Cardiovascular Disease Flashcards
1
Q
Describe the burden of CVD in Canada.
A
- Heart disease and stroke costs the Canadian economy around $25 billion every year in physician services, hospital costs, lost wages and decreased productivity.
- Since 1952, the cardiovascular death rate in Canada has declined by more than 75%.
Data from the Heart and Stroke Report 2022.
2
Q
Define: Cardiovascular disease.
A
Diseases and injuries of the heart and blood vessels (in the heart, brain and throughout the body)
3
Q
Define: atherosclerosis
A
Build up of plaque in arteries, narrowing of arteries and limiting blood flow
4
Q
Define: coronary heart disease
A
Build up of plaque in coronary arteries, which may lead to a heart attack
Atherosclerosis in coronary arteries = CHD
5
Q
Define: myocardial infarction
A
Heart attack = loss of blood flow to the heart
6
Q
Define stroke.
A
Loss of blood flow to the brain
7
Q
Define: thrombosis
A
Formation of blood clot inside a vessel
8
Q
Describe the progression of atherosclerosis.
A
- LDL transport cholesterol to cells.
- If LDL is not taken up by cells it keeps circulating in the blood.
- The longer LDL circulates in the blood, the more likely it will be oxidized, then:
- Uptake by macrophage
- Foam cell formation
- Fatty plaques
- Atherosclerosis
9
Q
Describe the key steps in the development of atherosclerosis.
A
- Arterial endothelial cell injury
- Entry of LDL cholesterol (which will be oxidized given enough time) and phagocytic cells
- Phagocytes engorge LDL forming foam cells
- Formation of fatty plaques; narrowing of blood vessels; can lead to myocardial infarction or rupture (thrombus)
10
Q
What are 4 unmodifiable risk factors for CHD?
A
- Age
- Gender (male > female)
- Family history
- Ethnicity
11
Q
What are modifiable risk factors for CHD? [9]
A
- High blood cholesterol
- High blood pressure
- Diabetes
- Overweight/obesity
- Excessive alcohol use
- Physical inactivity
- Smoking
- Stress
- Poor diet
12
Q
Describe the classic diet-heart hypothesis.
A
- Dietary characteristics like high saturated fat, high cholesterol, and low PUFA lead to:
- Elevated serum cholesterol levels
- Atheromatous plaque
- Coronary arteries narrow
- Myocardial infarction
13
Q
Describe how serum cholesterol is measured.
A
- Lipid profile
- Blood test in FASTING state that reports:
- Total cholesterol
- LDL cholesterol
- HDL cholesterol
- Triacylglycerols
14
Q
What component of a lipid profile appears to be most predictive of CHD risk?
A
- The ratio of total cholesterol: HDL cholesterol
- Or the ratio of LDL: HDL
- Or apoB: apoA
- Looking at ratios is of greater validity and significance in clinical diagnostic than measuring total cholesterol only.
Recall: the main apolipoproteins of LDL = apoB; and the main apolipoproteins of HDL = apoA
15
Q
Dietary cholesterol seems to have a major influence on serum cholesterol.
True or False?
A
False.
Dietary cholesterol does not seem to have a major influence on serum cholesterol.
16
Q
Dietary cholesterol does not seem to have a major influence on serum cholesterol.
True or False?
A
True.
17
Q
Describe how plant sterols affect cholesterol levels.
A
- Cholesterol absorption is decreased by intake of plant sterols.
- Plant sterols and plant stanols lower cholesterol absorption by displacing cholesterol in the mixed micelles.
18
Q
Dietary fat does seem to modify serum cholesterol.
True or False?
A
True.
Replacing saturated fats or CHO with MUFA or PUFA decreases total cholesterol to HDL cholesterol ratio.
19
Q
Dietary fat does not seem to modify serum cholesterol.
True or False?
A
False.
Replacing saturated fats or CHO with MUFA or PUFA decreases total cholesterol to HDL cholesterol ratio.
20
Q
What are the current recommendations regarding dietary fat?
