What is the most appropriate next step in evaluating a 68-year-old patient with a history of Diabetes Mellitus (DM) and Hypertension (HT) presenting with retrosternal chest pain, nausea, and sweating, and electrocardiogram (ECG) findings of ST segment elevation in leads II, III, and aVF?

Right-Sided ECG is the Most Appropriate Next Step for This Patient

The most appropriate next step in evaluating this 68-year-old patient with inferior STEMI is to obtain a right-sided ECG to assess for right ventricular involvement.

Rationale for Right-Sided ECG

The patient presents with classic signs of acute myocardial infarction:

• Retrosternal chest pain with associated nausea and sweating
• ST-segment elevation in leads II, III, and aVF on ECG, indicating an inferior wall STEMI

According to the 2025 ACC/AHA guidelines, right-sided leads should be obtained in patients with inferior STEMI to evaluate for right ventricular involvement 1. This recommendation is critical because:

1. Right ventricular infarction complicates approximately 25% (range 20-60%) of inferior MIs 2
2. The presence of RV involvement significantly alters management and prognosis
3. Early identification allows for appropriate treatment modifications

Clinical Significance of Right Ventricular Involvement

Right ventricular infarction in the setting of inferior STEMI has important implications:

• Hemodynamic consequences: RV failure can lead to reduced left ventricular filling and hypotension 2
• Treatment modifications: Patients with RV infarction require:
  • Cautious use of nitrates, opioids, and diuretics that may reduce preload
  • Potential need for fluid resuscitation to maintain adequate RV preload 1
• Prognostic value: Patients with inferior STEMI complicated by RV infarction have markedly worse outcomes and higher mortality compared to isolated inferior STEMI 2

Diagnostic Accuracy of Right-Sided ECG

Right-sided ECG is highly sensitive for detecting RV involvement:

• ST elevation ≥1 mm in lead V4R has 93% sensitivity and 93% predictive accuracy for RV infarction 3
• ST elevation in right precordial leads is often transient, disappearing within 10 hours of symptom onset 3
• This makes early acquisition of right-sided ECG crucial for accurate diagnosis

Why Right-Sided ECG Before Other Options

1. Why not cardiac enzymes first (option B)?

   • While cardiac enzymes confirm myocardial necrosis, they don't identify the specific territory involved
   • Reperfusion therapy should not be delayed waiting for enzyme results 1
   • The diagnosis of STEMI is already established by the ECG findings

2. Why not ECHO first (option A)?

   • Although echocardiography can detect wall motion abnormalities, right-sided ECG is more immediately available
   • ECHO may be useful after right-sided ECG to confirm findings and assess complications

3. Why not chest X-ray first (option C)?

   • Chest X-ray provides limited information about myocardial injury
   • It doesn't help determine the presence of RV involvement, which is critical for management

Management Implications

Identifying RV involvement will guide immediate treatment decisions:

• Fluid management strategy (may need volume expansion rather than restriction)
• Cautious use of medications that reduce preload
• Consideration of early reperfusion therapy
• Need for closer monitoring due to higher risk of complications

Conclusion

The patient's ECG showing ST elevation in leads II, III, and aVF clearly indicates an inferior wall STEMI. Given the high prevalence of right ventricular involvement in inferior infarctions and its significant impact on management and prognosis, obtaining a right-sided ECG is the most appropriate next step in evaluation.