가장 유용한 표지자는 Cardiac-specific troponin입니다.

시간에 따른 Serum cardiae marker의 변화

	상승시작	최고농도	정상화	민감도	특이도	정상범위
Myoglobin	1-2시간	6-7시간	1일	90%	80%	<85 ng/mL
CK-MB	3-6시간	12-24시간	2-3일	95%	96%	<3 ng/mL
Cardiac troponin	2-6시간	10-24시간	5-14일	95-100%	96%	cTnI <0.4 ng/mL cTnT <0.1 ng/mL

Myoglobin

CK(= CPK, creatinine phosphokinase)

CK
1. 에너지 저장기구에 관여하는 효소 Creatine + ATP ↔ phosphocreatine + ADP
2. 분포장기: 골격근, 심장근육, 뇌에 다량. 방광, 태반, 위장관, 갑상샘, 자궁, 신장, 폐, 전립선, 비장, 간, 췌장 등에 소량 존재
3. 외상이나 골격근 질환 시에도 상승하므로 특이도가 매우 떨어짐
CK isoenzyme(동질효소)
1. CK-MM → 근육 손상 시 증가
2. CK-BB → 뇌조직 손상 시 증가
3. CK-MB → 심근 손상 시 증가(특히, MI일 경우!! )

CK isoenzyme 중에 CK-MB (MB isoenzyme of CK)를 사용하게 됩니다.

CK-MB
- CK에 비해 특이도가 높지만, cardiac surgery, myocarditis, electrical cardioversion에서도 증가 가능
- CK-MB mass/CK activity ≥2.5: CK-MB 상승이 골격근보다 심근에서 기인했을 가능성이 높음, 진단적이지 못함
  - chest pain onset 24-36시간 이내에 측정 시 95% 이상 sensitivity, specificity. 흉통 발생 후 3-12시간에 상승, 24시간에 peak, 48-72시간에 baseline

가장 오래 지속되고, 가장 특이도가 높은 검사
STEMI 발생 이후 7-10일까지 상승 가능
- 병원에 늦게 도착하여 다른 marker가 정상인 경우 유용
- 짧은 기간 내에 재발한 MI에서는 myoglobin이나 CK-MB가 더 유용

troponin이 상승할 수 있는 원인(AMI 제외)

Cardiac causes	Noncardiac causes
Acute and chronic heart failure Acute inflammatory myocarditis, endocarditis/pericarditis Aortic dissection Aortic valve disease Apical balloon syndrome Bradyarrhythmia, heart block Cardiac contusion Cardiac surgery, post–percutaneous coronary intervention, endomyocardial biopsy Cardioversion Hypertrophic cardiomyopathy Myocardial trauma Tachycardia/tachyarrhythmia	Acute pulmonary edema Acute pulmonary embolism Cardiotoxic drugs COPD Chronic renal failure Difficult exercise/excessive effort Infiltrative diseases (amyloidosis) Nonacute critical cardiac disease Pulmonary hypertension Rhabdomyolysis Sepsis Stroke, subarachnoid hemorrhage

생체표지자의 장단점 비교

심장 생화학지표	장점	단점
Cardiac troponins	Powerful tool for risk stratiﬁcation Greater sensitivity and speciﬁcity than CK-MB Detection of recent MI up to 2 weeks after onset Useful for selection of therapy Detection of reperfusion	Low sensitivity in very early phase of MI (less than 6 h after symptom onset) and requires repeat measurement at 8 to 12 h, if negative Limited ability to detect late minor reinfarction
CK-MB	Rapid, cost-efﬁcient, accurate assays Ability to detect early reinfarction	Loss of speciﬁcity in setting of skeletal muscle disease or injury, including surgery Low sensitivity during very early MI (less than 6 h after symptom onset) or later after symptom onset (more than 36 h) and for minor myocardial damage (detectable with troponins)
Myoglobin	High sensitivity Useful in early detection of MI Detection of reperfusion Most useful in ruling out MI	Very low speciﬁcity in setting of skeletal muscle injury or disease Rapid return to normal range limits sensitivity for later presentations

참고자료

Tiwari RP, Jain A, Khan Z, et al. Cardiac troponins I and T: molecular markers for early diagnosis, prognosis, and accurate triaging of patients with acute myocardial infarction. Mol Diagn Ther 2012;16(6):371–81.
French JK, White HD. Clinical implications of the new definition of myocardial infarction. Heart 2004;90(1):99–106.
Aydin S, Ugur K, Aydin S, Sahin İ, Yardim M. Biomarkers in acute myocardial infarction: current perspectives. Vasc Health Risk Manag 2019;15:1–10.
Anderson JL, Adams CD, Antman EM, et al. 2012 ACCF/AHA focused update incorporated into the ACCF/AHA 2007 guidelines for the management of patients with unstable angina/non-ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2013;61(23):e179–347.