B P5 C39 Non ST Elevation Acute Coronary Syndromes Flashcards
(124 cards)
The pathogenesis of NSTE-ACS involves five processes operating singly or in various combinations:
(1) Disruption of an unstable atheromatous plaque
(2) Erosion of an atheromatous plaque
(3) Coronary arterial vasoconstriction
(4) Gradual intraluminal narrowing of an epicardial coronary artery caused by progressive atherosclerosis or restenosis after percutaneous coronary intervention (PCI)
(5) Oxygen supply-demand mismatch
Three mechanisms may lead to plaque disruption:
Most common mechanism of ACS?
Plaque fissure with inflammation
Plaque fissure without inflammation
Plaque erosion
Plaque rupture - most common
Plaque erosion - 40% of ACS cases
_________________ characteristically have large lipid pools with foam cells and a thin fibrous cap.
Plaques that rupture
The key steps in thrombus formation include _____.
(1) Adhesion of platelets to the arterial wall
(2) Platelet activation
(3) Platelet degranulation and further activation
(4) Parallel expression of tissue factor with activation of the coagulation cascade.
Four observations support the central role of coronary artery thrombosis in the pathogenesis of NSTE-ACS:
(1) Autopsy findings of thrombi in the coronary arteries typically localized to a ruptured or eroded atherosclerotic plaque
(2) Visualization by optical coherence tomography (OCT), invasive coronary arteriography, or coronary computed tomographic angiography (CCTA) of plaque ulceration and/or irregularities in the fibrous cap of atherosclerotic plaque, consistent with plaque rupture and thrombus formation;
(3) Elevation of serum markers of platelet activity, thrombin generation, and fibrin formation;
(4) Improvement in clinical outcome with antiplatelet and anticoagulant therapies.
Vasoconstriction causing dynamic obstruction of coronary arterial flow may result from _________________ or from ________________________
Spasm of epicardial coronary arteries (Prinzmetal’s vasospastic angina)
Constriction of small, intramural muscular coronary arteries (vasoconstrictors released by platelets, from endothelial dysfunction)
Atypical manifestations, such as dyspnea without chest discomfort and pain limited to the epigastrium or indigestion, represent “anginal equivalents.”
These atypical findings are more prevalent in _____ and can lead to under recognition, undertreatment, and worse outcomes
Women
Older adults
Diabetes mellitus (DM)
CKD
Dementia
Characteristics of plaque rupture
Lipid rich
Collagen poor, thin fibrous cap
Interstitial collagen breakdown
Abundant inflammation
Smoot muscle cell apoptosis
Macrophage predominance
Less expression of hyaluronidase-2 and hyaluronan-receptor CD 44
Large number of nonculprit plaques and grater panvascular instability
Male predominance
High level of LDL-C
Characteristic of plaque erosion
Lipid poor
PG and GSG rich
Nonfibrillar collagen breakdown
Few inflammatory cells
Endothelial cell apoptosis
Secondary neutrophil involvement
Profound alteration of hyaluronan metabolism resulting in hyaluronan accumulation
Smaller number of nonculprit plaques and less panvascular instability
Female predominance
High level ot TG
The most common abnormalities on the 12-lead ECG are _______________________, which are more likely to be present while the patient is symptomatic.
ST-segment depression and T wave inversion
If possible, comparison with a recent ECG is important because dynamic ST-segment depression as little as 0.05 mV is a sensitive (but not specific) marker for NSTE-ACS. Deep (>0.2 mV) T wave inversions are compatible with, but not necessarily diagnostic of, NSTE-ACS,
Transient ST-segment elevation lasting less than 20 minutes occurs in up to ______ of patients and suggests either UA or coronary vasospasm.
10%
Transient ST-segment elevation lasting less than 20 minutes occurs in up to 10% of patients and suggests either UA or coronary vasospasm.
__________________ are the biomarkers of choice to identify myocardial injury, thus distinguishing between NSTE-ACS and UA.
Cardiacspecific troponins I (cTnI) and T (cTnT)
Role of noninvasive testing in patients with established or suspected NSTE-ACS
(1) establishing the presence (or absence) of significant CAD
(2) diagnosing CAD as the cause of cTn elevation in patients who may have other explanations (see previous section)
(3) evaluating the extent of residual ischemia after initiation of medical therapy to guide management
(4) localizing the territory of ischemia before revascularization in patients with multivessel disease
(5) assessing left ventricular (LV) function.
The safety of early stress testing in patients with NSTE-ACS has been debated, but symptom-limited or pharmacologic stress testing appears to be safe after ______________ of stabilization without symptoms of active ischemia or other signs of hemodynamic or electrical instability.
at least 24 hours
For most patients, electrocardiographic exercise stress testing is recommended if the ECG at rest _______________________
lacks significant baseline abnormalities (e.g., ST depressions, bundle-branch block, electronic pacing)
If significant baseline ECG abnormalities are present, ________________________ should be performed before and immediately after exercise.
Stress perfusion or echocardiographic imaging
High-risk findings on the stress test:
Severe ischemia as reflected by ST-segment depression ≥0.2 mV before stage 3
Hypotension with exercise, ventricular tachyarrhythmia
New or worsening LV dysfunction
Recommended imaging in the ED in patients with chest discomfort and suspected ACS who are at low risk at presentation
CCTA
CCTA in patients with or suspected of having NSTE-ACS can help to (1) recognize or exclude the presence of epicardial CAD, (2) identify which vessel(s) have obstruction, and (3) assist in risk stratification and prognosis
CCTA in patients with or suspected of having NSTE-ACS can help to _____.
(1) recognize or exclude the presence of epicardial CAD
(2) identify which vessel(s) have obstruction
(3) assist in risk stratification and prognosis
_________can provide precise measurements of ventricular volumes and function, detect and assess ventricular wall edema, identify areas of infarcted versus viable hibernating myocardium, establish the presence of myocardial perfusion, quantify wall motion, and identify myocardium at risk in patients with NSTE-ACS
CMR
Addition of high-resolution late gadolinium enhanced imaging can help provide this information when CMR alone is inconclusive.
Features suggesting thrombus include
Lobular intraluminal masses with a rounded or polypoid shape;“haziness” of a lesion
Approximately ______ of patients with a clinical diagnosis of NSTEACS have significant coronary obstruction
% obstructive disease in multiple epicardial arteries
LM with multivessel disease _____
3VD _____
2VD _____
1VD _____
No obstruction _____
90%
LM with multivessel disease 10%
3VD 35%
2VD 25%
1VD 20%
No obstruction 10%
In the clinical setting, __________ are used most commonly to guide coronary stent placement
IVUS or OCT