Frequency of Surgery Cancellations Associated With Myocardial Infarction or Death 6 Months After Coronary Stent Placement

Observational studies report a decreased risk of postoperative adverse cardiac events among patients following percutaneous coronary intervention (PCI) when surgery is more than 6 months after coronary stent placement^1-4; however, the frequency and timing of surgery cancellations due to preoperative adverse cardiac events or death in the interval between the scheduling of the procedure and the procedure itself is unknown. Changes in medical condition may account for 28% of surgery cancellations.⁵ In addition, prior research on adverse postoperative events may be biased by the unavoidable selection criterion that a patient must first experience surgery in order to be studied.⁶ With little information on the frequency and factors associated with surgery cancellations following PCI, it is difficult to quantify the impact of this bias. We hypothesize that surgery cancellations are more frequent in the first 6 months following the placement of a drug-eluting stent (DES) and that a higher proportion of early cancellations are associated with acute myocardial infarction (MI) or death.

The study cohort includes all patients receiving a PCI within the Veterans Affairs (VA) Healthcare System from fiscal year 2000-2010. The study was granted institutional review board approval with a waiver of informed consent at the Birmingham VA Medical Center. Data on PCIs were linked with the VA Surgical Package to identify all scheduled noncardiac surgical procedures occurring in the 2 years following PCI. Surgery cancellations were then identified among the scheduled surgical procedures using the VA Surgical Package, and the VA Medical Statistical Analysis Software (SAS) files were queried for instances of acute MI not related to the PCI (International Classification of Diseases, Ninth Revision, Clinical Modification codes 410.x1) or death within 30 days of a cancelled surgery date. The VA Medical SAS files were used to define demographics and other comorbidities present at the time of stent placement. The characteristics of the scheduled surgical procedures were compared using χ² test statistics. Analyses were then limited to only cancelled surgical procedures, and the characteristics of cancellations related to MI or death were examined using the χ² test.

Of the 33 046 scheduled noncardiac surgical procedures within 2 years of PCI, 4387 (13.3%) were cancelled, with 46.7% of these cancelled surgical procedures proceeding to subsequent surgery (47.2% to DES placement and 46.2% to bare metal stent [BMS] placement; P = .53). Cancellations were more frequent among patients with a BMS (14.2%) than among patients with a DES (12.4%) (P < .001) and were highest among patients with a history of chronic kidney disease (16.6%; P < .001) or a recent episode of congestive heart failure (16.0%; P < .001). They were also more common for planned digestive (23.3%) or vascular (17.1%) procedures (P < .001; Table). Cancellation rates were highest in the first 6 months following stent placement (15.1% for <6 months vs 12.6% for >6 months; P < .001) and remained significantly elevated among patients with a BMS beyond 6 months (13.5% of patients with a BMS vs 11.8% of patients with a DES; P < .001).

Death or an MI diagnosis accompanied 6.0% of cancellations (4.2% of completed surgical procedures; P < .001) and was more frequent among cancellations within 6 months following PCI (8.5%) compared with those beyond 6 months (4.9%) (P < .001; Figure). Cancellations related to MI or death were more frequent among patients whose stent was placed for an MI (9.4%; P < .001) and among planned respiratory (10.4%) or vascular procedures (8.7%) (P < .001). The proportion of cancellations related to death or MI did not vary by stent type (5.9% with DES vs 5.9% with BMS; P > .99).

This research addresses the important gap of potential selection bias in the current literature examining adverse postoperative outcomes among patients experiencing PCI.⁶ One limitation of our study is that a surgery must first be scheduled in order to be cancelled, so we are likely underestimating the magnitude of cancellations. To conclude, we found that surgery cancellations were most frequent in the 6 months after PCI and that these cancellations were more likely to be associated with a diagnosis of acute MI or death. These results are consistent with prior findings of an increased risk of cardiac events in the 6 months following PCI regardless of surgery⁴ and further support planning of elective surgery at least 6 months after PCI.

Corresponding Author: Mary T. Hawn, MD, MPH, Stanford University, 300 Pasteur Dr, M121 Alway Bldg, Stanford, CA 94306 (mhawn@stanford.edu).

Published Online: October 7, 2015. doi:10.1001/jamasurg.2015.3078.

Author Contributions: Dr Hawn had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design: Graham, Hollis, Hawn.

Acquisition, analysis, or interpretation of data: Graham, Hollis, Richman.

Drafting of the manuscript: Graham.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Graham, Richman.

Obtained funding: Hawn.

Administrative, technical, or material support: Graham.

Conflict of Interest Disclosures: None reported.

Funding/Support: Funding for this study was provided by the Department of Veteran Affairs Health Services Research and Development grant IIR 09-347.

Role of the Funder/Sponsor: The Department of Veteran Affairs had no role in the design and conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Disclaimer: The content is solely the responsibility of the authors and does not necessarily represent the official views the Department of Veterans Affairs or the US government.

Previous Presentation: This paper was presented at the 39th Annual Meeting of the Association of VA Surgeons; May 4, 2015; Miami Beach, Florida.