A retrospective study showed that intraoperative dexmedetomidine administration was associated with decreased risk of 1-year mortality after cardiac surgery. In a previous randomized controlled trial, 285 elderly patients undergoing cardiac surgery were randomized to receive either perioperative dexmedetomidine or placebo (normal saline) administration. The purpose of this 6-year follow-up study is to investigate whether perioperative dexmedetomidine can improve long-term outcomes in those recruited elderly patients after cardiac surgery.

Dexmedetomidine is a highly selective alpha 2-adrenergic receptor agonist that provides anti-anxiety, sedation, and modest analgesic effects. In a retrospective cohort study of patients undergoing cardiac surgery, perioperative dexmedetomidine administration was associated with decreased risk of 1-year mortality. Theoretically, perioperative dexmedetomidine may exert the following favorable for cardiac surgery patients: (1) reduces perioperative opioid consumption and thereby mitigates opioid-induced immunosuppression, (2) dampens hyper-inflammatory response induced by surgery, and (3) improves postoperative sleep quality. However, prospective studies investigating the long-term effects of perioperative dexmedetomidine in cardiac surgery patients are still lacking.

In a previous randomized controlled trial, 285 patients of 60 years or older who were scheduled to undergo coronary artery bypass graft surgery and/or valve replacement surgery were randomized to receive either perioperative dexmedetomidine administration (0.6 microgram/kg in 10 minutes before anesthesia induction, followed by a continuous infusion at a rate of 0.4 microgram/kg/h until the end of surgery, then a continuous infusion at a rate of 0.1 microgram/kg/h until the end of mechanical ventilation) or placebo (normal saline, administered in the same rate or volume for the same duration as in the dexmedetomidine group). The results showed that perioperative dexmedetomidine reduced the incidence of pulmonary complications and shortened the duration of mechanical ventilation after surgery.

The purpose of this 6-year follow-up study is to investigate the effects of perioperative dexmedetomidine on the long-term outcomes in elderly patients after cardiac surgery.

Inclusion Criteria:

1. Age of 60 years or older;
2. Scheduled to undergo cardiac surgery (coronary artery bypass graft and/or valve replacement surgery);
3. Provide written informed consents.

Exclusion Criteria: Patients who meet any of the following criteria will be excluded.

1. Preoperative history of schizophrenia, epilepsia, Parkinson syndrome, or severe dementia;
2. Inability to communicate in the preoperative period because of severe visual/auditory dysfunction or language barrier;
3. History of brain injury or neurosurgery;
4. Preoperative sick sinus syndrome, severe bradycardia (HR < 50 bpm), second-degree or above atrioventricular block without pacemaker;
5. Severe hepatic dysfunction (Child-Pugh class C);
6. Severe renal dysfunction (requirement of renal replacement therapy);
7. Other conditions that are considered unsuitable for participation.