What is the immediate management for ECG changes indicating Right Ventricular Hypertrophy (RVH), Left Ventricular Hypertrophy (LVH), Bundle Branch Block (BBB), ST-Elevation Myocardial Infarction (STEMI), and Non-ST-Elevation Myocardial Infarction (NSTEMI)?

Immediate Management of ECG Changes in RVH, LVH, BBB, STEMI, and NSTEMI

Patients with STEMI require immediate reperfusion therapy, preferably primary PCI within 90 minutes of first medical contact, while NSTEMI patients need urgent risk stratification and invasive management within 24 hours. 1

ECG Diagnostic Criteria and Initial Management

ST-Elevation Myocardial Infarction (STEMI)

• Diagnostic criteria: New ST elevation at the J point in ≥2 contiguous leads:
  • ≥2 mm in men ≥40 years, ≥2.5 mm in men <40 years, or ≥1.5 mm in women in leads V2-V3
  • ≥1 mm in other contiguous leads 1
• Immediate management:
  1. Obtain 12-lead ECG within 10 minutes of first medical contact 1
  2. Activate STEMI protocol with early notification of PCI-capable hospital
  3. Target first medical contact-to-device time ≤90 minutes 1
  4. Initiate dual antiplatelet therapy and anticoagulation
  5. Monitor for life-threatening arrhythmias with continuous ECG 1

Non-ST-Elevation Myocardial Infarction (NSTEMI)

• Diagnostic criteria: New horizontal or down-sloping ST depression ≥0.5 mm in ≥2 contiguous leads and/or T-wave inversion >1 mm in ≥2 contiguous leads 1
• Immediate management:
  1. Risk stratification using GRACE or TIMI scores
  2. High-sensitivity troponin measurement
  3. For very high-risk patients (hemodynamic instability, recurrent angina, life-threatening arrhythmias): immediate invasive strategy (<2 hours)
  4. For high-risk patients: early invasive strategy (<24 hours) 1
  5. Dual antiplatelet therapy and anticoagulation

Right Ventricular Hypertrophy (RVH)

• ECG findings: Right axis deviation, dominant R wave in V1, deep S waves in V5-V6, right atrial enlargement
• Immediate management:
  1. Assess for underlying cause (pulmonary hypertension, congenital heart disease, pulmonary embolism)
  2. Evaluate for right heart failure signs (elevated JVP, peripheral edema)
  3. Obtain echocardiography to confirm RVH and assess right ventricular function
  4. Treat underlying cause (e.g., oxygen for hypoxemia, diuretics for volume overload)

Left Ventricular Hypertrophy (LVH)

• ECG findings: Increased QRS amplitude, ST depression and T-wave inversion in lateral leads
• Immediate management:
  1. Assess for underlying cause (hypertension, aortic stenosis, hypertrophic cardiomyopathy)
  2. Evaluate for signs of heart failure
  3. Obtain echocardiography to confirm LVH and assess left ventricular function
  4. Important caveat: LVH can mask or mimic ST-segment changes of ischemia 1

Bundle Branch Block (BBB)

• Right Bundle Branch Block (RBBB):

  • ECG findings: QRS ≥120 ms, rSR' pattern in V1-V2, wide S waves in I and V6
  • Management:
    • RBBB does not significantly interfere with STEMI diagnosis 2
    • ST-segment elevation can still be identified and interpreted 1
    • In patients with chest pain and RBBB, await high-sensitivity troponin results before deciding on immediate angiography unless clear ST-elevation is present 2

• Left Bundle Branch Block (LBBB):

  • ECG findings: QRS ≥120 ms, broad monophasic R wave in I, aVL, V5-V6, absence of Q waves in V5-V6
  • Management:
    • New or presumably new LBBB should not be considered diagnostic of acute MI in isolation 1
    • Use Sgarbossa criteria to identify STEMI: concordant ST elevation ≥1 mm in leads with positive QRS 1
    • For patients with clinical suspicion of ongoing myocardial ischemia with new or presumed new LBBB, consider emergency coronary angiography 1
    • Apply transcutaneous pacing pads in patients with STEMI who develop LBBB with first-degree AV block 2

Special Considerations and Pitfalls

STEMI Equivalents

• Posterior MI: ST depression in V1-V4 with upright T waves
  • Obtain posterior leads (V7-V9) to identify ST elevation ≥0.5 mm 1
• Wellens' syndrome: Deeply inverted or biphasic T waves in V2-V3
• De Winter pattern: Upsloping ST depression with tall symmetric T waves in precordial leads
• Hyperacute T waves: Tall, symmetric T waves preceding ST elevation 3

Confounding Factors

• Ventricular pacing: May prevent interpretation of ST changes
  • Consider reprogramming pacemaker if patient is not pacemaker-dependent 1
  • Urgent angiography may be necessary for diagnosis
• Non-diagnostic initial ECG: Repeat ECGs every 15-30 minutes if clinical suspicion remains high 1
• Relief of symptoms with nitroglycerin: Does not rule out MI
  • If ST elevation normalizes with nitroglycerin, consider coronary spasm 1

Algorithm for Management Decision

1. Obtain 12-lead ECG within 10 minutes of first medical contact
2. Interpret ECG for:
   • ST elevation meeting STEMI criteria
   • STEMI equivalents
   • ST depression or T-wave inversion suggestive of NSTEMI
   • BBB patterns with signs of ischemia
   • RVH or LVH patterns
3. For STEMI or STEMI equivalents:
   • Activate STEMI protocol
   • Aim for primary PCI within 90 minutes
   • If PCI not available within 120 minutes, consider fibrinolysis within 30 minutes of first medical contact 1
4. For NSTEMI:
   • Risk stratify using GRACE or TIMI score
   • Very high-risk: immediate invasive strategy (<2 hours)
   • High-risk: early invasive strategy (<24 hours)
5. For BBB with suspected ischemia:
   • RBBB: Interpret ST changes as in normal ECG
   • LBBB: Apply Sgarbossa criteria; if positive or strong clinical suspicion, consider emergency angiography
6. For RVH/LVH without acute ischemic changes:
   • Evaluate for underlying cause and treat accordingly

Remember that time is myocardium - rapid recognition and appropriate triage are essential for improving outcomes in patients with acute coronary syndromes.