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COH 320 Week 2
Cardiovascular Disease
According to the Mayo Clinic, cardiovascular disease “generally refers to conditions that involve narrowed or blocked blood vessels that can lead to a heart attack, chest pain (angina) or stroke”.
CVD and Mortality
CVD Mortality
CVD is the leading cause of death worldwide.
CVD caused 17.1 million deaths in 2009.
CVD caused 29% of all deaths in 2009.
Over 80% of CVD deaths occurred in low and middle-income countries.
Global CVD Mortality, 2009
Relative Mortality due to Cardiovascular Disease
Decline in CVD Mortality Developed Nations
Deaths from CVD have declined dramatically in developed countries (USA, Great Britain, Australia/New Zealand and western Europe).
Since 1970, US mortality from coronary heart disease and stroke declined approximately 50%.
This declining trend is due to major advances in the prevention and treatment of hypertension, hypercholesterolemia, ischemic heart disease, heart failure and related conditions that predispose to fatal heart attacks and strokes.
Decline in CVD Mortality: 1970-2000, USA
CVD and DALY
Disability Adjusted Life Years: CVD
The CVD burden is highest in developing nations of Asia, South America and Africa (DALY > 5,100 per 100,000).
DALY are lowest in more advanced societies of North America, Europe and Australia (DALY < 3,000 per 100,000).
Developing nations suffer more lost years of healthy life due to premature death from CVD (60-70%) whereas developed nations lose more years of healthy life due to disability from CVD (50-60%).
Cardiovascular Disease: Disability Adjusted Life Years (DALY), 2004
Risk Factors for CVD
Major Risk Factors for CVD
1. Tobacco Addiction
2. Elevated LDL Cholesterol
3. Low HDL Cholesterol
4. High blood pressure
5. Elevated Blood Glucose
6. Obesity
7. Physical Inactivity
8. Dietary Factors (Diet high in fat, salt and carbohydrates and low in fruits and vegetables)
Contributing risk factors-
Low Socioeconomic Status
Chronic Infection and Inflammation
Elevated Lipoprotein(a)
Psychological Factors (depression, anger proneness, hostility, stress, acute life-events, breakdown in social structures, loss of social support and cohesion)
Coronary Heart Disease (CHD)
Coronary Heart Disease (CHD) Global Burden
Of the more than 17 million deaths caused by cardiovascular disease annually, more than 7.2 million (approximately 42%) are attributable to coronary (ischemic) heart disease (CHD).
CHD is nearly always a consequence of longstanding atherosclerosis and the development of atheromatous plaques that occlude the coronary arteries.
CHD often culminates in myocardial infarction and sudden cardiac death.
Disability Adjusted Life Years (DALY) Coronary Heart Disease, 2004
High DALY were observed in developing nations including Russia, India, North Africa and the Middle East.
Low DALY were observed in developed nations (USA, Canada, Western Europe, Japan and Australia/New Zealand) and also in the Chinese population, most likely the result of improved prevention and treatment strategies.
Disability Adjusted Life Years (DALY) for Ischemic Heart Disease
Risk Factors of CHD
Major risk factors for ischemic heart disease have been called the “four horsemen of the apocalypse”.
They include cigarette smoking, hypertension, elevated cholesterol and type 2 diabetes mellitus.
Cholesterol measures are divisible into various fractions, e.g., high density lipoprotein (HDL) cholesterol and low density lipoprotein (LDL) cholesterol.
Smoking and Mortality from CHD British Physicians Study
Smoking and CHD
Tobacco carcinogens, reactive oxygen species (ROS) and other constituents and derivatives of cigarette smoke are highly inflammatory to blood vessels and appear to be cofactors in atherogenesis (Howard et al., 1998).
Smoking has also been found to elevate serum cholesterol possibly through effects on liver metabolism (Muscat et al., 1991).
Chronic smokers often develop severe chronic lung diseases such as emphysema and chronic bronchitis and such conditions compromise the oxygenation of hemoglobin thereby intensifying ischemic conditions in the myocardium and other tissues.
Smoking and CHD Effect of Nicotine
There are multiple biological mechanisms by which cigarette smoking and nicotine addiction elevate the risk of CHD.
