Dissecting the "Triple Hit" of Perioperative Neurocognitive Disorders after CABG: A Narrative Review of Microemboli, Hypoperfusion, and Inflammation.

Perioperative neurocognitive disorders, encompassing a spectrum from delirium to long-term cognitive decline, remain one of the most significant and prevalent complications following coronary artery bypass grafting, profoundly impacting patient recovery and quality of life. However, perioperative neurocognitive disorders represent only one facet of a broader spectrum of perioperative neurologic injury (PNI) that also includes overt stroke and prognostically crucial silent brain infarcts. The etiology of this injury spectrum is unequivocally multifactorial. This comprehensive review conceptualizes the intricate pathogenesis of post-coronary artery bypass grafting neurologic injury through an expanded "triple-hit" framework. Building on the foundational "double-hit" hypothesis of embolism and hypoperfusion, this model integrates the massive systemic inflammatory response as a third, synergistic pillar. We posit that it is the convergence of these three intraoperative insults-microembolic events, cerebral hypoperfusion, and inflammation-acting in a vicious cycle on a patient's preexisting cerebral vulnerabilities (the "vulnerable brain") that overwhelms cerebral reserve and precipitates the full spectrum of PNI. This review systematically deconstructs the pathophysiological mechanisms of each component, critically appraises clinical evidence for the entire PNI spectrum, evaluates the influence of evolving surgical and anesthetic techniques, and explores the pivotal causal link between postoperative delirium and the trajectory toward long-term dementia. Finally, drawing on authoritative guidelines, we synthesize the evidence into a holistic, team-based, and actionable perioperative brain health pathway, providing practical guidance for the entire perioperative team to preserve the cognitive function that defines patients' quality of life.