A study looking at the timing of coronary artery bypass grafting (CABG) after the occurrence of acute myocardial infarction (AMI), suggests that although patients who undergo CABG within 24 hours of AMI more often present in cardiogenic shock, there is no significant outcome difference with those who undergo CABG after 24 hours.
The study authored by Valentino Bianco (University of Pittsburgh Medical Center, Pittsburgh, USA) and colleagues, published in The Journal of Thoracic and Cardiovascular Surgery (JTCVS), assessed all patients who underwent CABG at the University of Pittsburgh Medical Center from 2011–2017 after an AMI. According to the authors, CABG is often delayed in the acute setting in an effort to limit associated operative morbidity and mortality. However, they add, delayed surgical revascularisation with the presumption of increasing patient stability and improving outcomes may not be applicable in all cases.
Bianco and colleagues hypothesised that the timing of CABG after AMI may not be consistently associated with postoperative outcomes. In order to test this theory, they carried out a comparative analysis of 2,058 patients, after time from myocardial infarction presentation to the CABG procedure, including all-cause mortality and readmission.
The study population was divided into two CABG timing cohorts, including those whose procedure was carried out less than 24 hours after AMI (n=292) and those whose procedure took place after 24 hours or more (n=1,766).
Previous percutaneous coronary intervention (PCI), cardiogenic shock, and intra-aortic balloon pump were more prevalent in the less than 24 hours group, the study team wrote, as well as noting that operative mortality was significantly higher in the less than 24 hours cohort (7.19% vs 3.79%; p=0.01). Diabetes mellitus, peripheral vascular disease, serum creatinine, age, chronic obstructive pulmonary disease, and immunosuppression were significant predictors (p<0.05) of mortality, they add.
The study’s authors found that significantly more patients in the less than 24 hours time cohort presented with ST-Elevation Myocardial Infarction (STEMI), required an intra-aortic balloon pump (IABP), and were in cardiogenic shock, but they concluded that CABG timing was not a significant independent predictor of time to death or major adverse cardiac and cerebrovascular events (MACCE)-related readmission.
The significantly higher incidence of acute haemodynamic compromise appeared to be the most relevant determinants of heightened short-term mortality risk in the less than 24 hours group, Bianco et al note, adding that, on risk-adjusted multivariable analysis, neither cardiogenic shock nor IABP placement were independent predictors of elevated operative mortality or readmission.
Discussing the findings, Bianco et al write that the lack of a significant association between time of CABG and patient outcomes “potentially has far-reaching implications and may be indicative of the need to consider foregoing delays in performing surgical revascularisation in the setting of AMI”.
The authors add: “Other recent data are encouraging and support that delaying CABG beyond one day did not affect mortality. Our data are novel in that they show no significant difference in mortality or readmission, whether CABG is performed within 24 hours or after one day. Therefore, delaying surgical revascularisation with the presumption of increasing patient stability and improving outcomes may not be applicable in all cases, especially when the burden of associated comorbid disease is taken into consideration.”
They conclude that the findings indicate that in the presence of good clinical and surgical judgment, satisfactory outcomes can be achieved for patients with AMI undergoing CABG, for all time intervals.