What is the diagnosis and management of a patient with sinus rhythm, ST depression in leads V4 and V5 on electrocardiogram (ECG), presenting with sudden severe neck and upper back pain, hypertension, tachycardia, and normal oxygen saturation?

Acute Aortic Dissection Until Proven Otherwise

This patient requires immediate CT angiography of the chest to rule out acute aortic dissection before any antiplatelet, anticoagulation, or invasive cardiac procedures are initiated, as the sudden nape and upper back pain pattern is highly characteristic of aortic dissection and administering ACS therapies without excluding dissection can be fatal. 1

Critical Diagnostic Priorities

Immediate Actions Required

• Obtain bilateral arm blood pressures immediately, as a difference >20 mmHg between arms has high specificity for aortic dissection 1
• Perform urgent CT angiography of the chest or bedside echocardiography, as the sudden nape and upper back pain pattern is atypical for ACS but highly characteristic of aortic dissection involving the ascending aorta or arch 1
• Do NOT administer antiplatelet agents, anticoagulation, or fibrinolytics until aortic dissection is definitively excluded, as these therapies are absolutely contraindicated and potentially fatal in dissection 1

Why Aortic Dissection is the Primary Concern

The clinical presentation has multiple red flags that strongly favor dissection over typical ACS:

• Sudden onset nape and upper back pain while sitting is far more consistent with aortic dissection than typical ACS, which usually presents with chest discomfort 1
• Acute hypertension (160/90 vs usual <130/90) represents a common finding in proximal aortic dissection, as the body attempts to maintain distal perfusion 1
• ST depression in V4-V5 can occur with aortic dissection when the dissection involves or compromises the coronary ostia, particularly the right coronary artery, mimicking NSTE-ACS 1, 2, 3
• Approximately 40% of patients with aortic dissection have ECG changes that can mimic ischemia, and initiating ACS treatment protocols without excluding dissection can be fatal 1

Critical Pitfall to Avoid

Never assume ACS based on ST depression alone when the pain pattern is atypical—the "atypical" location of pain (nape and upper back) should raise red flags, as sudden severe posterior pain is a classic dissection presentation that should never be dismissed 1. Case reports document fatal outcomes when patients with dissection were taken directly to the catheterization laboratory based on ECG changes alone 2, 3.

If Aortic Dissection is Excluded: NSTE-ACS Management

Immediate Diagnostic Workup

• Obtain high-sensitivity cardiac troponin immediately, with repeat measurement at 1-2 hours if initial value is non-diagnostic 1
• Calculate HEART or TIMI risk score once troponin results are available, as the combination of ongoing symptoms, ST depression, and elevated troponin would indicate high-risk NSTE-ACS requiring urgent invasive strategy 1
• Perform bedside echocardiography to exclude alternative diagnoses and identify regional wall motion abnormalities that would corroborate ongoing myocardial ischemia 4

Medical Management (Only After Dissection Excluded)

• Aspirin 162-325 mg chewed immediately 1
• P2Y12 inhibitor: ticagrelor 180 mg or prasugrel 60 mg loading dose, preferred over clopidogrel for high-risk patients 1
• Anticoagulation: fondaparinux, enoxaparin, or unfractionated heparin 1
• Morphine (i.v. or s.c.) reserved for patients with persisting severe chest pain 4
• Oxygen therapy only if blood oxygen saturation <90% or respiratory distress 4

Risk Stratification Based on ST Depression

The ST depression in V4-V5 carries significant prognostic implications:

• ST depression ≥0.05 mV in two or more contiguous leads is suggestive of NSTE-ACS and linked to adverse prognosis 5
• ST depression >0.1 mV is associated with an 11% rate of death and MI at 1 year 5
• ST depression >0.2 mV carries about a six-fold increased mortality risk 5
• Patients with ST depression have higher risk for subsequent cardiac events compared with those with isolated T-wave inversion or normal ECG 4, 5

Invasive Strategy Timing

• Urgent coronary angiography within 2-24 hours for patients with confirmed NSTE-ACS and high-risk features such as elevated troponin and ST depression 1
• Immediate angiography (<2 hours) if the patient develops hemodynamic instability, ongoing refractory ischemia, or life-threatening arrhythmias 1

Alternative Considerations

Tachycardia-Related ST Depression

The heart rate of 109 bpm could theoretically contribute to rate-dependent ST depression, particularly in the setting of acute hypertension and sympathetic hyperactivity 6. However, this should never delay exclusion of life-threatening diagnoses like aortic dissection or ACS 6, 7.

Hypertensive Emergency with LVH

The acute hypertension could represent hypertensive emergency with left ventricular hypertrophy causing ST depression 8. However, the sudden onset nape and back pain pattern is inconsistent with this diagnosis and mandates exclusion of dissection first 1.

Monitoring and Disposition

• Continuous ECG monitoring for arrhythmias should be continued for at least 24 hours 5
• Serial troponin measurements should be obtained 5
• Place defibrillator patches if ongoing ischemia is present until urgent revascularization is performed 4
• Blood work on admission should include cardiac troponin, serum creatinine, hemoglobin, hematocrit, platelet count, blood glucose 4