Coronary Angiography Within 30 Days From Coronary Artery Bypass Graft Surgery: Indications, Findings, and Outcomes

Abstract

Background. The incidence, indications, and outcomes of coronary angiography (CAG) performed within 30 days following coronary artery bypass graft surgery (CABG) have received limited study. Methods. We reviewed patients who underwent CAG within 30 days following CABG between April 2018 and September 2021 at a large quaternary healthcare system. Results. Of 2209 patients who underwent CABG during the study, 111 (5%) underwent CAG within 30 days following CABG. Mean age was 65 ± 10 years and they had high prevalence of comorbidities. Graft utilization was as follows: left internal mammary artery (LIMA) (84%); saphenous vein graft(s) (SVG) (81%); and right internal mammary artery (RIMA) (22%). The most common presentations/indications for angiography were cardiogenic shock (41%), ST-segment-elevation myocardial infarction (32%), and achieving complete revascularization by percutaneous coronary intervention (PCI) (16%). The LIMA, RIMA, and SVGs were completely/partially occluded in 41 (44%), 10 (42%), and 11 (50%) of patients, respectively. Of the 111 patients who underwent CAG, 55 (50%) underwent PCI, including 47 (85%) to the native vessel and 8 (15%) to the bypass graft, and 19 (17%) underwent repeat sternotomy. Overall, 29 patients (26%) required 30-day readmission following CAG and 19 (17%) died. Conclusion. The incidence of CAG within 30 days following CABG is approximately 5%. Patients who need CAG following CABG have high complication rates (26% readmission and 17% mortality, respectively, at 30 days).

J INVASIVE CARDIOL 2023;35(5):E248-E253. Epub 2023 February 15.

Key words: bypass graft, coronary angiography, coronary artery bypass graft surgery, early graft failure, percutaneous coronary intervention

Coronary artery bypass graft surgery (CABG) is the most commonly performed cardiac surgery.¹ Graft failure has multiple causes, such as thrombosis, endothelial dysfunction, intimal hyperplasia, oxidative stress, and vasospasm and can occur early (within 30 days) or later post CABG.^2-6 We examined the incidence, indications, and clinical outcomes of patients who underwent coronary angiography within 30 days following CABG in a large quaternary healthcare system.

Methods

We retrospectively examined the incidence, indications, and outcomes of coronary angiography performed within 30 days following CABG at Allina Health Minneapolis Heart Institute, Mercy, and United Hospitals between April 2018 and September 2021.

CABG urgency was defined as emergent if CABG was needed within 24 hours and urgent if CABG was needed between 24 hours and 7 days. The target vessels for bypass grafts were determined based on surgical notes and coronary angiography procedure notes. The graft patency was evaluated as either complete occlusion, partial occlusion, competitive flow, or patent. Patient presentation and indications for coronary angiography within 30 days following CABG were recorded.

Non-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI) were defined according to the American College of Cardiology–National Cardiovascular Data Registry (NCDR) CathPCI Registry definitions^.7

Study data were managed using REDCap (Research Electronic Data Capture) tools hosted at the Minneapolis Heart Institute Foundation.^8,9 REDCap is a secure, web-based software platform designed to support data capture for research studies, providing: (1) an intuitive interface for validated data capture; (2) audit trails for tracking data manipulation and export procedures; (3) automated export procedures for seamless data downloads to common statistical packages; and (4) procedures for data integration and interoperability with external sources.^8,9

This study was approved by the institutional review board.

Statistical analysis. Categorical variables were expressed as percentages and compared using Pearson’s Chi-square test or Fisher’s exact test, as appropriate. Continuous variables are presented as mean ± standard deviation or as median (interquartile range [IQR]) and compared using the Student’s t test or the Wilcoxon rank-sum test, as appropriate. Statistical analyses were performed using Stata, version 17.0 (StataCorp) and R, version 4.1.3 (R Foundation for Statistical Computing) in RStudio environment, version 2022.07.02 (RStudio, PBC).

