15. Acute Coronary Syndrome Flashcards
Results from disruption of a plaque with subsequent platelet aggregation and formation of an intracoronary thrombus (Jarzembowski lecture)
Acute Coronary Syndromes
Form of ACS that results depends on
the degree of coronary obstruction and associated ischemia
Following are examples of: – Unstable angina (UA) – Non-ST-Elevation Myocardial Infarction (NSTEMI)
Partially occlusive thrombus:
ST-Elevation Myocardial Infarction (STEMI) is:
• Complete obstruction:
Most important distinction to make is between ACS are:
causes of ST elevation on the ECG (STEMI) and those that do not (UA, NSTEMI)
Severity of symptoms and laboratory findings progress from
UA through NSTEMI to STEMI
Presents as an acceleration of ischemic symptoms – Sudden increase in frequency, duration, and/or intensity of ischemic episodes – Episodes of angina at rest – New onset of angina episodes – Not relieved by usual doses of nitroglycerin
Unstable Angina
Does nitroglycerin help with unstable angina?
NO
Acute Myocardial Infarction 1. Characteristic pain: 2. Sympathetic effect: 3. Parasymp. 4. Inflammatory response
• Severe, persistent, typically substernal • Diaphoresis and Cool and clammy skin *vagal effect ~ Nausea, vomiting, Weakness • Mild fever
Cardiac findings in Acute MI
• S4(and S3if systolic dysfunction present) gallop • Dyskinetic bulge (in anterior wall MI) • Systolic murmur (if mitral regurgitation or VSD)
Where may these findings be present? • Pulmonary rales (if heart failure present) • Jugular venous distention (if heart failure or right ventricular MI)
In acute MI
How do you make diagnosis and distinction among ACS?
– Presenting symptoms – Acute ECG abnormalities – Detection of specific biomarkers of myocardial necrosis
ECG abnormalities in Non-STEMI
ST segment depression and/or T wave inversions • May be transient and correlate with chest pain (UA) or persist (NSTEMI)
Evolution of ECG in STEMI
Initial ST segment elevation, followed over the
course of hours by inversion of the T wave and
Q wave development
Necrosis of myocardial tissue causes
disruption of the sarcolemma and the
release of intracellular molecules into the
bloodstream; we see this rise above threshold in:
NSTEMI and STEMI
Cardiac troponins (cTn) Rise at:
Peak at:
– Assays for cTnI and cTnT detect cardiac
forms and provide a specific measure of
cardiac injury
– Begin to rise at 3-4 h
– Peak 18-36 h
Serum marker: Creatine Kinase (CK)
Rise at:
Peak at:
– CK-MB isozyme localized mainly in the
heart
– Begins to rise at 3-8 h
– Peaks at 24 h
Typical symptoms of unstable angina
Crescendo, rest,
or new-onset
severe angina
When do we see elevated serum biomarkers
in nonSTEMI and STEMI
NOT unstable angina
What do we expect to see on ECG for unstable angina?
ST depression and/or T wave inversion
Prolonged “crushing” chest pain,
more severe and wider radiation
than usual angina
Symptoms for NonSTEMI and STEMI
What do we see on ECG for
nonSTEMI
STEMI
ST depression and/or T wave inversion
ST elevation (and Q waves later)
What are requirements of ACS tx?
Requires rapid initiation of therapy to limit
myocardial damage and minimize complications
• Therapy must:
– Address the intracoronary thrombus
– Provide anti-ischemic measures to restore the oxygen supply/demand balance
What is the difference in approach to tx STEMI compared to UA/NSTEMI?
– Patients with STEMI typically have total coronary
occlusion and benefit from immediate reperfusion
therapies whereas patients with NSTEMI do not
Big list of complications from MI
Recurrent ischemia (angina)
• Arrhythmias
– Ventricular fibrillation, supraventricular arrhythmias,
conduction blocks
• Myocardial dysfunction
– Congestive heart failure, cardiogenic shock
• Mechanical complications
– Papillary muscle rupture, free wall rupture, ventricular
septal rupture, ventricular aneurysm
• Pericarditis
• Thromboembolism
Most important predictor of post-MI outcome is the
Standard post-discharge therapy after STEMI
– Aspirin
– b blocker
– HMG-CoA reductase inhibitor
– ACE inhibitor (if LV dysfunction)
High risk of sudden cardiac death if LV ejection
fraction is _____
< 30%
****Prophylactic implantation of implantable cardiofibrillator
What anti ischemic therapies shoud be used after STEMI/NSTEMI
B-blockers
nitrates
Ca+ channel blockers
