EPIDEMIOLOGY OF (CHD)

Report
EPIDEMIOLOGY OF
CORONARY HEART
DISEASES(CHD)
The salient epidemiological
observations about CHDs are :
• Large population differences in CHD incidence
and mortality rates
• Strong correlation between population
differences In CHD rate and population
differences in mean level and distribution of RFs
especially lipids.
• Within population , a strong and continuous
correlation between several RFs (S.Ch, BP,
Smoking) and future risk of CHD
• Tracking of CHD RFs among children into
adulthood
• Incidence and RFs of CHD in migrants rapidly
approached level of adopted population
• Trends in CHD mortality rate , case fatality rate,
and incidence occur over very short period (5-10
years)
• The decline in CHD mortality rate seen in
industrial countries include all ages, both
sexes, and all races
• The above decline is associated with
decline in death rate , from stroke, all
CVDs, and non-CVDs
• RCTs found direct effect of decrease in RFs on
subsequent disease rate. Prospective studies
found that established RFs and associated
health behavior can be safely modified
• Epidemiological evidences are consistent with
clinical and laboratory findings about causes and
mechanism of atherosclerosis , which underlies
the manifestation of CHDs
Risk Factors of CHDs
Dyslipidemia
• Hypercholesterolemia is the most specific and
the most essential factor
• There is a strong correlation between amount
and duration of lowering S.Ch with decreased
risk of CHD
• Lowering S.Ch is not associated with increase in
mortality from non-CHDs
Dyslipidemia
• LDL-c is a major component of T.Ch, and
positively associated with CHD risk. It is affected
by changes in diet and weight
• HDL-C is negatively associated with CHD risk. It
is affected by exercise, weight, and smoking. It
is higher in women
• The role of TG is less consistent. It is positively
associated with T.Ch, and negatively with HDL-C
level.
Hypertension
• It is a strong RF especially in populations
with high prevalence of CHDs
• SBP is better predictor of CHD events
than DBP
• Life-style measures are more effective
than mass medication in management of
mild HT
Cigarette Smoking
• RR is about 2 , higher in young and in population with
high prevalence of CHD
• Cessation of smoking is important in primary and
secondary prevention of CHDs
• Positive association between CHD risk and amount (but
not duration) of smoking
• Passive smoking also increases CHD risk
• The risk is mediated mainly through increased plasma
fibrinogen
Smoking Cessation Measures
• Personal advice, smoking cessation clinic, and
nicotine withdrawal therapy were tried for
smoking cessation with poor results.
• The following were tried for smoking cessation
with strong effects:
• Social pressure, prohibition of smoking in public
places and work, restricted advertisement, and
heavily taxed cigarette trade.
Diabetes Mellitus
• Diabetics have very high risk which is
equal in men and women
• It removes the relative protection of
premenapausal women
• Insulin resistance is associated with HTG,
low HDL-C, and high BP
Obesity
• It increases risk of CHD, stroke, and other
CVDs
• It is associated with DM, HT, high TG, high
TCh, and low HDL-C
• Central obesity is particularly more
dangerous
Physical Inactivity
• CHD epidemic is associated with decreased
physical activity at work and home
• Physical activity is difficult to be measured
• Exercise can decrease BP, weight , and
improves lipid profile
• Even light exercise as walking is beneficial
Other Risk Factors :
• Male Sex: CHD are 2 times more frequent in
males
• Positive family history: aggregation of CRFs or
increased susceptibility to a particular RF
• Dietary factors: the amount of fat, saturated fat,
and cholesterol in the diet increases CHD risk.
