Acute Aortic Dissection Until Proven Otherwise
This patient requires immediate evaluation for acute aortic dissection, which is the most life-threatening diagnosis that must be ruled out before considering acute coronary syndrome. The sudden onset of severe nape and upper back pain in a patient with acute hypertension (160/90 vs usual <130/90), tachycardia, and ST depression on ECG creates a classic presentation for aortic dissection that can mimic ACS 1.
Critical Diagnostic Priorities
Immediate Actions (Within 10 Minutes)
Obtain bilateral arm blood pressures immediately - a difference >20 mmHg between arms has high specificity for aortic dissection and must be assessed before initiating antiplatelet or anticoagulation therapy 1.
Perform urgent bedside echocardiography or CT angiography of the chest - 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 sudden onset of nape and upper back pain while sitting (not exertional, not positional) is far more consistent with aortic dissection than typical ACS, which usually presents with chest discomfort 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.
The acute hypertension (160/90 vs baseline <130/90) represents a 30+ mmHg systolic increase and is a common finding in proximal aortic dissection as the body attempts to maintain distal perfusion 1.
Tachycardia (HR 109) with tachypnea (RR 23) in the setting of severe pain suggests significant physiologic stress, but the normal oxygen saturation argues against primary pulmonary pathology 1.
If Aortic Dissection is Excluded
Proceed with NSTE-ACS Evaluation
Obtain high-sensitivity cardiac troponin immediately with repeat measurement at 1-2 hours if initial value is non-diagnostic 1.
The ST depression in V4-V5 places this patient at intermediate-to-high risk for NSTE-ACS, with ST depression ≥0.5 mm being highly suggestive of acute ischemia 1.
Calculate HEART or TIMI risk score once troponin results are available - the combination of ongoing symptoms, ST depression, and elevated troponin would indicate high-risk NSTE-ACS requiring urgent invasive strategy 1, 2.
Immediate 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 with fondaparinux, enoxaparin, or unfractionated heparin 1.
Beta-blocker and nitrates for ongoing ischemia - target heart rate 50-60 bpm and blood pressure control 1.
High-intensity statin (atorvastatin 80 mg or rosuvastatin 40 mg) 1.
Invasive Strategy Timing
Urgent coronary angiography within 2-24 hours is indicated if NSTE-ACS is confirmed with elevated troponin and ST depression, as this represents high-risk features 1, 3.
Immediate angiography (<2 hours) is required if the patient develops hemodynamic instability, ongoing refractory ischemia, or life-threatening arrhythmias 1.
Critical Pitfalls to Avoid
Never assume ACS based on ST depression alone - 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.
The "atypical" location of pain (nape and upper back) should raise red flags - while ACS can present atypically, sudden severe posterior pain is a classic dissection presentation that should never be dismissed 1.
Do not be falsely reassured by normal oxygen saturation - this does not exclude either aortic dissection or ACS 1.
The acute hypertension is a critical clue - while hypertension can occur with ACS, the sudden elevation from baseline in the context of posterior pain strongly suggests dissection 1.