Delirium and Cognitive Decline after Cardiac Interventions

Abstract

Coronary artery bypass grafting and percutaneous coronary intervention effectively relieve symptoms of angina pectoris. Both treatment strategies, however, remain associated with some degree of postoperative delirium and/or cognitive decline. The aim of this thesis was to investigate delirium and cognitive decline after cardiac interventions. We compared cognitive outcomes and brain integrity as assessed by magnetic resonance imaging and spectroscopy of two revascularization strategies on the beating heart, off-pump coronary artery bypass grafting and percutaneous coronary intervention. We investigated the effect of suppression of the systemic inflammatory response by high dose steroids at the induction of general anesthesia on the development of delirium and the influence of postoperative delirium on subsequent cognitive decline. We found a protective effect of the presence of cardiac collaterals on cognitive outcome and a harmful effect of occurrence postoperative delirium on the development of cognitive decline and the extent of recovery from decline in the first year after surgery. The studied comparisons did not result in a difference in outcome. At 7.5 years follow-up, off-pump CABG patients had a similar or perhaps slightly better cognitive performance compared with PCI patients and magnetic resonance spectroscopy did not demonstrate significant alteration differences in brain integrity. Demographic variables were more important determinants of long-term cognitive outcome than mode of revascularization. The intraoperative administration of dexamethasone did not reduce the incidence or duration of delirium in the first 4 days after cardiac surgery. The work presented in this thesis contributes to a better understanding of the complex, multifactorial etiology of these burdensome complications of cardiac interventions and the influence of one of these phenomena, delirium, on the subsequent development of the other, cognitive decline, in the postoperative trajectory. Despite our increasing body of knowledge of both postoperative delirium and cognitive dysfunction, it is unlikely that these complications will ever be complete avoided. The many technical advances that have been made in revascularization techniques and perioperative care since the start of the first trials reported in this thesis do contribute to prolonged post-procedural survival and improved quality of life, but also allowed increasingly frail patients to undergo complex and extensive cardiac surgical procedures, increasing the need for preventive strategies.