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 is the most common underlying cause for coronary artery disease?
Atherosclerosis
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Put in context, Diabetes > smoking > HTN, are the most acceleratory (i.e., worst) risk factors for atherosclerosis. Patients with diabetes are managed as a cardiovascular disease equivalent.
What are the major and minor risk factors for coronary artery disease (CAD) collectively?
Most common:
- Atherosclerosis
Most severe:
- Diabetes
Other Major Risk Factors:
- Smoking
- Hypertension
- Hyperlipidemia
- Family history of premature of CAD (<45 men and <55 women)
- Family history of MI (men <55 and <65 in females)
Other Minor Risk Factors:
- Low HDL
- Obesity
- Sedentary lifestyle
- Stress
- Alcohol excess
- ESRD
- HIV
- mediastinal radiation
A 55-year-old woman comes to the office due to exertional dyspnea for 3 months. The patient has had no chest pain. Medical history is significant for hypertension and chronic kidney disease. Medications include furosemide, amlodipine, and lisinopril. The patient has never smoked cigarettes. Temperature is 37 C (98.6 F), blood pressure is 128/80 mm Hg, and pulse is 80/min. Oxygen saturation is 98% on room air. BMI is 27. There is no jugular venous distension. Cardiopulmonary examination is normal. Trace bilateral pedal edema is present. Laboratory studies are as follow:
Hemoglobin 10.8 g/dL, Blood urea nitrogen 38 mg/dL, Serum creatinine 2.2 mg/dL, Estimated glomerular filtration rate 28 mL/min/1.73. ECG is unremarkable. Chest x-ray reveals clear lung fields. Which of the following is the most appropriate next step in management of this patient?
Patients with chronic kidney disease (CKD) are at increased risk of coronary artery disease (CAD) and cardiovascular events. Physicians should have a low threshold for pursuing cardiac stress testing (eg, stress echocardiography) in CKD patients with atypical CAD symptoms (eg, exertional dyspnea). Chronic kidney disease (CKD) independently increases the risk for coronary artery disease (CAD) and cardiovascular events. This association may be due to altered calcium balance (eg, secondary hyperparathyroidism) leading to arterial calcium deposition and accelerated atherosclerosis, loss of protein in the urine facilitating an unfavorable lipid profile (ie, high LDL/HDL ratio), or increased systemic inflammation contributing to accelerated atherosclerosis and instability of atherosclerotic plaques. Although symptomatic CAD usually presents with typical symptoms (ie, anginal chest pain), patients with CKD, particularly women, are more likely to have atypical symptoms (eg, anginal equivalents such as dyspnea or nausea). Therefore, high suspicion should exist for stable angina in this patient with several months of exertional dyspnea (a possible “anginal equivalent” in the setting of CKD and other risk factors for CAD (eg, hypertension). Cardiac stress testing in the form of stress echocardiography or treadmill stress testing is most appropriate.
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?
Diabetes accelerates atherosclerosis and is considered a CAD equivalent for the justifiable rationale of being the most severe risk factor for the development of CAD. Diabetes works as a synergistic component with considering other risk factors. When considering concomitant conditions such as hypertension (which is a stand alone risk factor for CAD), the need for blood pressure control amplifies in importance. Thus patients with diabetes should keep their blood pressure below 140/90 mmHg. Diabetics with nephropathy (proteinuria ≥500 mg/day) have a recommended blood pressure of <130/80 mmHg .
In diabetic patients, does tight glycemic control reduce the risk for developing coronary heart disease or stroke?
No. Tight glycemic control does mitigate this risk of developing microvascular disease (retinopathy, nephropathy, and neuropathy), however, does not lower the risk of macrovascular disease (stroke or coronary heart disease).
What makes diabetes the most significant risk factor in terms of CAD?
The risk of mortality is equivalent to patients with established coronary heart disease and prior MI.
How does smoking mitigate the development of coronary heart disease?
Smoking is an important modifiable CHD risk factor. Most studies have shown that the most significant increase in CHD risk is in patients smoking ≥1 packs daily. The risk of cardiovascular events declines rapidly after smoking cessation and approaches that of nonsmokers in 2-3 years.
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.
