Regarding the pathophysiology and management of NSTEMI and unstable angina, all of the following are true EXCEPT:
A. Dual antiplatelet therapy with aspirin and a P2Y12 inhibitor is contraindicated in unstable angina
B. Beta-blockers reduce myocardial oxygen demand and are first-line agents in both conditions
C. Elevated cardiac troponins distinguish NSTEMI from unstable angina
D. Both conditions result from partial coronary artery occlusion with preserved distal flow
Explanation
Distinguishing NSTEMI from Unstable Angina
Key Point
The cardinal difference between NSTEMI and unstable angina is the presence or absence of myocardial necrosis, detected by elevated cardiac biomarkers (troponin, CKMB).
Pathophysiology
Both conditions result from partial coronary occlusion (usually from plaque rupture with superimposed thrombosis) that allows some distal perfusion. This contrasts with STEMI, where complete occlusion causes transmural infarction.
Biomarker Distinction
Table
Feature
Unstable Angina
NSTEMI
Symptoms
Chest pain at rest or with minimal exertion
Same as UA
ECG
No ST elevation; may have T-wave changes or be normal
ST depression, T-wave inversion, or dynamic changes
Troponin
Normal
Elevated
Diagnosis
Clinical + ECG (no biomarker rise)
Clinical + ECG + elevated troponin
High-YieldNEET PG
Troponin elevation is the only biochemical marker that separates NSTEMI from unstable angina.
Dual Antiplatelet Therapy (DAPT)
Clinical Pearl
DAPT with aspirin + P2Y12 inhibitor (clopidogrel, prasugrel, or ticagrelor) is standard of care in BOTH unstable angina AND NSTEMI. This is a cornerstone of acute coronary syndrome management.
Why the distractor is wrong: The statement "DAPT is contraindicated in unstable angina" is false. DAPT is indicated in both conditions and reduces recurrent ischemic events.
Medical Management Common to Both
1.
Beta-blockers — reduce heart rate, contractility, and myocardial oxygen demand; reduce anginal frequency and reinfarction risk
2.
ACE inhibitors — reduce afterload and improve ventricular remodeling
3.
Statins — plaque stabilization and anti-inflammatory effects
4.
Anticoagulation — unfractionated heparin or LMWH to prevent thrombotic extension
5.
Nitrates — symptom relief (but no mortality benefit)
Mnemonic: ABCDE of ACS management — Aspirin + Anticoagulation, Beta-blockers, Coronary angiography, Dual antiplatelet therapy, Enzyme inhibitors (ACE-I) and statins.
Why Each Distractor Is Correct
Option 0: Elevated troponins are the biochemical hallmark of NSTEMI and distinguish it from unstable angina — TRUE.
Option 1: Both UA and NSTEMI result from partial occlusion with preserved distal flow — TRUE.
Option 3: Beta-blockers are first-line agents in both conditions for symptom relief and prognostic benefit — TRUE.
Harrison 21e Ch 297
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