Efficacy and hemodynamic safety of perioperative dexmedetomidine for the prevention of postoperative delirium in elderly patients undergoing cardiac surgery: an updated systematic review and meta-analysis of randomized controlled trials

Abstract

Background Postoperative delirium (POD) is a common and clinically important complication after cardiac surgery in older adults. We performed an updated systematic review and meta-analysis of randomized controlled trials (RCTs) to evaluate the efficacy and hemodynamic safety of perioperative dexmedetomidine for POD prevention in older adults undergoing cardiac surgery. Methods We searched PubMed, Embase, Scopus, and the Cochrane Central Register of Controlled Trials from inception through July 12th, 2026 for RCTs comparing perioperative dexmedetomidine with placebo or alternative sedative /analgesic regimens in elderly patients aged 60 years or older, or in extractable elderly subgroups, undergoing cardiac surgery. Primary outcomes were POD incidence and delirium duration. Secondary outcomes included length of intensive care unit (ICU) stay, length of hospital stay, and the risk of bradycardia and hypotension. Results Fifteen RCTs involving 3,274 patients were included. Perioperative dexmedetomidine was associated with a lower incidence of POD (Risk Ratio [RR] 0.70, 95% Confidence Interval [CI] 0.56 to 0.86, p = 0.001, I2 = 19%; GRADE: moderate certainty) and shorter duration of delirium among patients with POD (Mean Difference [MD] −1.12 days, 95% CI −1.89 to −0.35, p = 0.01, I2 = 83%; GRADE: low certainty). The apparent benefit was more evident in active-comparator trials than in placebo/saline-controlled trials, but this comparator-dependent pattern should not be interpreted as proof of a uniform neuroprotective effect. However, dexmedetomidine was associated with increased bradycardia (RR 2.08, 95% CI 1.31 to3.31, p = 0.0019, I2 = 0%; GRADE: low certainty). No significant differences were observed for length of ICU stay, length of hospital stay, or hypotension. Conclusion Perioperative dexmedetomidine may reduce POD incidence in selected older cardiac surgery patients, particularly when compared with selected active sedative or analgesic regimens. However, the certainty of evidence was moderate, and the effect was less clear in saline/placebo-controlled trials. Evidence for delirium duration was based on few affected patients, showed substantial heterogeneity, and should not drive the main clinical conclusion. Dexmedetomidine increased reported bradycardia, and clinical use should be individualized with careful hemodynamic monitoring. Systematic review registration https://osf.io/f6nwu