CORONARY HEART DISEASE
Dr. Urfi
Definition
• 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
• Modern epidemic
• Responsible for 25-30% of deaths in most industrialized countries
• Not an unavoidable attribute
Spectrum
• Angina pectoris
• Myocardial infarction
• Irregularities of heart
• Cardiac failure
• Sudden death
Has variable course of natural history
Burden of disease
• CVDs are the number 1 cause of death globally: more people die annually from CVDs than from any other cause
• An estimated 17.9 million people died from CVDs in 2016, representing 31% of all global deaths. Of these deaths, 85% were due to heart attack and stroke
• Proportional mortality ratio: 30% of all deaths in males and 25% in females
• Loss of life expectancy: average gain would be from 3.4 years to 9.4 years for males
• CHD incidence rate
• Age specific death rate
• Prevalence rate
• Case fatality rate (within 28 days of onset)
• Measurement of risk factor levels
• Medical care
Epidemicity
• Epidemics began at different times in different countries
• United States-began in 1920s; declined by 1968
• Britain-1930s
• Other European countries-still later
• CHD is still the single most frequent cause of death among men < 65 years
• Highest mortality in European regions followed by South-East Asia region
• Japan-lowest incidence in developed world
India
• Single most important cause of death (2015)
• Steep increase in urban areas as compared to rural areas
• Prevalence: Urban (6.4%); Rural (2.5%)
• Overall prevalence -37/1000
• According to medical certification of cause of death in India-25.1% of all urban deaths are due to CHD
• Mortality rate due to IHD: 132/ lac population
IHD among South Asians
• Tends to occur at an earlier age; mean age of onset is almost a decade earlier
• Females: Males ratio higher as compared to developed world
• Case-fatality is higher
• Occurs in presence of normal or near normal levels of conventional coronary risk factors
Risk factors
• Aetiology is multifactorial
Non-modifiable Modifiable
Age Cigarette smoking
Sex High blood pressure
Family history Elevated serum cholesterol Genetic factors Diabetes
Personality Obesity
Sedentary habits Stress
Smoking
• Major risk factor; doubles the risk
• 25% of CHD deaths in <65 years male
• Important cause of sudden death in <50 years male
• Risk is directly related with no. of cigarettes smoked per day
• Independent risk factor as well as synergistic with other risk factors
• Risk of death decreases substantially within one year of quitting and by 10-20 years is same as non-smoker
• MI patients- fatal recurrence is reduced by 50%
Smoking
Mechanism s
CO induced atherogenesis
Nicotinic + of adrenergic drive
raising BP and Oxygen drive Lipid metabolism
with fall in protective HDL
Hypertension
• Single most useful test for identifying individuals with high risk
• Accelerates atherosclerotic process (more so if hyperlipidaemia is present)
• Systolic BP is better predictor of CHD
• Treating raised BP reduces risk of MI by 16%
Serum cholesterol
• Elevation associated with increased risk of MI and CHD as whole
• Triangular relationship between habitual diet, blood cholesterol-lipoprotein levels and CHD
• Threshold level: 220 mg/dl or more
• LDL (apolipoprotein-B) is most directly related with CHD
• VLDL is more important for peripheral vascular disease than CHD
• HDL (apolipoprotein A-I) is protective
• Total cholesterol/HDL ratio of <3.0 is the clinical goal for CHD prevention
Diabetes:
• Risk of CHD is increased to 2-3 times
• CHD accounts for 30-50% of deaths in diabetics >40 years of age
Genetic factors:
• Positive family history increases the risk
• Most important determinants of individual’s TC and LDL levels
Physical activity:
• Sedentary life-style
• Regular physical activity increases HDL and decreases body weight and blood pressure
Hormones:
• Hyperestrogenemia leads to atherosclerosis ---->CHD, Stroke, Peripheral vascular disease
Type A personality:
• Type A > Type B personality
• Associated with competitive drive, restlessness, hostility, urgency, impatience
Alcohol:
• High alcohol intake (75 gm or more per day)
Oral contraceptives:
• Higher systolic and diastolic BP
• Higher risk of MI
Miscellaneous:
• Possible role of dietary fibre, sucrose, soft water, dysnoea on exertion and low vital capacity
Prevention
A. Population strategy
• i.
Prevention in whole population• ii. Primordial prevention in whole population
B. High risk strategy
C. Secondary prevention
A. Population strategy
Principle:
Small changes in risk factor levels in total populations can achieve the biggest reduction in mortalityAim:
To shift the whole risk factor distribution in the direction of “biological normality”Specific interventions:
1. Dietary changes:
• Reduction in fat intake to 20-30% of total energy intake
• Saturated fat <10% of total energy intake
• Dietary cholesterol <100mg per 1000 kcal per day
• Increase in complex carbohydrate
• Avoid alcohol
• Daily salt intake to 5gm or less
2. Smoking:
• To achieve smoke free society
• Effective information and education activities, fiscal measures and smoking cessation programmes
3. Blood pressure:
• Even a small reduction in average BP (2 or 3 mm Hg) would produce a large reduction in incidence in cardiovascular complications
• Aim is to reduce the mean population BP levels
4. Physical activity:
Primordial prevention:
• Particularly important for developing countries
• Preventing the emergence and spread of CHD risk factors
• Aim is to change the community as a whole, not individuals subject
B. High risk strategy
i. Identifying risk
• BP measurement
• Serum cholesterol
• Those who smoke
• Family h/o CHD
• Diabetes
• Obesity
• Young women on OCPs
ii. Specific advice
• Preventive care
• Motivation to take
positive action against all identified risk factors
Disadvantage of high risk strategy
• Intervention (treatment) may be effective in reducing the disease in a high risk group,
• But it may not reduce the disease to the same extent in the general population, which consists of symptomatic, asymptomatic, high risk, low-risk and healthy people
• More than half of CHD cases occur in those who are not apparently at special risk
C. Secondary prevention
• To prevent recurrence and progression of disease
• 25% of those who suffer from acute MI die within 1 hour & would never reach the hospital; another 8-10% would die in next 24 hours in the hospital; among survivors 10% die within first year
• Drugs (role of beta-blockers)
• Surgery (CABG, PTCA)
• Preventive measures- Cessation of smoking, control of BP and diabetes, healthy nutrition, exercise promotion
WHO Response
• All Member States ( 194 countries) agreed in 2013 on global mechanisms to reduce the avoidable NCD
burden including a "Global action plan for the prevention and control of NCDs 2013-2020“
• This plan aims to reduce the number of premature deaths from NCDs by 25% by 2025 through nine voluntary global targets
National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular
Diseases and Stroke (NPCDCS)
• Launched in 2010 in 100 districts across 21 States, in order to prevent and control the major NCDs
• The main focus of the programme is on:
Health promotion, Early diagnosis,
Management and referral of cases,
Strengthening the infrastructure and capacity building
Main strategies of NPCDCS
• Health promotion through behavior change
• Outreach Camps are envisaged for opportunistic screening at all levels in the health care delivery system
• Management of chronic Non-Communicable diseases, especially Cancer, Diabetes, CVDs and Stroke through early diagnosis, treatment and follow up through setting up of NCD clinics.
• Build capacity at various levels of health care
• Provide support for diagnosis and cost effective
treatment at primary, secondary and tertiary levels of health care
• Provide support for development of database of NCDs