NSTEMI and Unstable Angina MCQ — NEET PG Practice Question | NEETPGAI
NSTEMI and Unstable Angina
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stethoscope Medicine
Which single clinical or biochemical feature best distinguishes NSTEMI from unstable angina in a 58-year-old man presenting with acute chest pain and dynamic ST-segment changes on ECG?
A. Elevation of cardiac troponin I or T above the 99th percentile upper reference limit
B. Presence of chest pain at rest or with minimal exertion
C. Angiographic evidence of coronary artery disease
D. ST-segment depression or T-wave inversion on 12-lead ECG
Explanation
Distinguishing NSTEMI from Unstable Angina
The Core Difference
Key Point
The presence or absence of myocardial necrosis, detected by elevated cardiac biomarkers, is the single most important discriminator between NSTEMI and unstable angina. Both conditions present with acute coronary syndrome (ACS) symptoms, but only NSTEMI involves myocardial injury.
Comparison Table
Table
Feature
NSTEMI
Unstable Angina
Cardiac Troponin
Elevated (>99th percentile)
Normal / not elevated
Myocardial Necrosis
Present
Absent
ECG Changes
ST-depression, T-wave inversion, or normal
ST-depression, T-wave inversion, or normal
Chest Pain
Acute, at rest or minimal exertion
Acute, at rest or minimal exertion
Prognosis
Higher short-term mortality
Lower short-term mortality
Angiography
Coronary stenosis/thrombosis
Coronary stenosis/thrombosis
Why Troponin is the Discriminator
1.
Specificity for myocardial injury: Troponin I and T are structural proteins released only when myocyte necrosis occurs.
2.
Timing: Troponin becomes detectable within 2–4 hours of symptom onset; peak at 24–48 hours.
3.
High sensitivity and specificity: Modern high-sensitivity troponin assays detect even small amounts of myocardial damage.
4.
Prognostic value: Elevated troponin predicts worse outcomes and guides intensity of antiplatelet/anticoagulant therapy.
High-YieldNEET PG
The 2016 ESC Guidelines and 2014 ACC/AHA Guidelines define NSTEMI as ACS with elevated cardiac biomarkers; unstable angina is ACS without biomarker elevation.
Clinical Pearl
In clinical practice, serial troponin measurements (at presentation and 3 hours, or high-sensitivity troponin at 0 and 1–3 hours) are mandatory in all suspected ACS to rule in or rule out myocardial infarction. A single negative troponin does not exclude NSTEMI if the clinical suspicion remains high.
Mnemonic
NSTEMI = Necrosis + Troponin Elevation; UA = Ischemia only (no Troponin)
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