[Circulating troponin I assay: uses and misuses in medical practice]

Area of Science:

• Biochemistry
• Cardiology
• Clinical Diagnostics

Context:

• Cardiac troponin I (cTnI) is crucial for myocardial contractile function.
• Assays for circulating cTnI are highly specific for the cardiac isoform.
• Accurate quantification of myocardial injury requires recognizing both free and combined cTnI.

Purpose:

• To highlight the diagnostic utility of cardiac troponin I (cTnI) assays.
• To emphasize cTnI's specificity in diagnosing postoperative cardiac complications.
• To explore cTnI's role in assessing acute circulatory failure and acute coronary syndrome.

Summary:

• Circulating cTnI assays are specific for cardiac injury, aiding diagnosis of postoperative complications by excluding peripheral muscle trauma.
• cTnI levels reflect the severity of acute circulatory failure from various origins (cardiac, hemorrhagic, septic).
• While confirming acute coronary syndrome severity, cTnI's predictive role for mortality and hospital admissions is limited; positive results in asymptomatic patients require further investigation for occult cardiac disease.

Impact:

• Enhances the diagnosis of cardiac complications, particularly postoperatively.
• Provides a reliable marker for the magnitude of acute circulatory failure.
• Confirms acute coronary syndrome severity and offers prognostic value, guiding patient management.