The Chest Pain That Doesn't Fit the Story
You are a Paramedic called to a 58-year-old woman with central chest tightness that began 40 minutes ago while she was resting. She describes it as 'pressure' radiating to the left jaw, associated with nausea and sweating. She has type 2 diabetes, hypertension, and a 30-pack-year smoking history. On examination: HR 54, BP 88/56, RR 20, SpO2 95% on room air, temperature 36.6 °C. She is pale and clammy. A 12-lead ECG shows 2 mm ST elevation in leads II, III, and aVF, with reciprocal depression in I and aVL. There is no ST elevation in V1–V4. Your nearest PCI centre is 55 minutes away; the nearest ED with thrombolysis capability is 18 minutes away. The patient is anxious and asks if she can 'just go to the local hospital'.
1. Interpret the ECG and explain the anatomical and clinical significance of the findings, including why the inferior leads are involved.
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Interpretation: acute inferior ST-elevation myocardial infarction (STEMI).
- Leads II, III, aVF look at the inferior wall of the left ventricle, supplied in most people by the right coronary artery (RCA) - occasionally the circumflex.
- Reciprocal depression in I and aVL supports the diagnosis (these leads view the high lateral wall, opposite the inferior wall).
- V1–V4 are not elevated - so there is no anterior involvement; but check for right ventricular (RV) involvement by looking at V4R (and V1): ST elevation in V4R suggests RV infarction, which is a preload-dependent state.
- Haemodynamics fit: HR 54 (inferior MI commonly causes bradycardia via increased vagal tone or AV node ischaemia, since the RCA supplies the AV node in ~90% of people) and BP 88/56 (hypotension, possibly from RV involvement or vagal response).
- Implication: this is a time-critical occlusion, and the low BP plus bradycardia means you must be careful with nitrates and with any drug that reduces preload.
2. The patient wants to go to the local ED. Compare the two destination options and justify your recommendation using the available times.
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Option A - PCI centre, 55 minutes: primary PCI is the preferred reperfusion strategy if it can be delivered within 120 minutes of first medical contact (and ideally within 90 minutes of arrival at the PCI centre). Door-to-balloon at a PCI centre is typically 30–60 minutes, so total ischaemic time here is roughly 55 + 30–60 = 85–115 minutes - within the acceptable window.
Option B - local ED with thrombolysis, 18 minutes: thrombolysis is indicated when PCI cannot be delivered within 120 minutes of first medical contact. Here PCI can be delivered within that window, so thrombolysis is a fallback, not the first choice. Thrombolysis carries bleeding risk (including intracranial haemorrhage) and is less effective than PCI.
Recommendation: PCI centre, because the total time to reperfusion is within the 120-minute window and PCI is superior. The local ED is the right choice only if PCI becomes unavailable (e.g., cath lab closed, transfer delay pushes total beyond 120 minutes) - in that case, thrombolyse at the local ED and transfer for rescue/early PCI.
However, the patient's hypotension and bradycardia complicate the picture: she is not a stable STEMI, and a long transfer in a hypotensive patient is risky. This is a judgement call - if she deteriorates (e.g., BP falls further, signs of cardiogenic shock), the local ED becomes the safer immediate destination. The answer is not 'always PCI'; it is 'PCI if the patient can safely make the journey within the window'.
3. List the pharmacological and non-pharmacological interventions you would initiate, and identify the drugs you must avoid or use with caution given her haemodynamics.
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Non-pharmacological:
- High-flow oxygen only if SpO2 <94% - she is 95%, so titrate, do not routinely give high-flow O2 (hyperoxia can worsen outcomes).
- Continuous ECG monitoring, IV access, defibrillator ready.
- Position: semi-recumbent; if RV involvement is suspected, avoid anything that drops preload.
- Pre-alert the PCI centre with the ECG and times.
Pharmacological (per protocol):
- Aspirin 300 mg chewed (unless contraindicated).
- P2Y12 inhibitor (e.g., ticagrelor or clopidogrel) if protocol permits and no contraindication.
- Anticoagulation (e.g., heparin) per local protocol.
- Analgesia - cautious; opioids can worsen hypotension.
- Antiemetic for nausea.
Avoid / use with caution:
- Nitrates - contraindicated in hypotension (BP <90 systolic) and suspected RV infarction; they reduce preload and can cause profound hypotension. Her BP is 88/56, so do not give GTN.
- Beta-blockers - avoid in bradycardia and hypotension.
- Any drug that further slows the heart - she is already at 54.
- Fluid bolus - if RV infarction is suspected, a cautious fluid challenge may help preload, but reassess frequently (watch for pulmonary oedema).
The exam point: the 'textbook' STEMI cocktail is wrong for this patient because of her haemodynamics.