Results

Of 2209 patients who underwent CABG during the study period, 111 (5%) underwent coronary angiography within 30 days after their surgery. The mean age was 65 ± 11 years and 69% of patients were men with high prevalence of comorbidities, ie, hypertension (86%), diabetes mellitus (51%), and prior heart failure (27%) (Table 1). The mean surgical time was 365 ± 131 minutes and cardiopulmonary bypass was used in 83%. In these 111 patients, CABG was performed urgently in 49%, electively in 38%, and emergently in 13%. Of the 111 patients, 78 (70%) had an isolated CABG, 29 (26%) had a concomitant valve procedure, and 10 (9%) had a concomitant aortic surgery and a valve procedure.

The most common number of bypass grafts was 3 (36%), followed by 4 (23%) and 2 (21%) (Table 2). Graft utilization was as follows: left internal mammary artery (LIMA) in 84%; saphenous vein graft(s) (SVG) in 81%, right internal mammary artery (RIMA) in 22%, and left radial artery in 5.5%. The target vessels for the grafts are illustrated in Figure 1.

Intraoperative complications were common in patients who underwent coronary angiography early post CABG, as follows: STEMI in 12 (11%), cardiac arrest in 12 (11%), cardiogenic shock in 12 (11%), acute kidney failure requiring dialysis in 7 (6.3%), blood loss (>300 mL) in 13 (12%), left ventricular support device placement in 19 (17%), and respiratory failure in 6 patients (5.4%).

The median time from CABG to angiography was 3 days (IQR, 1-7); 83 of 111 patients (75%) underwent angiography during their CABG admission (Table 1). The remaining 28 patients (25%) underwent coronary angiography within 30 days following CABG after being discharged.

The most common presentation/indication for coronary angiography following CABG was cardiogenic shock in 45 patients (41%) followed by STEMI in 36 patients (32%). Achieving complete revascularization was the indication in 18 patients (16%) (Figure 2).

The incidence of complete graft occlusion was similar across graft types: LIMA (18%), RIMA (25%), non-sequential SVG (19%), and sequential SVG (18%) (P=.54). However, the incidence of partial graft occlusion was higher in non-sequential SVG (41%) compared with LIMA (26%), sequential SVG (23%), and RIMA (17%) (P<.01). Complete occlusion of at least 1 bypass graft was observed in 35 patients (32%) and all bypass grafts were patent in 36 patients (32%). The findings of the coronary angiographies are demonstrated in Figure 3 and Figure 4.

Of the 111 patients who underwent coronary angiography, 55 (50%) underwent percutaneous coronary intervention (PCI), with 47 (85%) to the native vessel and 8 (15%) to the bypass graft; 19 (17%) underwent repeat sternotomy. Coronary angiography and PCI were performed emergently in 51%.

Overall, 30-day readmission following coronary angiography occurred in 29 patients (26%). Reasons for readmission were heart failure in 8 (7.2%), infection in 7 (6.3%), nausea/dizziness in 7 (6.3%), anemia/bleeding in 6 (5.4%), cardiogenic shock in 5 (4.5%), worsening shortness of breath in 5 (4.5%), additional catheterization laboratory visit in 4 (3.6%), thoracentesis in 3 (2.7%), angina in 3 (2.7%), stroke in 3 (2.7%), graft thrombosis in 2 (1.8%), pleural effusion in 2 (1.8%), pericardiocentesis in 2 (1.8%), pericarditis in 2 (1.8%), surgical debridement in 2 (1.8%), NSTEMI in 1 (0.9%), and cardiac arrest in 1 patient (0.9%).

Of the 111 patients who underwent coronary angiography, 57 (51%) did not have any further complications at 30-day follow-up. Follow-up was available for all patients and post-CABG 30-day mortality was 17% (19 patients died).

Discussion

The main findings of our study are: (1) the incidence of coronary angiography within 30 days of CABG was approximately 5%; (2) the most common presentation/indication for coronary angiography was cardiogenic shock (41%) followed by STEMI (32%); (3) complete occlusion of at least 1 graft was observed in 32%; and (4) 30-day readmission and mortality occurred in 26% and 17%, respectively.

