Coronary artery Disease/CHD/Epidemiology of CHD

1. Coronary heart disease
Dr. Sanjeev Gupta
Professor, Dept of Community Medicine
LN Medical College Bhopal.

2. Introduction:
• “Impairment of heart function due to
inadequate blood flow to the heart compared
to its needs, caused by obstructive changes in
the coronary circulation to the heart“
• Cause of 25-30 per cent of deaths in most
industrialized countries.
• Named as modern EPIDEMICS

3. • Manifest itself in many presentations :
• a. angina pectoris of effort
• b. myocardial infarction
• c. irregularities of the heart
• d. cardiac failure
• e. sudden death.

4. Measuring the burden of disease
• (a) Proportional mortality ratio: CHD is held
responsible for about 30 per cent of deaths in men and
25 per cent of deaths in women
• (b) Loss of life expectancy : average gain in life
expectation that would follow a complete elimination of
all cardiovascular deaths if other mortality rates remain
unchanged. The benefit would range for men from 3.4
years to 9.4 years, and even greater for women.

5. Contd……
• (c) CHD incidence rate: This is the sum of fatal and
nonfatal attack rates
• ( d) Age-specific death rates :Age-specific death
rates suggest a true increase in incidence.
• ( e) Prevalence rate : The prevalence of CHD can be
estimated from cross-sectional surveys using ECG
for evidence of infarction and history of prolonged
chest pain.

6. (f) Case fatality rate : This is defined as the proportion of
attacks that are fatal within 28 days of onset.
"sudden deaths" be defined to include deaths occurring
instantly or within an estimated 24 hours of the onset of
acute symptoms or signs“.
• 25-28 per cent of patients who suffer a heart attack die
suddenly. In about 55 per cent of all cardiac deaths
mortality occurs within the first hour

7. • (g) Measurement of risk factor levels : These
include measurement of levels of cigarette
smoking, blood pressure, alcohol consumption
and serum cholesterol in the community.
• (h) Medical care : Measurement of levels of
medical care in the community are also
pertinent.

8. Epidemicity
• CHD began at different times in different countries.
• Countries where the epidemic began earlier are now showing a
decline.
• The reasons for the changing trends in CHD are not precisely
known. The WHO has completed a project known as MONICA
"(multinational monitoring of trends and determinants in
cardiovascular diseases)" to elucidate this issue.
• Inverse relation between social class and CHD in developed
countries

9. International variations

10. Coronary heart disease in India
• It was expected to be the single most important
cause of death by the year 2015.
• There is a considerable increase in prevalence of CHD
in urban areas during the last decade.
• According to medical certification of cause of death
data, 25.1 per cent of total deaths in urban areas are
attributable to diseases of the circulatory system.

12. Risk factors

13. Smoking
• The risk declines quite substantially within one year of
stopping smoking and more gradually thereafter until, after
10-20 years,
• Possible mechanisms carbon monoxide induced
atherogenesis; nicotine stimulation of adrenergic drive
raising both blood pressure and myocardial oxygen
demand; lipid metabolism with fall in "protective" high-
density lipoproteins, etc.
• The degree of risk of developing CHD is directly related to
the number of cigarettes smoked per day

15. Hypertension
• In the past, emphasis was placed an the
importance of diastolic blood pressure.
• Many investigators feel that systolic blood
pressure is a better predictor of CHD than is
the diastolic. However, both components are
significant risk factors.

16. To further refine CHD
risk prediction based
on serum
lipid levels, a total
"cholesterol/HDL
ratio" has been
developed. A ratio of
less than 3.5 has
been recommended
as a clinical goal for
CHO prevention

17. Other risk factors
• Diabetes : The risk of CHD is 2-3 times higher in
diabetics than in non-diabetics.
• Genetic factors : A family history of CHD is
known to increase the risk of premature death.
• Physical activity : Sedentary life-style is
associated with a greater risk of the
development of early CHD.

18. • Hormones : The pronounced difference in the
mortality rates for CHO between male and
female
• Type A personality : Type A behaviour is
associated with competitive drive, restlessness,
hostility and a sense of urgency or impatience.
Type-A individuals are more coronary prone to
CHD than the calmer, more philosophical Type B
individuals

19. • Alcohol : High alcohol intake, defined as 75 g
or more per day is an independent risk factor
for CHD, hypertension and all cardiovascular
diseases
• Oral contraceptives: Women using oral
contraceptives have higher systolic and
diastolic blood pressure.

