Clinical Use of High-sensitivity Cardiac Troponin in Patients With Suspected Myocardial Infarction

Raphael Twerenbold, MD; Jasper Boeddinghaus, MD; Thomas Nestelberger, MD; Karin Wildi, MD; Maria Rubini Gimenez, MD; Patrick Badertscher, MD; Christian Mueller, MD

Disclosures

J Am Coll Cardiol. 2017;70(8):996-1012. 

In This Article

What to Do in Patients With Mild hs-cTn Elevations?

Mild cTn elevations are those just above the 99th percentile (e.g., up to 3 times the 99th percentile) and have a broad differential diagnosis.[27] In patients presenting with acute chest pain, the PPV of mild cTn elevations for MI is only about 50%.[66] In patients in whom mild cTn elevations are detected for other presenting symptoms or possibly during screening with an even lower pre-test probability for MI, the PPV of mild cTn elevations for MI is even lower. The following 3 key questions should help to rapidly identify the underlying cause of mild cTn elevations and to guide optimal management of these challenging patients (Figure 4).[67]

Figure 4.

3 Key Questions to Facilitate Work-Up of Patients Presenting With Mild Elevations of hs-cTn
Three key questions to facilitate work-up of patients presenting with mild elevations of hs-cTn. CMR = cardiac magnetic resonance imaging; MPI-SPECT = myocardial perfusion imaging single-photon emission computed tomography; PPV = positive predictive value; ST-segment ↓ = ST-segment depression; other abbreviations as in Figures 1, 2, and 3.

First, what is the pre-test probability for MI based on symptoms, signs, and ECG findings? For example, in a patient with typical acute chest pain that started only 2 h ago and is associated with ST-segment depression, mild cTn elevations perfectly match the clinical scenario of MI, because cardiomyocyte injury is a time-dependent phenomenon in MI. This patient has a >95% likelihood of MI and requires immediate treatment for MI.

Second, is there a readily identifiable non-MI cause for the observed mild cTn elevation? Basic clinical assessment for age often provides important clues, such as pre-existing structural heart disease, including left ventricular hypertrophy, or obvious non-MI acute cardiac disorders such as acute heart failure, acute tachyarrhythmia, severe sepsis, or acute pulmonary embolism. The more plausible the alternative cause for mild cTn elevations, the less likely that any immediate further diagnostic workup for MI is justified and/or necessary.

Third, which additional diagnostic test is useful? In nearly all patients, changes in cTn should be assessed by repeating the cTn measurement after 1 h.[66] The higher the change in cTn within 1 h, the higher the likelihood of MI. Echocardiography will be helpful, if, for example, valvular heart disease or heart failure is the suspected cause of symptoms and cTn elevation. Cardiac magnetic resonance imaging is helpful to differentiate coronary from other patterns of cardiomyocyte injury and can thereby avoid coronary angiography in many patients with a low likelihood of MI.

Last, but not least, it is important to remember that mild cTn elevation indicates an increased risk for death irrespective of its cause and should always trigger a search for treatable causes.

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