Inferior STEMI with Right Ventricular Involvement in a Hospital Without PCI

Recognise the physiology. Inferior ST elevation with hypotension after nitrates, plus ST elevation in V1, is an inferior STEMI with probable right ventricular infarction. The right ventricle is a thin-walled volume-dependent conduit: it needs filling pressure to push blood through the pulmonary circuit. Nitrates dropped preload and precipitated the hypotension. Do not give any more.

First 30 minutes, in order:

1. Stop nitrates. No morphine, no diuretics, no further GTN - all reduce preload.
2. Lie the patient flat, continuous ECG and 5-minute blood pressures, defibrillator at the bedside, two large-bore IVs.
3. Oxygen only if SpO2 <90% (target 94–98%); routine high-flow oxygen in an uncomplicated infarct is harmful.
4. Crystalloid 250 mL boluses, up to 500–1000 mL, titrated to systolic >90 mmHg. Watch for pulmonary congestion - the fluid is a bridge, not a treatment for a failing left ventricle.
5. Record right-sided leads (V4R) and posterior leads. V4R elevation confirms the diagnosis and explains the hypotension; do not delay treatment waiting for them.
6. Atropine 1 mg IV every 3–5 minutes to a maximum of 3 mg for symptomatic bradycardia. If it fails, transcutaneous pacing (which may not capture or may not raise output in an ischaemic right ventricle) and/or a chronotropic/vasopressor infusion.
7. Aspirin 300 mg chewed, a P2Y12 inhibitor, anticoagulation per local protocol, high-intensity statin.
8. Decide on reperfusion in parallel - do not sequence it after everything else.

Most avoided intervention: nitrates (and by extension any preload-reducing drug such as morphine or furosemide). In right ventricular infarction they can precipitate profound, sometimes fatal, hypotension.

Decision: give fibrinolysis now. The choice between primary PCI and fibrinolysis is a time decision, not a preference. Primary PCI is superior when it can be delivered within about 120 minutes of first medical contact. Here first medical contact is already past, the road transfer is 3 hours, and the ambulance is delayed a further 40 minutes - realistic door-to-balloon time will exceed 200 minutes. Within 12 hours of symptom onset, with no contraindications and a diagnosis made on the ECG, the mortality benefit of reperfusion now outweighs the advantage of a better procedure delivered too late. Door-to-needle should be under 30 minutes.

Caveats that change the emphasis, not the decision:

• Cardiogenic shock is a relative indication for urgent transfer for PCI, but an untreated occluded artery during a 4-hour journey is worse than a lytic given now with rescue transfer planned.
• Correct the preload first: fibrinolysis in a patient with a systolic of 84 mmHg is still reasonable, but do not give it while the patient remains profoundly under-filled if a 250 mL bolus fixes it.
• Use weight-adjusted tenecteplase, and give aspirin, clopidogrel/ticagrelor and anticoagulant as part of the same bundle.

Judging success at 60–90 minutes: resolution of pain, greater than 50% resolution of ST elevation in the lead with maximum elevation, and reperfusion arrhythmias. Failure of any of these, or persisting instability, means rescue PCI - start arranging the ambulance transfer at that point regardless of the original plan.

Differential in order of likelihood:

1. Ongoing right ventricular ischaemia - the commonest cause. Reperfusion has not yet occurred or has failed.
2. High-grade atrioventricular block from AV nodal ischaemia (the right coronary artery supplies the node in most people). Check the rhythm strip; atropine may have been ineffective because the block is infranodal.
3. Mechanical complication - ventricular septal rupture or acute mitral regurgitation from papillary muscle rupture. Look for a new harsh murmur, a palpable thrill, abrupt pulmonary oedema, and a bedside echocardiogram if available.
4. Over-filling or under-filling: reassess with lung ultrasound; do not keep pouring in fluid if crackles and B-lines appear.
5. Bleeding or a pericardial effusion after anticoagulation, and other causes of shock unrelated to the infarct.

Management changes:

• Start noradrenaline to keep mean arterial pressure above 65 mmHg rather than relying on fluid alone; avoid dobutamine as a single agent because vasodilatation will worsen the hypotension.
• If complete heart block is present, pace (transcutaneous then transvenous if achievable) and expedite reperfusion; pacing alone will not fix an ischaemic ventricle.
• Bedside echo answers the mechanical-complication question and redirects to urgent surgery or transfer.
• Escalate the reperfusion plan: this is now a failed or complicated lytic, i.e. rescue PCI, and the transfer conversation must happen now rather than after another hour of observation.
• Involve the receiving PCI centre by phone early, so the patient arrives as a planned rescue rather than an unannounced crash transfer.