Outcomes of patients with prior coronary artery bypass graft who present with acute coronary syndrome

Abstract

Generally, patients with prior coronary artery bypass graft (CABG) are often under-represented in acute coronary syndrome (ACS) clinical trials. Nevertheless, there is growing global attention concerning their short- and long-term prognosis. Some reports suggest prior CABG as an independent risk factor for increased mortality, while others report an equal or a more favorable prognosis despite their adverse baseline clinical characteristics. The reasons for this ‘risk-mortality paradox’ need to be further evaluated. More recent reports showed a significant reduction in in-hospital morbidity and mortality over a 20-year period of follow up that may be attributed to the improvement in surgical CABG techniques and increased use of evidence-based therapies over the past two decades. In the current review we discuss the available literature regarding outcomes of prior CABG patients who are presenting with ACS.

Keywords::

• acute coronary syndrome
• coronary artery bypass graft
• evidence-based therapy
• mortality
• outcome

Acknowledgements

The authors would like to acknowledge all who work in Qatar Cardiovascular Research Center (QCRC) and actively contributed in preparation and assembly of the data of this article.

Financial & competing interest disclosure

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending or royalties.

No writing assistance was utilized in the production of this manuscript.

Key issues

• While the scenario of acute coronary syndromes (ACS) presentation and outcomes were altered in the last three decades as a result of public awareness of the risk factors for CAD and improvement in primary and secondary prevention of evidence-based medication, those patients with prior coronary artery bypass graft (CABG) still had higher incidence of adverse baseline clinical characteristics and comorbidities compared with those without prior CABG.

• In patients presented with ACS, data concerning whether or not prior CABG is considered as an independent risk factor for mortality is still a matter of debate.

• Patients with prior CABG presented more with unstable angina/non-ST-elevation myocardial infarction (STEMI) than ST-elevation MI/left bundle branch block-MI. The efficacy of reperfusion therapy is less well characterized in those patients. Nevertheless, percutaneous coronary intervention (PCI) improves clinical outcomes compared with medical therapy alone, while redo CABG does not seem to further improve the clinical outcomes. However, the guidelines did not define a specific recommendation for the optimal reperfusion strategy (fibrinolysis vs PCI) in patients with prior CABG and presented with STEMI.

• At present, the optimal antithrombotic therapy for patients with prior CABG presenting with ACS is not known, and the existing data are conflicting. However, the implementation of robust evidence-based management strategies to optimize their clinical outcomes is warranted.

• When presented with ACS, those patients with prior CABG had a higher prevalence of prior stroke as most of studies revealed. However, the occurrence of stroke as a new complication in those patients is still controversial.

• Despite the benefit of CABG in reducing morbidity and mortality, the impact of prior CABG in patients presenting with ACS according to gender is not well defined.

• Women had higher death rates when compared with men. They were also consistently shown to be less treated with evidence-based therapies than men.

• While, it is clear that the gender gap in mortality is narrowed in patients undergoing PCI with high-risk ACS, STEMI and cardiogenic shock complicating AMI, there are differences in the benefit of early PCI among low-risk non-STEMI patients according to gender.

• Contemporary studies have cast doubt on the widely held belief that women fare worse with PCI and CABG than do men because of technical factors (e.g., smaller artery size, greater age and more comorbidities).

• Despite the worse clinical profile, a recent report showed that women had similar outcome when compared with men, and hence the ‘gender gap’ is altered in patients with prior CABG, although the understanding of the gender gap in outcomes following CABG has increased, but a clear concept of how CABG may ameliorate the worse outcomes of female in comparison with male gender as observed before, yet need to be further defined.

Notes