Coronary Artery Disease Flashcards
What is stable angina, and how does it develop?
Stable angina results from fixed atherosclerotic plaques in coronary arteries causing a mismatch between oxygen supply and demand during exertion, where oxygen demand exceeds supply. This is caused by a gradual narrowing of heart blood vessels by atherosclerosis and becomes symptomatic after about 75% stenosis.
What are the major and minor risk factors for coronary artery disease (CAD)?
Most common:
- Hypertension
Most severe:
- Diabetes
Other Major Risk Factors:
- Smoking
- Hyperlipidemia
- Family history of premature of CAD, age (>45 men, >55 women)
- Family history of MI in (men <55 and <65 in females)
Other Minor Risk Factors:
- Low HDL
- Obesity
- Sedentary lifestyle
- Stress
- Alcohol excess
- ESRD
- HIV
- mediastinal radiation
What is the number one modifiable risk factor for CAD?
Smoking. Smoking cessation results in the greatest immediate improvement in a patient for CAD. Within one year after stopping smoking the risk of CAD decreases by 50% and within two years after stopping smoking the risk is reduced by 90%. This means that of all risk factors for CAD, including diabetes mellitus, hypertension, hyperlipidemia, and weight loss management, smoking is the number one modifiable risk factor in patients with CAD.
What is the role of HDL and LDL in CAD risk?
High LDL increases plaque formation; low HDL reduces reverse cholesterol transport and worsens CAD risk.
How does diabetes mellitus impact CAD risk?
DM accelerates atherosclerosis and is considered a CAD equivalent; tight glycemic control reduces risk. This is the most severe risk factor.
What prognostic factors are associated with worse outcomes in CAD?
- Left ventricular EF <50%.
- Left main or multi-vessel disease.
- Higher Killip classes at presentation (e.g., heart failure, cardiogenic shock) are directly linked to increased short-term mortality.
- Extent of ischemia on stress testing: The larger the area of ischemia, the worse the prognosis.
- Age: Older age is a risk amplifier due to cumulative atherosclerotic burden and comorbidities but is less predictive than EF and Killip class.
What factors predict mortality in ACS patients?
- Older age.
- Higher Killip class.
- Reduced EF.
- Extent of myocardial damage on imaging.
What are the typical symptoms of stable angina pectoris?
Substernal pressure or tightness lasting 1-5 minutes, worsened by exertion or stress, and relieved by rest or nitroglycerin.
How does exertion trigger angina symptoms?
Exertion increases myocardial oxygen demand, unmasking ischemia due to fixed coronary stenosis.
What is the significance of angina that improves with rest or nitroglycerin?
Relief with rest or nitroglycerin suggests ischemia and helps differentiate from non-cardiac causes.
What are the key steps in clinically managing patients with CAD presenting with chest pain?
Patients with suspected ACS should be given aspirin 325 mg (if not already administered) and can be given sublingual nitroglycerin if experiencing active chest pain. Further evaluation should consist of troponin I levels and, in the setting of ongoing chest pain, serial ECGs approximately every 30 minutes. The general recommendation is the collection of at least 2 troponin levels 3 hours apart, keeping in mind that levels may require up to 6-12 hours from the onset of symptoms to become detectable. Patients with significantly elevated troponin levels are diagnosed with non-ST elevation myocardial infarction, and those with negative troponin levels but ongoing chest pain and/or evolving ischemic ECG changes may be diagnosed with unstable angina. Patients with negative troponin levels and no other clinical suggestion of ACS can be discharged with a diagnosis of noncardiac chest pain or undergo stress testing for further evaluation.
What features help differentiate ischemic chest pain from other causes like musculoskeletal pain?
Ischemic pain is poorly localized, non-reproducible by palpation, and not positional or pleuritic.
What are the indications for performing a stress test in suspected CAD?
Stress testing is used to confirm CAD diagnosis, assess severity, and evaluate therapy response or risk stratification. Pretest probability may help guide management, particularly for the patients with nonspecific or no changes on ECG in an at risk age category, and with or without risk factors.
What would preclude a patient from being able to perform an ECG Stress Test?
Patients who have baseline ECG abnormalities such as left bundle branch block, pre-existing ST segment changes, or left ventricular hypertrophy. Stress testing is only performed on those who can actually perform the test and without ECG findings at presentation. Exercise stress ECGs has the highest sensitivity for those who are able to exercise and have a normal ECG at baseline, thus is the initial test for normal baseline ECG.
How is an exercise stress ECG performed, and what findings indicate ischemia?
Patients are stressed with exercise to increase their heart rate to 85% of maximum predicted for their age where the maximum heart rate is calculated by subtracting age from 220.
What would indicate a positive stress test?
ST-segment changes; >1 mm depression indicates ischemia.
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Sudden onset of heart failure.
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ventricular arrhythmia.
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Hypotension.
What are the advantages of stress echocardiography over an exercise ECG?
Stress echo detects wall motion abnormalities and is preferred in patients with baseline ECG changes.
What is the gold-standard test for diagnosing CAD, and when is it indicated?
Coronary angiography is indicated in patients with high-risk stress test results, refractory angina, or acute STEMI.
