Myocardial Infarction Flashcards
Epidemiology of Myocardial Infarction
More common in older patients
* Approximately 60%–65% of MIs occur in patients > 65 years of age.
* Approximately 33% of MIs occur in patients > 75 years of age.
* 80% of all MI-related deaths occur in patients > 65 years of age.
* Men > women
Risk Factors of Myocardial Infarction
- Hypertension
- Hyperlipidemia
- Smoking
- Age
- Family history of premature coronary heart disease (CHD)
Family history of premature coronary heart disease (CHD), is defined as:
- A 1st-degree male relative < 45 years of age
- A 1st-degree female relative < 55 years of age
elderly individuals are more likely to have these features of CAD/MI:
- Have STEMI than NSTEMI
- Have a silent or unrecognized MI
- Present with atypical symptoms (e.g., weakness, confusion, syncope)
- Have higher in-hospital mortality
- Have heart failure associated with an MI
Patient Presentation with an MI
Crushing, substernal chest pain (exertional/non-exertional)
Radiation to jaw, shoulders or one/both arms
Associated Symptoms of an MI:
Nausea
Emesis
Diaphoresis
SOB
Lightheadedness, sudden dizziness
Fatigue
Heartburn/indigestion
DDx of chest pain By Organ System
Skin: Herpes Zoster
Breast: Fibroadenomas, Mastitis, Gynecomastia
MSK: costochondritis, precordial catch syndrome, pectoral muscle strain,
rib fx, cervical or thoracic spondylosis (C4-T6), myositis
Esophageal: spasm, rupture, GERD, esophagitis, neoplasm
GI: PUD, gallbladder dz, liver abscess, subdiaphragmatic abscess,
pancreatitis
Pulmonary causes of chest pain
- Pleural effusion
- Pneumonia
- Neoplasm
- Viral infections
- Pneumothorax
- PE
Cardiac causes of chest pain
- ACS
- Aortic
Dissection - Pericarditis
- Myocarditis
- Stable Angina
- Severe AS
- Severe HCM
Stable plaque features
- Thick fibrous cap
- Narrowing of an artery → inability to meet oxygen demand with ↑ exertion
- May lead to stable angina (symptoms only with exertion)
Unstable plaque
- Thin fibrous cap
- Massive inflammatory cell infiltrate
- ↑ Activity of metalloproteinase enzymes –> weakens the fibrous cap
- ↑ Lipid content
- Angiogenesis
- Rupture of unstable plaque in a coronary artery → thrombosis
Partial occlusion of the coronary artery
- → affects the inner myocardium (subendocardium) → may cause:
- NSTEMI
- Unstable angina
- if the ischemia does not result in cell death it is injury
if the ischemia does not result in cell death it is ____
injury
Myocardial Ischemia
supply/demand mismatch
Can occur in the setting of:
* increased myocardial tissue mass
(hypertrophy)
* increased workload on the
myocardium(tachycardia, exercise)
* increased tissue “stress” (cardiac
dilatation)
Complete occlusion → transmural infarction →
STEMI
Myocardial Injury:
elevation of at least one troponin (>99th percentile), with or without, ischemic symptoms
Myocardial Injury on EKG
Myocardial Infarction on EKG
Cell death (aka necrosis)
caused by ischemia.
Myocardial Ischemia on EKG
Acute Coronary Syndrome
Group of clinical symptoms compatible with acute myocardial ischemia and includes unstable angina (UA), non-ST-segment
elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI)
New left bundle branch block (LBBB) PLUS symptoms → ______
STEMI until proven otherwise
Time course for Serum markers in acute MI: What is the onset, peak and duration of Troponin, CK, LDH and Myoglobin?
ACS Management Strategies: Outpatient clinic
- If clinical suspicion for ACS –> quickly obtain
history, EKG*à transfer by EMS to ED - There is no validated decision tool to
safely rule out ACS in outpatient setting
ACS Management Strategies: With EMS
- En route to hospital, pt should be placed on
cardiac monitoring, receive 162 to 325 mg of
ASA, supplemental O2 if SpO2 < 90%,
sublingual NTG 0.4 mg q5 mins for chest pain
