Earliest reliable enzyme to increase in AMI

Ans. a (CPK-MB). (Ref. Harrisons, Medicine, 18th/ Chapter 246.)#Earliest enzyme elevated after AMI:hFABP and Myoglobin#Most specific enzyme:Troponin T (returns nomal in 5-14 dys)#Enzyme imp in Reinfarction:CPKMB (returns nomal in 2-3 dys)#Most common cause of death in AMI:VT leading to VF#Post-AMI autoimmune pericarditis (7 dys later):Dressier syndrome#Time after AMI when cardiac muscle is most subjected to rupture: 3-7 dys#Microscopic changes after AMI: - Neutrophils:1-3 dys of AMI - Lymphocytes:4-7 dys of AMI - Grabulation tissue:7-14 dys of AMIDIAGNOSIS OF AMI# In first six hours ECG is gold standard.# Changes include ST elevation (transmural ischemia) and Q waves (transmural infarct)- CPK-MB is test of choice in first 24 hours of AMI- Cardiac troponin I is used within the first 4 hours upto 7-10 days. More specific:- LDH is elevated from 2 to 7 post Ml day. LDH decrease is specific for cardiac muscles.# Radioisotope Thallium-201 scanning is used to distinguish ischemic from non-ischemic myocardium/ to detect reversible ischemia.# Radioactive stannous pyrophosphate is used to distinguish normal from damaged myocardium.# 2D-ECHO is best initial modality for assessment of valvular abnormalities, wall motion & ventricular ejection fraction (i.e. ventricular function).