A 62-year-old man presents to the emergency department for evaluation of chest pain. The patient reports that he was lifting heavy boxes at work when he suddenly became nauseous, and sweaty, and developed substernal chest discomfort radiating down his left arm. The patient states that the pain has been persistent. Past medical history includes hypertension, hyperlipidemia, diabetes, and a 10-pack year smoking history. Temperature is 37°C (98.6°F), blood pressure is 100/71 mmHg, pulse is 89/min, respiratory rate is 14/min, and oxygen saturation is 99% on room air. The patient appears clammy and pale. Physical examination is otherwise unremarkable. Defibrillator pads are placed, and IV access is established. Initial laboratory results and electrocardiogram are shown below. A platelet P2Y 12 receptor blocker is administered. Laboratory values: Hemoglobin 13 g/dL, White blood cell count (WBC) 16,000/mm^3
and Troponin 120 ng/mL. What is next best step in management?
This patient has low blood pressure, therefore administration of nitroglycerin may worsen his clinical condition. Administration of aspirin and heparin is a more appropriate therapy. All patients with NSTEMI should receive aspirin, heparin, and a platelet P2Y12 receptor blocker unless there are contraindications, as well as cardiac catheterization for definitive management with revascularization. This patient presents with features of acute coronary syndrome (ACS). He has evidence of ischemic changes on his electrocardiogram (anterolateral ST-depressions) and an elevated troponin level, confirming a non-ST elevation myocardial infarction (NSTEMI). The next best step in management is administration of aspirin and heparin, in addition to a platelet P2Y12 receptor blocker and cardiac catheterization with revascularization if needed. Coronary artery disease (CAD), is caused by atherosclerosis of the coronary arteries, which occurs when plaque builds up in the vessels, eventually narrowing the lumen, and causing a mismatch between oxygen supply and demand of the heart. Over time, reduced oxygen supply can lead to myocardial ischemia or infarction. The acute management for all patients with suspected ACS involves assessment of stability including airway, breathing, and circulation. Patients should be placed on continuous cardiac telemetry, be given supplemental oxygen, and have cardiac defibrillator pads placed in the event the patient develops a shockable arrhythmia. All patients that have evidence of STEMI, NSTEMI, or unstable angina should receive aspirin therapy if there are no contraindications (e.g. recent gastrointestinal bleed), as early administration has been shown to decrease mortality. In addition, patients with NSTEMI should be given heparin, additional antiplatelet therapy, as well as cardiac catheterization with revascularization if needed.
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.
How is a stress echo performed?
An echo is done before and after exercise.
What would be the indication of ischemia with a stress echocardiography?
Wall motion abnormalities (akinesia or dyskinesia or hypokinesia).
What pharmacological agent is typically paired with a stress ECHO?
Dobutamine. This increases myocardial oxygen demand by increasing heart rate, blood pressure, and cardiac contractility.
What are the common side effects associated with dobutamine during a stress test?
Tachycardia, hypertension, and arrhythmias.
When is a stress ECHO contraindicated?
When a patient has a history of tachyarrhythmia.
What is the role of nuclear stress testing in CAD diagnosis?
Nuclear stress testing uses radiotracers (Tc-99/SPECT or Rb-82/PET) to identify perfusion deficits and assess myocardial viability. Decreased uptake of the nuclear isotope during exercise that will improve with rest (indication of ischemia). Stable defects, where the perfusion is poor throughout the study, indicates an old scar tissue.
Which pharmacologic agent would you use for a patient unable to perform physical exercise?
Dobutamine adenosine, Regadenoson, or dypyridamole. These agents are given with either an ECHO or nuclear perfusion study.
Pharmacologic agents (adenosine, Regadenoson, or dypyridamols) can’t be used under what circumstance?
restrictive heart diseases.
What is the primary purpose of a pharmacologic stress test?
To evaluate coronary artery disease by simulating the effects of exercise on the heart when a patient is unable to exercise and complete a physical stress test.
True or False: Dobutamine is a vasodilator used in pharmacologic stress tests.
False. Dobutamine is a synthetic catecholamine that increases heart rate and contractility.
Fill in the blank: Dypyridamole is primarily used in pharmacologic stress tests as a __________.
vasodilator, same as adenosine. Since diseased coronary arteries are already maximally dilating at rest to increase blood flow, they receive a relatively less blood flow when the entire coronary system is pharmacologically vasodilated.
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.
What does a negative stress test indicate?
