see also:

• cardiac markers (troponin)

• troponin is a complex of three regulatory proteins (troponin C, troponin I, and troponin T) that is integral to muscle contraction in skeletal muscle and cardiac muscle, but not smooth muscle.
  • Troponin C binds to calcium ions to produce a conformational change in TnI
  • Troponin T binds to tropomyosin, interlocking them to form a troponin-tropomyosin complex
  • Troponin I binds to actin in thin myofilaments to hold the troponin-tropomyosin complex in place
• cardiac I and T subtypes of troponin are sensitive and specific indicators of damage to myocardium and thus are the current main cardiac markers for myocardial injury
• troponin elevation following cardiac cell necrosis starts within 2–3 hours, peaks in approx. 24 hours, and persists for 1–2 weeks

• see acute myocardial infarction (AMI/STEMI/NSTEMI)
• with minimally obstructed coronary arteries on angiography:
  • coronary causes (Myocardial Infarction With Nonobstructive Coronary Arteries (MINOCA)):
    • coronary dissection
    • plaque disruption
    • coronary spasm
    • microvascular dysfunction
    • coronary thrombus or embolus
  • myocardial disorders
    • myocarditis eg. COVID-19 coronavirus (2019-nCoV / SARS-CoV-2)
    • Takotsubo cardiomyopathy
    • other cardiomyopathies
  • type 2 events (see below)

• these are not directly related to acute coronary insufficiency but to other events such as:
  • tachyarhythmias such as atrial fibrillation
  • sepsis / septicaemia
  • pulmonary embolism (PE) and other causes of acute RV strain such as exacerbation of chronic obstructive pulmonary disease (COPD) or pulmonary hypertension
  • the shocked hypotensive patient
  • pre-eclampsia and eclampsia
  • myocardial toxins eg. chemotherapy agents, animal toxins
  • carbon monoxide poisoning
  • cyanide poisoning
  • extreme exertion eg. marathons
  • rhabdomyolysis
  • cardiac contusion in trauma to the chest
  • after defibrillation or DC cardioversion
  • after coronary angioplasty
  • after radiofrequency ablation
  • after cardiac surgery of heart transplant

• end stage renal failure (ESRF)
• inflammatory conditions such as polymyositis (PM) or dermatomyositis
• chronic myocardial ischaemia