What to do in case of ECG (electrocardiogram) signs of ischemic changes?

Management of ECG Showing Ischemic Changes

All patients with ECG signs of ischemic changes must be rapidly assessed within a predetermined chest pain protocol, with immediate continuous electrocardiographic monitoring and a 12-lead ECG obtained within 10 minutes, followed by risk stratification based on whether ST-segment elevation is present to determine if urgent reperfusion therapy is needed. 1

Immediate Actions (First 10 Minutes)

• Obtain a 12-lead ECG within 10 minutes of first medical contact for any patient with suspected ischemic changes 2
• Initiate continuous electrocardiographic monitoring immediately to detect life-threatening arrhythmias, as ventricular arrhythmias occur in 2-20% of acute coronary syndrome cases 1, 2
• Measure vital signs including blood pressure in both arms if aortic dissection is suspected, heart rate, and temperature 1
• Perform focused cardiovascular examination looking specifically for signs of left ventricular dysfunction (rales, S3 gallop), acute mitral regurgitation, pericardial friction rub, pulse deficits, or unequal pulses 1
• Draw cardiac troponin immediately upon presentation, as troponin is the most sensitive test for myocardial injury 3

Risk Stratification Based on ECG Pattern

STEMI Pattern (Highest Risk)

• ST-segment elevation ≥0.1 mV in two or more contiguous leads (except V2-V3 which require ≥0.2 mV in men ≥40 years, ≥0.25 mV in men <40 years, ≥0.15 mV in women) mandates immediate reperfusion therapy within 30 minutes 1, 4, 2
• Triage immediately to urgent reperfusion therapy (primary PCI or fibrinolysis) 1
• Patients with confounding patterns (bundle branch block, paced rhythm, LV hypertrophy) are at highest risk for death 1

STEMI-Equivalent Patterns Requiring Urgent Reperfusion

• Posterior MI: ST depression in V1-V3 with tall R waves and upright T waves—obtain posterior leads V7-V9 showing ST elevation ≥0.05 mV 1, 4, 2
• Left main/multivessel disease: ST depression ≥0.1 mV in eight or more leads with ST elevation in aVR and/or V1 1, 2
• New or presumed new left bundle branch block with clinical suspicion of MI 2
• Right ventricular MI: Obtain right precordial leads V3R-V4R showing ST elevation ≥0.05 mV in inferior MI 4, 2

Non-STEMI Pattern (Intermediate-High Risk)

• New horizontal or down-sloping ST depression ≥0.05 mV in two contiguous leads 4, 2
• T-wave inversion ≥0.1 mV in two contiguous leads with prominent R wave or R/S ratio >1 4, 2
• Apply risk stratification tools: TIMI, PURSUIT, GRACE, or NCDRACTION scores to guide intensity of management including anticoagulation therapy and timing of invasive assessment 1

Low-Risk Pattern

• Isolated T-wave changes or normal ECG have lowest mortality risk but do not exclude acute coronary syndrome—5-40% of patients with evolving MI have normal admission ECG 1, 3

Serial ECG Protocol

• Obtain serial ECGs at 15-30 minute intervals for patients with ongoing symptoms and initially non-diagnostic ECG, as dynamic changes occur frequently 1, 2
• Continue serial ECGs because they detect injury in an additional 16.2% of AMI patients and identify patients with 2.5 times greater risk of acute coronary syndromes 2
• Repeat ECG at 3-4 hours has 39% sensitivity and 88% specificity for MI 2

Continuous Monitoring Duration

• Continue uninterrupted monitoring for at least 24-48 hours after MI or for patients with moderate-to-high risk ACS 1, 2
• Extend monitoring to 48-72 hours for all patients with confirmed acute MI 2
• Continue beyond 72 hours if hemodynamic instability, persistent ischemia, or ongoing arrhythmias are present 2

Immediate Medical Management for Non-STEMI

• Administer aspirin 75-325 mg immediately if ACS suspected and no contraindications 3
• Initiate anticoagulation with low molecular weight heparin or unfractionated heparin 3
• Give beta-blocker and nitrates (oral or intravenous) for persistent or recurrent chest pain 3

Disposition Decisions

High-Risk Features Requiring CCU Admission and Urgent Angiography

• Recurrent ischemia despite medical therapy 3
• Early post-infarction unstable angina 3
• Elevated troponin levels 3
• Hemodynamic instability 3
• Evidence of left ventricular dysfunction on examination 1

Low-Risk Criteria Allowing Outpatient Follow-Up

• No recurrent chest pain 3
• Normal or unchanged ECG 3
• Two negative troponin measurements (at presentation and 6-12 hours from symptom onset) 3
• No high-risk features 3

Critical Pitfalls to Avoid

• Never rely on a single troponin measurement drawn less than 6 hours from symptom onset—this may miss myocardial injury 3
• Do not wait for cardiac biomarker results to initiate reperfusion therapy in STEMI 2
• Remember that one-third of patients with acute chest pain have normal admission ECG, yet 5-40% develop MI 3
• Do not dismiss ongoing chest pain despite non-diagnostic ECG—this mandates emergency coronary angiography even without ST elevation 1, 2
• Recognize that ST deviation occurs in non-ischemic conditions including acute pericarditis, left ventricular hypertrophy, left bundle branch block, Brugada syndrome, and stress cardiomyopathy 4
• Obtain additional leads (posterior V7-V9, right precordial V3R-V4R) when standard leads are non-diagnostic but clinical suspicion remains high 4, 2
• Compare with previous ECGs when available, as unchanged ECG reduces risk of MI and life-threatening complications 1

Prognostic Implications

• More profound ST-segment shift involving multiple leads/territories correlates with greater myocardial ischemia and worse prognosis 4, 2
• Patients with ST-segment deviation ≥0.5 mm have 16.3% one-year incidence of death or new MI versus 6.8% for isolated T-wave changes 1
• Substantial risk of death occurs in early hours after MI, with 17% of sudden deaths occurring within first 30 days 1