What is the management for ST segment elevation in lead V4R, indicating a potential right ventricular myocardial infarction?

Management of ST Segment Elevation in Lead V4R

ST segment elevation in lead V4R strongly indicates right ventricular infarction and requires immediate management with primary PCI when possible, while avoiding vasodilators and maintaining adequate right ventricular preload through IV fluid administration.

Diagnosis and Significance

ST-segment elevation in lead V4R is highly diagnostic of right ventricular involvement in the setting of inferior myocardial infarction. This finding has important clinical implications:

• ST elevation ≥0.1 mV in V4R has high sensitivity (88%) and specificity (78%) for right ventricular infarction 1
• It serves as a strong, independent predictor of in-hospital mortality (relative risk 7.7) and major complications (relative risk 4.7) 1
• Right ventricular infarction typically occurs with occlusion of the right coronary artery proximal to the first right ventricular branch 2

Initial Management Algorithm

1. Immediate Reperfusion Strategy

   • Primary PCI should be performed as soon as possible as it results in rapid hemodynamic improvement 3
   • If PCI is unavailable, fibrinolytic therapy is appropriate, particularly in hypotensive patients 3

2. Hemodynamic Support

   • Maintain right ventricular preload:
     • Administer IV fluid loading rapidly with careful hemodynamic monitoring 3
     • Target adequate right ventricular filling pressures to maintain cardiac output

3. Medications to AVOID:

   • Vasodilators (can worsen hypotension in RV infarction)
   • Specifically avoid:
     • Nitrates
     • Diuretics
     • ACE inhibitors/ARBs
     • Opioids (if possible) 3

4. Management of Common Complications:

   • Atrial fibrillation: Correct promptly as atrial contribution to right ventricular filling is crucial 3
   • Heart block: Implement dual chamber pacing if heart block develops 3

Clinical Recognition

Right ventricular infarction should be suspected in patients with:

• Inferior STEMI (particularly with proximal right coronary artery occlusion)
• Clinical triad (though insensitive) of:
  • Hypotension
  • Clear lung fields
  • Elevated jugular venous pressure 3

Additional ECG Findings

• Q-waves and ST-segment elevation in V1-V3 may also suggest right ventricular infarction 3
• ST elevation in V4R correlates with depressed right ventricular ejection fraction (33% vs 40% in those without ST elevation) 4
• Right precordial leads (V3R-V4R) should be routinely recorded in all cases of inferior STEMI, especially when shock is present 3

Monitoring and Follow-up

• Continuous cardiac monitoring for arrhythmias
• Careful hemodynamic assessment
• Echocardiography to confirm diagnosis and assess right ventricular function 3

Prognostic Implications

While right ventricular infarction significantly increases in-hospital mortality and complications, the post-hospital course (after 1 year) appears similar between patients with and without right ventricular involvement 1.

Pitfalls to Avoid

1. Missing the diagnosis: Always record right precordial leads in inferior STEMI
2. Inappropriate vasodilator use: Can precipitate profound hypotension
3. Inadequate fluid resuscitation: Right ventricular preload must be maintained
4. Delayed reperfusion: Time is critical for myocardial salvage
5. Overlooking false negatives: Some patients with RV involvement may not show ST elevation in V4R, particularly with concomitant posterior involvement 2