Acute coronary syndrome: Clinical sciences

Summary

Acute Coronary Syndrome (ACS) is a critical condition involving sudden decreased blood flow to the heart, presenting with chest pain and requiring prompt diagnosis and treatment. The three types of ACS—STEMI, NSTEMI, and unstable angina—differ in their causes and severity. Early assessment includes focused history, physical examination, ECG, and biomarkers like troponin. Initial management (MONA) involves morphine, oxygen, nitrates, and aspirin, followed by statins and beta-blockers. Reperfusion therapy options like PCI or fibrinolytics are essential for STEMI, while NSTEMI and unstable angina require careful risk stratification and angiography. Timely treatment can improve outcomes and reduce mortality.

Takeaways

• 😀 ACS (Acute Coronary Syndrome) is a critical condition that must be ruled out when a patient presents with acute chest pain.
• 😀 The three types of ACS are STEMI (ST-Elevation Myocardial Infarction), NSTEMI (Non-ST-Elevation Myocardial Infarction), and Unstable Angina.
• 😀 STEMI results from complete blockage of a coronary artery, leading to transmural myocardial infarction.
• 😀 NSTEMI is caused by a supply-demand mismatch, leading to a non-transmural, sub-endocardial infarct.
• 😀 Unstable Angina involves myocardial ischemia without infarction and requires urgent intervention.
• 😀 Initial assessment for ACS should include a focused history, physical examination, and a 12-lead ECG within 10 minutes of arrival.
• 😀 ECG findings are crucial; STEMI is confirmed by ST-segment elevation in two contiguous leads, and new LBBB can mask ST-elevation.
• 😀 Mona (Morphine, Oxygen, Nitrates, and Aspirin) is a foundational treatment approach for ACS, along with Statins and Beta-blockers.
• 😀 In STEMI, reperfusion therapy should be initiated within 12 hours, with PCI (Percutaneous Coronary Intervention) as the preferred approach within 90 minutes.
• 😀 NSTEMI diagnosis requires troponin levels to differentiate from Unstable Angina, with elevated troponin indicating myocardial infarction.
• 😀 Fibrinolytics should not be used in NSTEMI or Unstable Angina; only PCI or CABG (Coronary Artery Bypass Grafting) is indicated for high-risk patients.

Q & A

What is Acute Coronary Syndrome (ACS)?

Acute Coronary Syndrome (ACS) refers to a group of conditions caused by a sudden decrease in coronary blood flow, leading to cardiac ischemia. The three main types are STEMI, NSTEMI, and unstable angina.

What are the main types of ACS, and how do they differ?

The three main types of ACS are: STEMI (ST-Elevation Myocardial Infarction), which is caused by complete blockage of a coronary artery leading to a transmural infarct; NSTEMI (Non-ST-Elevation Myocardial Infarction), caused by a supply-demand mismatch resulting in a sub-endocardial infarct; and unstable angina, which causes myocardial ischemia without infarction.

How should a patient presenting with chest pain be initially assessed?

A patient presenting with chest pain should undergo an initial assessment that includes a focused history and physical examination (H&P), along with a 12-lead ECG, which should be obtained within 10 minutes of hospital arrival.

What are common symptoms associated with ischemic chest pain?

Ischemic chest pain often worsens with exertion and is not relieved by rest. It may present as discomfort, pressure, tightness, or a burning sensation, and can radiate to the epigastrium, left shoulder, arm, neck, and lower jaw. Other symptoms include palpitations, dyspnea, diaphoresis, nausea, vomiting, dizziness, and syncope.

What are some key physical examination findings in patients with ACS?

Physical examination findings in ACS can vary. Signs of cardiogenic shock, such as hypotension, tachycardia, diaphoresis, cool extremities, and pale skin, may be present. Other findings include evidence of acute heart failure, such as jugular venous distension, crackles on lung auscultation, new S3 Gallop, new or worsening murmur, orthopnea, and edema.

What initial treatments should be started in patients suspected of having ACS?

The initial treatments for ACS include MONA: Morphine (for pain management), Oxygen (if needed to maintain O2 saturation above 90%), Nitrates (for vasodilation), and Aspirin (325 mg for anti-platelet effects). Additionally, a high-intensity statin like atorvastatin and a beta blocker like metoprolol should be administered.

How is STEMI diagnosed on an ECG?

STEMI is diagnosed when ST segment elevation is observed in two contiguous leads on the ECG. If a left bundle branch block (LBB) is present, it can mask ST elevation, but a new LBB with symptoms consistent with ACS can still be considered a STEMI.

What is the preferred reperfusion therapy for STEMI if it's within 12 hours of symptom onset?

The preferred reperfusion therapy for STEMI, if symptoms began within 12 hours, is percutaneous coronary intervention (PCI), which involves coronary angiography followed by balloon angioplasty and stenting. If PCI is unavailable within 90 minutes, fibrinolytics (e.g., TPA) can be used to break down the clot.

How can NSTEMI and unstable angina be differentiated?

NSTEMI and unstable angina can be differentiated by measuring troponin levels. In NSTEMI, troponin is elevated, indicating myocardial infarction, while in unstable angina, troponin remains normal as ischemia hasn't caused infarction.

What are the management strategies for unstable angina?

For unstable angina, management includes starting dual anti-platelet therapy, anticoagulants, and performing early risk stratification using tools like the TIMI or GRACE score. High-risk patients should undergo angiography within 24 hours, while low-risk patients may undergo non-invasive stress testing.