JH IM Board Review - Coronary Artery Disease I Flashcards
Insufficient coronary blood flow occurs when:
2
- A plaque leads to arterial stenosis.
- Endothelial dysfunction prevents adequate vasodilation during exercise.
==> Can occur in the absence of severe luminal narrowing.
RFs for CAD - Strong:
9
- Older age.
- Male.
- Postmeno females.
- Up LDL, down HDL.
- Smoking.
- HTN.
- DM.
- Obesity/sedentary lifestyle.
- FHx of early CAD.
RFs for CAD - MODERATE:
5
- UP TGs.
- Small dense LDL.
- Up homocysteine.
- Stress or depression.
- Inflammatory markers (CRP, fibrinogen).
RFs for CAD - MILD:
2
- Lp(a).
2. C.pneumoniae.
A low HDL is an … for CAD.
Independent RF.
Importance of small dense LDL:
It has the lowest affinity for the LDL receptor and is therefore cleared to the least degree from plasma by the liver.
==> It may be the most atherogenic type of LDL.
Homocysteinuria:
Rare homozygous genetic disorder impairing homocysteine metabolism ==> SEVERE PREMATURE ATHEROSCLEROSIS.
…-…% of the population are heterozygous for homocysteinuria, which may account for up to …% of cases of premature atherosclerosis.
1-2%.
30%.
Homocysteinuria - Tx of elevated homocysteine levels with folate, B6, B12, does …
NOT reduce the risk of AMI or death.
Elevated Lp(a) means …
Increased number of LDL particles that contain the large glycoprotein apoprotein (a), which has a higher density than LDL.
==> MORE ATHEROGENIC.
Elevated Lp(a) is a/w …
CAD.
Niacin, estrogen, fenofibrate, and bezafibrate all reduce Lp(a).
However, …
NONE of these tx have been shown to reduce CVD events.
Elevated CRP and fibrinogen are a/w MIs and CAD.
BUT, …
It is unclear if they cause CAD or are simply markers of an associated inflammatory process.
C.pneumoniae has been isolated from atheromas and may contribute to plaque inflammation.
However, …
Pts hospitalized with an ACS had no reduction in CVD events when treated with long-term GATIFLOXACIN.
Which factors does the FRS use to assess cumulative risk?
- Age.
- Smoking.
- SBP.
- Tx for HTN.
- Total CH.
- HDL.
FRS cumulative risk score stratifies pts as:
- Low risk <10% CHD at 10y.
- Intermediate risk 10-20% at 10y.
- High risk >20% at 10y.
The most recent guidelines use which score?
The Pooled Cohort Equations (PCEs).
Approx. …% of pts with chronic stable angina have a normal resting ECG.
50%.
The presence of CAD can never definitively ruled in or out through stress testing alone, because …
Stress testing can yield both false(-) and false(+) results.
The se of an exercise treadmill test is approx …% and the sp is approx …%.
70%.
80%.
Stress testing can help …
Risk-stratifying the pts.
==> To determine the risk for future CVD events and death.
Need to know pretest probability for having CAD.
The clinician should be able to determine from Hx and PEx alone whether a pt has low, medium, or high pretest probability of CAD:
2 examples:
25yo woman with atypical sx and no RFs for CAD ==> Very low pretest probability.
75yo man with exertional angina and a history of HTN, DM, high CH, and smoking ==> High pretest probability.
Pretest probability helps stress test …
Result interpretation.
Stress tests add … for pts with either high or low pretest probabilities for CAD.
LITTLE DIAGNOSTIC INFO.
Stress tests are most useful for diagnosing CAD in pts with …
INTERMEDIATE pretest probability.
Stress test results should be categorized as:
4
- Inadequate.
- Negative.
- Positive low risk.
- Positive high risk.
Features of a high risk stress test:
- Exercise-induced hypotension.
- Angina or ischemic ECG changes at a low workload (<6min or <4 METS on Bruce protocol).
- ST-depression >2mm.
- ST-depression >6mm into recovery period.
- Any ST-elevation.
- V-arrhythmias.
- Imaging reveals reversible defects in multiple territories or LV cavity dilation.
Pts with positive stress tests w/o high-risk features are often treated …
Medically.