High consumption of fish and plant food offer
protection
• Natural antioxidants: lipid soluble (vitamin E,
B-carotene) and water soluble (vitamin C,
flavonides) decreases CHD risk
• Haemostatic factors:
Hyperfibriniginemia
High coagulation factor VII
Impaired fibrinolytic activity
High PAI-1
• Oral Contraceptives: through:
Increases body weight, BP and PAI-1
Decreases HDL-C level
Altering blood coagulability , platelet
function, fibrinolytic activity, and integrity of
vascular endothelium
• Alcohol intake: takes J –shape curve with
CHD risk
• Stress and type a personality: Increased sympathetic
activity lead to increase catecholamine release, which
will increase BP, PR, FFA, increases myocardial O2
demand, deceases O2 supply and alter platelet function
• Socioeconomic status: in developed countries, the
association is inverse
In developing countries the association is positive
• Job characteristics: perceived job stress, role
ambiguity, job change, unemployment, and retirement
• Hyperuricemia: not established
• Hyperhomocystenemia: easily corrected by
folic acid
• Hypercalcemia
• Role of trace elements: exposure to antimony,
cobalt, and lead
• Inhalant occupational exposure: carbon
disulphide, glyceryl nitric esters
• Water hardness: negative association with CHD
risk
• Antiphospholipid antibodies: anticardiolipin,
and anticephalothin antibodies
• Infection: Chlamydial pneumonia, dental
infection, severe viral illnesses
Manifestations of CHDs
Angina Pectoris
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A major cause of disability from 4th decade
onward
Subjective diagnosis, with no gold standard
Rose questionnaire, : low sensitivity , specificity,
and positive predictive value
Resting ECG: not sensitive
Ambulatory and exercise ECG : expensive
Radioisotope scan: not practical
Coronary angiography: not practical
• The more severe and persistent symptoms, the greater
the risk of major coronary events
• The greater the number of indicators of myocardial
ischemia, the more advanced the disease and the worse
prognosis
• Various treatment procedures are palliative rather than
curative
• PTCA is cheaper and more palliative than CABG. Both
are not better than medical treatment regarding survival
Myocardial Infarction
• 50% of MI cases are either atypical, missed, or
misdiagnosed as seen by ECG surveys looking for Q or
QS waves
•
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The following factors were found to improve survival:
Prevention of VF early in the attack
Initial treatment with aspirin or thrombolytic agents
Long-term treatment with aspirin, B-blockers, and ACE
inhibiters
 Avoidance of smoking
 Rehabilitation programs
 Cholesterol lowering treatment
Sudden death
• Definitions are variable from instantaneous
death to death within 5 minutes, 1 hour, 3 hour,
12 hour, 24 hour.
• 70% of coronary deaths occurred outside the
hospital. This led to:
 development of mobile CCU
 Para-medical services
 population training programs in resuscitation
• 20-40% of potential coronary deaths had no
history, symptoms, or autopsy findings of any
diagnosis
• Autopsy studies found that sudden death could
also be due to pneumonia, valvular heart
disease, or alcohol overdose
• 50% of all deaths occurring within 28 days of
severe chest pain occur within 2 hours of onset
and mostly within very few minutes
Chronic Heart Failure
• It account for small proportion of deaths,
but increasing
• Its prevalence is increasing because of
increase aging and increase in survival
from CHD
• It follows history of MI or myocardial
ischemia at many occasions
• Admission for HF increases with increased
age, increased number of admissions for
other coronary events and with DM
• It is a significant contributor to hospital
cost
• ACE inhibiters are beneficial in increasing
survival
Inter-relationship of various CHD
manifestations
• One type of CHD increases risk of other manifestations
• 20% of CHD victims have sudden death as a first
manifestation
• More than 50% of coronary deaths and MI have history
of AP or MI
• MI may terminate or initiate AP
• Myocardial ischemia on exercise test after MI indicate
high risk of death or re-infarction
• Women have lower rates of sudden death and
MI than men, but have almost similar rates of AP
• Women have lower rates of CHD mortality than
men
• A PARADOX: those admitted for coronary
emergency without previous history have worse
prognosis than those who have positive history
Prevention of CHDs
Primordial Prevention
1. National policies and programs on food
and nutrition
2. Comprehensive policies to discourage
smoking
3. Programs for prevention of HT
4. Programs to promote regular physical
activity
• The strategy is to introduce population
wide interventions to lower population
levels of smoking, obesity, saturated fat
consumption, and salt intake.
• The strategy is to maintain health
promoting diet, social and economic
conditions which support non-smoking and
physically active life-style
Specific actions
1. Tobacco control
• Political commitment and support
• Special emphasis on the control among women,
children, and adolescents.
• Effective health education
• Legislations and implementation of these legislations
• Role model by health professionals and school teachers
• Strengthening of cultural and religious values against
smoking
Examples of Legislations
• Banning smoking in public places, schools, and health
care facilities
• Banning vending machines and selling cigarettes to
children
• Banning of tobacco advertisement and promotion
• Preventing new investment in the development of
tobacco industry
• Increasing taxation on tobacco product
• Appropriate warning labels
2. Physical Activity
• Activities should be feasible and able to be incorporated
into daily life
• Encouraging sports activities at schools and workplace
• Formulation and use of guidelines on physical exercises
• Changing the misconception of both women and
community about obesity through health education
3. Nutrition and dietary modification
• It should cover all aspects of food chain
from production to consumption
• Multi-sectoral collaboration is essential
(agricultural, trade, industry, education,
health)
• Health education and specific legislations
are basic components
Dietary Guidelines
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•
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A balanced intake of calories
A reduced salt content of the diet
A reduced total saturated fat intake
A rise in the consumption of fruits and vegetables
Prevention of unhealthy dietary habits and stopping the
cultural invasion of fast food
It is necessary to strengthen the role of the school health
curriculum which should cover the knowledge and
attitudes needed for CVD prevention

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