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Acute coronary syndrome: Difference between revisions
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The results from the ECG and [[troponin]] test will reveal the diagnosis: | The results from the ECG and [[troponin]] test will reveal the diagnosis: | ||
* ST-elevations are present in ECG leads corresponding to a part of the heart supplied by a specific vessel -> the diagnosis is STEMI | * ST-elevations are present in two consecutive ECG leads corresponding to a part of the heart supplied by a specific vessel -> the diagnosis is STEMI | ||
* ST-elevations are not present in ECG leads corresponding to one part of the heart -> the diagnosis is NSTE-ACS | * ST-elevations are not present in ECG leads corresponding to one part of the heart -> the diagnosis is NSTE-ACS | ||
** Troponins are elevated and are dynamic -> the diagnosis is NSTEMI | ** Troponins are elevated and are dynamic -> the diagnosis is NSTEMI | ||
** Troponins are not elevated -> the diagnosis is UA | ** Troponins are not elevated -> the diagnosis is UA | ||
== Troponins == | |||
In both STEMI and NSTEMI, the troponin levels increase, peak, and then start to decrease. For this reason, if you measure the troponin level at 2 different times in an AMI, the troponin level is going to be higher or lower at the second measurement, depending on whether the troponin peak had been reached or not at the time of the first measurement. This is called a ''rise and/or fall'' in troponin and is often referred to as troponin ''dynamics''. Many conditions can cause troponin elevation, but troponin dynamics are highly specific for AMI. As such, if the diagnosis of AMI is not immediately certain, a repeat troponin measurement should be taken after 1 – 3 hours, and if a rise and/or fall is present, the diagnosis is certain. A significant rise and/or fall is defined as a change of > 20 – 50%. | In both STEMI and NSTEMI, the troponin levels increase, peak, and then start to decrease. For this reason, if you measure the troponin level at 2 different times in an AMI, the troponin level is going to be higher or lower at the second measurement, depending on whether the troponin peak had been reached or not at the time of the first measurement. This is called a ''rise and/or fall'' in troponin and is often referred to as troponin ''dynamics''. Many conditions can cause troponin elevation, but troponin dynamics are highly specific for AMI. As such, if the diagnosis of AMI is not immediately certain, a repeat troponin measurement should be taken after 1 – 3 hours, and if a rise and/or fall is present, the diagnosis is certain. A significant rise and/or fall is defined as a change of > 20 – 50%. | ||
However, the magnitude of troponin elevation corresponds to the myocardial damage. While conditions like [[heart failure]] and [[myocarditis]] also can cause troponin elevation, they virtually never cause a very large elevation in troponins. if the troponin levels are very high (even if only measured once), the risk for AMI is sufficiently high that we proceed to invasive management without waiting for a repeat troponin. Modern high-sensitivity troponin assays have an upper normal limit of normal of approx. 14 ng/L. As the single-measurement troponin increases beyond 1000 ng/L the specificity for AMI increases. | However, the magnitude of troponin elevation corresponds to the myocardial damage. While conditions like [[heart failure]] and [[myocarditis]] also can cause troponin elevation, they virtually never cause a very large elevation in troponins. if the troponin levels are very high (even if only measured once), the risk for AMI is sufficiently high that we may proceed to invasive management without waiting for a repeat troponin. Modern high-sensitivity troponin assays have an upper normal limit of normal of approx. 14 ng/L. As the single-measurement troponin increases beyond 1000 ng/L the specificity for AMI increases. | ||
[[File:Time course of troponin.png|thumb|323x323px|The change in troponin levels after an AMI over time and depending on size. <ref>https://pubmed.ncbi.nlm.nih.gov/23547823/</ref>]] | [[File:Time course of troponin.png|thumb|323x323px|The change in troponin levels after an AMI over time and depending on size. <ref>https://pubmed.ncbi.nlm.nih.gov/23547823/</ref>]] | ||
Modern high-sensitivity troponin assays can detect a rise in troponins 1 – 3 hours after the infarction. As such, the troponins may be normal if measured early. In these cases, a repeat measurement should be performed 1 – 3 hours later. | Modern high-sensitivity troponin assays can detect a rise in troponins 1 – 3 hours after the infarction. As such, the troponins may be normal if measured early. In these cases, a repeat measurement should be performed 1 – 3 hours later. | ||
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All patients with suspicion for ACS should have their heart rhythm continuously monitored with a rhythm monitor. The risk for fatal arrhythmias is highest in the first days after an AMI. | All patients with suspicion for ACS should have their heart rhythm continuously monitored with a rhythm monitor. The risk for fatal arrhythmias is highest in the first days after an AMI. | ||
[[Category:Cardiology]] | == References == | ||
<references />[[Category:Cardiology]] | |||
[[Category:Internal Medicine (POTE course)]] | [[Category:Internal Medicine (POTE course)]] | ||