Acute Coronary Syndromes 1-3

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a characteristic ECG change that indicates STEMI?

Transient ST-segment elevation

Pathological Q wave development (correct)

ST-segment depression

T wave inversion

Which of the following is often observed in NSTEMI?

Transient T wave elevation

Absent Q waves

T wave inversion (correct)

Persistent ST-segment elevation

Which biomarker indicates myocardial cell necrosis/infarction?

Troponin (correct)

Blood glucose

C-reactive protein

White blood cell count

In the diagnosis of ACS, which step is crucial before establishing treatment?

Confirm or rule out ACS secondary to obstructive CAD Signup and view all the answers

What does ST-segment depression typically indicate?

Myocardial ischemia Signup and view all the answers

Which physical symptoms are commonly associated with Acute Coronary Syndromes?

Pain and apprehension Signup and view all the answers

Which of the following is NOT part of risk stratification in ACS diagnosis?

Verification of family history Signup and view all the answers

Which of the following ECG changes is usually transient in Unstable Angina (UA)?

T wave inversion Signup and view all the answers

What is the primary aim of immediate management in acute coronary syndromes?

To relieve ongoing ischaemia and pain Signup and view all the answers

Which of the following is NOT a criterion for diagnosing acute myocardial infarction?

High blood glucose levels Signup and view all the answers

Which medication is recommended as an initial treatment for acute coronary syndromes?

Aspirin 300 mg PO stat Signup and view all the answers

Which component is necessary alongside elevated cardiac troponin values for a diagnosis of acute myocardial infarction?

At least one sign of myocardial ischaemia Signup and view all the answers

What is the role of supplemental oxygen in the immediate management of acute coronary syndromes?

Given only if SaO2 is below a certain level Signup and view all the answers

What is one of the goals in managing acute coronary syndrome to prevent the recurrence of adverse ischaemic events?

Inhibit or prevent ongoing coronary thrombosis Signup and view all the answers

Which type of ECG change is associated with signs of myocardial ischaemia?

ST segment elevation Signup and view all the answers

Which of the following findings indicates the presence of acute myocardial injury?

Cardiac troponin values ≥ 99th percentile of URL Signup and view all the answers

What are the three major clinical subtypes of acute coronary syndromes?

Unstable Angina, NSTEMI, STEMI Signup and view all the answers

What primarily triggers acute coronary syndromes?

Atheromatous plaque disruption Signup and view all the answers

What distinguishes Unstable Angina from NSTEMI?

Presence of myocardial necrosis Signup and view all the answers

Which subtype of acute coronary syndrome results from complete occlusion of an epicardial coronary artery?

STEMI Signup and view all the answers

What characterizes NSTEMI in terms of enzymatic evidence?

Positive evidence of myocardial necrosis Signup and view all the answers

Which sign is NOT typically associated with acute coronary syndromes?

Extreme thirst Signup and view all the answers

What leads to the increased risk of myocardial infarction in Unstable Angina?

Presence of an active prothrombotic surface Signup and view all the answers

What phase follows the phase of ischemia in acute myocardial infarction?

Phase of necrosis Signup and view all the answers

What causes the ST-segment elevation in STEMI on an ECG?

Complete occlusion of the coronary artery Signup and view all the answers

During what time frame does cell necrosis begin after the onset of occlusion in myocardial infarction?

Within 20-40 minutes Signup and view all the answers

In terms of management, what distinguishes NSTEMI management from STEMI management?

NSTEMI may require pharmacological intervention without immediate surgery Signup and view all the answers

What is a major underlying factor contributing to acute coronary syndromes?

Advanced atherosclerotic disease Signup and view all the answers

What is typically seen in patients with STEMI in terms of physiological condition?

Abnormal cardiac rhythms and increased risk of sudden cardiac death Signup and view all the answers

Which of the following is NOT a clinical feature of acute coronary syndromes?

