How to manage a patient with ventricular pacing and suspected acute myocardial infarction (AMI) using Sgarbossa criteria?

Managing Suspected Acute Myocardial Infarction in Patients with Ventricular Pacing Using Sgarbossa Criteria

The modified Sgarbossa criteria should be used to diagnose acute myocardial infarction (AMI) in patients with ventricular pacing, as they offer superior sensitivity (81%) compared to the original criteria (56%) while maintaining high specificity (96%). 1

Understanding Sgarbossa Criteria in Ventricular Paced Rhythm

Original Sgarbossa Criteria

The original criteria for diagnosing AMI in ventricular paced rhythm include three ECG findings:

• ST-segment elevation ≥1 mm concordant with the QRS complex (sensitivity 18%, specificity 94%) 2
• ST-segment depression ≥1 mm in leads V1-V3 (sensitivity 29%, specificity 82%) 2
• ST-segment elevation ≥5 mm discordant with the QRS complex (sensitivity 53%, specificity 88%) 2

A score ≥3 points (with concordant ST elevation = 5 points, concordant ST depression = 3 points, and excessive discordant ST elevation = 2 points) indicates high likelihood of AMI 3

Modified Sgarbossa Criteria

The modified criteria improve diagnostic accuracy by:

• Replacing the fixed 5 mm discordant ST elevation with a proportional measurement: ST/S ratio ≤-0.25 (ST elevation to S wave depth ratio) 1
• Making the criteria unweighted, where any positive criterion suggests AMI 3
• Adding concordant ST-depression in V4-V6 can further increase sensitivity to 86% 1

Clinical Application Algorithm

1. Initial Assessment:

   • For patients with ventricular pacing presenting with chest pain or symptoms suggestive of AMI, obtain immediate 12-lead ECG 2
   • Do not delay ECG acquisition due to presence of pacemaker 4

2. ECG Interpretation:

   • Apply modified Sgarbossa criteria to the ECG 1
   • Look for any of the following:
     • ST-segment elevation ≥1 mm concordant with QRS complex
     • ST-segment depression ≥1 mm in leads V1-V3
     • ST/S ratio ≤-0.25 in leads with discordant ST elevation
     • Concordant ST-depression in V4-V6 (additional criterion) 1

3. Management Decision:

   • If any modified Sgarbossa criterion is positive:
     • Consider immediate reperfusion therapy (PCI preferred) 5
     • Strong advocacy for emergent cardiac catheterization is warranted 3
   • If criteria are negative but clinical suspicion remains high:
     • Obtain serial ECGs to detect dynamic changes 2
     • Monitor cardiac biomarkers 3

Important Considerations

• The modified Sgarbossa criteria have a negative likelihood ratio of 0.19, making them valuable for ruling out AMI when negative 1
• Patients with ventricular pacing and AMI represent a high-risk population with increased mortality 4
• Relying solely on clinical symptoms without ECG interpretation may lead to missed diagnoses or treatment delays 5
• Serial ECGs are important as dynamic changes may develop over time, revealing additional criteria that were not initially present 3

Common Pitfalls to Avoid

• Do not dismiss chest pain in paced patients as non-cardiac without proper ECG analysis 4
• Avoid delaying reperfusion therapy when modified Sgarbossa criteria are positive, even if symptoms are atypical 3
• Remember that the requirement for temporary pacing in STEMI does not by itself constitute an indication for permanent pacing 2
• Do not rely on the original criteria alone, as they have lower sensitivity (56%) compared to the modified criteria (81%) 1