Acute Coronary Syndrome

Introduction

 Acute Coronary Syndrome (ACS) describes any constellation of clinical symptoms due to myocardiac ischemia. It includes acute myocardiac infarction(MI) [ST elevation MI (STEMI) and non-ST elevation MI (NSTEMI) and unstable angina.

High risk of group :

i.New onset (<2months) angina that is severe and frequent (>3 episodes/day).

ii. Accelerating angina ,i.e.previosly chronic stable angina which becomes distinctly more frequent,severe, prolonges, or precipitated by lessexertion than before.

iii. Angina at rest ( >20minutes)

A.  Clinical Features

&

 Diagnosis

1. Symptoms

•Chest pain/discomfort, usually retrosternal, central or in the left chest, may radiate to jaw or down upper limb

• May be crushing , pressing or burning

• Severity of pain is variable

• May be difficult to differentiate btw symptoms of STEMI and UA/NSTEMI

•Left ventricular failure(some)

•Unexplain fatigue, SOB, epigastric discomfort, nausea and vomit.

2. Physical Examination

•To identify precipitating factors and consequences of UA/NSTEMI

3. Investigation

•ECG :

i.ST segment depression >0.05 mV

ii. T wave inversion –marked >0.2mV symmetrical T-wave inversion in pericordial leads.

• Troponin, cardiac enzymes (CKMB, AST, LDH)

• Echocardiography

•CXR, FBC, PT, PTT, LFT, creatinine, BUSE, glucose, and lipid profile.

B. MANAGEMENT

1. General Measures

•Admit to CCU for observation. Monitor cardiac rhythm for 24-48 hr. Pt encourage to report any recurrence of pain.

•Bed rest, sedation and analgesics should be administered as in AMI. IV morphine is recommended for pt with persistent or recurrrent symptoms despite anti-ischaemic therapy. IV morphine is given as bolus 2-5mg with IV anti-emetic e.g. IV metoclopramide (Maxalon) 10mg. Repeat dose may be given.

•BP every 15-30 min for a few hr,then every 1-2hr.

•IV line for drug administered.

•O2 via nasal prongs.

•Serial ECG and cardiac enzyme to detect AMI and silent and recurrent ischemid.

•Other coronary risk factor (eg. DM, hypercholesterolaemia) & precipitating factor (eg,anaemia) should be treated.

2. Anti-Thrombotic Therapy

• Combination of aspirin (ASA), Clopidogel, unfractional heparin (UFH) or low molecular weight heparin (LMWH), with or without a platelet GP IIb/IIIa receptor antagonist is the optimal therapy.

Low Risk UA/ NSTE MI pt	High Risk UA/NSTEMI pt
ASA + Clopidogel + SC LMWH or IV UFH	ASA + Clopidogel + SC LMWH or IV UFH + IV platelet GP IIb/IIIa antagonist

a.  Antiplatelet agents :

•Choice of agents:

-Cyclo-oxygenase inhibitors : Aspirin.

-Adenosine diphosphate(ADP) receptor antagonists : Clipidogrel , Ticlopidine

•Dose :

-Aspirin 300mg chewed or crushed and swallowed for rapid effect, then 75-150mg daily (if no contra-indication)

-Clopidrogel 300mg start followed by 75mg daily

-  Ticlopidine 250mg (for aspirin hypersensitivity and intolerance). Associated with neutropenia in 2% of pt. Monitoring of FBC (2-4 weekly for the first 3-4months) is important.

b. Anticoagulants

•IV  unfractionated Heparin (UFH) decreases incidence of MI in pt with UA. It is given as bolus dose of 5000 U followed by infusion of 1000 U per hour. The infusion rate is adjusted by regular monitoring of aPTT, keeping it to 1.5-2.5X control. This should be maintained for 2-5 days.

•Low molecular weight heparin (LMWH) available include dalteparin, nadroparin ( Fraxiparine) & enoxaparin ( Clexane).

Recommended Dosage
UFH	IV Bolus	•80 U/kg (maximum of 5000 U) •Infusion of 18U/kg/h (max 1000)
	Target aPTT	•1.5-2.5 times or approximately 60-80s •It should be monitored and measured
LMWH	Enoxaprin ( Clexane) Nadroparin ( Fraxiparine)	•1mg/kg 5C.bd* •0.1 ml/ 10kg.5C.bd*

c. Platelet glycoprotein IIb/IIIa receptor antagonist

RECOMMENDED DOSAGE		The dosing regime for the initial phase pharmacological therapy preceeding PCl(upstream use) & during PCl are as follow:
1.Abciximab       (Reopro)	Upstream use & planned PCI PCI	•IV Bolus 0.25mg/kg h before procedure. •Follow by continuous infusion of 0.125µg/kg per min (to a max of 10µg/min) for 12 h. • •IV Bolus 0.25mg/kg h for 10-60min before the start of PCI •Followed by continuous infusion of 0.125µg/kg per min(to a maxi of 10µg/min) for 12 h.
2. Eptifibatide (Integrilin)	PCI	•IV Bolus 180µg/kg •Immediately followed by a 2µg/kg/min infusion •Then a second 180µg/kg bolus 10min later. •The infusion should be continued until hospital discharge ,up to 18-24h. •

2. Eptifibitide	Upstream use	•IV Bolus 180µg/kg (max 22.6mg) over 1-2min •Follow by an infusion of 2µg/kg /min ( max of 15mg/h) for 72h or until hospital discharge . •In the cases of PCI, the infusion should be continued for 96h.
3. Tirofiban (Aggrastat)	Upstream use PCI	•IV Bolus 0.4µg/kg /min for 30min •Follow by an infusion of 0.1 µg/kg /min for 48-108h •In the cases of PCI, the infusion should be continued 12-24h after PCI. • •IV Bolus of 25µg/kg given over 3-7min (max 10ml/min) •Follow by maintenance infusion of 0.15µg/kg /min for 8-10h post PTCA