Headache Signup and view all the answers

Which statement about the pathophysiology of myocardial infarction is true?

Cell necrosis can begin within 20-40 minutes of occlusion. Signup and view all the answers

Study Notes

Acute Coronary Syndromes (ACS)

ACS encompass a variety of myocardial ischemic conditions.
All ACS are caused by acute plaque rupture, which ultimately blocks coronary arteries, decreasing blood flow to the heart.
There are three clinical subtypes:
- Unstable Angina (UA)
- Non-ST Segment Elevation Myocardial Infarction (NSTEMI)
- ST-Segment Elevation Myocardial Infarction (STEMI)

Aetiology & Pathogenesis

ACS usually occurs as a complication of advanced atherosclerotic coronary artery disease
Plaque disruption leads to coronary thrombosis, which can partially or completely occlude coronary arteries.
Complete and sustained occlusion of the culprit artery leads to STEMI.
Incomplete and/or transient/intermittent occlusion of the culprit artery leads to UA or NSTEMI.

Clinical Presentation of ACS

UA is characterized by:
- acceleration in frequency or severity of chest pain
- new-onset severe anginal pain
- prolonged anginal chest pain occurring at rest
Pain is due to unstable plaque rupture and incomplete or transient occlusion of an epicardial coronary artery
NSTEMI is marked by:
- unstable plaque rupture and significant partial/intermittent occlusion of an epicardial coronary artery
- positive enzymatic evidence of myocardial cell necrosis
STEMI is marked by:
- unstable plaque rupture and thrombosis leading to a complete occlusion of an epicardial coronary artery
- a sustained period of myocardial ischemia
- transmural myocardial cell necrosis (infarction)
- ischaemia-induced electrical instability, leading to abnormal cardiac rhythms and an increased risk of sudden cardiac death

Acute Myocardial Infarction

Cell necrosis begins 20-40 minutes following occlusion of a coronary artery, with a progressive pattern from subendocardium to the epicardium.
Significant necrosis occurs within 2-3 hours.
The rate of necrosis depends on the residual flow in the coronary artery and the extent of collateral blood flow.
There are two phases:
- Phase of Ischemia (reversible injury)
- Phase of Infarction (irreversible injury)

Diagnosis of ACS

Primary steps:
- Confirm or rule out ACS secondary to obstructive CAD
- Risk stratification (determine patient’s 6-month risk of adverse cardiovascular events)
Diagnostic approach:
- Thorough clinical assessment:
  - Clinical presentation, medical history, physical examination
  - Serial cardiac biomarker changes (serum levels of myoglobin, CK-MB & troponin (I / T), biomarkers of myocardial cell necrosis/infarction.)
  - ECG changes (ST-segment changes, T-wave abnormalities, pathological Q wave development)
- Risk assessment scores (e.g. TIMI, GRACE scores)

Clinical Management of ACS

Aims of immediate management:
- Relieve ongoing ischemia and ischaemic pain
- Prevent potentially fatal outcomes:
  - Prevent and/or inhibit ongoing coronary thrombosis
  - Prevent the recurrence of adverse ischemic events
Immediate management strategies:
- Analgesic and anti-ischaemic therapy
- Aspirin 300 mg PO STAT (if intolerant, clopidogrel)
- Supplemental oxygen (only if SaO2 <90%)
- Morphine (5-10 mg IV) if pain relief is not achieved with aspirin

