Myocardial Infarction Flashcards
How would you define an MI?
A myocardial infarction occurs when blood flow to (a part of) the heart stops or decreases
- Cardiac muscle gets damaged
- Often occurs in coronary artery
- Leads to cell death, which will release troponin
What symptoms are associated with an MI?
- Pain
- Sweating, nausea, vomiting
- Breathlessness, weakness, fatigue
- Loss of consciousness
What sort of chest pain characterises an MI?
Tightness, pressure and squeezing. Can also be knife-like, tearing or burning
Pain may radiate to left arm, lower jaw, neck, shoulder
What is Levine’s sign? As seen in an MI?
person localises chest pain by clenching one or both fists over their sternum (historical, but not necessarily accurate)
What percentage of MIs are silent?
22-64%
What are risk factors for getting an MI?
- Old age
- Actively smoking
- High blood pressure
- Diabetes Mellitus
- Total cholesterol, low HDL, high LDL and high triglycerides
Other risk factors include male sex, obesity, alcohol use
What happens if cardiac myocytes are not supplied with sufficient oxygen?
If the impaired blood flow is sustained, an ischemic cascade is triggered:
- Heart cells in the territory of the blocked coronary artery die and do not grow back
- Collagen scar replaces heart tissue
- Apoptosis of affected cells
What are the two types of MIs, as described by their location in the cardiac wall?
Ischemia first affects the subendocardial region, which will begin to die within 15-30 minutes after blood loss
- This is just below the inner surface of the heart
- Most susceptible to damage
- Subendocardial infarction
When the MI persists, a transmural infarction can arise
What are the risks after an MI?
Post-MI, there is myocardial scarring which leads to an alteration in the conduction pathway, putting someone at risk for:
- Arrhythmias
- Heart block
- Aneurysm of the heart ventricles
- Inflammation of heart wall
What is often the cause of an MI?
Atherosclerotic plaques can rupture, leading to the formation of blood clots that block the (coronary) artery
How is an MI diagnosed?
An MI is defined by increased troponin, as well as one of the following:
- Symptoms relating to ischemia
- Changes on ECG
- Changes in the motion of the heart wall
- Demonstration of a thrombus
Blood tests will show elevated troponon I and troponin T
What are patients who experience a STEMI at risk of?
Patients experiencing acute STEMI are at risk for developing life-threatening arrhythmias like ventricular fibrillation which causes sudden cardiac arrest, sometimes referred to as a “massive heart attack”.
How do you treat a STEMI?
CPR and defibrillation
What is characteristic of a NSTEMI?
No elevation of the ST interval - potential depression, as seen on an ECG
Often subendocardial
What is angina?
Angina is a type of chest pain that results from reduced blood flow to the heart
What causes angina to flarre up?
The pain is often triggered by physical activity or emotional stress
What are the symptoms of stable angina?
- shortness of breath
- nausea
- fatigue
- dizziness
- profuse sweating
- anxiety
What are risk factors for stable angina?
Being overweight, history of heart disease, high lipids, hypertension, diabetes, smoking, sedentary lifestyle
WHat is unstable angina?
Unstable angina is chest pain that occurs at rest or with exertion or stress. The pain worsens in frequency and severity. Unstable angina means that blockages in the arteries supplying your heart with blood and oxygen have reached a critical level.
How do you manage unstable angina?
giving nitroglycerin or antiplatelet medication
How would you manage a NSTEMI?
300 mg aspirin
Another anti-platelet: ticagrelor, clopidogrel
Antithrombin therapy with fondaparinux sodium should also be offered
What is the prognosis for an MI?
Without treatment, about a quarter of those affected by MI die within minutes, and about forty percent within the first month
Morbidity and mortality from myocardial infarction has however improved over the years due to earlier and better treatment
What includes secondary prevention of cardiovascular events?
For secondary prevention, patients should be offered treatment with an ACE inhibitor, a beta-blocker, dual antiplatelet therapy, and a statin.
Treatment with aspirin should continue indefinitely
How would you manage a STEMI?
Coronary reperfusion therapy (either primary PCI or fibrinolysis) should be delivered as soon as possible in eligible patients with a STEMI
In addition to aspirin, most patients with a STEMI should be offered a second antiplatelet agent
What dose of ramipril, aspirin, ticagrelor and bisoprolol should be given?
Aspirin: 75mg daily
Ramipril: 2.5 mg daily
Ticagrelor: 60mg daily in combination with aspirin
Bisoprolol: 5-10 mg daily
What are non-pharmaceutical ways to manage acute coronary syndromes?
Revascularisation procedures such as percutaneous coronary intervention (PCI) or coronary artery bypass graft (CABG) are often appropriate, alongside drug treatment, for patients with an ACS
What complications can occur after an acute coronary syndrome?
Arrhythmias
Stroke
Heart failure
What is the HAS-BLED score?
HAS-BLED is a scoring system developed to assess 1-year risk of major bleeding in people taking anticoagulants for atrial fibrillation (AF)
What parameters are used in the HAS-BLED score?
A calculated HAS-BLED score is between 0 and 9 and based on seven parameters with a weighted value of 0-2:
- Hypertension (1)
- Abnormal liver or renal function (2)
- Stroke (1)
- Bleeding (1)
- Labile INR (1)
- Age > 65 (1)
- Drugs or alcohol (1)
At what HAS-BLED score would you consider someone high-risk?
A score of ≥3 indicates “high risk”, but does not necessarily mean that an anticoagulant cannot be given, as some risk factors may be modified
What is the CHA2DS score?
The CHA2DS2-VASc score is a widely used medical tool used to guide physicians on blood thinning treatment to prevent stroke in people with non-valvular atrial fibrillation
Purpose -> risk of stroke
What parameters are used in the CHA2DS score?
CHAD2 score is calculated based on:
- Congestive heart disease (1)
- Hypertension (1)
- Age >75 (2)
- Diabetes Mellitus (1)
- Prior Stroke or TIA (2)
- Vascular disease (1)
- Agre 65-74 (1)
- Female sex
At what CHA2DS score do you start treatment? What treatment is appropriate?
NICE guidelines recommend that if the patient has a CHA2DS2-VASc score of 2 and above:
- oral anticoagulation therapy (OAC) with a vitamin K antagonist (VKA, e.g. warfarin with target INR of 2-3)
- one of the direct oral anticoagulant drugs (DOACs, e.g. dabigatran, rivaroxaban, edoxaban, or apixaban)
is recommended
