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: Mitra Chitsazan, M.D.[2] Yamuna Kondapally, M.B.B.S[3]; Tarek Nafee, M.D. [4]; Sabawoon Mirwais, M.B.B.S, M.D.[5]

Synonyms and keywords: acute coronary syndrome, acute coronary syndromes, ST-elevation myocardial infarction, Non-ST-segment elevation acute coronary syndrome, 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. Traditionally, ACS has been classified into non-ST-elevation myocardial infarction (NSTEMI), ST-elevation MI (STEMI), and unstable angina. 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

Defining Lesion Severity. 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization. (Please do not edit).

Angiography to Define Anatomy and Assess Lesion Severity

The standard procedure for defining coronary anatomy and assessing the degree of coronary artery stenosis is still coronary angiography.

• Severe Stenosis: diameter stenosis severity of 70% for non-left main disease and 50% for left main illness .
• A diameter stenosis severity of 40% to 69% is referred to as an angiographically intermediate coronary stenosis, and it usually necessitates further examination to determine its physiological significance .
• Longer lesions may cause more ischemia than a single severe lesion .

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.
• To view the detailed differential diagnosis of chest pain click here.

• 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%)

SYNTAX Score to Calculate the Complexity of Coronary Artery Lesions. 2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization. (Please do not edit.)

Class IIb

" 1. In patients with multivessel CAD, an assessment of CAD complexity, such as the SYNTAX score, may be useful to guide revascularization (Level of Evidence B-R)".

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.

2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization. Recommendations to prefer PCI or CABG (Please do not edit)

Patients With Complex Disease

Class I

"1. In patients who require revascularization for significant left main CAD with high complexity CAD, it is recommended to choose CABG over PCI to improve survival (Level of Evidence: A) "

Class IIa

" 2. In patients who require revascularization for multivessel CAD with complex or diffuse CAD (eg, SYNTAX score >33), it is reasonable to choose CABG over PCI to confer a survival advantage (Level of Evidence B-R)".

Patients with Diabetes

Class I

"1. In patients with diabetes and multivessel CAD with the involvement of the LAD, who are appropriate candidates for CABG, CABG (with a LIMA to the LAD) is recommended in preference to PCI to reduce mortality and repeat revascularizations(Level of Evidence: A) "

Class IIa

" 2. In patients with diabetes who have multivessel CAD amenable to PCI and an indication for revascularization and are poor candidates for surgery, PCI can be useful to reduce long-term ischemic outcomes (Level of Evidence B-NR)".

Class IIb

" 3. In patients with diabetes who have left main stenosis and low- or intermediate-complexity CAD in the rest of the coronary anatomy, PCI may be considered an alternative to CABG to reduce major adverse cardiovascular out-comes. (Level of Evidence B-R)".

Patients With Previous CABG

Class IIa

" 1. In patients with previous CABG with a patent LIMA to the LAD who need repeat revascularization, if PCI is feasible, it is reasonable to choose PCI over CABG (Level of Evidence B-NR)".

'' 2. In patients with previous CABG and refractory angina on GDMT that is attributable to LAD disease, it is reasonable to choose CABG over PCI when an internal mammary artery (IMA) can be used as a conduit to the LAD (Level of Evidence C-LD)

Class IIb

" 3. In patients with previous CABG and complex CAD, it may be reasonable to choose CABG over PCI when an IMA can be used as a conduit to the LAD (Level of Evidence B-NR)".

Dual antiplatelet therapy (DAPT)

Class IIa

" 1. In patients with multivessel CAD amenable to treatment with either PCI or CABG who are unable to access, tolerate, or adhere to DAPT for the appropriate duration of treatment, CABG is reasonable in preference to PCI(Level of evidence B-NR)".

Revascularization in Pregnant Patients

Class IIa

" 1. In pregnant patients with STEMI not caused by spontaneous coronary artery dissection (SCAD), it is reasonable to perform primary PCI as the preferred revascularization strategy. (Level of Evidence C-LD)".

'' 2. In pregnant patients with NSTE-ACS, an invasive strategy is reasonable if medical therapy is ineffective for the management of life-threatening complications (Level of Evidence C-LD)

Revascularization in Older Patients

Class I

"1. In older adults, as in all patients, the treatment strategy for CAD should be based on an individual patient’s preferences, cognitive function, and life expectancy(Level of Evidence: B-NR) "

Revascularization in Patients With Chronic Kidney Disease

Class I

"1. In patients with CKD undergoing contrast media injection for coronary angiography, measures should be taken to minimize the risk of contrast-induced acute kidney injury(Level of Evidence: C-LD) "

''2. In patients with STEMI and CKD, coronary angiography and revascularization are recommended, with adequate measures to reduce the risk of AKI.(Level of evidence C-EO )''

Class IIa

" 3. In high-risk patients with NSTE-ACS and CKD, it is reasonable to perform coronary angiography and revascularization, with adequate measures to reduce the risk of AKI (Level of Evidence B-NR)".

