1 and suppression of thromboxane A₂ synthesis, plays a central role in mitigating arterial thrombotic risk.⁵ Its efficacy in both primary and secondary prevention of atherosclerotic cardiovascular disease has been firmly established through large randomized trials and collaborative meta-analyses.⁶
In the perioperative and periprocedural setting, interruption of aspirin therapy has been consistently associated with an increased risk of acute cardiovascular events.⁷ Observational studies and systematic reviews have identified aspirin withdrawal as a potential trigger for myocardial infarction, particularly in patients with underlying coronary artery disease.⁸ This risk is magnified in patients with prior coronary stent implantation, in whom premature discontinuation of antiplatelet therapy has been strongly linked to stent thrombosis, myocardial infarction, and death. Registry data further demonstrate that non-adherence or interruption of antiplatelet therapy remains a major contributor to adverse cardiovascular outcomes following percutaneous coronary intervention.⁹
Reflecting this robust evidence base, international cardiology guidelines uniformly emphasize the continuation of aspirin therapy in most patients undergoing non-cardiac procedures, especially those with prior coronary revascularization or high thrombotic risk.¹⁰ These recommendations are consistently echoed across perioperative cardiovascular care guidelines and expert consensus documents, which caution against routine aspirin discontinuation except in procedures associated with prohibitively high bleeding risk.¹¹
Despite clear guideline consensus, real-world practice remains heterogeneous. Surveys of cardiologists, anesthesiologists, and surgeons reveal substantial variability in periprocedural aspirin management, often driven by concern for bleeding rather than cardiovascular risk stratification.¹² This discordance between evidence-based recommendations and clinical practice has led to the proliferation of retrospective observational studies evaluating aspirin interruption strategies in various procedural settings.
However, such real-world analyses are inherently limited by confounding by indication, selection bias, and incomplete capture of cardiovascular outcomes. Importantly, studies reporting null or zero-event cardiovascular outcomes are particularly vulnerable to misinterpretation, as the absence of observed events does not equate to the absence of risk in underpowered cohorts.¹³ Perioperative troponin elevations detected using high-sensitivity assays further illustrate that subclinical myocardial injury is often overlooked in routine clinical data, underscoring the challenges in outcome ascertainment.
In this context, the present study examines periprocedural aspirin management in patients with cardiovascular history undergoing colonoscopy within a routine clinical practice setting. Rather than attempting to challenge established cardiology guidelines, this analysis aims to describe observed event patterns while explicitly acknowledging the methodological constraints of retrospective real-world safety assessments in cardiovascular risk populations.

Materials and Methods

Study Design and SettingThis study was designed as a retrospective, single-center, observational cohort analysis conducted at the Cardiology Outpatient and Inpatient Consultation Clinics of Ankara Atatürk Sanatoryum Research and Education Hospital, a tertiary referral center where routine pre-procedural cardiology consultation is performed for patients with cardiovascular disease undergoing non-cardiac procedures.
All adult patients (≥18 years) who underwent elective outpatient colonoscopy between January and September 2025, and who had a documented history of cardiovascular disease and/or chronic aspirin use, were retrospectively screened for eligibility.
Following the index colonoscopy, patients entered routine clinical follow-up as part of standard medical care, and their subsequent clinical course continues to be monitored through regularly scheduled outpatient visits and hospital encounters.
Given the retrospective observational design, no protocol-mandated follow-up schedule was implemented. For the purposes of the present analysis, only patients with at least 12 months of post-procedural clinical information already available in the electronic medical record were included.
Clinical follow-up data were obtained from routinely collected medical records and were available through September 2025.
Cardiovascular disease was defined as a documented history of at least one of the following: Coronary artery disease confirmed by prior coronary angiography, prior percutaneous coronary intervention, prior coronary artery bypass graft surgery, or chronic ischemic heart disease under active cardiology follow-up.
Chronic aspirin use was defined as daily acetylsalicylic acid therapy (81–300 mg) for at least 30 consecutive days prior to the index colonoscopy. Patients receiving aspirin for either primary or secondary prevention were included, reflecting real-world clinical practice.
Inclusion and Exclusion CriteriaPatients were included if they met all of the following criteria:
-Age ≥ 18 years
-Elective outpatient colonoscopy during the study period
-Documented cardiovascular disease and/or chronic aspirin therapy
-Availability of complete baseline and follow-up data for at least 12 months
Patients were excluded if they had:
-Colonoscopy performed in inpatient or emergency settings
-Active gastrointestinal bleeding at the time of colonoscopy
-Known bleeding diathesis or platelet disorder
-Active malignancy under ongoing treatment
-Concomitant endoscopic or surgical procedures during the same session
-Incomplete or ambiguous documentation regarding aspirin exposure
Periprocedural aspirin management was determined by routine clinical practice and physician judgment following cardiology consultation. No protocol-mandated allocation was applied.
Patients were categorized into two groups:
1.Aspirin Continuation Group: aspirin maintained without interruption
2.Aspirin Interruption Group: aspirin temporarily discontinued 3–5 days before colonoscopy
Patients with aspirin discontinuation exceeding 5 days were excluded to maintain homogeneity of exposure.
Data CollectionDemographic data, cardiovascular risk factors, cardiac history, aspirin use, colonoscopy indications, and available procedural information were retrieved from the institutional electronic medical record system.
Follow-up data were obtained from outpatient clinic visits, hospitalization records, and cardiology databases within the institutional healthcare system.
Study Endpoints included clinically documented gastrointestinal bleeding within 30 days and up to 12 months after colonoscopy, major adverse cardiovascular events (myocardial infarction, ischemic stroke, unstable angina requiring hospitalization, or cardiovascular death), and all-cause mortality.
Outcome assessment was limited to clinically documented events; systematic surveillance using high-sensitivity cardiac troponin assays was not performed.
Ethical ApprovalThe study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Ankara Bilkent City Hospital (Date: 2023-10-24, No: TABED 2-23-22).
Statistical AnalysisContinuous variables were summarized as mean ± standard deviation or median (interquartile range), as appropriate, and categorical variables were expressed as counts and percentages. Comparisons between patients in whom aspirin was discontinued and those in whom aspirin was continued were performed using unpaired Student’s t test or Mann–Whitney U test for continuous variables, depending on data distribution, and Fisher’s exact test for categorical variables due to the low frequency of clinical events.
The primary analyses focused on clinically documented gastrointestinal bleeding, myocardial infarction, and all-cause mortality within 30 days following colonoscopy. Composite cardiovascular outcomes, including death or myocardial infarction, were also evaluated. Causes of death were adjudicated based on available clinical documentation; deaths without a clearly identifiable cardiovascular etiology were classified as non-cardiac.
Absolute risk differences (ARD) were calculated to describe between-group differences in event rates. Given the observational design and limited number of outcome events, the study was not powered to detect small between-group differences, and no multivariable regression modeling was performed to avoid overfitting. Accordingly, results are presented as descriptive and exploratory, without claims of equivalence or non-inferiority.
No adjustment for multiple comparisons was applied, as analyses were hypothesis-generating in nature. Statistical analyses were conducted using SPSS software (version 23), with a two-sided p-value < 0.05 considered statistically significant.
Reporting GuidelinesThis study is reported in accordance with the STROBE guidelines.

