EPIDEMIOLOGY OF
CORONARY HEART DISEASES
(CHDs)
Dr Faris Al-Lami
MB ChB MSc PhD FFPH
Salient Epidemiological
Observations
• 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
Salient Epidemiological
Observations
• 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)
Salient Epidemiological
Observations
• 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
Salient Epidemiological
Observations
• 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
of smoking
• Passive
smoking also increases CHD risk
• The risk is mediated mainly through increased
plasma
fibrinogen
Smoking Cessation Measures
Effective Measures
:
• Social pressure
• Prohibition of smoking in public places and
work
• Restricted advertisement
• Heavily taxed cigarette trade.
Smoking Cessation Measures
Ineffective Measures
• Personal advice
• Smoking cessation clinic
• Nicotine withdrawal therapy
Diabetes Mellitus
• Diabetics have a 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
Other Risk Factors :
• 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
Other Risk Factors :
• 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
Other Risk Factors :
• Stress and type A personality
: Increased sympathetic
activity lead to increase catecholamine release, which
will increase BP, PR, FFA, increases myocardial O2
demand, deceases
O
2
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
Other Risk Factors
• Hyperuricemia
: not established
• Hyperhomocystenemia
: easily corrected by
folic acid
• Hypercalcemia
• Role of trace elements
: exposure to antimony,
cobalt, and lead
Other Risk Factors
• 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
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
Angina Pectoris
• 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
Myocardial Infarction
• 50% of MI cases are either atypical, missed, or
misdiagnosed as seen by ECG surveys looking for Q or QS
waves
• 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
Sudden Death
• 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 accounts 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
Chronic Heart Failure
• 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
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
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
• 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
The Regional Situation
In the WHO Region for the Eastern
Mediterranean, Chronic Diseases (CVD,
Cancer, Diabetes etc..) account for 52% of all
deaths and 47% of the disease burden in EMR
during the year 2005
This burden is likely to rise to 60% in the year 2020.
The conventional risk factors may explain 75% of
chronic diseases.
Cardiovascular
Chronic Respiratory
Disease
Type 2 Diabetes
Cancer
Chronic Diseases result in
percent of deaths
4
52
EMR Adult Population
EMR/NCD RISK FACTORS
Smoking
16-65%
Hypertension 12-35%
Diabetes
7-25%
Over weight-obesity 40-70%
Dyslipidemia
30-70%
Physical Inactivity
80-90%
Stepwise data from some EM countries
Country
Year of
field work
DM %
HT %
Overweight &
Obesity %
Iraq
2006
10.4
40.4
66.9
Jordan
2007
16
25.5
67.4
Saudi
Arabia
2005
17.9
26
Syrian Arab
Republic
2003
19.8
28.8
56.3
Kuwait
2005
16.7
24.6
81.2
Egypt
2005
16.5
33.4
76.4
Sudan
2005
19.2
23.6
53.9
Prevalence of Smoking according to STEPwise Survey in
EM countries
21.6
29
12.9
24.7
15.7
21.8
12
0
10
20
30
40
Iraq
Jordan
Saudi
Arabia
Syrian Arab
Republic
Kuwait
Egypt
Sudan
%