What is the most likely diagnosis for a patient in their late 60s with sudden onset severe pressure-like bilateral shoulder pain, nausea, hypertension (high blood pressure), and type 2 diabetes, with an electrocardiogram (EKG) showing significant anteroseptal elevation and inferior depression?

ST-Elevation Myocardial Infarction (STEMI)

This patient is experiencing an ST-elevation myocardial infarction (STEMI) with anteroseptal involvement and reciprocal inferior changes. 1, 2

Clinical Presentation Confirms STEMI

The constellation of findings definitively establishes this diagnosis:

• Sudden-onset severe pressure-like pain lasting hours represents the classic ischemic symptom pattern required for STEMI diagnosis 1, 2
• Bilateral shoulder pain is an established anginal equivalent, particularly common in this demographic (late 60s) and represents referred pain from myocardial ischemia 3, 4
• Associated nausea is a frequent autonomic symptom accompanying acute myocardial infarction, especially in patients with diabetes 3, 4
• Non-positional nature excludes pericarditis, which characteristically improves with leaning forward 1

ECG Findings Are Diagnostic

The electrocardiographic pattern is pathognomonic for STEMI:

• Significant anteroseptal ST-elevation indicates acute occlusion of the proximal left anterior descending artery 1, 2
• Inferior ST-depression represents reciprocal changes, not a separate infarct territory, and actually strengthens the diagnosis of anterior STEMI 1
• This ECG pattern meets the universal definition requiring "new or presumably new significant ST-T changes" in the setting of ischemic symptoms 1

Why Other Diagnoses Are Excluded

Myocarditis does not present with this ECG pattern—it typically shows diffuse ST-elevation without reciprocal changes and would not explain the sudden severe pressure-like pain 5, 6

Acute pericarditis is excluded by: (1) the non-positional nature of pain, (2) the presence of reciprocal ST-depression (pericarditis shows diffuse ST-elevation without reciprocal changes), and (3) the anteroseptal localization rather than diffuse changes 1, 5, 6

Aortic dissection would present with tearing pain radiating to the back, blood pressure differential between arms, and would not produce this specific ECG pattern of anteroseptal elevation with inferior reciprocal changes 1

High-Risk Features Demanding Immediate Action

This patient has multiple factors predicting poor outcomes:

• Type 2 diabetes and hypertension confer a 3-5 times greater risk of post-infarct mortality 2, 7
• Age in late 60s increases mortality risk substantially 1
• Anteroseptal location indicates large territory at risk with potential for significant left ventricular dysfunction 2
• Duration of several hours means ongoing myocardial necrosis with time-dependent salvage window closing 1

Immediate Management Protocol

Activate the cardiac catheterization laboratory immediately without waiting for troponin results 1, 2. The ECG diagnosis alone is sufficient to proceed with primary percutaneous coronary intervention (PCI), which is the preferred reperfusion strategy 1, 2.

Concurrent actions while preparing for catheterization:

• Administer aspirin 160-325 mg chewed plus a P2Y12 inhibitor (ticagrelor 180 mg or prasugrel 60 mg if no contraindications) 1
• Provide morphine titrated intravenously for pain relief and to reduce sympathetic activation 1, 2
• Oxygen supplementation only if saturation <90%—routine oxygen is not indicated 1
• Continuous ECG monitoring with defibrillation capability for potentially fatal arrhythmias 1

Critical Pitfall to Avoid

Do not delay reperfusion therapy to obtain cardiac biomarkers 1, 2. The ECG showing significant ST-elevation in the setting of ischemic symptoms is sufficient for STEMI diagnosis and immediate catheterization 1. Troponin elevation lags behind ECG changes and waiting for results causes preventable myocardial death 1.