Management for Unstable Angina & NSTEMI

Management goals:
- relieve and/or prevent chest pain.
- prevent myocardial infarction.
Treatment approaches:
- Antiplatelets
- Nitrates
  - Reduce preload and myocardial oxygen demand
  - Dilate coronary arteries
- Beta blockers
  - Reduce myocardial oxygen demand
  - Reduce heart rate and blood pressure
- ACE inhibitors
  - Reduce risk of ischemia, heart failure, and death.
- Statins
  - Reduce levels of LDL (and triglycerides)
  - Increase HDL levels
- Oxygen
- Intravenous heparin
  - Prevent thrombus formation
  - May be given as a bolus or continuous infusion
  - If patient is at a high risk of bleeding then a lower dose (e.g., unfractionated heparin 5000 IU IV bolus followed by a 1000-1500 IU/h infusion) may be given instead.
- Glycoprotein IIb/IIIa inhibitors (e.g., abciximab, eptifibatide, tirofiban)
  - Reduce platelet activation
  - Used in high risk patients
- Coronary artery bypass surgery
- Percutaneous coronary intervention
  - Used to open blocked coronary arteries
  - Involves inserting a balloon catheter into the blocked coronary artery and inflating the balloon to open it.
- Emergency cardiac care

Management for STEMI

Treatment aims:
- Reopen the blocked coronary artery as quickly as possible to restore blood flow to the heart.
- Prevent further damage to the heart.
Treatment approaches:
- Primary percutaneous coronary intervention (PCI) is the preferred treatment strategy
  - Aims to quickly open the blocked coronary artery.
  - A catheter with a balloon at the end is inserted into the blocked coronary artery.
  - The balloon is inflated to open the blockage, and a stent may be placed in the artery to help keep it open.
- If PCI isn't available within 90 minutes of arrival, a thrombolytic therapy can be given:
  - These medications break up the blood clot that is blocking the coronary artery.
- Aspirin given by mouth (300 mg chewable)
- Oxygen
- Beta blockers, if hemodynamically stable
- Nitrates, if hemodynamically stable
- ACE inhibitors, if hemodynamically stable
- Statins, to help prevent further heart damage
- Heparin
- Glycoprotein IIb/IIIa inhibitors
- Reperfusion therapies (coronary angioplasty/stenting, coronary artery bypass surgery)
- Emergency cardiac care

Risk Stratification of ACS

Goal: identify patients who are at an increased risk of short-term (e.g., 6 months) adverse cardiovascular events.
Factors that contribute to risk stratification:
- Age
- Gender
- History of heart disease
- Diabetes
- Hypertension
- Hyperlipidemia
- Smoking
- Obesity
- Family history
- ECG changes
- Biomarker levels (e.g., troponins and CK-MB)

Clinical Outcomes

Treatment outcomes:
- Improved survival rates
- Reduced incidence of heart attacks
- Reduced likelihood of future cardiovascular events.

Pharmacology of Drugs Used in ACS

Aspirin:
- Anti-platelet agent
- Irreversibly inhibits cyclooxygenase (COX-1) in platelets, preventing production of Thromboxane A2 (TXA2), a potent platelet aggregator.
Clopidogrel:
- Anti-platelet agent
- Irreversible inhibitor of ADP receptors on platelets, inhibiting platelet aggregation.
Nitroglycerin:
- Vasodilator
- Reduces preload and myocardial oxygen demand; dilates coronary arteries.
β-blockers:
- Reduce myocardial oxygen demand by lowering heart rate and blood pressure.
ACE inhibitors:
- Inhibit the conversion of angiotensin I to angiotensin II.
- Lower blood pressure
- Reduce afterload.
Statins:
- Reduce LDL cholesterol levels and increase HDL cholesterol levels
Heparin:
- Anti-coagulant
- Binds to antithrombin III, increasing its activity and inhibiting coagulation factors.
Glycoprotein IIb/IIIa inhibitors:
- Anti-platelet agents.
- Bind to the glycoprotein IIb/IIIa receptor on platelets, inhibiting platelet aggregation.
Thrombolytic Agents:
- Break down blood clots within a blocked coronary artery.
- Examples include Alteplase (tPA), Streptokinase, and Tenecteplase.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on Acute Coronary Syndromes (ACS) including its clinical subtypes, aetiology, pathogenesis, and clinical presentation. This quiz covers essential information about unstable angina, NSTEMI, and STEMI, which are crucial for understanding myocardial ischemic conditions.