CABG after asymptomatic COVID-19 was associated with broadly similar early recovery measures in a small retrospective cohort, although postoperative complications were more frequent among patients with documented prior infection. Külahcıoğlu and colleagues compared 37 patients with prior asymptomatic SARS-CoV-2 infection with 39 patients without documented previous COVID-19. Their findings raise a question about residual postoperative risk but do not establish that prior infection caused the complications or determine when bypass surgery should be scheduled.
Study Design and Patient Population
The investigators reviewed isolated coronary artery bypass grafting at Ankara City Hospital in Turkey during 2021–2022. Eligible patients were 18 to 80 years old. Patients with symptomatic COVID-19, active preoperative infection or fever, redo sternotomy, or concomitant cardiac procedures were excluded.
The 76 patients were predominantly male (81.6%) and generally low risk, with most operations performed electively. Mean age was approximately 63 years in both groups, mean ejection fraction was approximately 52%, and median EuroSCORE II was below 1%. These characteristics limit application of the results to unstable patients, complex combined operations, or higher-risk populations.
Prior infection was identified through health records, and asymptomatic status was assessed retrospectively using records and patient contact. The comparison group had no documented prior infection; it was not proven to have never been infected. Vaccination status, viral variant information, serology, and systematic pulmonary function testing were unavailable.
CABG After Asymptomatic COVID-19: Early Outcomes
The groups had similar graft distributions, operative duration, bypass time, and cross-clamp time. Five patients underwent off-pump surgery, so the cohort was not exclusively exposed to cardiopulmonary bypass. Most patients received three or four grafts.
| Outcome | No documented prior COVID-19 (n=39) | Prior asymptomatic COVID-19 (n=37) |
|---|---|---|
| Any postoperative complication | 0 | 6 (16.2%) |
| Mortality | 0 | 1 (2.7%) |
| Reintubation | 0 | 2 (5.4%) |
| Rehospitalization | 2 (5.1%) | 6 (16.2%) |
| Median extubation time | 450 minutes | 450 minutes |
| Mean postoperative hospital stay | 6.9 days | 6.7 days |
Intensive care duration, total hospital stay, noninvasive ventilation, ward oxygen requirement, and transfusion exposure also showed no statistically significant differences. With so few patients and events, these results cannot establish equivalence or exclude clinically important differences.
Understanding the Complication Signal
The absolute difference in composite complications was 16.2 percentage points, with a reported 95% confidence interval of 3.8 to 31.1 percentage points. The six events in the prior-infection group comprised two bleeding revisions, one pericardial effusion, one saphenous wound infection, one sternal dehiscence, and one postoperative COVID-19 diagnosis.
These events have different potential causes. Their combination into one endpoint does not identify a single postviral mechanism, and the inclusion of a postoperative COVID-19 diagnosis further complicates interpretation as an effect of previous infection. Complications were obtained from routine records rather than independent adjudication. The association deserves further study but is not proof of a causal effect.
The authors did not perform multivariable logistic regression because the event count was too small for stable estimates. Similar baseline averages therefore should not be read as complete control of confounding. Several clinical comparisons were made without adjustment for multiple testing, adding uncertainty to an isolated statistically significant result.
What the Timing Subgroup Can and Cannot Show
Among patients with prior asymptomatic infection, nine underwent surgery within four weeks and 28 underwent surgery at least four weeks after infection. No statistically significant differences were detected in the reported recovery, respiratory support, operative, or complication outcomes.
This exploratory subgroup was markedly underpowered. Nine earlier operations cannot demonstrate that surgery within four weeks is as safe as later surgery, establish a minimum waiting interval, or justify changing scheduling recommendations. Decisions must account for the individual’s coronary disease, clinical urgency, recovery from infection, and multidisciplinary assessment.
Inflammatory and Respiratory Findings
Both groups showed the expected laboratory response to cardiac surgery: albumin decreased, inflammatory markers and white cell counts rose, and platelet and composite inflammatory indices changed over the postoperative course. Most markers did not show consistent separation between groups. Arterial oxygen and carbon dioxide values also changed over time without significant between-group differences at matched measurements.
These findings suggest that routine measurements did not reveal a distinct generalized recovery pattern attributable to prior asymptomatic infection in this cohort. They do not exclude more subtle pulmonary, vascular, or immune effects. The study did not directly test a mechanism linking previous infection with bleeding, wound complications, or other adverse events.
Relevance for Perfusion and Cardiac Surgical Teams
For perfusion teams, the study adds procedure-specific information about a largely elective CABG population while reinforcing the limits of routine laboratory comparisons. Bypass and cross-clamp durations were comparable, but the study did not evaluate an alternative circuit, anticoagulation strategy, oxygen-delivery target, or blood-management protocol. It provides no evidence for changing perfusion technique solely because a patient had an asymptomatic infection.
The practical value is in preoperative communication: identify the infection history, residual symptoms, operative urgency, and relevant pulmonary findings, and interpret them alongside the patient’s overall risk. Similar average recovery measures should be considered together with the complication signal and the uncertainty around both observations.
Limitations and Disclosures
This was a small, retrospective, single-center study using operations performed in 2021–2022. Retrospective symptom recall and undetected infections in the comparison group could misclassify exposure. Missing vaccination and variant data limit relevance to other periods. Low event counts, unadjusted comparisons, different operating surgeons, and a heterogeneous composite endpoint restrict causal interpretation.
Follow-up focused on early postoperative outcomes. The study cannot address medium-term recovery, long-term graft patency, or later cardiovascular events. The sample-size calculation targeted a large effect in a continuous measure and does not establish adequate power for rare complications or mortality. Larger contemporary multicenter studies are needed before drawing CABG timing conclusions.
The authors report no external funding or competing interests. Institutional ethics approval and written informed consent were reported.
Original Article
Külahcıoğlu E, Yaşar MS, Şimşek E. The impact of prior asymptomatic COVID-19 infection on outcomes following coronary bypass surgery. Journal of Cardiothoracic Surgery. 2026;21:853. doi:10.1186/s13019-026-04489-9.
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