Winslow Homer: “White Mountains”. Epidemiology of Cardiovascular Disease Brubaker, et. al....

Winslow Homer: “White Mountains”

Epidemiology of Epidemiology of Cardiovascular Cardiovascular

DiseaseDisease

Brubaker, et. al.

Chapter 1:1-22

Definitions:Definitions: Epidemiology: Finding

demographic associationsPrevalenceCorrelationsRisk Factors and Prediction

Etiology: Cause / EffectMechanisms: How does this Cause cardiovascular disease?

You Define: You Define:

Prevention:Intervention:Rehabilitation:

Where does the “Exercise Physiologist” most impact CAD?

Cardiovascular DiseasesCardiovascular Diseases

Coronary Artery DiseaseAccounts for nearly 50% of all CVD

Arterial HypertensionLeft Ventricular Dysfunction

(Congestive Heart Failure)Valvular DiseaseCardiac Dysrhythmias

““A Life Every 29 A Life Every 29 Seconds”Seconds”

The American Heart Association

First the Good News:First the Good News:

Since 1988, deaths from CVD has declined about 20%!

BUT…BUT…

Cardiovascular DiseaseCardiovascular DiseaseMortality rates increase - 1900sToday >1 million die each year!!Cost? Nearly $300 Billion / year!!!!The number of “Procedures” to

treat CAD has increased ~400% since 1979

Why did this disease become more prevalent after 1900?

How are risk factors identified?

How Do We Do in How Do We Do in Nebraska?Nebraska?

From: NHLBI –http://hp2010.nhlbihin.net/cvd_frameset.htm

Compared to Texas:Compared to Texas:

Houston voted the “Fattest City in USA”

Or Colorado:Or Colorado:

Colorado Springs voted the “Most FitCity in the USA”

Conclusion:Conclusion: As we know more and the public

is more aware of the various genetic and lifestyle risk factors, Primary Prevention Programs may gain impact strength.

We have better therapies.More people are SURVIVING

CAD, and will benefit from Secondary Prevention Programs.

You Define:You Define:Primary Prevention:Secondary Prevention:

Risk Factor IDRisk Factor Reduction

What is the Primary Role of PREVENTION in Cardiac Rehab?

RISKRISKAbsolute vs. Relative Absolute vs. Relative An individual’s

chance (risk, probability) of developing CAD in the next 5-10 years…

But what does it MEAN?

Comparing that individual’s risk to others like him or her…

RR = iAR/pAR

iAR = individual’s AR

pAR = population AR

Case Study #1:Case Study #1: Fred is 38, with

hypertension and a poor blood lipid profile:

His Absolute Risk is 7%

The average risk for males 35-39 is 5%

7% / 5% = 1.4 times the risk of developing CAD…

All About Risk Factors:All About Risk Factors:Traditional: Well documented,

understood risk factors -The big “9”Emerging: Evidence is mounting

linking these factors to CADMarkers: Other characteristics

linked to CAD – perhaps indicating a genetic “cluster” of characteristics

You may ask…You may ask…Where do they get the

population data to determine absolute and relative risk?

Framingham Risk Score: Page 21

That brings us to “Epidemiological Studies”

Study Designs: Study Designs: Epidemiological: Large

“cohorts” for longitudinal studies:Looking for “Relationships”

Intervention: Modifying suspected risk factors, and measuring CAD outcomes

Randomized Clinical Trials: Not feasible nor ethical

Framingham Heart StudyFramingham Heart Study City of Framingham, MA (pop 50,000) Massive health screenings every 2

years 30+ year study (1948- ) Looked at various health factors

related to disease and mortality Some factors seemed to be

significantly associated with (correlated with) CVD

Traditional Risk FactorsNon-Mod vs. Modifiable Increasing Age Male Gender Family History

Tobacco Use High Cholesterol Hypertension Physical Inactivity Obesity Diabetes

The “Big 9”: 6 Targets of Prevention

After Framingham: After Framingham: Read through your references at the

end of this chapter…I.e. NHANES III (Nat’l Health and Nutrition Examination Survey)

Framingham is the “Grand Daddy” of CAD Epidemiological Studies.

This is usually “Step One” in determining what is causing a “rash of illnesses” such as seen with CVD after 1900

Intervention: Zeroing in Intervention: Zeroing in on Cause-Effecton Cause-EffectOnce a factor (I.e. Smoking) is

linked to the risk of developing CAD,

Study the effect of intervening with the risk factor (I.e. quit smoking) on CAD risk…

MRFIT: Multiple Risk Factor Intervention Trial

A Closer Look at the A Closer Look at the Traditional Risk Factors: Traditional Risk Factors:

Know the “Big 9” Know the 6

Modifiable Factors

Know the acceptable levels for PRIMARY PREVENTION

Assignment: Assignment: Read: Foster, Procari. (2001).

