What is the role of beta (β) blockers after cardiac surgery?

Role of Beta Blockers After Cardiac Surgery

Beta blockers should be continued in patients undergoing cardiac surgery who are already receiving beta blockers for treatment of conditions with ACCF/AHA Class I guideline indications such as angina, symptomatic arrhythmias, or hypertension. 1

Continuation of Pre-existing Beta Blocker Therapy

• Beta blockers should not be discontinued perioperatively in patients already taking them, as abrupt discontinuation can lead to increased risk of adverse cardiac events, including myocardial infarction (RR 2.70,95% CI 1.06 to 6.89 within first 30 days after cessation) 2
• When discontinuation is necessary, beta blockers should be gradually reduced over 1-2 weeks with careful monitoring to avoid severe exacerbation of angina, myocardial infarction, and ventricular arrhythmias 3
• Chronically administered beta-blocker therapy should not be routinely withdrawn prior to major surgery, including cardiac surgery 3

Benefits of Beta Blockers After Cardiac Surgery

• Patients discharged with beta blockers after cardiac surgery exhibit substantially lower long-term mortality rates (10% vs 19%, adjusted HR 0.65,95% CI 0.49-0.87) 4
• One-year mortality is significantly lower in patients discharged with beta blockers (2.2% vs 7.2%, adjusted OR 0.54,95% CI 0.30-0.97) 4
• This mortality benefit extends to patients without prior myocardial infarction or heart failure 4
• Beta blockers reduce the incidence of postoperative atrial fibrillation following coronary artery bypass surgery 5

Optimal Beta Blocker Management

• Beta blockers should be titrated to achieve a target heart rate of 60-65 bpm for optimal perioperative outcomes 2
• An absolute mean perioperative heart rate lower than 70 bpm is associated with the best clinical outcomes 2
• Each 10-bpm reduction in heart rate is estimated to reduce the relative risk of cardiac death by 30% in post-MI patients 2
• Beta blocker medication should be held if heart rate drops below 50 bpm or systolic blood pressure falls below 100 mmHg 2

Potential Risks and Monitoring

• Beta blockers can cause depression of myocardial contractility and may precipitate heart failure and cardiogenic shock in susceptible patients 3
• Careful monitoring for bradycardia and hypotension is essential, as beta blockers significantly increase the risk of intraoperative bradycardia (OR 4.97,95% CI 3.22 to 7.65) and hypotension (OR 1.84,95% CI 1.31 to 2.59) 6
• If signs of heart failure develop, the dose of beta blocker may need to be lowered or the medication temporarily discontinued 3

Choice of Beta Blocker

• Carvedilol may be more effective than metoprolol in preventing postoperative atrial fibrillation following coronary artery bypass surgery 5
• For patients with bronchospastic disease who require beta blockade, consider using a beta-1 selective agent (like metoprolol) at the lowest possible dose, potentially administered in smaller doses three times daily instead of larger doses twice daily 3

Special Considerations

• In patients with heart failure with reduced ejection fraction, beta blockers reduce mortality and heart failure hospitalization when patients are in sinus rhythm, but this benefit is not seen in patients with atrial fibrillation 7
• Beta blockers may mask tachycardia occurring with hypoglycemia, though other manifestations such as dizziness and sweating are not significantly affected 3