Acute coronary syndromes

Resident Survival Guide

Acute Coronary Syndrome Chapters
Heart Attack Patient Information
Unstable Angina Patient Information
Overview
Classification Unstable Angina Non-ST Elevation Myocardial Infarction ST Elevation Myocardial Infarction
Causes
Differential Diagnosis
Treatment
AHA/ACC Guidelines for Acute Coronary Syndrome
Guideline for Risk Stratification in ACS
Guideline for Pre-Hospital Evaluation and Care
Guidelines for Initial Management of ACS
Guidelines for Patients with Atrial Fibrillation Complicating ACS

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Yamuna Kondapally, M.B.B.S[2]; Tarek Nafee, M.D. [3]; Sabawoon Mirwais, M.B.B.S, M.D.[4]

Synonyms and keywords: acute coronary syndrome ST elevation myocardial infarction Non-ST-segment elevation acute coronary syndrome Non-ST-elevation ACS Non-ST-segment elevation ACS unstable angina STEMI UA NSTEMI NSTE-ACS

Overview

Acute coronary syndrome (ACS) refers to a spectrum of conditions resulting from acute myocardial ischemia and/or infarction that is most often due to an abrupt reduction in coronary blood flow. The most common symptom prompting diagnosis of ACS is chest pain, often radiating to the left arm or angle of the jaw, pressure-like in character, and associated with nausea and sweating. ACS should be distinguished from stable angina, which is chest pain that develops during exertion and resolves at rest. Unstable angina is differentiated from NSTEMI by the absence of elevated cardiac biomarkers. The basic pathology in both conditions involves a non-occlusive thrombus formation from a previously disrupted atherosclerotic plaque causing an inadequate blood supply to the heart muscle. Though ACS is usually associated with coronary thrombosis, it can also be associated with other causes such as cocaine use. Cardiac chest pain can also be precipitated by anemia, bradycardias or tachycardias.

Classification

• Traditionally, ACS has been classified into:
  • Unstable angina (UA)
  • Non-ST-segment elevation myocardial infarction (NSTEMI)
  • ST-segment elevation myocardial infarction (STEMI).

• According to this classification, unstable angina was defined as clinical and electrocardiographic (ECG) evidence of myocardial ischemia in the absence of an elevated troponin level.
• However, the widespread use of the high-sensitivity troponin assays made UA and NSTEMI indistinguishable since it was shown that almost all patients previously named UA actually have increased high-sensitivity troponin levels.
• In other words, it is very unlikely that patients with clinical and ECG evidence of myocardial ischemia have normal high-sensitivity troponin levels.
• Consequently, in recent guidelines, the acute coronary syndromes are classified into two broad categories:
  • Non-ST-segment elevation acute coronary syndrome (NSTE-ACS), encompassing :
    • Non-ST-segment elevation myocardial infarction (NSTEMI)
    • Unstable angina
  • ST-segment elevation myocardial infarction (STEMI)

• Therefore, acute coronary syndromes can be classified as follows:

Acute coronary syndromes

Non-ST-elevation acute coronary syndrome (NTE-ACS)

ST elevation myocardial infarction

Unstable angina

Non-ST-segment elevation myocardial infarction

Causes

• ACS is characterized by a sudden imbalance between myocardial oxygen consumption and demand, which is usually the result of coronary artery obstruction.
• The most common causes of coronary artery obstruction are:
  • Atherosclerotic plaque rupture and subsequent coronary thrombus
• Other conditions may also cause an imbalance, including:
  • Excessive myocardial oxygen demand (in the setting of a stable flow-limiting lesion)
  • Coronary artery spasm causing vasospastic (Prinzmetal) angina
  • Coronary embolism
  • Coronary arteritis
  • Noncoronary causes of myocardial oxygen supply-demand mismatch :
    • Hypotension
    • Severe anemia
    • Hypertension
    • Tachycardia
    • Hypertrophic cardiomyopathy
    • Severe aortic stenosis
    • Nonischemic myocardial injury:
      • Myocarditis
      • Cardiac contusion
      • Cardiotoxic drugs
  • Multifactorial causes:
    • Stress cardiomyopathy (Takotsubo cardiomyopathy)
    • Pulmonary embolism
    • Severe heart failure (HF)
    • Sepsis

For a complete list of causes for UA click here, for NSTEMI click here, and for STEMI click here.

