What are the recent American Heart Association (AHA) guidelines for preventing perioperative myocardial infarction (MI)?

Recent AHA Guidelines on Perioperative MI Prevention

The 2024 AHA/ACC guidelines prioritize continuation of statins in all patients currently taking them and initiation in statin-naïve patients meeting ASCVD criteria, while beta-blocker recommendations have become more restrictive, focusing on continuation in patients already on therapy rather than routine initiation. 1

Statin Therapy (Class I Recommendations)

The most robust evidence supports aggressive statin management:

• Continue all statins perioperatively without interruption in patients already taking them to reduce major adverse cardiac events (MACE). 1
• Initiate statins in statin-naïve patients who meet criteria based on ASCVD history or 10-year risk assessment, with intention for long-term use beyond the perioperative period. 1
• Large cohort data (n=780,591) demonstrates 9.9% of patients receiving perioperative lipid-lowering therapy had lower surgical mortality compared to those without such therapy. 1
• In vascular surgery specifically, atorvastatin 20 mg daily initiated 30 days preoperatively reduced the composite endpoint of cardiac death, nonfatal MI, stroke, and unstable angina from 26% to 8% at 6 months (P=0.031). 1

Key caveat: While statin reloading showed promise in one study (5.6% absolute risk reduction in 30-day MACE), the guidelines note this requires additional RCTs before routine recommendation. Surgery should not be delayed for lipid testing. 1

Beta-Blocker Therapy (Nuanced Approach)

The beta-blocker recommendations have evolved significantly due to conflicting evidence:

• Continue beta-blockers in patients already taking them - withdrawal increases 1-year mortality dramatically (HR: 2.7) and postoperative discontinuation carries 50% mortality versus 1.5% with continuation. 2
• Do NOT routinely initiate beta-blockers in beta-blocker-naïve patients, particularly within 1 day of surgery. 1

The evidence controversy centers on timing and patient selection:

• Meta-analyses excluding the controversial DECREASE trials show beta-blockers reduce nonfatal MI (RR: 0.69) but increase nonfatal stroke (RR: 1.76), hypotension (RR: 1.47), bradycardia (RR: 2.61), and all-cause mortality (RR: 1.30) when started ≤1 day before surgery. 1
• The POISE-1 trial (n=9000) demonstrated these harms definitively when high-dose, long-acting beta-blockers were started shortly before surgery. 1

If beta-blockers are initiated (based on older evidence from DECREASE trials that remains controversial):

• Start bisoprolol 2.5-5 mg daily beginning 7-30 days before surgery 2, 3
• Titrate to resting heart rate 50-60 bpm preoperatively 1, 2
• Maintain heart rate <70-80 bpm intraoperatively and postoperatively 2
• Use long-acting, beta-1 selective agents (bisoprolol or atenolol preferred over metoprolol) 1

RAAS Inhibitor Management

The 2024 guidelines provide new clarity on ACE inhibitors and ARBs:

• Consider omitting RAAS inhibitors 24 hours before elevated-risk surgery in patients with controlled hypertension to limit intraoperative hypotension (Class IIb, Level B-R). 1
• Continue RAAS inhibitors perioperatively in patients taking them for heart failure with reduced ejection fraction (HFrEF) (Class IIa, Level C-EO). 1
• Meta-analysis of 6,022 patients showed more intraoperative hypotension with continuation but no difference in MACE. 1

Antiplatelet Therapy

• Continue aspirin perioperatively for secondary prevention unless bleeding risk is extremely high (e.g., intracranial surgery). 2
• Maintain dual antiplatelet therapy in patients with recent coronary stents. 2
• Delay elective surgery: ≥14 days after balloon angioplasty, ≥30 days (4-6 weeks) after bare-metal stent, ≥6-12 months after drug-eluting stent. 1, 2
• In urgent surgery requiring stent discontinuation, continue aspirin if possible and restart thienopyridine as soon as possible postoperatively (Class IIa). 1, 2

Coronary Revascularization

Routine prophylactic coronary revascularization is NOT recommended before noncardiac surgery in stable coronary artery disease (Class III, Level B). 1, 2

Revascularization should only occur for standard indications:

• Significant left main coronary artery stenosis 1
• 3-vessel disease (especially with LVEF <0.50) 1
• 2-vessel disease with proximal LAD stenosis and either LVEF <0.50 or demonstrable ischemia 1
• High-risk unstable angina or acute MI 1

Postoperative Monitoring

The guidelines remain uncertain about routine screening:

• Measure troponin and obtain ECG when signs or symptoms of ischemia, MI, or arrhythmia are present (Class I). 1
• Routine postoperative screening with troponin or ECG in asymptomatic high-risk patients has uncertain benefit (Class IIb) - the value depends on having a defined management strategy for positive results. 1
• Do NOT perform routine screening in unselected patients without symptoms (Class III). 1

Critical Pitfalls to Avoid

1. Never withdraw beta-blockers or statins abruptly in patients already taking them - this dramatically increases mortality. 2
2. Do not start beta-blockers the day before surgery - this provides inadequate beta-blockade and may worsen outcomes. 2
3. Do not perform prophylactic revascularization simply because a patient is having noncardiac surgery. 1, 2
4. Do not delay surgery for lipid testing - statin initiation can occur without baseline LDL values. 1