Clonidine in patients undergoing noncardiac surgery

Area of Science:

• Cardiology
• Anesthesiology
• Pharmacology

Background:

• Sympathetic nervous system activation is common during and after noncardiac surgery.
• Low-dose clonidine can blunt central sympathetic outflow.
• Clonidine may potentially prevent perioperative myocardial infarction and death without causing hemodynamic instability.

Purpose of the Study:

• To evaluate the efficacy and safety of low-dose clonidine in patients undergoing noncardiac surgery.
• To determine if clonidine reduces the composite outcome of death or nonfatal myocardial infarction.
• To assess the impact of clonidine on perioperative hemodynamic stability.

Main Methods:

• A blinded, randomized trial with a 2-by-2 factorial design.
• 10,010 patients with or at risk for atherosclerotic disease were enrolled across 135 centers.
• Patients received either clonidine (0.2 mg/day) or placebo, continued for 72 hours post-surgery.

Main Results:

• Clonidine did not significantly reduce the primary composite outcome of death or nonfatal myocardial infarction (HR, 1.08; P=0.29).
• Myocardial infarction rates were similar between clonidine and placebo groups (6.6% vs. 5.9%; P=0.18).
• Clonidine significantly increased the risk of clinically important hypotension (47.6% vs. 37.1%; P<0.001) and nonfatal cardiac arrest (0.3% vs. 0.1%; P=0.02).

Conclusions:

• Low-dose clonidine administration in noncardiac surgery patients did not decrease the rate of death or nonfatal myocardial infarction.
• Clonidine use was associated with an increased risk of hypotension and nonfatal cardiac arrest.
• The findings suggest clonidine is not beneficial for preventing major adverse cardiac events in this population and may increase risks.