Acute Coronary Syndromes Flashcards
Greatest specific cause of CVD mortality
CAD
Stable ischemic heart disease definition
Exertional chest pain (or equivalent) that is chronic
May be asymptomatic
Typically seen in the outpatient clinic setting
Pathophysiology of stable ischemic heart disease
Obstructive (collaterals) or non-obstructive coronary artery plaque
Intact fibrous cap
Minimal platelet activation, inflammation
Other conditions: aortic stenosis, HOCM
Angina pectoris
Pain or discomfort in the chest caused by
insufficient blood supply to the heart muscle
Typically brought on by exertion or emotional stress
Typically lasts 1-15minutes
Relieved by rest and nitroglycerin
Populations more likely to have non-classical presentation of angina pectoris
women, elderly, people with diabetes
Diagnostic value of exercise stress ECG depends on the __________________ of having coronary artery disease
pre test probability
Stress nuclear scintigraphy
Nuclear imaging method, areas of blood flow are “hot”, areas of infarct or ischemic tissue will remain “cold”. Pre- and post-stress results may indicate areas that will benefit from myocardial revascularization
Fractional flow reserve
Measure pressure upstream and downstream of blockage- can gauge functional (rather than anatomic) severity of a plaque
Treatments that relieve symptoms of stable ischemic heart disease
Nitrates, calcium channel blockers, beta blockers, re-vascualrization (stent/ angioplasty or CABG)
Treatments that prevent adverse outcomes (MI, stroke, death) of stable ischemic heart disease
Lifestyle measures Aspirin Statins ACE-Is P2Y12 receptor blockers
In stable ischemic heart disease, CABG is superior to medical therapy for two specific types of disease:
- L main disease
- severe three vessel disease with reduced LV function
Unstable ischemic heart disease is also called…
acute coronary syndrome
Unstable ischemic heart disease definition
New or rapidly progressive symptoms
Typically seen in the emergency room setting
Unstable ischemic heart disease pathophysiology
obstructive coronary artery plaque; plaque rupture or erosion; platelet activation, inflammation, thrombus
Why do plaques rupture?
- mechanical factors- shear stress
- inflammation
- exogenous factors ex smoking
- endogenous factors ex catecholamines
Why do coronary arteries thrombose?
- activation of intrinsic clotting (tissue factor)
- platelet activation
- endothelial dysfunction
Platelet activation triggers
catecholamines cigarette smoking collagen tissue factor vWF
Platelet activation feed back
ADP
Serotonin
TXA2
Acute coronary syndrome includes:
- unstable angina
- NSTMEI
- STEMI
Characteristics of unstable angina
- mild or no changes to ECG
- no biochemical evidence of myonecrosis
Characteristics of NSTEMI
- T inversion on ECG
- some biochemical evidence of myonecrosis
Characteristics of STEMI
- ST elevation on ECG
- much biochemical evidence of myonecrosis
Steps in emergency assessment of acute coronary syndrome
Characterize discomfort onset, character, severity
Identify risk factors
Physical Examination – signs of instability
Cardiac Biomarkers (Troponin, CK-MB)
ECG (ST depression or ST elevation)
Rule out other causes of chest pain
TIMI risk score
Used to risk stratify patients presenting with unstable angina/ NSTEMI
- score of 0-2= lower risk, do stress test ECG to gain further info
- score of 3-7= higher risk, do invasive revascularization (cath)
Treatments that relieve symptoms of unstable angina/ NSTEMI
nitroglycerine, morphine
Treatment that prevents adverse events in unstable angina/ NSTEMI
Anti-platelet therapy Anti-thrombin therapy Statins Beta-blockers ACE-Inhibitors Revascularization Lifestyle measures
Antiplatelet therapy agents
aspirin (irreversibly blocks COX1, decreased production of TXA2, less platelet activation)
P2Y12 receptor blockers (irreversibly inhibit receptor on platelet membrane to prevent formation of GpIIbIIIa complex)
GpIIbIIIa inhibitors (directly prevent fibrionogen cross linking)
Anti- thrombin agents
Heparin, direct thrombin inhibitors, Factor Xa inhibitors
Should fibrinolytic therapy be used for unstable angina or NSTEMI?
NO- no benefit since vessel is not fully occluded, only harm from bleeding risk
In what cases should stents/ CABG be used for unstable angina or NSTEMI?
- High risk features (L main or 3 vessel disease with reduced LV function)
Management of STEMI
PROMPT Reperfusion Aspirin P2Y12 Receptor blocker Cardiac Care Unit Care Statin Beta-blocker ACE-Inhibitor Cardiac Rehab
List some problems with thrombolytic therapy
Failure to open infarct artery ~40%
Intracranial hemorrhage 1-2%
Contraindications up to 40%
Lytic outcomes consistently inferior to timely PCI
If fibrinolytic therapy is to be used in a patient with STEMI, what is the time frame for administration?
30 minutes, with rescue PCI if fibrinolytic doesn’t work
What is the ideal/ goal time frame for reperfusion by stent/ angioplasty in STEMI?
90 minutes
List some complications following MI
Ventricular arrhythmias- poor prognosis if more than 48 hours after MI
Post-MI pericarditis
Cardiogenic shock- prognosis is very poor
Congestive heart failure
What region of the heart is most vulnerable to infarct expansion?
antero-apical region- thinnest area of myocardium, greatest curvature, greatest deforming forces, site of thrombus due to stasis, site of rupture