" 4. In low-risk patients with NSTE-ACS and CKD, it is reasonable to weigh the risk of coronary angiography and revascularization against the potential benefit(Level of Evidence C-EO)''

Class III (No Benefit)

"5. In asymptomatic patients with stable CAD and CKD, routine angiography and revascularization are not recommended if there is no compelling indication. (Level of Evidence:B-R) "

Revascularization in Patients Before Noncardiac Surgery

Class III (No Benefit)

"1. In patients with non–left main or noncomplex CAD who is undergoing noncardiac surgery, routine coronary revascularization is not recommended solely to reduce perioperative cardiovascular events. (Level of Evidence:B-R) "

Revascularization in Patients to Reduce Ventricular Arrhythmias

Class I

"1. In patients with ventricular fibrillation, polymorphic ventricular tachycardia (VT), or cardiac arrest, revascularization of significant CAD is recommended to improve survival. (Level of Evidence: B-NR) "

Class III (No Benefit)

"2. In patients with CAD and suspected scar-mediated sustained monomorphic VT, revascularization is not recommended for the sole purpose of preventing recurrent VT. (Level of Evidence:C-LD) "

Revascularization in Patients With Spontaneous coronary artery dissection (SCAD)

Class IIb

" 1. In patients with SCAD who have hemody-namic instability or ongoing ischemia despite conservative therapy, revascularization may be considered if feasible (Level of Evidence C-LD)".

Class III (Harm)

"2. Routine revascularization for SCAD should not be performed (Level of Evidence:C-LD) "

Revascularization in Patients With Cardiac Allografts

Class IIa

" 1. In patients with cardiac allograft vasculopathy and severe, proximal, discrete coronary lesions, revascularization with PCI is reasonable (Level of Evidence C-LD)".

2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization (Please do not edit). RECOMMENDATIONS FOR ADDRESSING PSYCHOSOCIAL FACTORS AND LIFESTYLE CHANGES AFTER REVASCULARIZATION

Cardiac Rehabilitation and Education

Class I

"1. In patients who have undergone revascularization, a comprehensive cardiac rehabilitation program (home-based or center-based) should be prescribed either before hospital discharge or during the first outpatient visit to reduce deaths and hospital readmissions and improve quality of life (Level of Evidence: A) "

''2. Patients who have undergone revascularization should be educated about CVD risk factors and their modification to reduce cardiovascular events. (Level of evidence C-LD)''

Smoking Cessation in Patients After Revascularization

Class I

"1. In patients who use tobacco and have undergone coronary revascularization, a combination of behavioral interventions plus pharmacotherapy is recommended to maximize cessation and reduce adverse cardiac events (Level of Evidence: A) "

''2. In patients who use tobacco and have under-gone coronary revascularization, smoking cessation interventions are recommended during hospitalization and should include supportive follow-up for at least 1 month after discharge to facilitate tobacco cessation and reduce morbidity and mortality (Level of evidence A)''

Psychological Interventions in Patients After Revascularization

Class I

"1. In patients who have undergone coronary revascularization who have symptoms of depression, anxiety, or stress, treatment with cognitive behavioral therapy, psychological counseling, and/or pharmacological interventions is beneficial to improve quality of life and cardiac outcomes (Level of Evidence: B-R) "

Class IIb

" 2. In patients who have undergone coronary revascularization, it may be reasonable to screen for depression and refer or treat when it is indicated to improve quality of life and recovery. (Level of Evidence C-LD)".

2021 ACC/AHA/SCAI Guideline for Coronary Artery Revascularization (Please do not edit). Revascularization Outcomes

Assessment of Outcomes in Patients After Revascularization

Class I

"1. With the goal of improving patient outcomes, it is recommended that cardiac surgery and PCI programs participate in state, regional, or national clinical data registries and receive periodic reports of their risk-adjusted out-comes as a quality assessment and improvement strategy (Level of Evidence: B-NR) "

Class IIa

" 1. With the goal of improving patient outcomes, it is reasonable for cardiac surgery and PCI programs to have a quality improvement program that routinely 1) reviews institutional quality programs and outcomes 2) reviews individual operator outcomes 3) provides peer review of difficult or complicated cases 4) performs random case reviews (Level of Evidence C-LD)".

Class IIb

" 3. Smaller volume cardiac surgery and PCI programs may consider affiliating with a high-volume center to improve patient care. (Level of Evidence C-EO)".