Acute Coronary Syndromes Flashcards
What is ACS?
acute myocardial ischemia resulting from an imbalance between myocardial oxygen demand and supply
Spectrum of conditions
silent ischemia
SIHD
UA
NSTEMI
STEMI
Development of ischemia
rupture of atherosclerotic plaque –> platelet adherence, activation, aggregation and activation of the clotting cascade –> fibrin and platelets form clot –> ischemia
Classification
type 1: spontaneous MI - atherosclerotic plaque rupture
type 2: MI secondary to ischemic imbalance - Oxygen supply or demand mismatch to heart (examples: vasospasm, anemia, hypotension)
Epidemiology
Median age at ACS presentation is 68 years
Males are more likely to have ACS: Ratio of males:females is approximately 3:2
For some patients, ACS is the initial presentation of CAD
In the United States, >780000 persons per year will experience an ACS: Approximately 70% of these will have NSTEMI
Risk factors
obesity, smoking, genetics, older age, male, positive FH of CAD, presence of peripheral arterial disease, diabetes, prior MI, renal insufficiency, sedentary lifestyle
Precipitating factors
exertion, emotional stress, cold air/extremes in temperature, recent exercise, diet - large meal, emotions - fright/anger, coitus, smoking, walking against the wind
Signs and symptoms
Retrosternal chest pain: May radiate to shoulder, down the left arm, to the back or to the jaw; Most often at rest
Nausea or vomiting Diaphoresis
Shortness of breath
Atypical symptoms
more likely in:
* Elderly
* Females
* Diabetics
* Impared renal function
* Dementia
Symptoms:
* Epigastric pain
* Indigestion
* Stabbing or pleuritic pain
* Increasing dyspnea in the absence of chest pain
Patients with chest pain and high- risk features such as…
continuing chest pain
severe dyspnea
syncope/presyncope palpitations
Should transported by emergency medical services when available
Delay in care
Patients with STEMI do not seek medical care for approximately 1.5 to 2 hours after symptom onset: Patient delay times are often longer in women, blacks, the elderly, and Medicaid patients Reasons for delay
1. Inappropriate reasoning that symptoms will be self-limited or are not serious
2. Attribute symptoms to other preexisting conditions
3. Fear of embarrassment should symptoms turn out to be a “false alarm”
4. Reluctance to trouble others unless “really sick”
5. Preconceived stereotypes of who is at risk for a heart attack, especially women
6. Lack of knowledge of the importance of rapid action, the benefits of calling EMS or 9-1-1, and the availability of reperfusion therapies
7. Attempted self-treatment with prescription and/or nonprescription medications
Healthcare providers should educate patients to recognize and respond to an acute event!
Diagnosing ACS
All patients with acute chest pain should have an ECG within 10 minutes of arrival at an emergency facility
All patients presenting to the ED with acute chest pain and suspected ACS should have troponin measured as soon as possible after presentation
ECG STEMI
STEMI: Persistent electrocardiographic
(ECG) ST elevation
Q wave changes: Often not present on initial ECG, but develops over hours to days; Electrical ‘hole’- scar tissue cannot conduct electricity; May disappear after early reperfusion if stunned tissue can recover; Often remain permanently
ECG NSTEMI and UA
NSTEMI and UA:
May have normal ECG; ST depression, transient ST-elevation, or new T-wave inversion are possible; Q wave changes unlikely; No ST elevation
Myocardial injury biomarkers
Released from necrotic myocytes (injured heart cells) into bloodstream
Troponin is the gold standard: High sensitivity troponin- PREFERRED - Measured in ng/L; Greater sensitivity and negative predictive values; Shorter time from onset of chest pain to a detectable concentration
Conventional troponin: Measured in ng/mL
What is the difference between sensitivity and specificity?
sensitivity: likelihood of detecting a disease when it exists (true positive rate)
specificity: likelihood of not detecting a disease when it does not exist (true negative rate)
Myocardial injury biomarkers: troponin
Troponin: Highly sensitive results specific for detecting
myocardial injury
Normal value is undetectable: High sensitivity troponin < 14ng/L; Conventional troponin < 0.05ng/mL
Need to check trend: 3 levels over 12 hours; Initial may be negative
troponin may be elevated by other conditions
Myocardial injury biomarkers: CK MB
Creatinine kinase myocardial band (CK MB): No longer used (no benefit); Less sensitive than troponin, and substantially more tissue injury is required for its detection
Stable angina vs unstable angina
Stable angina: Chest pain occurs during physical
exertion - Predictable; Relieved by rest; Lasts a short time (<5 minutes)
Unstable angina: Chest pain may occur at rest, while sleeping, or with little physical exertion; Comes as a surprise; Is more severe and lasts longer than stable angina (may be >30 minutes)
