RATIONAL PRESCRIBING IN ISCHAEMIC HEART DISEASE - MANAGEMENT PRINCIPLES

STABLE ANGINA: Chest pain on exertion, relieved by rest

Investigations: 
- FBC (anaemia)
- ESR (inflammation)
- U&E

Follow tree:
	- ECG: rest vs stressed
		- +ve: high workload (medical therapy) vs low workload (coronary angiography)
		- -ve: review diagnosis
	
	- Coronary angiography:
		- triple vessel disease: CABG
		- 1-2 vessel disease: medical therapy + CABG/PTCA	(percutaneous transluminal coronary angiography)

Look at Fig 3.56 pp 251 Davidsons for an excellent diagram. 


Management Principles:
1) Acute: relieve symptoms, 2) Chronic: prophalyxis (angina, AMI)

Acute: relieve symptoms
	- nitrates: tablets/spray/patch/IV: venodilatation --> reduce preload/afterload --> reduce wall stress, direct vasodilatory effect on coronary vessels. Dose: tablet (500ug) / spray (300ug/spray)
		- names: GTN, isosorbide di/mononitrate, S/E: headaches, palpitations, hypotension (syncope), resistance (6-8hrs nitrate free). 

Chronic: prophalyxis
	- nitrates: prescribe the patient with nitrates so that they can relieve pain. Can be used before embarking on exercise. 
	- beta-blockers: tablets: bind to B1-adrenergic receptors --> reduce heart rate, BP, contractility --> reduce heart stress. Cardio-selective preparations are best! Dose: 50-100mg atenolol
		- names: atenolol, metoprolol, bisoprolol
	- Ca2+ blockers: tablets: bind to Ca2+ channels --> antagonise them --> reduce influx of Ca2+ (cardiac + smooth) --> reduce contractility --> reduce stress + vasodilation.
		- names: dihydropyridines (nifidipine) - use with b-blockers, diltiazem + verapamil - use alone, are more useful for antiarrthymic activity
	- aspirin (75-300mg/day): inhibit platelet aggregation. 

General prescribing is: aspirin, nitrates, beta-blocker. Add Ca2+ blocker if need be. 


UNSTABLE ANGINA: Chest pain which gets worse rapidly / at rest / & not ECG or enzyme evidence of AMI

Investigations:
- FBC (anaemia)
- ESR (inflammation)
- U&E

Follow tree: 
	- Medical therapy: 
		- Low risk: aspirin, b-blockers, nifidipine
		- High risk: aspirin, b-blockers, nifidipine, heparin
			- Persisting pain: IV nitrates
	- if Low Risk:
		- ETT: rest vs stress 
			- +ve: high workload (medical therapy) vs low workload (angiography)

		- Coronary angiography:
			- triple vessel disease: CABG
			- 1-2 vessel disease: PTCA/CABG/medical therapy
	- If High Risk:
		- Coronary angiography straight away

Management Principles
1) Acute: relieve symptoms, 2) Chronic: prophaylyxis (angina, AMI)