A
- Minimize intakes of saturated and trans fats
- AMDR: n-6 PUFA 5-10%
- AMDR: n-3 PUFA 0.6-1.2%
- No recommendations for MUFA
- AMDR: fat 20-35%
21
Q
Elevated serum cholesterol is a risk factor for CHD.
True or False?
A
True.
22
Q
Elevated serum cholesterol is not a risk factor for CHD.
True or False?
A
False.
Elevated serum cholesterol is a risk factor for CHD.
23
Q
Dietary fat composition appears to influence serum cholesterol.
True or False?
A
True.
24
Q
Dietary fat composition does not appear to influence serum cholesterol.
True or False?
A
False.
It does appear to influence serum cholesterol.
25
Do dietary fatty acids influence risk for CHD?
* Findings from observational studies and experimental trials are mixed.
26
Why is evidence regarding dietary fat and CHD risk conflicting?
* Epidemiological studies are difficult to interpret.
* What replaces saturated fat is important
27
Why are epidemiological studies difficult to interpret?
* Difficult to separate effects of nutrients from dietary patterns or lifestyle factors
* Studies may be done on secondary prevention
* Difficulties in conducting “good” observational and experimental nutrition studies
28
Based on the forest-plot, replacing SFA with CHO leads to statistically significant slight increase in risk of CHD in cohort studies.
True or False?
True.
The CI of the pooled analysis of 11 cohorts does not include 1
29
Based on the forest-plot, replacing SFA with MUFA leads to statistically significant increase in risk of CHD in cohort studies.
True or False?
False.
The CI of the pooled analysis of 11 cohorts includes 1.
30
Based on the forest-plot, replacing SFA with PUFA leads to statistically significant decrease in risk of CHD in cohort studies.
True or False?
True.
The CI of the pooled analysis of 11 cohorts does not include 1.
31
What is the latest evidence about dietary fat and CVD risk?
* Lowered intake of dietary saturated fat and replacement with polyunsaturated vegetable oil reduced CVD by ≈30% (RCTs)
* Benefits from lower intake of saturated fat coupled with higher intake of polyunsaturated and monounsaturated fat (prospective cohort studies)
* NO benefits: replacement of saturated fat with mostly refined carbohydrates and sugars (clinical trials)
32
Why might the 'diet-heart' hypothesis be too simplistic?
* Most inter-individual variation in serum cholesterol is NOT related to dietary fat/cholesterol intake.
* Factors other than blood cholesterol are important in the etiology of CHD
33
List dietary factors that may influence CVD.
* Saturated fats/PUFA/n-3 fatty acids
* Glycemic index
* Whole grains/fiber
* Anti-oxidants
* Phytochemicals
* Vitamin D
* Magnesium
* Alcohol
* B vitamins (folate, B6, B12, etc)
* And more...
34
Describe omega-3 fatty acids and their role in CVD risk, as well as possible mechanisms [4].
* Hypothesis generated from observation of lower rates of CHD in populations with very high intake of fish such as Greenland and Japan
* Possible mechanisms:
* Effects on blood lipids (TAG lowering)
* Anti-arrythmic effects
* Anti (less)-inflammatory effects
* Anti-thrombotic effects
35
Describe the role fiber may play in CVD risk.
* May reduce serum cholesterol by binding to bile acids in the gut
* Major pathway of cholesterol excretion in the body
* May also improve glycemic control, insulin resistance and weight control
* Whole grains: source of fiber, phytochemicals, magnesium, etc.
36
Describe the role anti-oxidants may play in CVD risk.
* Hypothesis that anti-oxidants may protect the arterial wall and prevent LDL oxidation
* Note: Oxidation of LDL particles is an important step in the progression of atherosclerosis.
## Footnote
E.g., tocopherols, ascorbic acid, beta-carotene, selenium
37
Describe the role phytochemicals play in CVD risk.
