Acute Coronary Syndrome Management

Diagnosis and Initial Management

• In patients with suspected STEMI and ventricular paced rhythm, urgent cardiac catheterization is required to confirm diagnosis and initiate therapy, as pacemaker rhythm prevents reliable interpretation of ST-segment changes, according to the European Society of Cardiology 1, 2
• Primary PCI is the preferred reperfusion strategy, as recommended by the European Society of Cardiology 1
• If primary PCI cannot be performed within 120 minutes from STEMI diagnosis, consider fibrinolytic therapy within 12 hours of symptom onset, as suggested by the European Society of Cardiology 1
• For patients with resuscitated cardiac arrest and ECG consistent with STEMI, primary PCI is recommended by the European Society of Cardiology 1
• Ongoing chest pain despite medical therapy warrants urgent angiography even without diagnostic ECG changes, as recommended by the European Society of Cardiology 2

Pre-Hospital and Hospital Management

• Regional networks should be designed to deliver reperfusion therapy expeditiously, with direct transfer to PCI-capable centers, as recommended by the European Society of Cardiology 1
• Continuous ECG monitoring with defibrillator capacity is essential in all patients with suspected STEMI, according to the European Society of Cardiology 1

Diagnostic Adjuncts

• Echocardiography can be useful to detect regional wall motion abnormalities when ECG diagnosis is unclear, as suggested by the American Heart Association 3
• The Sgarbossa criteria are used for diagnosing AMI in patients with Left Bundle Branch Block (LBBB) and ventricular paced rhythms, including:
• The modified Sgarbossa criteria replace the third criterion with a proportional measurement, significantly improving sensitivity to 91% while maintaining high specificity of 90%, with a positive likelihood ratio of 9.0 4
• When evaluating a patient with LBBB or ventricular paced rhythm and suspected AMI, obtain a 12-lead ECG immediately and apply the modified Sgarbossa criteria, including looking for concordant ST elevation ≥1 mm in any lead, checking for ST depression ≥1 mm in leads V1-V3, and calculating ST/S ratio in leads with discordant ST elevation (ratio ≤-0.25 is positive) 4
• If any criterion is positive, activate cardiac catheterization lab immediately, as recommended by the American Heart Association and American College of Cardiology 4, 1, 2

Special Considerations

• ST depression in V1-V3 is highly specific (82%) for AMI in paced rhythms, and posterior leads (V7-V9) should be considered if suspecting posterior wall involvement, with ST elevation ≥0.05 mV in V7-V9 helping to identify posterior MI that might be missed on standard leads, as recommended by the American College of Cardiology 4, 5
• Consider reprogramming the pacemaker in non-dependent patients to allow evaluation of intrinsic rhythm, but do not delay invasive investigation, as recommended by the European Heart Journal 1, 2
• Do not wait for troponin elevation before activating the cath lab if modified Sgarbossa criteria are positive, as early reperfusion saves myocardium, and beware of false negatives, as the absence of Sgarbossa criteria does not rule out AMI, with clinical judgment remaining important 4, 2

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