2. Neurologic injury and coronary revascularization strategies
Cardiovascular disease, mostly represented by coronary artery disease (CAD) and stroke, is the major cause of death in the United States (27). The management of CAD, and the choices between medical therapy, percutaneous coronary intervention (PCI) and CABG, remains an intensely debated topic (28,29).
Current evidences support CABG as the optimal revascularization strategy for patients with left main or multivessel disease, high overall complexity disease (high SYNTAX scores) and patients with diabetes or chronic kidney disease (30-34). This is primarily driven by improved intermediate- and long-term survival, reduced myocardial infarction and fewer repeat revascularization procedures. However, in patients with less complex and less diffuse disease, PCI is often considered a better alternative (30,31), because it provides similar survival benefit with less short-term morbidity. Stroke and neurologic injury are an important component of the latter and when used in composite primary endpoints in randomized trials the benefit of CABG is often reduced or offset, leading to the non-inferiority/superiority of PCI with a significant impact on revascularization guidelines.
The higher rate of early stroke is a significant limitation of traditional on-pump CABG compared to PCI and carries a dramatic effect on long term survival (35,36). Evidence from a recent patient-data meta-analysis (35) showed that the long term neurologic benefit of PCI is driven mostly by the significantly higher peri-operative stroke risk after CABG, given that the rate between 31 days and 5 years were comparable (PCI 2.2.% vs CABG 2.1%, HR 1.05, 95%CI 0.80 - 1.38). Similarly, the SYNTAX trial (37), despite an initial neurologic advantage of PCI at 12-months, showed equivalent stroke rate between PCI and CABG at 5 years (38).
Analogous findings were reported by Gaudino (36): both early and delayed stroke have an extraordinary impact on operative and long-term mortality post isolated CABG (21.3% vs 2.4%, p<0.001 and 10.9% vs 3.4% at 8 years, p<0.001). Meta-regression analysis showed that techniques directed at minimizing aortic manipulation rather than intrinsic patients characteristics had a protective effect on neurologic outcome (β=-0.009 and p=0.01 for off-pump CABG).
Finally, an increasing body of data supports the correlation between evidence of “asymptomatic” brain injury on Diffusion-Weighted Magnetic Resonance Imaging (MRI) and long term neurologic injury (cognitive and functional decline) after both cardiac (39-41) and non-cardiac surgery (42).