20. PREVENTION OF CHD
a. Population strategy
(i) prevention in whole populations
(ii) primordial prevention in whole populations
b. High risk strategy
c. Secondary prevention

21. a. Population strategy
• The strategy should therefore be based on mass approach
focusing mainly on the control of underlying causes (risk
factors) in whole populations, not merely in individuals.
• Based on the principle that small changes in risk factor
levels in total populations can achieve the biggest
reduction in mortality
• The aim should be to shift the whole risk-factor
distribution in the direction of "biological normality"

22. Specific interventions
1. Dietary changes : Reduction of fat intake to 20-30 per cent of
total energy intake consumption of saturated fats must be limited
to less than 10 per cent of total energy intake; some of the
reduction in saturated fat may be made up by mono and poly-
unsaturated fats
• A reduction of dietary cholesterol to below 100 mg per 1000 kcal
per day
• an increase in complex carbohydrate consumption {i.e.,
vegetables, fruits, whole grains and legumes)
• avoidance of alcohol consumption; reduction of salt intake to 5 g
daily or less.

23. 2. Smoking : As far as CHD is concerned, present evidence does
not support promotion of the so-called "safer cigarette" . The
goal should be to achieve a smoke-free society, and several
countries are progressing towards this goal.
3. Blood pressure : It has been estimated that even a small
reduction in the average blood pressure of the whole
population by a mere 2 or 3 mm Hg would produce a large
reduction in the incidence of cardiovascular complications
4. Physical activity : Regular physical activity should be a
part of normal daily life.

24. PRIMORDIAL PREVENTION
• It involves preventing the emergence and spread of CHO risk
factors and life-styles that have not yet appeared or become
endemic.
• Several well-planned risk factor intervention trials (e.g., The
Multiple Risk Factor Intervention Trial (MRFIT) in the US , The
Stanford Heart Disease Prevention Programme in California, and
The North Kerelia Project in Finland have demonstrated that
primary prevention can achieve substantial reduction in the
incidence of coronary heart disease.

25. b. High risk strategy
• (i) Identifying risk : High-risk intervention can only start
once those at high risk have been identified.
• (ii) Specific advice : Having identified those at high risk,
the next step will be to bring them under preventive care
and motivate them to take positive action against all the
identified risk factors,

26. c. Secondary prevention
• Secondary prevention (SP) must be seen as a
continuation of primary prevention. It forms an
important part of an overall strategy. The aim of
secondary prevention is to prevent the recurrence
and progression of CHD.
SP is a rapidly expanding field with much research in
progress (e.g., drug trials, coronary surgery, use of
pace makers).

27. Revascularization procedures for patients
with angina pectoris
The indications for coronary artery
revascularization i.e. coronary artery bypass
grafting (CABG) and percutaneous transluminal
coronary angioplasty (PTCA.)

28. RISK FACTOR INTERVENTION TRIALS
1. Stanford-Three-Community Study:
To determine whether community health education can
reduce the risk of cardiovascular disease, a field experiment.
• was undertaken in 1972 in three northern California towns
with populations varying between 12,000 and 15,000.
• In two of these towns intensive mass education campaigns
were conducted against cardiovascular risk factors over a
period of 2 years.
• The third community served as a control.

29. 2. The North Kerelia Project: A county in the eastern part of Finland,
where CHD is particularly common.
• Its 185,000 inhabitants work mostly in farming and forestry and live in
the countryside.
• Two aims : (a) to reduce the high levels of risk factors for
cardiovascular disease (e.g., smoking, blood pressure and serum
cholesterol), and
• (b) to promote the early diagnosis, treatment and rehabilitation of
patients with CV disease.
• A control population was established in a neighboring county which
has similar CV mortality.

30. Other trials were:
4. Oslow diet/smoking Intervention Study
5. Lipid Research Clinics Study
• Secondary prevention trials : Secondary
prevention trials are aimed at preventing a
subsequent coronary attack or sudden death.
3. The multiple risk factor intervention trial
(MRFIT) carried . out in USA was aimed at
high risk adult males aged 35-57 years.

31. Thank you