Pts with positive tests and high-risk features are more likely to have high-risk coronary anatomy (LAD disease, 3-vessel disease).
The best approach usually requires …
Cardiac catheterization and revascularization.
Types of stress tests - 2 options for stress:
- Exercise.
2. Pharmacologic.
Types of stress tests - 2 options for imaging:
- Nuclear isotope.
2. Echo.
Pharmacologic stress test uses which agents?
- Dobutamine.
- Adenosine agonists = adenosine, dipyridamole, regadenoson.
==> dilation is greater in normal arteries resulting in STEAL phenomenon from diseased vascular beds.
Nuclear isotopes used in stress tests (2):
- Thallium-201.
2. Technetium-99m (sestamibi).
Thallium 201 is a …
Potassium analogue taken up by myocardial cells.
==> Hypoperfused initially shows decreased uptake.
==> Tracer redistributes over several hours.
Thallium 201 is helpful in distinguishing …
Ischemia from infarcted myocardium.
Technetium-99m (sestamibi) is …
Also taken up by myocardial cells BUT BINDS IRREVERSIBLY.
==> No late washout makes it IDEAL for imaging MI and USA.
Tc-99m has … energy.
Better agent for …
Higher proton energy.
==> Better agent for imaging obese pts.
To decide which stress test is best for a given pt, ask 2 questions:
- Can the pt exercise?
2. Does the resting ECG have ST-segments abnormalities?
Can the pt exercise?
Yes ==> Treadmill.
No ==> Drug-induced stress.
Does the resting ECG have ST-segment abnormalities?
If there are baseline ST-segment abnormalities (eg LVH with strain, paced rhythm, LBBB, ST depression, accessory pathways)
==> Then, the ECG alone may not permit an accurate diagnosis of ischemia, and an IMAGING modality will be required.
Stress test is very safe:
1-2 deaths per 10,000 tests.
Stress test should be avoided in:
7
- Pts with active USA.
- Severe AS.
- Possible AD.
- Severe HTN.
- Tachy/bradyarrhythmias.
- HCM.
- Other forms of outflow obstruction.
Pharmacologic testing with adenosine agonists should be avoided in pts w/:
(2)
- Severe COPD.
2. Active wheezing.
Calcium score screening CT is a …
Noninvasive and quantitative assessment of coronary artery calcification.
Higher coronary artery calcium scores are a/w …
Increased risk for MI and death.
Calcium score screening CT should be obtained only in …
Asx pts.
A coronary artery calcium score of 0 is a/w …
Excellent survival, w/ all-cause, 10y mortality risk <1% or <0.1% per y.
Coronary calcification can also be measured by …
CCTA (coronary CT angio).
CCTA allows for …
Direct coronary artery visualization of a beating heart with little motion artifact.
Most accurate noninvasive modality in ruling out CAD with a very high negative predictive value (>95%)?
CCTA.
CCTA is less accurate in differentiating degrees of coronary artery stenosis >…%.
The PPV varies between …-… .
50%.
60-90%.
Coronary angio is considered the … for diagnosing CAD.
Gold standard.
Refer for cardiac catheterization if:
3
- Need to confirm or exclude CAD.
- Medical tx fails to relieve anginal sx.
- Hx and noninvasive testing suggest high-risk coronary anatomy.
Treatment of chronic CAD:
- Address modifiable RFs.
- Correct illnesses that precipitate or exacerbate angina (eg infection, anemia, thyroid disease).
- Consider medications to relieve angina (beta-blockers, nitrates etc).
- Consider medications that decrease morbidity and mortality.
- Revascularization of chronic CAD (PCI, CABG).
Beta blockers DO NOT reduce mortality in pts with …
Chronic stable angina w/o MI or HF.
Beta blockers reduce BOTH morbidity and mortality in pts with …
Recent MI or HF with CAD.
Which CCBs should NOT be used in pts with ACS?
Short-acting dihydropyridines.
==> They increase mortality.
***Long-acting agents are safe and effective in treating pts with chronic stable angina.
Ranolazine - MoA:
Inhibits the late inward Na current.
==> Indirectly reducing the Na-dependent calcium current during ischemic conditions.
==> Leading to improvement in ventricular diastolic tension and O2 consumption.