Differentiating Acute coronary syndromes from other Diseases

• View the page on diagnosis using the clinical prediction rule for ACS for more detail.
• Acute Coronary Syndrome (ACS) may be differentiated from other diseases as follows:

Organ System	Diseases	Presentation										Diagnostic Tests						Past Medical History						Other Findings
		Chest Pain					GI Symptoms			Pulmonary	Neck
		On Palpation	On inspiration	Radiating to Extremeties	Radiating to Back	With Movement	Nausea or Vomitting	Epigastric Pain	Odynophagia or Dysphagia	Shortness of Breath	Jugular Distention	Cardiac Biomarkers	CBC Findings	ESR	D-Dimer	EKG Findings	CXR Findings	DM	Hyperlipidemia	Obesity	Trauma	Inxn*	Htn
Cardiovascular	Acute Coronary Syndrome			+	+		+	+		+		+				+		+	+	+			+	•Palpitations •Sweating
	Aortic Dissection			+	+					+		-					+		+	-			+	•Pain maximal upon onset •Pain difficult to treat with opiates •Weak pulse in one arm compared to other •Syncope •Symptoms similar to stroke •Smoking
	Brugada Syndrome	No chest pain														+								•Syncope •Cardiac arrest •ST-segment elevation •F/H of sudden cardiac death
	Takotsubo carditis	Sudden onset of chest pain mimicking myocardial infarction					+	+		+		+				+				-				•Extreme emotional or physical stress•syncope •Women>men •ST segment elevation •Left ventricular apical ballooning on echo •Normal coronary arteries
	Pericarditis		+	+	+	•Relieving factor: Sitting up and leaning forward •Aggravating factor: Lying down and breathing deep				+			+	+		+	+				+	+		•Other causes:Malignancy, autoimmune disorders, chest trauma •Pericardial friction rub
Organ System	Diseases	Presentation										Diagnostic Tests						Past Medical History						Other Findings
		Chest Pain					GI Symptoms			Pulmonary	Neck
		On Palpation	On inspiration	Radiating to Extremeties	Radiating to Back	With Movement	Nausea or Vomitting	Epigastric Pain	Odynophagia or Dysphagia	Shortness of Breath	Jugular Distention	Cardiac Biomarkers	CBC Findings	ESR	D-Dimer	EKG Findings	CXR Findings	DM	Hyperlipidemia	Obesity	Trauma	Inxn*	Htn
Pulmonary	Pleuritis (pleurisy)	+	+	+	+	•Aggravating factor: Deep breathing				+			+	+			+				+	+		•Other causesPulmonary embolism, malignancy, autoimmune diseases
	Pulmonary Embolism		+			•Aggravating factors: Deep breathing, coughing, eating, bending and stooping				+					+		+							•Other causes: Immobility, pregnancy, oral contraceptive pills
	Pneumonia		+							+			+	+			+					+		•Complications: Sepsis, ARDS, Lung abscess
Gastrointestinal	GERD							+	+											+				•Other symptoms: Hoarseness, Dry cough at night, Sensation of lump in throat etc
	Esophageal Spasms			+	+	+			+	+							+						+	• Risk factors: Anxiety or depression and drinking wine, very hot or cold foods
	Esophagitis						+	+	+				+	+				+				+		• Causes: Hiatal hernia, infection, medications, radiation therapy
	Gastritis						+	+	+				+	+			+					+		• Causes: H.pylori infection, bile reflux, alcohol use, alcohol use
Organ System	Diseases	Presentation										Diagnostic Tests						Past Medical History						Other Findings
		Chest Pain					GI Symptoms			Pulmonary	Neck
		On Palpation	On inspiration	Radiating to Extremeties	Radiating to Back	With Movement	Nausea or Vomitting	Epigastric Pain	Odynophagia or Dysphagia	Shortness of Breath	Jugular Distention	Cardiac Biomarkers	CBC Findings	ESR	D-Dimer	EKG Findings	CXR Findings	DM	Hyperlipidemia	Obesity	Trauma	Inxn*	Htn
Musculoskeletal	Muscle sprain/Spasm	+	+			+															+			• Causes: Over use, dehydration, electrolyte abnormalities
	Costochondritis	+	+	+	+	+				+			+	+			+				+	+		• Risk factors: Rheumatoid arthritis, ankylosing spondylitis, Reiter's syndrome
	Rib fracture/Trauma	+	+	+	+	+				+			+	+			+				+			• Complications: Pneumothorax, hemothorax, surgical emphysema
Psychiatry	Anxiety (Panic Attack)	Chest tightness					+			+														• Other symptoms: Palpitations, trembling, sweating, choking, light headed, hot or cold flashes.

