Pathophysiology
- Proximal occlusion of a major coronary artery
ECG
- Diagnosis usually on the basis of ECG
- The ST segments rise in the leads corresponding to the part of the heart that is damaged
- The V leads – anterior infarction
- VL and V5/6 – lateral infraction
- III and VF – inferior infarction
- STEMI is dx when there is
- >1mm of ST elevation (STE) in at least 2 contiguous limb leads
- E.g. I + VL; III + VF)
- Or >2mm of STE in at least 2 contiguous precordial leads
- Or new LBBB
- >1mm of ST elevation (STE) in at least 2 contiguous limb leads
- Prompt treatment by PCI or thrombolysis can prevent myocardial damage, so Q waves don’t develop
- Q wave is considered pathological if it is >1 small square wide (>0.04s) and/or >2 small square tall (>2mm)
- Sequence of ECG in a pt with STEMI
- STE
- T wave inversion in affected leads
- After a few days, ST segment returns to baseline and Q waves develop
TREATMENT FOR ACS
Acute management for pts with symptoms of ACS
Pre-hospital
- Aspirin – [300mg po]
- Analgesia + antiemetic – IV (avoid i.m. injections due to risk of bleeding)
- Morphine [5-10mg]
- Metoclopramide – [10mg]
- Sublingual GTN – [300mcg]
Hospital management
- ECG – to distinguish STEMI from NSTEMI/UA
- Oxygen – if saturation <94%
Immediate STEMI management
- Cardio referral
- PCI – for pts presenting within 12 hrs of chest pain
-
- Involves either balloon angioplasty or stent implantation
- Give gp IIb/IIIa inhibitor alongside PCI
- Abciximab
- Thombolysis if PCI unavailable (don’t give to pts who don’t have STE)
- Streptokinase
- Start heparin
Immediate NSTEMI management
- Cardio referral
- PCI – if GRACE score is high
- Do not give thrombolytic therapy
Tx once ACS pts are stable
- Anti-platelet therapy
- Clopidogrel/ticagrelor and aspirin
- Beta blocker
- Atenolol – [5mg IV]
- ACE-Inhibitors
- Statins
- Aim for total cholesterol <4mmol/L and HDL>1mmol/L
Full drug regime – after discharge
- Aspirin [100mg]
- Metoprolol [50mg b.i.d]
- Ramipril [2.5-10mg]
- Simvastatin [50mg b.i.d]
- Clopidogrel [300mg loading + 75mg maintenance]
- Epleronone [25mg]