Mortality benefit of coronary angioplasty vs. conservative strategy in patients with prior coronary artery bypass surgery presenting with non-ST elevation myocardial infarction
Authors: Khan S , Thillainathan B , Pavitt C , Dhamrait S 
Published: November 2020

Abstract

Background
Patients with prior coronary artery bypass graft (CABG) surgery have been excluded or under-represented in many of the trials of percutaneous coronary intervention (PCI) vs. conservative strategy in the management of patients presenting with non-ST elevation myocardial infarction (NSTEMI). Therefore, limited data supports the use of PCI in this context. Given the higher risk profile of these patients, clinicians may default to a conservative strategy given the lack of evidence of benefit of PCI. Our institution consists of one PCI and one non-PCI acute site and serves a population of 500 000 including a uniquely high proportion of the elderly with a high follow up rate and an ideal, interesting population to study with many patients offered a conservative strategy.

Methodology
Patients who presented over a 5 year period from Jan 2012 to Dec 2017 with NSTEMI and prior CABG were identified from Myocardial Ischaemia National Audit Project (MINAP) returns. Hospital records were reviewed to exclude patients with type 2 MI and ST elevation MI. We identified patients who were managed conservatively or with PCI and assessed outcomes at the end pf December 2019, giving a follow up range of 2–7 years. The primary outcome was all cause death or myocardial infarction. Secondary outcome measures included readmission at 30 days and 1 year, angina, need for revascularisation.

Results
206 patients were identified (mean age 77.7y, 26% female) of whom 107 were managed medically and 99 underwent angiography. 74 (36%) of patients were admitted to the non-interventional site, of which 27 patients underwent angiography. Overall, 48 (23%) went on to have PCI (only 7% of patients from the non-PCI site). 29 patients had PCI to the native coronaries, 16 to a bypass graft and the remainder to both. Age and clinical frailty score (CFS) was significantly higher in patients managed conservatively. The primary end point occurred in a high proportion of patients (124, 74.6%) consisting of 28 MI and 96 deaths during the follow up period. Age at presentation, clinical frailty score (CFS), presence of heart failure and absence of statin use were were significantly associated with the primary outcome. There was a significant difference in the primary outcome in patients managed conservatively (113/158; 72%) compared to those who had PCI (11/48; 23%), P&lt;0.001.

Conclusion
PCI in NSTEMI patients with prior CABG is significantly associated with improved survival and less myocardial infarction compared to a conservative strategy in this retrospective audit of our patient population, but PCI patients are younger and less frail, which, in themselves, could suggest treatment bias and might confer a survival benefit. PCI rates varied significantly when patients were assessed in non-interventional acute site compared to a PCI site which has important implications for service provision. A large-scale randomised control trial is warranted to guide best practice.

Funding Acknowledgement
Type of funding source: None