GeriQBank · Paper III
Rise and fall of cardiac markers after acute coronary syndrome
- Chapter
- Cardiovascular System & Thromboembolism
- Years asked
- Not recorded in the source
- Frequency
- Set 1× in Paper III (2009–2025)
As set in the university paper
Explain, with an appropriate diagram, the rise and fall of cardiac enzymes following an acute coronary syndrome.
Paper III · Cardiovascular Medicine · asked ×1 · 7-mark note · see in paper list
Answer framework
- The principle — leakage and kinetics; the troponin-based definition of MI
- Time course of each marker — myoglobin, CK-MB, troponin, LDH, AST
- Drawing the diagram — axes and curves
- Why the time course matters — early presentation; late presentation; re-infarction; infarct size
- Older people — high-sensitivity cut-offs; kidney disease; non-ischaemic causes
An exam answer plan drawn from the detailed answer below. Use it to attempt the question first.
Detailed answer
Pro · free in betaAttempt it firstOutline your answer as a 7-mark note before revealing it — definition, causes, evaluation, management and the geriatric angle.Reveal answer
Short revision answer
- Dying heart-muscle cells leak proteins that appear, peak and clear at their own pace (depending on size, location in the cell and clearance). MI = a rise and/or fall of cardiac troponin with at least one value above the 99th percentile upper reference limit, plus evidence of ischaemia; high-sensitivity troponin I or T is preferred over the less sensitive and less specific CK-MB.
- Myoglobin: rises within 30 minutes, is raised in all infarcts by 6–10 hours, peaks at ~12 hours and is cleared by 24 hours — sensitive but not cardiac-specific, so a normal value is the useful one. CK-MB: rises at 4–9 hours, peaks within 24 hours, normal by 48–72 hours (MB is 20% of CK in heart muscle versus 5% in skeletal muscle).
- Troponin I and T: rise within 2–4 hours, peak at 12–24 hours and stay raised for 7–14 days or longer (troponin T may peak twice — within 24 hours and around day 4 — normalising in 10–14 days). LDH: rises at 6–12 hours, peaks at 1–3 days, normal by 8–14 days (not cardiac-specific). AST (1954) was the first marker and is now obsolete.
- Diagram: time on the x-axis (hours, then days, to about 2 weeks) and level as multiples of the upper reference limit on the y-axis; myoglobin earliest and shortest; CK-MB peaking at about a day and gone by day 2–3; troponin rising early with a long tail to 1–2 weeks; LDH latest and broadest.
- Early presentation: the first troponin may be normal — repeat at 3–6 hours (sooner with high-sensitivity assays); the diagnosis rests on the change. Late presentation: CK-MB is normal by 72 hours but troponin stays up for 1–2 weeks. Suspected re-infarction (within 28 days): measure troponin at once and at 3–6 hours — a rise of more than 20% indicates re-infarction. Levels reflect infarct size, though reperfusion washout can mislead.
- Older people: the high-sensitivity 99th percentile rises with age over 60 and with comorbidity, but age-specific cut-offs aren't recommended — rely on serial change (sex-specific cut-offs are recommended). Troponin T rises in chronic kidney failure (troponin I is more reliable there), and many non-ischaemic conditions raise troponin, so interpret it with the clinical picture and ECG.
Condensed by GeriClinics from the detailed answer below, with no new facts added.
A. The principle
When heart muscle cells die, their proteins leak into the blood. Each marker appears, peaks and clears at its own pace, depending on its size, where it sits in the cell and how it is cleared.
Myocardial infarction is now diagnosed by a rise and/or fall of cardiac troponin, with at least one value above the 99th percentile upper reference limit, together with evidence of ischaemia. Troponin I or T is the preferred marker, measured with high-sensitivity assays; CK-MB is less sensitive and less specific.
B. Time course of each marker
Myoglobin: can rise within 30 minutes, is raised in all infarctions by 6–10 hours, peaks at about 12 hours and is cleared by the kidneys within 24 hours. Sensitive but not specific to the heart, so a normal value is more useful than a raised one.
CK-MB: rises 4–9 hours after injury, peaks within 24 hours and returns to normal by 48–72 hours. About 20% of creatine kinase in heart muscle is MB, compared with 5% in skeletal muscle.
Cardiac troponin I and T: rise within 2–4 hours, peak at about 12–24 hours and stay raised for 7–14 days or longer. Troponin T may show two peaks, within 24 hours and on about day 4, and returns to normal in 10–14 days.
Lactate dehydrogenase (LDH): rises at 6–12 hours, peaks at 1–3 days and returns to normal in 8–14 days. Not specific to the heart.
Aspartate aminotransferase (AST): the first marker used (1954); not specific to the heart and no longer used.
C. Drawing the diagram
Put time on the x-axis (hours, then days, up to about 2 weeks) and the level as a multiple of the upper reference limit on the y-axis, with the upper reference limit as a horizontal line.
Draw myoglobin as the earliest, short peak (about 12 hours, gone by 24 hours); CK-MB peaking at about a day and back by day 2–3; troponin rising early, peaking at 12–24 hours with a long tail to 1–2 weeks; and LDH as the latest, broad curve peaking at 1–3 days and back by 1–2 weeks.
D. Why the time course matters
Early presentation: the first troponin may still be normal. Take blood on arrival and again 3–6 hours later (sooner with high-sensitivity assays); the diagnosis rests on the rise and/or fall.
Late presentation: CK-MB is back to normal by 72 hours, but troponin stays raised for 1–2 weeks, so troponin can still show a recent infarction.
Suspected re-infarction (within 28 days): measure troponin at once and again 3–6 hours later. If it is already raised but stable or falling, a rise of more than 20% indicates re-infarction.
Infarct size and prognosis: troponin, CK and CK-MB levels relate to infarct size, though after reperfusion the troponin level can mislead because of washout.
E. Older people
With high-sensitivity assays the 99th percentile shifts higher with age over 60 and with comorbidity. Age-specific cut-offs are not recommended; rely on the change between serial samples. Sex-specific cut-offs are recommended.
Troponin T can rise in chronic kidney failure without infarction; troponin I is more reliable there.
Troponin is raised in many non-ischaemic cardiac and non-cardiac conditions, so a raised value is not always coronary ischaemia: interpret it with the clinical picture and ECG.
How was your recall?
Rating marks the question complete. “Need another pass” also adds it to your bookmarks.
References
- Aydin S, Ugur K, Aydin S, et al. Biomarkers in acute myocardial infarction: current perspectives. Vasc Health Risk Manag. 2019;15:1–10. — Rise, peak and clearance of myoglobin, CK-MB, troponins, LDH and AST. Open access (CC BY-NC 3.0)
- Chan D, Ng LL. Biomarkers in acute myocardial infarction. BMC Med. 2010;8:34. — Troponin kinetics and infarct size. Open access (CC BY 2.0)
- Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Eur Heart J. 2019;40(3):237–269. — Read in the Amsterdam UMC repository copy, marked CC BY: definitions, sampling, re-infarction, age and sex
Written in GeriClinics' own words from the sources above, and checked against them. Not yet clinically reviewed.
Spotted an error or something out of date?Report a problem with this page