Medications that decrease morbidity and mortality:
- Aspirin.
- Lipid-lowering agents.
- ACEIs.
Aspirin reduces risk of …
MI and death.
All pts with CAD should be on aspirin unless …
There is a clear contraindication.
The major indication for revascularization in CHRONIC CAD is for …
Relief of angina sx in pts on optimal medical management.
Percutaneous coronary intervention (PCI) has 2 components:
- Percutaneous transluminal coronary angioplasty (PTCA), in which a balloon is used to split the atheromatous plaque and stretch the artery.
- Stent deployment, which provides a metal scaffold to help maintain artery patency.
2 types of stents:
- Bare metal stents (BMSs).
2. Drug-eluting stents (DESs).
Deciding between BMS and DES:
2
- No survival differences. DES reduces risk of repeat target-vessel revascularization and reinfarctions.
- BMS should be used in pts who cannot tolerate long-term dual-antiplatelet tx.
The 4 thienopyridines:
- Clopidogrel.
- Prasugrel.
- Ticagrelor.
- Ticlopidine.
Complications of PCI - Restenosis - Mechanism?
Incompletely understood but likely involves NEOINTIMAL THICKENING caused by smooth muscle cell proliferation.
Restenosis - The dilated segment can shrink because of …
Elastic recoil.
Restenosis - Incidence peaks between … after PCI but has significantly decreased with DES use.
3-6mo.
Other complications of PCI:
1-2% risk of emergent bypass.
2-4% risk of MI (ie thrombosis).
1% risk of death.
PCI risk of complications increases with lesions that are …
Long, tubular, eccentric, and calcified.
In pts with stable CAD, PCI is quite effective in reducing angina, but it does NOT …
Reduce the risk of death or MI.
CABG is … for relieving anginal sx.
EXCELLENT.
CABG benefits compared with PCI:
Decreased repeated revascularization procedures.
CABG - Complications:
- Sternal wound infection.
- MI.
- Stroke.
- Post-op arrhythmias.
- Death.
Characteristics of pts with stable CAD who have lower mortality rates after CABG:
- Left main disease.
- 3-vessel CAD and decreased LV function **. (Weaker rec.)
- 3-vessel CAD and ischemia at low workload.
- 2-vessel or 3-vessel disease with proximal LAD involvement.
- Pts with DM: Higher 5y survival with CABG than with PCI.
Following CABG, use statin therapy, which can help …
Decrease graft vessel disease (even in pts with only mild LDL elevation).
How does multivessel PCI compare with CABG in pts with left main or 3-vessel CAD?
- At 1y ==> Major adverse cardiac events rates are higher in the PCI group, largely caused by an increased rate of repeat revascularization.
- At 1y ==> Rates of death and MI are the same in both groups, but STROKE is more likely to occur with CABG.
Consider calculating the SYNTAX score to determine if CABG or PCI is preferable.
SYNTAX is an …
Angiographic scoring system that uses various angio parameters to assess multivessel CAD complexity.
Pts with LOW SYNTAX scores have … differences in outcomes when treated with either multivessel PCI or CABG.
No.
Pts with a HIGH SYNTAX score derive greater benefit from …
CABG, which is a/w less major cardiac events (cardiac death and MI).
Smoking cessation decreases CHD event risk by …% within 3y.
60%.
BP control — A …-…mmHg reduction results in a …% reduction in cardiovascular events.
5-6mmHg.
16%.
Reduction in serum cholesterol by …% reduces cardiovascular events by …% and cardiovascular death by …%
10%
18%
10%
DM increases risk of heart disease by …-… in men and …-… in women.
2x-4x
3x-7x.
Though data are limited, maintaining ideal body weight and staying physically active may reduce risk of MI by …%.
50%.
Aspirin as primary prevention — In men, pooled data suggest a …% reduction in first MI.
33%.
In women, aspirin as primary prevention reduces the risk of … in those >65y but has NO effect on …
Stroke.
MI or death from CVD.
Statins reduce the risk of first MI, even in pts with …
Moderately elevated cholesterol.
Hormone tx increases the risk of CVD in the …
First 2 years of use.
Moderate alcohol intake (one drink per day) decreases risk of MI by …-…%.
30-50%.