Clinical Cases: Serial Monitoring Differentiates Acute and Chronic hs-TnT Elevation

Patients with increased hs-cTnT at admission and a typical presentation of ACS but without an absolute δ change ≥7ng/L are usually found to have UAP with hs-cTnT increases due to underlying chronic cardiac damage. (In the case a previous MI of the anterior wall)

With the use of absolute δ changes, a rise and/or fall of at least 9.2 ng/L for a population consisting of patients with ACS and non-ACS conditions, or 6.9 ng/L for an ACS population seems to be more adequate than relative δ changes for ruling out AMI.¹

The present results suggest that clinical assessment, ECG analysis and serial measurement of hs-TnT in serum showing lack of rise or fall in its kinetic activity indicating chronic myocardial injury.

Case 6

62-year-old man

Key signs and symptoms

Left chest tightness on minimal effort for the past 4 days, duration 15 minutes, responds to nitrates

Medical history

Similar symptoms 3 years ago when he was diagnosed with an acute anterior wall infarction, since then suffering from heart failure with exertional dyspnoea NYHA II. Diabetes mellitus, arterial hypertension

Clinical examination

Normal

Laboratory test results

Results		Reference range
CRP 4 mg/dL		<5 mg/dL
D-dimers 1,1 mg/dL		<0,5 mg/dL
Serum creatinine 0,9 mg/dL		<9 mg/dL
GFR 75 mL/min/1,73 m²		>90 mL/min/173 m²
Leukocytes 7,92/nL		4.4 – 11.3/nL
NT-proBNP 450 ng/L		<300 ng/L to rule-out AHF and >900 ng/L HF likely if 50–75 year-old (confirmation with imaging)

ECG

Sinus rhythm, QS complex V1 – V3, persistent ST Segment elevations in V1 – V4 as an expression for previous anterior wall infarction.

Troponin kinetic profile

Contrast-enhanced cardiac MRI

Magnetic resonance imaging (MRI) indicating a previous myocardial infarction of the anterior wall.

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Diagnosis

Unstable angina

(and heart failure following a previous anterior wall infarction)

Typical angina pectoris, although an elevated cTnT-hs level was found at admission. In order to distinguish between acute and a chronic cTnT-hs elevation; troponin levels must be monitored with serial testing. The changes in troponin levels are below 50 % (<7 ng/L). In this case the small changes in concentration are indicative of chronic myocardial damage. This is consistent with the magnetic resonance imaging (MRI), indicating a previous myocardial infarction of the anterior wall.

Diagnosis

Unstable angina

Conclusion

There is no rise or fall in cTnT-hs values needed for AMI diagnosis.

References