* Have anti-oxidant properties
* Stilbenoids (e.g., resveratrol from grapes and pterostilbene from blueberries) modify gene expression through epigenetic mechanisms which may explain their anti-oxidant and anti-inflammatory properties
## Footnote
E.g., Flavonoids, stilbenoids, and others.
38
Why is low vitamin D associated with a higher risk of CHD? [3]
* Decreasing inflammation
* Endothelial function
* Reducing vascular stiffness
39
What are possible mechanisms explaining why low vitamin D is associated with higher risk for CHD? [3]
* Vitamin D receptor (VDR) and VDR responsive elements in DNA
* Regulation of gene expression
* Epigenetic mechanisms.
40
What are mechanisms for why low magnesium is associated with higher risk for CHD? [3]
* Modulating vascular smooth muscle tone
* Endothelial cell function
* Myocardial excitability
41
Describe the role of B-vitamins in CHD risk.
* B vitamins are needed to metabolize homocysteine.
* Increased homocysteine is a risk factor for CHD
42
Is red wine protective against CHD?
* Possibly in moderation (1-2 drinks/day)
* Contains: Resveratrol; other polyphenolic compounds (antioxidants); alcohol
* Excess alcohol is harmful
* No evidence that 'non-drinkers' should drink
43
Why may it be more useful to examine dietary patterns and not nutrients in relation to CVD risk?
We eat foods that contain nutrients.
We don't eat nutrients in isolation.
44
Describe two diets that are associated with reduced CVD risk.
* **'Prudent diet'**: a high intake of vegetables, fruit, legumes, whole grains, fish, and lean meats (poultry)
* **'Mediterranean diet'**: a high intake of vegetables, fruits, legumes, nuts, olive oil (MUFA), and seafood
45
Describe a diet that is associated with increased CHD risk.
* **'Western diet'**: higher intakes of red and processed meats, sweets, and desserts, high fat dairy, refined grains.
46
What did the PREDIMED study determine about the Mediterranean diet?
* A MD with olive oil or nuts significantly reduced CVD risk compared to a low fat diet
* This may be because the MD enhances cardioprotective lipid profiles, which improves glucose metabolism and decreases inflammation levels.
47
What are the current dietary recommendations for prevention of heart disease?
* Eat a balanced diet that emphasizes vegetables and fruit, whole grains, and minimizes saturated fat
* Encourage intake of omega-3 fatty acids (e.g., fish)
48
Describe the Canadian Food Guide 2019.
* The Food Guide continues to encourage Canadians to choose a variety of **nutritious foods and beverages** while highlighting that healthy eating is more than the foods you eat.
* Health Canada encourages Canadians to be mindful of their eating habits, to cook more often, to enjoy their food, and to eat meals with others.
* The new Food Guide recommends the **regular intake of vegetables, fruit, whole grains and protein foods**, and among protein foods, to consume plant-based more often. The intention is not to reduce total fat in the diet; rather it is to help **reduce intakes of saturated fat** while encouraging foods that contain mostly unsaturated fat.
49
Does dairy increase CHD risk?
* SF do not all have the same effect; SF from dairy may not increase LDL in a clinically significant way
* MCFA may lead to better weight management
* MUFA/PUFA increase HDL and lower total cholesterol (oleic acid)
* Other ingredients in dairy: calcium, iodine, potassium, bioactive peptides, vitamin D, vitamin A
50
What are the American Heart Association Lifestyle recommendations?
* Use up at least as many calories as you take in
* Aim for at least 150 minutes of moderate physical activity or 75 minutes of vigorous physical activity, or an equal combination of both, each week.
51
What are the American Heart Association Diet recommendations?
* Eat a variety of nutritious foods from all food groups
* Emphasize fruits, vegetables, whole grains, low fat dairy, skinless poultry and fish, nuts and seeds, legumes, non-tropical vegetable oils
* Limit saturated and trans fat, sodium, red meat, sweets, sugar-sweetened beverages.
## Footnote
Diets that fit this pattern = DASH or MD
52
Which apolipoprotein is associated with HDL?
apo A
53
Which apolipoprotein is associated with LDL?
apoB
