Hypotension After Inferior STEMI: Right Ventricular Infarction and the Reperfusion Clock
A 58-year-old man with a 25-pack-year smoking history presents 90 minutes after sudden severe retrosternal chest pain, nausea and diaphoresis. He is pale and drowsy. Blood pressure is 84/52 mmHg in both arms, pulse 48/min and regular, respiratory rate 24/min, oxygen saturation 94% on room air. Jugular venous pressure is 12 cm with a positive Kussmaul sign; the lungs are clear and there is no peripheral oedema. The ECG shows 2–3 mm ST elevation in leads II, III and aVF, 1 mm ST elevation in right-sided lead V4R, and reciprocal ST depression in leads I and aVL. Bedside echocardiography shows inferior wall akinesis, a hyperdynamic apex and a small, underfilled right ventricle. Troponin results are pending. The nearest catheterization laboratory is 45 minutes away by road. The local hospital has no on-site PCI capability but has a physician-staffed ambulance and a signed transfer protocol.
1. Explain the haemodynamic picture and state which routine acute medications you would withhold and why. Outline your first-line pharmacological steps over the next 30 minutes.
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Rhythm and haemodynamics. This is an inferior STEMI with right ventricular involvement (V4R elevation), complicated by high-grade AV block. The right ventricle is preload-dependent: it needs venous return to generate forward flow. When the RV fails, the left ventricle is underfilled, so cardiac output and blood pressure become critically dependent on preload.
Withhold.
- Nitrates (including sublingual GTN) and morphine: both venodilate, reduce preload and can precipitate catastrophic hypotension in RV infarction; nitrates are also contraindicated at SBP <90 mmHg.
- Diuretics: the lungs are clear, so there is no left-sided congestion to treat.
- Early beta-blockers: bradycardia and hypotension make them hazardous at this moment.
- Routine high-flow oxygen: give oxygen only if SpO2 is <90%, since hyperoxia can increase coronary vascular resistance.
Do next.
- Two large-bore IV lines, continuous ECG, frequent BP and a defibrillator at the bedside.
- Cautious crystalloid boluses of 250 mL, reassessing BP, JVP and lung sounds after each; up to 1–2 L may be required, but stop if the lungs become wet.
- Atropine 0.5 mg IV every 3–5 minutes (maximum 3 mg) for symptomatic bradycardia; if it fails, apply transcutaneous pacing.
- If hypotension persists after fluids, add dobutamine 2.5–5 µg/kg/min for RV inotropic support, with noradrenaline if needed to maintain coronary perfusion pressure.
- Aspirin 300 mg chewed, a P2Y12 inhibitor and parenteral anticoagulation.
2. Given the 45-minute transport time, what is your reperfusion strategy and why? Address the role of fibrinolysis in this specific patient.
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Immediate transfer for primary PCI. He has a STEMI with shock caused by RV infarction, and the catheterization laboratory is only 45 minutes away. Guidelines recommend immediate coronary angiography and PCI in STEMI with cardiogenic shock regardless of symptom duration, because reperfusion is the only intervention that reverses the pump failure. A 45-minute transfer remains well within the accepted 120-minute first-medical-contact-to-device window, so there is no reason to accept a inferior reperfusion strategy.
Why fibrinolysis is the wrong choice here. Fibrinolysis is not absolutely contraindicated in RV infarction, but it is markedly less effective in patients with shock, and it commits the patient to a strategy with a significant failure rate at a moment when a PCI centre is close. Reserve fibrinolysis for the situation where PCI cannot be delivered within 120 minutes, and even then the presence of shock argues strongly for transfer.
Practical steps. Activate the PCI laboratory before departure and travel with a physician able to cardiovert or pace. Aspirin, heparin and a P2Y12 inhibitor should be given before transfer. Continue fluids and inotropes en route, and keep nitrates and diuretics off the prescription. If the patient deteriorates, consider temporary pacing and, in refractory shock, mechanical circulatory support at the PCI centre. Document the exact times of first medical contact, ambulance departure and expected device time.
3. Choose the antithrombotic regimen for transfer and list the parameters you will monitor, explaining any drug-specific concerns raised by his bradycardia and hypotension.
Read the worked answer
Antithrombotic regimen.
- Aspirin 300 mg chewed immediately.
- Unfractionated heparin 70–100 U/kg IV bolus (or enoxaparin 0.5 mg/kg IV) unless a fibrinolytic strategy is chosen.
- A P2Y12 inhibitor before transfer. Either ticagrelor 180 mg or prasugrel 60 mg is acceptable if primary PCI is planned and there is no prior stroke/TIA or active bleeding. Prasugrel is a reasonable choice here because ticagrelor can itself cause bradycardia and dyspnoea, and this patient is already at 48/min; clopidogrel 600 mg is the fallback if a potent agent is unavailable or fibrinolysis becomes necessary.
- Do not start a glycoprotein IIb/IIIa inhibitor in the ambulance; reserve it for the catheterization laboratory after the anatomy is known.
Monitoring during transfer. Continuous ECG with pacing pads applied, BP every 5 minutes, SpO2, respiratory rate, urine output, and mental state. Watch for progression to complete AV block or asystole, and for the appearance of pulmonary oedema after fluid loading - if crackles develop, stop fluids and reassess.
Additional cautions. Avoid beta-blockers and nitrates until he is stable. Check potassium, magnesium, glucose and creatinine on arrival. Warm the patient and treat pain with cautious IV opioid only in small increments, because opioids worsen hypotension through venodilation. Keep the destination team informed of the rhythm and BP trend.