Management of Acute Inferior Wall MI with RV Infarct
For patients with acute inferior wall myocardial infarction with right ventricular involvement, immediate volume loading with IV normal saline is essential, along with early reperfusion therapy, while avoiding nitrates and diuretics that can cause profound hypotension by reducing preload. 1, 2
Immediate Assessment and Diagnosis
- Obtain right-sided ECG leads, particularly V4R, as ST elevation ≥1mm is highly predictive of RV infarction (sensitivity 88%, specificity 78%) 2
- Look for the clinical triad of hypotension, clear lung fields, and elevated jugular venous pressure, which is specific but less than 25% sensitive for diagnosing RV infarction 2
- Perform echocardiography to assess RV function, detect mechanical complications, and exclude LV thrombus 3, 1
- Note that RV infarction occurs in up to 50% of inferior MIs and significantly increases in-hospital mortality to 25-30% compared to 6% in uncomplicated inferior MI 2, 4
Immediate Pharmacological Interventions
- Administer aspirin 162-325 mg to be chewed immediately unless contraindicated 1, 3
- Add a P2Y12 inhibitor (preferably prasugrel or ticagrelor, or clopidogrel if these are unavailable) 3, 5
- Provide appropriate analgesia with narcotic medications to minimize pain and anxiety 1
- Avoid nitrates in patients with RV involvement as they can cause profound hypotension by reducing preload 1, 2
- Avoid diuretics which can worsen hypotension in RV infarction 1, 2
Reperfusion Strategy
- Evaluate for immediate reperfusion therapy if presenting within 12 hours of symptom onset 1
- Consider primary percutaneous coronary intervention (PCI) if it can be performed within 90 minutes by skilled personnel 1, 3
- Complete revascularization of the right coronary artery including the major RV branch is associated with higher rate of RV function recovery and improved 30-day mortality 6
- Consider fibrinolytic therapy if no contraindications exist and PCI is not available within the appropriate timeframe 1, 3
Management of RV Infarction
- Maintain RV preload through aggressive volume loading with IV normal saline for hypotension (500-1000 mL initially, then reassess) 1, 2
- If cardiac output fails to increase after adequate volume loading, provide inotropic support with dobutamine 1, 2
- Consider intra-aortic balloon pump for persistent shock despite volume loading and inotropic support 1, 2
- Maintain AV synchrony through AV sequential pacing for symptomatic high-degree heart block 1, 2
Management of Conduction Disturbances
- Treat symptomatic sinus bradycardia (common in inferior MI) with IV atropine 0.5 mg, repeated up to 2.0 mg total 1
- Consider temporary pacing for symptomatic high-degree AV block, especially if unresponsive to atropine 1
- Have emergency equipment readily available, including atropine, lidocaine, transcutaneous pacing patches, transvenous pacemaker, defibrillator, and epinephrine 1
Ongoing Management
- Continue dual antiplatelet therapy (DAPT) with aspirin plus a P2Y12 inhibitor for 12 months unless contraindicated 3
- Start high-intensity statin therapy as early as possible and maintain long-term 3
- Initiate ACE inhibitors within 24 hours in patients with evidence of heart failure, LV systolic dysfunction, diabetes, or anterior infarct 3
- Consider beta-blockers only after hemodynamic stabilization, as they should be avoided in patients with hypotension, acute heart failure, or AV block 3, 1
Common Pitfalls and Caveats
- Early recording of lead V4R is crucial as ST elevation can resolve within 10 hours 1, 2
- Volume depletion may mask signs of RV involvement 1
- Avoid nitrates and diuretics in RV infarction due to risk of profound hypotension 1, 2, 4
- Do not administer beta-blockers or calcium channel antagonists to patients in a low-output state due to pump failure 1
- Recognize that patients with inferior wall STEMI with RV infarction have a markedly worse prognosis compared with patients with isolated inferior wall STEMI 4, 7