Results

Study PopulationFrom January to September 2025, a total of 5,643 elective outpatient colonoscopies were performed at the study center. Among these, 1,069 patients met the predefined inclusion criteria and had ≥12 months of longitudinal clinical data available in the electronic medical record; this cohort constituted the final study population.
Of the included patients, 357 (33.4%) continued aspirin therapy without interruption during the periprocedural period, whereas 712 (66.6%) underwent temporary aspirin discontinuation for 3–5 days prior to colonoscopy.
Baseline CharacteristicsBaseline demographic characteristics and major cardiovascular comorbidities were broadly comparable between the aspirin continuation and discontinuation groups, including age, sex distribution, and prevalence of hypertension, diabetes mellitus, and chronic kidney disease.
However, due to the retrospective design and absence of protocol-driven allocation, residual differences in unmeasured cardiovascular risk—such as coronary anatomy complexity, time since prior revascularization, and plaque burden—could not be systematically assessed.
Gastrointestinal Bleeding EventsClinically documented gastrointestinal bleeding events were infrequent in both groups. Within the first 30 days following colonoscopy, gastrointestinal bleeding occurred in 13 patients (1.8%) in the aspirin discontinuation group (13/712) and in 9 patients (2. 5%) in the aspirin continuation group (9/357).
The ARD between the two periprocedural aspirin management strategies was +0.8%, indicating a small absolute increase in bleeding risk associated with aspirin continuation. Based on the observed absolute risks, the number needed to harm (NNH) for aspirin continuation was 125.
The detailed data are provided in Supplementary Table 1 and Table 2.
Given the low number of events, relative effect measures should be interpreted with caution, and no formal inference regarding risk reduction or increase can be made.
No additional clinically overt gastrointestinal bleeding events were identified during extended follow-up of available medical records up to one year.
Cardiovascular OutcomesDuring short-term (≤30 days) follow-up, myocardial infarction was documented in 9 patients (1.3%) in the aspirin discontinuation group (9/712) and in 4 patients (1.1%) in the aspirin continuation group (4/357). The resulting absolute risk difference was −0.2%, favoring aspirin continuation; however, the small number of events precludes reliable estimation of relative treatment effects.
All-cause mortality occurred in 6 patients (0.8%) in the aspirin discontinuation group and 3 patients (0.8%) in the aspirin continuation group, with no absolute or relative difference between groups. Among fatal events, the majority were non-cardiac deaths (66.7% in both groups), based on available clinical documentation.
No ischemic stroke or unstable angina requiring hospitalization was recorded in either group during short-term or extended follow-up.
Given the observational design, absence of protocol-driven follow-up, and lack of systematic surveillance using high-sensitivity cardiac troponin assays, subclinical myocardial injury could not be assessed. The low incidence of myocardial infarction and mortality reflects the overall low observed cardiovascular event rate in this single-center cohort. Accordingly, these findings should be interpreted as descriptive associations rather than evidence of cardiovascular protection or safety equivalence between periprocedural aspirin management strategies.