The following table summarizes the significant history, and diagnostic test findings that will help differentiate the acute coronary syndromes from one another, as well as from other coronary artery diseases:

Acute Coronary Syndromes	History and Symptoms			Pathology		Diagnostic tests		Treatment		Complications	Prognosis
	Chest pain		Duration of Chest pain	Coronary Artery	Plaque	Cardiac Biomarkers (e.g.CK-MB, Troponins)	EKG Findings	Medical Therapy	Reperfusion (e.g. PCI, CABG, or Medical)
	At Rest	Exertion
Unstable Angina	+	+	<30 minutes	Partial occlusion	Erosion or Rupture (39%)	Normal	•Normal EKG findings (some cases) •Flipped or inverted T waves •ST segment depression •Non-specific ST-T changes	+		•Arrhythmias •Congestive heart failure •Hypotension •New mitral regurgitation •MI •Sudden death	•1 year mortality rate is 1.7%
NSTEMI	+	+	>30 minutes	Partial or complete occlusion	Rupture (56%) or Erosion	Elevated	•No EKG findings (some cases) •Flipped or inverted T waves •ST segment depression •Non-specific ST-T changes •New left bundle branch block	+	+	•Arrhythmias •Congestive heart failure •Hypotension •New mitral regurgitation •Ventricular aneurysms •Sudden death	•1 year mortality rate is 24.4% • 30-day mortality rate is about 2%
STEMI	+	+	>30 minutes	Complete occlusion	Rupture (50%-75%) or Erosion	Elevated	•ST elevation in at least 2 contiguous leads in V2-V3 •ST depression in at least two precordial leads V1-V4 •ST depression in several leads plus ST elevation in lead aVR (suggestive of occlusion of the left main or proximal LAD artery)	+	+	•Reinfarction •Arrhythmias •Left ventricular aneurysm •Pseudoaneurysm •rupture of papillary muscle, interventricular septum and LV free wall •Sudden death	•30 day mortality rate is 1.1% in <45 yrs and 20.4% in >75 yrs patients
Other Coronary Artery Diseases
Chronic stable angina	-	+	≤ 5 minutes	Severely narrowed coronary vessels	Stable plaque	Normal	•Normal EKG in 50% of cases •Down sloping, up sloping or horizontal ST-segment depression •T wave inversion	+		•Heart failure	•Estimated annual mortality rate is 0.9%-1.4% •Annual incidence of non-fatal MI between 0.5%-2.6% •1-year mortality rate is 1.3%
Prinzmetal's angina	•Occur at rest (Mid night to early morning) •Not associated with exertion		5-30 minutes	Coronary artery vasospasm	-	Normal	•Transient ST segment elevation	+		•Arrhythmias •MI	•5 year survival is excellent (90%-95%)

Differential Diagnoses of Acute Coronary Syndromes in the Setting of Chest Pain

Cardiac	Pulmonary	Vascular	Gastrointestinal	Orthopedic	Other
Myopericarditis Cardiomyopathiesa	Pulmonary embolism	Aortic dissection	Esophagitis Esophageal spasm	Musculoskeletal disorders	Anxiety disorders
Tachyarrhythmias	(Tension)-Pneumothorax	Symptomatic aortic aneurysm	Peptic ulcer, gastritis	Chest trauma	Herpes zoster
Acute heart failure	Bronchitis, pneumonia	Stroke	Pancreatitis	Muscle injury/inflammation	Anemia
Hypertensive emergencies	Pleuritis		Cholecystitis	Costochondritis
Aortic valve stenosis				Cervical spine pathologies
Tako-Tsubo cardiomyopathy
Coronary spasm
Cardiac trauma
Bold = Common and/or important differential diagnoses aDilated, hypertrophic and restrictive cardiomyopathies may cause angina or chest discomfort

Treatment

• To view the detailed treatment of Unstable angina/NSTEMI click here.
• To view the detailed treatment of STEMI click here.