Post on 25-Dec-2015
MI: Risk Factors and Primary Prevention
Risk Factors
Factors that appear to increase the general population’s chances of experiencing a health problem
Not a guarantee that any one individual will have the problem, but useful when applied to entire patient population
How are Risk Factors Determined?
Show a causal relationship between the risk factor and the disease through careful study
Association studied should have, if possible: Strength Consistency Specificity Proper Time Sequence A Potential Biological Explanation and/or Analogy A Dose-Response Relationship A large Testable Population
MI Risk Factors
Many can be reduced or avoided through Primary Prevention
Preventable Risk Factors and MI
Up to 90% of myocardial infarction risk comes from factors that can be changed long before MI occurs (Lancet, Sept. 2004)
Primary prevention: actions that stop the development of a disease before it even starts
Risk Factor: Smoking
Dose-response relationship without plateauEvery additional cigarette smoked increases
MI risk furtherReduces body’s ability to signal for
production of tPA, a natural clot-busting protein
Women smokers at further elevated risk
Primary Prevention: Smoking
Don’t startHowever much you smoke, smoke less.
Risk Factor: Hi LDL/ Lo HDL
Cholesterol:Vital component of cell wallsVital precursor to many hormonesHOWEVER, also major component of
atherosclerotic plaquesMade in the liver
LipoproteinsMake fat and cholesterol soluble in the
blood
Risk Factor: Hi LDL/ Lo HDL
Low Density Lipoprotein Carries cholesterol from liver to body for use “Bad” cholesterol High plasma LDL (>70-100 mg/dL) = more
atherosclerosis, MI High Density Lipoprotein
Carries cholesterol from body to the liver for elimination
“Good” cholesterol Low plasma HDL (<40mg/dL) = more
atherosclerosis, MI
Primary Prevention: Hi LDL/ Lo HDL
Dietary Changes:Decrease saturated fat consumption (<7%)Eliminate trans fat consumptionCholesterol in food NOT strong link to
increased LDLLifestyle Changes:
Increase activityNot always possible
Risk Factor: Chronic Hypertension
Continuously High Blood Pressure
Systolic > 140 mmHg
Linked to ¼ of MI cases
Strongly linked to arteriosclerosis and CVD
Primary Prevention: Hypertension
Dietary Changes: Reduce sodium intake Reduce simple sugar intake Get daily doses of Potassium and Calcium
Lifestyle changes Get more exercise, keep HR elevated for longer Decrease body fat Avoid stress
Again, not always possible
Abdominal Obesity and Diet
Obesity from excessive fat around the abdomen is a strong predictor of many other risk factorsHigh LDLHypertensionDiabetes
Waist:Hip ratio0.9 for men0.85 for women
Abdominal Obesity and Diet
However, poor diet can lead to all of those even without obesity
Eat fruits and vegetables
Avoid saturated fats and trans fats
Get >25g dietary fiber per day
Unavoidable MI Risk Factors
Genetics and MI risk factors
All previously mentioned risk factors can also be influenced by genesFamily history increases risk of
Hypercholesterolemia (High LDL)HypertensionAtherosclerosis
As genetics advances, we can separate “nature” from “nurture”
Specific genes and mutations shown to increase clotting risk, LDL, etc.
Gender
Estrogen linked to lower risk of MIPre-menopause: women at lower riskPost-menopause: women at same risk as
menMI leading cause of death for both men and
women
Aging
Some degree of atherosclerosis inevitable with age
Even with perfect health, risk of MI increases in old age
Diabetes
Failure of normal insulin functionType I: genetic, no insulin producedType II: acquired with some genetic
predisposition, insulin resistanceIncreases risk of high LDL and high
blood pressureFurther increases the risk of MI, possibly
due to damage caused by poorly controlled blood sugar
Recap
If a patient doesn’t think they can quit smoking, is there any use to trying to get them to smoke less?
True or false: only overweight patients have high blood pressure.
Which item should you leave out of your breakfast if you want to improve your LDL:HDL ratio the most: eggs, bacon, or milk?
Sources
Yusuf, et al, “Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART study): case-control study,” The Lancet, Volume 364, Issue 9438, Pages 937 - 952, 11 September 2004
Chobanian , et al, “Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure,” Hypertension. 2003;42:1206
Ulrich, et al, “A comprehensive linkage analysis for myocardial infarction and its related risk factors,” Nature Genetics, 2002, vol. 30, no2, pp. 210-214
Ardissino, et al, “Prothrombotic Genetic Risk Factors in Young Survivors of Myocardial Infarction,” Blood, 1999 94: 46-51