Tearing Chest Pain with an Inferior STEMI Pattern on ECG
A 62-year-old man with a 20-year history of poorly controlled hypertension presents 90 minutes after the sudden onset of severe, tearing anterior chest pain that radiated between his shoulder blades. He is diaphoretic and anxious. Blood pressure is 192/104 mmHg in the right arm and 158/88 mmHg in the left arm; pulse is 104/min and symmetric in both wrists. Lungs are clear. A 12-lead ECG obtained in triage shows 2 mm of ST-segment elevation in leads II, III, and aVF with reciprocal depression in leads I and aVL. The emergency physician has a thrombolytic at the bedside and must decide within minutes whether to give it, because the nearest catheterization laboratory is 3 hours away by ground transport.
1. What single bedside finding argues most strongly against giving the thrombolytic, and what should be done first?
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The interarm blood pressure differential (~34 mmHg systolic) is the decisive finding.
- A systolic difference of ≥20 mmHg between arms has poor sensitivity but high specificity for aortic dissection. Combined with abrupt, maximal-at-onset tearing pain radiating to the interscapular region in a chronically hypertensive patient, the pretest probability of dissection is high enough to change management.
- The inferior ST elevation is most plausibly explained by dissection extending into the right coronary ostium, not by plaque rupture. Acute dissection involving the ascending aorta (Stanford type A) is a surgical emergency.
- Thrombolysis is contraindicated: it can convert a contained false lumen into a free rupture, cause catastrophic hemorrhage, or provoke tamponade. This is one of the few situations where withholding reperfusion is the correct reflex.
- Immediate next steps: urgent CT angiography of the chest, abdomen, and pelvis (or transesophageal echo if the patient becomes unstable), continuous blood pressure and pulse control, and activation of cardiothoracic surgery. Do not give aspirin or heparin empirically until dissection is excluded.
2. The ECG meets STEMI criteria. Explain why satisfying STEMI criteria does not by itself dictate treatment, and list additional features that would push the probability toward dissection.
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ST-segment criteria are a probabilistic trigger, not a diagnosis. In registries, roughly 0.5–2% of patients treated for STEMI are ultimately found to have aortic dissection; conversely, dissection can produce ST elevation in any territory when a coronary ostium is involved. The correct reasoning step is to ask what disease process best explains all the findings, not just the tracing.
Features that raise the probability of dissection in this scenario:
- Abrupt, maximal-at-onset pain described as tearing or migratory
- Radiation to the back or between the scapulae
- Pulse deficit or blood pressure differential between limbs
- Focal neurologic deficit, syncope, or new aortic regurgitation murmur
- Pain out of proportion to ECG findings, or a history of hypertension without other atherosclerotic risk factors
- Widened mediastinum or new pleural effusion on chest radiograph
Conversely, a history of exertional angina, prior MI, and classic crescendo pain would favor plaque rupture and make immediate reperfusion appropriate.
3. CT angiography shows a type B dissection with a patent true and false lumen, no malperfusion, and no coronary involvement. Pain is now controlled; heart rate is 68/min and blood pressure 118/70 mmHg on intravenous labetalol. What is the strategy, and how does it differ from type A?
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Uncomplicated type B dissection is managed medically, not surgically.
- Continue titrated beta-blockade (target heart rate ~60/min, systolic blood pressure ~100–120 mmHg), adding a vasodilator only after rate control to avoid reflex tachycardia that increases shear stress (dP/dt).
- Aggressive analgesia; avoid straining and Valsalva.
- Serial imaging to surveil for aneurysm expansion, and monitoring for late complications: malperfusion, rupture, rapid expansion, or refractory pain/hypertension.
- Thoracic endovascular aortic repair is reserved for complicated type B disease - malperfusion of a limb, viscus, spinal cord, or kidney; rapid expansion; rupture; refractory hypertension or pain.
Contrast with type A: involvement of the ascending aorta carries a mortality of roughly 1–2% per hour untreated and mandates emergent open surgical repair, regardless of whether the patient is pain-free at that moment. Medical therapy in type A is a bridge to the operating room, not a destination.