Dr Lee’s Clinical Cases: hs-TnT Early “Rule-In” for AMI
30 March 2021
Review the clinical case details and select the most probable diagnosis below. More information on the diagnosis and Dr Lee’s opinion can be seen by clicking on the “Click to review the answer” button.
For his cases regarding hs-TnT Chronic Elevation non-AMI cases, click here to attempt them.
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Case Study: 59-year old manCase Study: 85-year old womanCase Study: 66-year man
Case
59-year old man
Key signs and symptoms
Chest tightness and cold sweating for 2 hours.
Medical history/ Clinical examination
Medical history: Coronary artery disease status post stent, diabetes, hyperlipidemia, chronic hepatitis C. Clinical examination: The presenting vitals are: BP 182/107mmHg, HR 95BPM, RR 20BPM, temperature 36.1C, oxygen saturation 97%, Glasgow coma scale 15.
Laboratory test results
Test
Value
Reference range
WBC (x103/μL)
8.19
3.54 – 9.06
Hemoglobin (g/dL)
16
10.8 – 14.9
NT-proBNP (pg/mL)
12.5
Rule out of acute heart failure (AHF): <300 pg/mL Rule in AHF: < 50 years: >450 pg/mL 50 – 75 years: >900 pg/mL >75 years: >1800 pg/mL
Coronary artery disease, 3-vessel disease, complicated with NSTEMI
•
Initial ECG showed normal by machine interpretation.
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Dynamic Troponin change and persistent symptoms justified the coronary angiography, which confirmed the RCA occlusion.
Author’s opinion
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The ECG interpreted by machine may be sometimes falsely negative. The dynamic change of troponin greater than 100% 3 hours later led to a review of ECG finding ST-elevation in III and aVF inferior leads.
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According to the criteria of the 2015 ESC guidelines, using the 0/1-hour algorithm, NSTEMI can be ruled in if T0 >52 ng/L or delta change at T1 >5 ng/L. This patient has T1 delta change of 14 ng/L. If apply ESC 0/1-hour algorithm, this patient would have been diagnosed two hours earlier.
Case
85-year old woman
Key signs and symptoms
Acute onset of dyspnea accompanied with diaphoresis and altered level of consciousness.
Medical history/ Clinical examination
Medical history: Hemiplegic stroke with dependent ADL (activities of daily living), COPD (Chronic obstructive pulmonary disease), osteoarthritis, hypertension, and coronary artery disease. Clinical examination: Irregular heart beat, systolic murmur at right upper sternal border, and bilateral rales. No leg edema. BP 132/50 mmHg, heart rate 75 BPM, respiratory rate 22 BPM, body temperature 36.1C, oxygen saturation 100%.
Laboratory test results
Test
Value
Reference range
WBC (x103/μL)
15.77
3.54 – 9.06
Hemoglobin (g/dL)
5.9
10.8 – 14.9
Creatinine clearance (ml/min)
2.2
0.6 – 1.2
NT-proBNP (pg/mL)
34851
Rule out of acute heart failure (AHF): <300 pg/mL Rule in AHF: < 50 years: >450 pg/mL 50 – 75 years: >900 pg/mL >75 years: >1800 pg/mL
ECG Marked ST-segment depression in leads V2 to V6 and slight ST-segment depression in leads I and aVL
Troponin kinetic profile
Chest X-ray
Cardiomegaly and mediastinal widening. Opacities at bilateral lungs
Transthoracic Echocardiography
Severe aortic stenosis with mild aortic regurgitation
The patient’s family chose to receive palliative care and she did not undergo emergency cardiac intervention. She died 2 days after ED admission.
Diagnosis
1.
Acute myocardial infarction/NSTEMI
2.
Acute pulmonary edema
The typical dynamic rise and fall of cTnT-hs confirmed the diagnosis of myocardial infarction.
Author’s opinion
•
The very high baseline (T0) TnT level raises the suspicion of MI. Formally it is a rule-in case although not automatically a MI. However, there are confounders caused troponin elevation with this patient such as older age, severe anemia, renal dysfunction, acute heart failure, hypoxia in presence of pulmonary edema. Therefore, diagnosis as a MI is unable to establish at T0.
Case
66-year man
Key signs and symptoms
Acute onset chest pain with radiation to left upper arm for 1 day. Chest pain persisted after took nitroglycerin. Also complained of exertional dyspnea.
Medical history/ Clinical examination
Clinical examination: BP 123/75mmHg, HR 109BPM, RR 20BPM, oxygen saturation 95%, Glasgow coma scale 15.
Laboratory test results
Test
Value
Reference range
WBC (x103/μL)
8.48
3.54 – 9.06
Segmented neutrophil (%)
56.7
50 – 70
Hemoglobin (g/dL)
17.9
10.8 – 14.9
Creatinine clearance (ml/min)
71.2
90 – 139
NT-proBNP (pg/mL)
204
Rule out of acute heart failure (AHF): <300 pg/mL Rule in AHF: < 50 years: >450 pg/mL 50 – 75 years: >900 pg/mL >75 years: >1800 pg/mL
ECG Normal sinus rhythm with mild ST elevation and Q wave over II and III
ST segment elevation in III and avF lead. Strict posterior leads not registered. Probably missed strict posterior MI and inferior involvement possible.
•
Coronary angiography showed stenosis in left circumflex artery.
Author’s opinion
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This is a good example why an initially very high cTnT-hs qualifies for rule-in of myocardial infarction.
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The patient had late onset of chest pain and presented with very high concentration of cTnT-hs at admission. Mueller-Hennessen et al study showed diagnostic performance was not further improved with repeat troponin testing when baseline cTnT-hs concentration > 80 ng/L.11
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Therefore, in chest pain patients with highly abnormal cTnT-hs concentrations at presentation, subsequent blood draws may not be required due to high PPV with single cTnT-hs result at admission. This is in line with current European Society of Cardiology guideline recommendation.2
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