Discussion

Current international gastroenterology and cardiology guidelines consistently recommend continuation of low-dose aspirin during low-risk endoscopic procedures, including diagnostic colonoscopy, based on evidence demonstrating minimal bleeding risk and potential harm associated with antiplatelet interruption.¹³ Large observational studies and randomized data have further shown that aspirin continuation does not significantly increase clinically relevant post-procedural bleeding, even in the setting of polypectomy.^14,15
Despite this well-established evidence base, real-world practice remains heterogeneous. In our cohort, aspirin was temporarily discontinued in approximately two-thirds of patients, highlighting a persistent gap between guideline recommendations and routine clinical decision-making. Similar patterns of non-adherence have been reported in real-world endoscopy registries, where physician judgment and perceived bleeding risk continue to influence periprocedural antiplatelet management.
Within this context, our findings demonstrate extremely low rates of gastrointestinal bleeding and an absence of documented cardiovascular events during both short-term and one-year follow-up, regardless of aspirin management strategy. Importantly, these results should not be interpreted as evidence supporting aspirin discontinuation. Prior studies have consistently shown that interruption of aspirin therapy is associated with an increased risk of acute coronary syndromes and other thrombotic events, particularly in patients with established cardiovascular disease.^16,17
The apparent safety observed in our cohort likely reflects the low-risk nature of outpatient colonoscopy, careful patient selection, and the limited statistical power inherent to retrospective observational studies when adverse events are rare. As emphasized in prior meta-analyses, the absence of observed harm in underpowered cohorts should not be equated with the absence of risk.
This study contributes contemporary real-world data illustrating that, despite strong guideline support for aspirin continuation during low-risk colonoscopy, periprocedural aspirin interruption remains common in routine practice, while observed bleeding and cardiovascular event rates remain low.

Limitations

Several important limitations of this study should be acknowledged.
First, the retrospective, single-center observational design precludes causal inference. Decisions regarding periprocedural aspirin continuation or discontinuation were based on physician judgment rather than protocol-driven allocation, introducing confounding by indication. Patients perceived to be at higher thrombotic risk may have been preferentially maintained on aspirin, whereas those considered lower risk were more likely to undergo temporary interruption. Consequently, observed differences in bleeding or cardiovascular outcomes may reflect baseline risk differences rather than causal effects of aspirin management.
Second, the very low number of observed clinical events—particularly major adverse cardiovascular events and mortality—substantially limits statistical power. The absence of observed events should not be interpreted as evidence of safety or equivalence, and the possibility of type II error cannot be excluded. Accordingly, this study is not designed to support non-inferiority, superiority, or safety conclusions.
Third, cardiovascular outcome ascertainment was limited to clinically documented events captured within the institutional healthcare system. Systematic surveillance for myocardial injury using high-sensitivity cardiac troponin assays was not performed, and asymptomatic or subclinical myocardial injury, including MINS, may have gone undetected.
Fourth, detailed information on coronary anatomy and thrombotic risk modifiers—including stent type and length, lesion complexity, time since percutaneous coronary intervention, and extent of multivessel coronary disease—was not uniformly available and therefore could not be incorporated into the analysis.
Fifth, bleeding outcomes were restricted to clinically overt gastrointestinal bleeding documented in medical records. Minor, self-limited, delayed, or extra-institutional bleeding events may have been underreported. In addition, endoscopic procedural characteristics—such as polypectomy size, number of biopsies, and use of prophylactic hemostatic measures—were not systematically captured.
Finally, although inclusion required the availability of at least one year of post-procedural clinical data in the medical record, this follow-up was retrospective and limited to routinely collected clinical encounters. Longer-term cardiovascular outcomes beyond this period were not assessed, and the potential impact of short-term aspirin interruption on late thrombotic events cannot be excluded.

Conclusion

In this single-center real-world cohort of chronic aspirin users undergoing elective outpatient colonoscopy, clinically significant gastrointestinal bleeding and cardiovascular events were rare, irrespective of whether aspirin was continued or temporarily discontinued. These findings are consistent with existing guideline recommendations and prior evidence supporting aspirin continuation during low-risk endoscopic procedures.
However, the frequent interruption of aspirin observed in routine practice underscores ongoing challenges in guideline implementation rather than uncertainty in the underlying evidence. Given the well-documented thrombotic risks associated with aspirin withdrawal, continuation of aspirin should remain the default strategy for low-risk colonoscopy, and observational findings such as ours should be interpreted as descriptive rather than practice-changing.

Declarations

Abbreviations

ARD: Absolute risk difference
GI: Gastrointestinal
MACE: Major adverse cardiovascular events
MINS: Myocardial injury after non-cardiac surgery
NNH: Number needed to harm
SPSS: Statistical Package for the Social Sciences
STROBE: Strengthening the Reporting of Observational Studies in Epidemiology

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About This Article

Received:

January 12, 2026

Accepted:

April 17, 2026

Published Online:

May 14, 2026