Coronary artery bypass surgery: The starting point of a long medical journey

Coronary artery bypass graft (CABG) surgery remains one of the most important therapeutic options in patients with coronary artery disease. With the increasing significance held by percutaneous coronary intervention (PCI) in the everyday life of cardiologists, one tends to forget that, in stable patients, coronary artery surgery maintains an advantage over PCI in patients with multivessel disease, and particularly for such patients as those with diabetes.1,2 From a psychological standpoint, however, many CABG patients are likely to consider that surgery, because of its more ‘aggressive’ nature, is a more definitive cure of their disease than is PCI (or medical treatment alone) and they may be less prone to take or keep measures that will control the evolution of the atherosclerotic disease, such as lifestyle modifications or long-term adherence to secondary prevention medications. It is to the credit of Zafrir et al. to have addressed this often-neglected issue, by analysing the possible impact of inadequate lipid control after CABG on long-term survival.3 They performed a retrospective analysis in a single-centre cohort of 1230 patients in whom lipid measurements were available after CABG. After adjusting for potential confounders, they found that patients with low-density lipoprotein cholesterol (LDL-C) levels > 100 mg/dl had twice the risk of long-term mortality compared to those with LDL-C levels achieving the recommended target (<70 mg/dl), while those with LDL-C from 70–100 mg/dl had their risk increased by one-third. Other lipid parameters such as high-density lipoprotein cholesterol (HDL-C or triglyceride levels, were also correlated with long-term mortality. The study is not free from methodological limitations; in particular, the authors used the last lipid values available, and do not describe whether the time from surgery to last lipid measurement was similar for all three categories of LDL-C. Indeed, an imbalance between these times might have major consequences on the association between LDL-C control and outcomes: supposing LDL-C control became less appropriate over time, a not unreasonable assumption,4 it would mean that patients with inadequate LDL-C control would have survived longer before the starting point of the analysis, compared with those with adequate LDL-C control; it would therefore not be surprising that the survival time after the starting point of the analysis would be shorter (i.e. a higher mortality after the starting point of the analysis, but a possibly identical or longer survival since CABG). In other words, Zafrir and colleagues do not provide proof that achieving the target LDL-C levels will improve survival; but their study is important as it rings an alarm bell for the comprehensive approach we should have in post-CABG patients, as with any other coronary artery disease (CAD) patients. In their population, only a minority of CABG patients (44%) had LDL-C levels within the recommended target, while 21.5% had LDL-C levels over 100 mg/dl. We have no idea, however, whether these figures greatly differed from other cohorts of CAD patients followed at the same centre. In other populations, it has been shown that CABG was associated with poorer lipid control, compared with other presentations of CAD,5 and that poor lipid control was also associated with higher C-reactive protein (CRP) levels.6 Lipid control can be poorer after CABG because of less adequate prescription of lipid-lowering medication, particularly high-dose statins. In our experience from the French registry of Acute ST-elevation and non-ST elevation Myocardial Infarction (FAST-MI) registries,7 as in others,8,9 patients hospitalised for an acute myocardial infarction and treated with CABG less frequently receive statins or high-intensity lipid-lowering therapy at discharge than patients treated with PCI. In FAST-MI, for overall statin prescription, the gap between CABG and PCI patients decreased over time, and the figures in the 2015 survey were quite similar for the two populations (92% and 94%, respectively) (Figure 1(a)); as regards high-intensity statin therapy, however, the delta between CABG and PCI patients remained constant over time (Figure 1(b)). In the European Action on Secondary and Primary Prevention by Intervention to Reduce Events (EUROASPIRE) I–III surveys, there was little difference in overall statin prescription rates between CABG and PCI patients, but the doses were not assessed.10 Prescription of recommended secondary prevention medications at hospital discharge in post-myocardial infarction patients according to use and type of revascularization procedures in the French registry of Acute ST-elevation and non-ST elevation Myocardial Infarction (FAST-MI) registries. (a) Statin therapy, (b) High-intensity lipid-lowering therapy and (c) Full recommended therapy. CABG: coronary artery bypass graft; PCI: percutaneous coronary intervention. Beyond the initial prescription of lipid-lowering medications, patient adherence is also an issue. In a recent meta-analysis of randomised trials comparing CABG with PCI, adherence to secondary prevention medications was poorer in CABG patients.4 In contrast, in an analysis of patients undergoing CABG or PCI for non-ST-segment myocardial infarction, Kurlansky et al. found similar (and low) rates of adherence to lipid-lowering agents in both populations.11 High adherence rates were even reported from a post-CABG study in Edmonton, Canada,12 or in the large Practice INNovation And CLinical Excellence (PINNACLE) registry;13 in the Edmonton study, however, only 66% of the patients achieved the recommended lipid target. Interestingly, Kurlansky et al. suggest that adherence to recommended medications may have less prognostic impact in CABG than in PCI patients,11 a finding that clearly diverges from the implications of the current study by Zafrir et al. Finally, lipid management is only part of the comprehensive management required to improve long-term outcomes. In the FAST-MI registries, following myocardial infarction, full guidelines-recommended medication regimen was much less frequently prescribed at discharge after CABG than after PCI (Figure 1(c)). Beside the afore-mentioned gap in prescription rates of high-intensity lipid-lowering treatment, large differences between the two revascularisation techniques were observed for dual antiplatelet therapy prescription after CABG in this post-myocardial infarction setting (35% vs 97%), and, as was also found in the Edmonton population,12 for use of angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) (69% in the CABG population vs 87% in PCI-treated patients). In this regard, cardiac rehabilitation may be particularly useful to improve prescription rates and patient adherence to their medications.14 Overall, in spite of its obvious methodological limitations, the study by Zafrir et al. draws our attention to the potential clinical importance, as in all other CAD patients, of a comprehensive approach in CABG patients: the procedure of coronary artery bypass surgery is in no way the end of the story, but should rather be considered the beginning of a (hopefully) long journey towards improved quality of life and increased life expectancy, requiring continued medical attention. The author(s) declared no potential conflicts of interest with respect to the research, authorship and/or publication of this article. The author(s) received no financial support for the research, authorship and/or publication of this article.