Nicotine itself is a powerful vasoconstrictor that elevates blood pressure and causes hypertension.
The first cigarette of the day induces sharp increases in both systolic and diastolic blood pressure (Gropelli et al., 1992).
Diabetes and CHD
Coronary heart disease often follows the diagnosis of type 2 diabetes, particularly in individuals with uncontrolled hyperglycemia and hyperinsulinemia.
In the Framingham Study, the risk of developing CHD was increased nearly three-fold in diabetic men and women (Kannel and McGee, 1979; Kannel et al., 1990).
Many other studies have reported similar findings.
Prevention of CHD
Ischemic/Coronary Heart Disease is influenced by multiple interactive factors including tobacco addiction, hypertension, dyslipidemia, insulin resistance, physical inactivity and obesity.
These individual factors rarely occur in isolation and the degree of hazard depends on the number of risk factors present in a given individual.
Fortunately, most CHD risk factors are modifiable through lifestyle choices, e.g., abstinence from tobacco use and consumption of a heart healthy diet (Sanderson et al., 2007).
Myocardial Infarction on a Global Scale
Diagnosis of Myocardial Infarction
Myocardial infarction presents with sudden chest pain typically radiating to the left arm or left side of the neck in combination with shortness of breath, nausea, vomiting, heart palpitations, sweating and anxiety.
Approximately 25% of myocardial infarctions occur without warning in the absence of prior chest pain or other symptoms. Often, the onset of myocardial infarction is gradual over several minutes providing time for emergency treatment.
Myocardial Infarction and Mortality, DALY, Incidence, and Case Fatality
Global Mortality & Morbidity Myocardial Infarction
According to recent WHO data, myocardial infarctions cause 7.2 million deaths annually in the world population.
Of these, approximately 5.1 million deaths occur in the populations of developing nations at relatively early ages (median age 50 years).
The remaining 2.1 million deaths from myocardial infarctions occur at later ages in populations of developed nations (median age 65 years).
More than 5 million people survive myocardial infarctions every year, the majority in developed nations where emergency care is available.
Fatal and Nonfatal Myocardial Infarctions, World Population, 2009
Fatal
Nonfatal
DALY Myocardial Infarction
The world pattern of DALY from myocardial infarction is similar to that for coronary heart disease.
High DALY are evident in populous developing nations, compared to low DALY in developed nations.
High DALY are also apparent in the populations of poverty-stricken countries of central Africa such as Sudan, Chad, Ethiopia and Nigeria.
Global DALY for Coronary Heart Disease and Myocardial Infarction by Income Level
Time Trends of Myocardial Infarction Rates
In developed countries, myocardial infarction mortality rates have declined in past decades.
Paradoxically, investigators have found no evidence of a decline in the incidence of myocardial infarction either in men or women; and in fact, the incidence rates actually increased in certain years.
The paradox is explainable in that more sensitive diagnostic tests are routinely being used for hospitalized patients with chest pain, possibly shifting the diagnosis of angina pectoris to myocardial infarction in some patients thereby increasing the incidence of myocardial infarction.
Incidence of Nonfatal Myocardial Infarction, USA, 1987-1994
Decline in Mortality and Case Fatality due to Myocardial Infarction, USA, 1970-2005
40 %
30
20
10
Case Fatality (%)
Risk Factors for Myocardial Infarctions
Risk Factors for Myocardial Infarction
Since ischemic/coronary heart disease is the root cause of most myocardial infarctions, certain primary risk factors are synonymous including tobacco addiction, hypertension, hyperglycemia (elevated blood glucose), hypercholesterolemia (elevated blood cholesterol) and chronic inflammation.
Nevertheless, the abrupt nature of a heart attack also involves other factors. Heart attack rates increase with intense exertion, either from psychological stress or vigorous physical exercise, especially if the exertion is more intense than usual.
Primary Prevention of Myocardial Infarction
Since the major risk factors are modifiable, myocardial infarction is preventable.
Primary prevention is the reciprocal of exposure to proven risk factors.
Avoid tobacco, eat a heart healthy diet, maintain blood pressure, blood glucose and blood lipids (cholesterol) within normal limits, exercise daily, and maintain optimal weight for height.
Lifestyle Modification and Cardiovascular Disease