The risks of exercise training. J.Cardiopulm.Rehab. 21(6):347-351.

Be ready to discuss: What are the benefits and challenges to increasing physical activity as Secondary Prevention?

Hearts in the News:Hearts in the News:

““President Bush Faints President Bush Faints After Choking on Pretzel”After Choking on Pretzel”His resting Heart Rate made

the news last year…Can you think what might have

influenced his brief fainting spell?

Think “baroreceptors”…Vasovagal Syncope

Tobacco:Tobacco:Just DON’T!Acute cardiovascular affects of nicotine

include hypertension, increased O2 demand by the heart, and decreased O2 delivery, risk of arrhythmias, and coronary artery spasm, and platelet aggregation

Every smoke puts a person a risk, but especially someone with progressing CAD!

RISK FACTOR: Chronic RISK FACTOR: Chronic Tobacco UseTobacco UseDecreases HDL cholesterol/LDL

oxidation Damages arterial endotheliumBegins atherosclerosis

Increases chronic blood pressure by increased Smooth Muscle proliferation

Increases Fibrinogen, RBC and blood viscosity.

Hyperlipidemia: High Fat Hyperlipidemia: High Fat in the Blood…in the Blood…Cholesterol “Types”:

Total: All types combinedHDL: High Density LipoproteinsLDL: Low Density Lipoproteins

Tell me what you know?

HDL: HDL: The “Good Guys” Inversely related to CAD:

As HDL goes UP – CAD goes DOWN“Reverse-Cholesterol Transport”

HDL’s may prevent cholesterol from becoming atherogenic and may even remove cholesterol from atherosclerotic arteries!

HDL > 60 mg/dl reduces CAD riskHDL < 40 mg/dl increases risk

LDL: LDL: The “Bad Guys”LDL carries cholesterol to the

peripheral arteries.It is Oxidized by endothelial cell

products…and acts as an “offending presence” injuring vessel walls:

LDL > 130 mg/dl increases CAD risk

Triglycerides:Triglycerides:Triglycerides are associated with

increased risk for CADBUT: blood TG’s vary greatly in

“feast”/famine and between individual responses to “feasts”

May be more of a Marker associated with obesity, physical inactivity, glucose intolerance etc.

TG > 150 mg/dl increases CAD risk

HypertensionHypertension

Damages vessel walls Increases afterload on the heart (=

more work)Leading cause of stroke & heart

failureAffects 40% of the U.S. !BP > 140 systolic and/or 90

diastolic increases CAD risk

Physical Inactivity Physical Inactivity

Physical Activity and/or Cardiorespiratory Fitness

Many intervention studiesHow Much? How Intense?

Assignment: You Tell Me!

Physical InactivityPhysical InactivitySee current Surgeon General’s

Report60% of Americans get no exercise!Contributes to CVD, obesity,

musculoskeletal disorders, GI disturbances, cancer, stress, HTN, high blood lipids, glucose intolerance

Glucose IntoleranceGlucose Intolerance May be partial intolerance, or full

(diabetes) High blood glucose will oxidize, destroying

cell walls Atherosclerosis is greatly accelerated Risk of clotting is increased Increases the risk of CAD >3 times in

Women! Often associated with other risk factors:

Obesity, hyperlipidemia etc.

RISK FACTOR: ObesityRISK FACTOR: Obesity

Location of fat distribution matters 25% attributed to genetics Most due to environment Increases HTN, glucose intolerance,

insulin resistance, triglycerides, decreases HDL,

BMI > 25 increases CAD risk in both men and women (more in men)

Percent of U.S. Population at Risk

0

10

20

30

40

50

60

BP TC SMOKE INACT

%

Risk Ratio2.1 2.4 2.5 1.9

from Casperson, C.J. Phys. Sports Med. 15:43-44, 1987.

Domains of CVD Domains of CVD Prevention: PrimaryPrevention: Primary

Strategies for apparently healthyGoal is to prevent onset of diseaseLifestyle changesFocus is on youth, young adults

and CAD-free adults

Secondary PreventionSecondary PreventionDesigned to improve outcome of

those with diseaseRisk profiles are very different after

CAD has “reared it’s ugly head”Goal is to reduce the risk of

SUBSEQUENT CAD eventsStrategies in primary prevention

also implemented – but more aggressively

Assignment: Assignment: Physical Activity Guidelines for

Primary Prevention – Cite your source.

Evaluate your AR and RR!Other emerging or controversial

risk factors:Groups of 3-4: Mini-ReportsDue Tuesday

Mini-Reports: 20 pts Mini-Reports: 20 pts Pages 17-19AHA/NHLBI Website helps:NHLBI: Web SiteAmerican Heart Association1-3 minutes:

What is it?Why do we think it may affect CAD risk?