Myocardial Ischaemia Flashcards
Myocardial Ischaemia – Stable angina results from
- Stable angina results from atherosclerotic plaques in the coronary arteries which restrict blood flow + oxygen supply to the heart, often precipitated by exercise and relieved by rest.
- Acute attacks of stable angina should be managed with sublingual GTN which can be taken before exercises known to bring on an attack. If attacks occur more than twice a week, drug therapy is needed…
Nitrates – further information
Unwanted effects such as flushing, headache + postural hypotension may limit therapy.
Sublingual GTN only last for 20-30 minutes When GTN is first used, the 300mcg tablet is often most appropriate. Duration of action may be prolonged by use of transdermal patches, but tolerance may develop.
Isosorbide dinitrate is more stable for those who require nitrates infrequently. MR preps = up to 12 hours
Acute coronary syndromes (ACS) is an umbrella term for 3 conditions
Unstable angina, NSTEMI and STEMI
Unstable angina and non-ST-segment elevation myocardial infarction (NSTEMI) occurs when
- A NSTEMI occurs when the clot has grown but has not fully occluded that artery. It usually occurs as a result of atherosclerotic plaque rupture and is characterised by stable angina that suddenly worsens, recurring or prolonged angina at rest, or new onset of severe angina. There is a risk of progression to a STEMI or sudden death.
Unstable angina and NSTEMI management
In patients with unstable angina/NSTEMI, Clopidogrel/Prasugrel/Ticagrelor is given with Aspirin for up to 12 months. An ACE inhibitor is also given.
- Oxygen: as patients are short of breath (because restricted oxygen is reaching the heart)
- Nitrates: to relieve Ischaemic pain. If sublingual GTN is not effective, I.V. or buccal GTN or I.V. Isosorbide dinitrate is given.
- Diamorphine/Morphine: if the pain continues by slow I.V. injection with + antiemetic (Metoclopramide)
- Aspirin: chewed/dispersed in water is given for the antiplatelet effect. It should be given with Clopidogrel, Prasugrel or Ticagrelor.
- Unfractionated heparin or Low molecular weight Heparin or Fondaparinux sodium: to prevent clot growing
- Patients without contraindications should receive beta-blockers which should be continued. If these are not appropriate, alternatives include diltiazem or verapamil.
- The Glycoprotein IIb/IIIa inhibitors EPTIFIBATIDE in combination with unfractionated heparin + Aspirin and TIROFIBAN in combination with unfractionated heparin + Aspirin + Clopidogrel can be used for unstable angina or for NSTEMI patients at high risk of an MI or death.
The above regime can also be used for patients undergoing percutaneous coronary intervention (STENT and CABG) to reduce the risk of vascular occlusion.
ST-segment elevation myocardial infarction (STEMI)
- A STEMI occurs when there is complete blockage of the artery due to a clot, therefore no blood reaches an area of the heart and hence that area of heart muscle dies… leading to long term complications.
STEMI management
Oxygen, Diamorphine/Morphine, Aspirin, Nitrates = same as above
Thrombolytic drug to open the blocked artery
Glycoprotein IIb/IIIa inhibitor: to reduce risk of vascular occlusion in immediate and high-risk patients during a percutaneous coronary intervention.
Unfractionated heparin or Low molecular weight heparin: to prevent clot growing during PCI.
ACE inhibitors or Angiotensin-II receptor antagonists: are shown to be of benefit.
- Monitor patients for Hyperglycaemia + give insulin if required
- Patients without contraindications should receive beta-blockers which should be continued.
- In patients who cannot be offered a PCI within 90 minutes of diagnosis, a THROMBOLYTIC drug with either unfractionated/low molecular weight HEPARIN or FONDAPARINUX.
STEMI long term management
- Dual Antiplatelet therapy: Aspirin + Clopidogrel/Prasugrel/Ticagrelor. If patients are intolerant of Clopidogrel then Aspirin + Warfarin can be given. If patients are intolerant of Aspirin and Clopidogrel, then Warfarin alone can be used.
NOTE: ASPRIN + CLOPIDOGREL/WARFARIN = INCREASED RISK OF BLEEDING.
- Beta-blockers should be given to all patients who are not contraindicated. Diltiazem or Verapamil may be considered if a beta-blocker cannot be used but they are contraindicated in left ventricular dysfunction
- ACE inhibitor or Angiotensin-II receptor antagonist. High dose may be needed to produce benefit.
- Statins: prevent narrowing of blood vessels as they reduce lipid levels. A high dose (80mg) is given
Duration of clopidogrel
- STEMI: 1 month
- NSTEMI: 12 months
- Elective: 1 month
- Bare metal stent: 4 weeks
- Drug-eluting stent: 12+ months
Common side effects of nitrates:
- Postural hypotension
- Throbbing headache
- Tachycardia
- Dizziness
- Flushing
- Dyspepsia
Myocardial Ischaemia – Stable angina treatment
- Patients should be given a B-blocker or a CCB. In those with left-ventricular dysfunction, a B-blocker should be started at a low dose and titrated slowly.
- If the above treatments ALONE FAIL to control symptoms, a combination of a B-blocker and Dihydropyridine CCB can be used (Amlodipine, Felodipine or MR Nifedipine).
- If this combination is not appropriate due to intolerances or contraindications to either drugs then ADDITION of a long-acting nitrate, Ivabradine, Nicorandil or Ranolazine can be considered
- If there are intolerances or contraindications to both drugs, then MONOTHERAPY with a long-acting nitrate can be considered.
Nitrates, CCB’s and Potassium channel activators (Nicorandil) all have a …. effect
- vasodilating and consequently blood pressure effect.
- Vasodilators in heart failure cause
arteriolar vasodilation which reduces vascular resistance + left ventricular pressure during systole, resulting in improved cardiac output.
Ivabradine works by
- lowering the heart rate by acting on the Sinus node. It is licensed to be used for patients with normal sinus rhythm in combination with a beta-blocker or when beta-blockers are contraindicated/not tolerated.
Ranolazine is an
- adjunctive therapy for patients who are inadequately controlled/intolerant of first-line antianginal drugs.