Improving the quality and quantity of life is the main goal of CABG and is dependent on long-term graft patency.^4,10-12 Early bypass graft failure is often associated with catastrophic outcomes.^13-16 Early (<1 month) graft failure is often due to technical factors, such as a small target vessel resulting in a poor distal runoff, size mismatch between the graft and the target vessel, graft ischemia, and endothelial disruption in the graft due to mechanical trauma.¹⁷

Studies in which patients were referred for coronary angiography following CABG due to suspected periprocedural myocardial ischemia are summarized in Table 3. Most of these studies included CABG-only patients and coronary angiography was performed within a few days following CABG (vs coronary angiography within 30 days from CABG in our study). These studies indicate that the incidence of early coronary angiography due to perioperative myocardial ischemia following CABG ranges from 0.7% to 5.3%, which is similar to our findings (5%). In addition, the incidence of graft pathologies ranged from 39% to 78% (vs 68% in our study). In these studies, the in-hospital and 30-day mortality rates ranged between 7.3%-24% and 7%-25%, respectively (vs 17% 30-day mortality in our study).

Both our study and prior studies demonstrate that early coronary angiography following CABG is associated with poor outcomes, with in-hospital to 30-day mortality rates ranging between 7% and 25% (Table 3). The differences in the incidence of coronary angiography and the outcomes following CABG may be explained by differences in the inclusion criteria, patient complexity, surgical techniques, and management strategies. Our study included all patients who underwent CABG (including concomitant aortic surgery or valve procedures). Furthermore, the timing of coronary angiography varied between studies, ranging from in-hospital to 30 days.

Study limitations. Our study has limitations. First, we did not analyze the characteristics of patients who underwent CABG, but did not require coronary angiography. Second, this study was performed in a single health system. Third, we did not have a clinical events adjudication committee or angiographic core laboratory. Fourth, while we obtained 30-day follow-up for all patients, we do not have long-term follow-up data.

Conclusion

Our study shows that the incidence of coronary angiography within 30 days of CABG was approximately 5%. The most common indications/presentations leading to coronary angiography were cardiogenic shock (41%) followed by STEMI (32%). Achieving complete revascularization was the indication in 16%. Patients who needed early coronary angiography following CABG had high complication rates, with 30-day readmission and mortality occurring in 26% and 17%, respectively.

Acknowledgments. The authors would like to thank the generous donors who have supported the 2022 MHIF internship program including Leonardus Loos and Shelley Holzemer for supporting a named intern for this study. The authors are grateful for the philanthropic support of our generous anonymous donors, and the philanthropic support of Drs Mary Ann and Donald A. Sens, Mrs Diane and Dr Cline Hickok, Mrs Wilma and Mr Dale Johnson, Mrs Charlotte and Mr Jerry Golinvaux Family Fund, the Roehl Family Foundation, and the Joseph Durda Foundation. The generous gifts of these donors to the Minneapolis Heart Institute Foundation’s Science Center for Coronary Artery Disease (CCAD) helped support this research project.

Affiliations and Disclosures

From Minneapolis Heart Institute and Minneapolis Heart Institute Foundation, Allina Health Abbott Northwestern Hospital, Minneapolis, Minnesota.

Disclosures: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. Dr Bapat has served as a consultant for Medtronic, Edwards Lifesciences, 4C Medical, and Boston Scientific. Dr Burke is a shareholder in MHI Ventures and Egg Medical. Dr Brilakis reports consulting/speaker honoraria from Abbott Vascular, American Heart Association (associate editor, Circulation), Amgen, Asahi Intecc, Biotronik, Boston Scientific, Cardiovascular Innovations Foundation (Board of Directors), ControlRad, CSI, Elsevier, GE Healthcare, IMDS, InfraRedx, Medicure, Medtronic, Opsens, Siemens, and Teleflex; research support from Boston Scientific, GE Healthcare; owner, Hippocrates LLC; shareholder in MHI Ventures, Cleerly Health, and Stallion Medical. The remaining authors report no conflicts of interest regarding the content herein.

Manuscript accepted January 18, 2023.

Address for correspondence: Emmanouil S. Brilakis, MD, PhD, Director of the Center for Complex Coronary Interventions, Minneapolis Heart Institute, Chairman of the Center for Coronary Artery Disease at the Minneapolis Heart Institute Foundation, 920 E 28th Street #300, Minneapolis, MN 55407. Email: esbrilakis@gmail.com

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