Stress testing can aid in the initial diagnosis of CAD as well as provide prognostic information in patients with known or highly suspected CAD. A positive stress test is resulted when patients have high-risk ECG features during the evaluation, for example >1 mm ST depression, ST elevation without Q waves. These results during the stress test likely have clinically significant CAD and a high short-term risk of cardiovascular events (eg, unstable angina, myocardial infarction). These patients should undergo coronary angiography and possibly revascularization (eg, stent placement, coronary artery bypass grafting). On the other hand, a negative exercise stress testing result (characterized by exertion to ≥85% of maximum heart rate with no significant ECG changes) denotes a <1% risk of cardiovascular events within the next year. The presence of diabetes mellitus does not affect the sensitivity or specificity of exercise stress testing however when patients have intermittent angina reliably related to exertion or relieved by rest, their condition is most consistent with atypical anginal pain and a longstanding history of diabetes mellitus likely has some degree of coronary artery disease, but the clinical significance is not clear. In this instance, a negative stress testing result still only indicates a low risk of future cardiac events and does not exclude the presence of nonobstructive (clinically insignificant) or microvascular CAD. Exercise stress testing is useful in the initial diagnosis of coronary artery disease (CAD) and in providing prognostic information in patients with known or highly suspected CAD. Patients with negative stress testing results have a <1% risk of cardiovascular events within the next year.
What medications can alter the results of a stress test?
Beta blockers, calcium channel blockers, and nitrates can cause false negative results on exercise and pharmacologic stress testing and should be held for 48 hours prior to testing. However, aspirin, statins, and lisinopril are not known to affect stress testing results.
How does gender impact the results of a stress test?
Female patients have a higher incidence of false positive ST-segment depression during exercise; however, female sex is not known to increase the rate of false negative results.
What lifestyle modifications are recommended for all CAD patients?
- Smoking cessation.
- BP control.
- LDL <70 mg/dL.
- Weight loss and regular exercise.
- Glycemic control in diabetes.
What pharmacologic therapies improve survival in stable angina?
Aspirin, beta-blockers, high-intensity statins, and ACE inhibitors improve survival in CAD.
Aspirin reduces the risk of _____ in patients with CAD.
MI
What is the role of beta-blockers in CAD management?
Beta-blockers reduce myocardial oxygen demand by decreasing heart rate and contractility.
How do nitrates relieve angina, and what are their potential side effects?
Nitrates dilate coronary arteries, reducing preload and afterload. Side effects: headache, hypotension, tolerance.
What is the medication given with angina symptoms are refractory to nitroglycerin, beta-blockers, or calcium-channel blockers?
Ranolazine. Side effect: Prolonged QT interval.
What is dual antiplatelet therapy (DAPT), and when is it used in CAD?
DAPT combines aspirin and a P2Y12 inhibitor (e.g., clopidogrel) and is used post-PCI or in ACS patients. Clopidogrel can be given in isolation when ASA is contraindicated.
What is the role of calcium channel blockers in CAD treatment?
CCBs reduce afterload and improve coronary perfusion and reduce angina, but are avoided in reduced EF due to negative inotropy.
What is the role of statins in both primary and secondary prevention of CAD?
Statins stabilize plaques, reduce LDL, and decrease cardiovascular events in primary and secondary prevention.
What are the indications for revascularization in CAD patients?
Revascularization is indicated in left main disease, multi-vessel CAD with symptoms, or failed medical therapy.
How does PCI differ from CABG in terms of indications and outcomes?
PCI is minimally invasive with quicker recovery. This tends to be the treatment for single vessel disease.
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CABG is preferred for complex multi-vessel (3 vessel or 2 vessel with DM) or left main disease.
What are the Sgarbossa criteria for diagnosing STEMI in the presence of a left bundle branch block (LBBB)?
Sgarbossa criteria include concordant ST elevation >1 mm in leads with positive QRS, or discordant elevation >5 mm.
How does left ventricular dysfunction influence management in CAD patients?
Left ventricular dysfunction (EF <40%) warrants ACE inhibitors/ARBs and potential ICD placement (EF <30%).
Myocardial reperfusion commonly precipitates what cardiovascular abnormalities?
Accelerated idioventricular rhythm, which appears similar on ECG to ventricular tachycardia but with a ventricular rate <100/min.
What complications can occur following an acute coronary syndrome?
Arrhythmias (VT/VF), cardiogenic shock, mechanical complications (e.g., rupture), and heart failure.
