ASSESSMENT OF CARDIOVASCULAR RISK

ASSESSMENT OF CARDIOVASCULAR RISK
M. Mohsen Ibrahim, Md
prof. of cardiology - cairo university
president of the Egyptian Hypertension Society
More than half. of coronary events occur unexpectedly and without warning
symptoms ; many of these are fatal.
Recognition of individuals at high risk of developing coronary events has become increasingly important in recent years because of the proven efficacy of both pharmacologic and non-pharmacologic interventions in prevention of cardiovascular disease.
Assessment of cardiovascular risk will help to identify those individuals who need aggressive life style modification, or require drug therapy.
Decision to treat asymptomatic patients with high blood pressure or dyslipedemia , extent of risk factors correction , and the need for noninvasive testing are important clinical implications of risk assessment.
Most of the methods used to predict future cardiovascular events are based on Framingham data where the residents in Framingham area (Massachusettes- USA) and their offspring are being followed for more than 50 years.
Definition of Risk Cardiovascular Endpoints
A number of endpoints can define the risk of developing cardiovascular events whether coronary or cerebral. Endpoints are used in epidemiologic and
Table 1
Cardiovascular Risk Factors
Idependent /Established Dependent/Emerging
* Homocysteine
* Lp (A)
Non-Modifiable *Small, Dense Ldl-Cholest
*Age * Other Lipid Disorders
*Gender *Abnormaliities In Blood Coagulation
*Family History * Coagulation Factors: V, Vll, Vlll
* Established Cvddis Plasma Fibriogen
Modifiable Coagulation Factors: V, Vll, Vlll
*Cigarette Smoking Platelets Abnormalities
*Hypertension Impaired Fibrinolysis: Pal-1
*Hypocholesterolemia *Inflammatory Markers
*Low Hdl - Cholesterol Reactive Protein
*Obesity Interlukins
*Diabetes Melitus *Impaired Glucose Tolerance
*Hypertriglyceridmia *Increased Oxidative Stress
Sedentary Life-Style *Personality Type
*Tachycardia
*Ethnic Group

experimental studies.
The question whether a certain therapeutic intervention is beneficial can be addressed through its effect on prevention, attenuation or delay in reaching these endpoints.
Endpoints are sometimes categorized as hard, soft and
surrogate.
Hard endpoints include totaI and coronary mortality, non fatal myocardial infarction, stroke and resuscitated cardiac arrest.
Examples of soft endpoint are angina, CABG,PTCA, days of hospitalization and time to first ischemic event
Surrogate endpoints include changes in parameters used in assessing cardiovascular disease progression such as coronary angiography, IVUS, MRI, ultrafast computed tomography, carotid artery duplex ultrasound, blood tests for inflammatory markers (e.g. hs CRP and CAMS) and changes in vascular endothelial function.
The Framingham investigators defined coronary heart disease (CHD) hard endpoints as myocardial infarction, unstable angina and CHD death.
Investigators assessing total cardiovascular risk add stroke to these hard endpoints.
Absolute and Relative Risk
The risk of developing a cardiovascular event or reaching an endpoint can be estimated in absolute and relative values.
Absolute risk is the probability of developing a cardiovascular event such as a hard endpoint over a given period of time e.g. the next 10 years.
If the absolute risk of an individual is for example 20% per 10 years, this means 20 of 100 such individuals will develop CHD or a recurrent CHD event within ten years.
To estimate the absolute risk for total cardiovascular events (CHD and stroke) the CHD risk is multiplied by a factor of 4/3.
Absolute risk levels rise progressively with age, even in the absence of risk factors.
Relative Risk is the ratio of the absolute risk of a given patient (or group) to that of a lower risk group.
The latter can be either the average risk in the whole population or in a group at very low risk i.e. devoid of risk factors.
The low risk state is defined according to Framingham as serum total cholesterol 160 to 199 mg/ dl. or LDL-C 100 to 129mg/dl, HDI-C more than 45mg/dl in men and more than 55mg/dI in women, blood pressure less than 120 mm
Hg systolic and less than 80 mm Hg diastolic in a non smoker and non diabetic.
Relative risk represents the ratio of the incidence of events in the exposed population (population with risk factors) divided by the incidence in unexposed persone.
A 3-fold increase in relative risk above the lowest risk level is designated moderately high risk, a 4-fold or greater increase is called high risk.
For patients without clinical atherosclerotic disease, the absolute risk of developing CHD or other atherosclerotic disease, during the next ten years, should strongly influence the intensity of lifestyle and therapeutic intervention.
In addition, as the absolute risk increases so the threshold for drug treatment of blood pressure and dyslipedemia should be lowered.
European recommendations
defined a high-risk state as10-year absolute risk for developing CHD of >20%.
This level of risk was identified as one that justifies management of the risk factors, particularly for the pharmacologic control of elevated blood pressure and cholesterol.
methods of assessment of cardiovascular risk
Clinical and laboratory evaluation : accurate measurement of blood pressure, weight and height, body fat distribution (waist circumference), testing blood for fasting blood sugar and lipid profile beside patient interrogation for positive family history, cigarette smoking, treatment of hypertension, diabetes or dyslipedemia is all what is needed for risk assessment.
Risk scoring and risk charts
A point scoring system has been developed by a number of investigators.
To each major risk factor (e.g.age, blood pressure, LDL, HDL-C, etc.) is assigned a number of points depending upon its level, the individual global risk is estimated by the sum of all points.
Global risk assessment is the estimation of absolute risk based on the summation of risk contributed by each risk factor.
Tables are available for risk points both for men and women that correspond to each risk factor (see Appendix). By consulting risk charts it is possible to determine both the relative and absolute risk of developing a CHD event in the next ten years.
Coronary risk charts are also developed by the European, British, Newzeland and canadian societies.
In European charts, risk of developing a cardiovascular event can be defined as very high when over 40%, high 20% to 40%, moderate 10% to 20%, mild 5% to 10%, and low when less
than 5%.
The most important risk factor in the point scoring system is aging.
Assess 10-years Absolute Risk Level For CHD
- Calculate The Number Of Points For Each Risk Factor
- Estimate Global Risk Score (Sum Of Points)
- Modify The Estimate In The Presence of other Risk Factors.
- Consult Coronary Risk Chart
American - Framingham
European
British
Newzeland
Canadian
Risk Score Modification:
The scoring system is modified by a number of factors which should be taken into consideration in global risk assessment and for the prediction of a severe single risk factor such as familial hyperlipedemia, uncontrolled hypertension, heavy cigarette smoking andyvery low HDL-C can increase the risk score above the sum of the total risk points.
A strong family history of premature CHD can impact incremental risk at any level of risk factors. The risk score is increased by a factor of 1.5 in presence of family history.
Obesity, physical inactivity and a number of emerging risk factors should be considered.
(SBP : systolic blood pressure
SBP-T: systolic blood pressure while on treatment, TC: total plasma cholesterol, Framin-S :standard Framingham risk factors, Framin -N: new Framingham risk factors used in risk scoring).
Certain ethic groups e.g.South Asian have higher absolute risk than whites.
Absolute risk varies among different populations independently of the major risk factors.
japanese have a much lower risk for CHD for a given set of risk factors than other populations.
Risk Score Modification
● SEVERE SINGLE RISK FACTOR
● Familial Hyperlipedemia
● Uncontrolled Hypertension
● Heavy Cigarette Smoking
● Very Low HDL-C
● STRONG FAMILY HISTORY OF PREMTURE CHD
● OBESITY
● PHYSICAL INACIVITY
● MULTIPLE EMERGING RISK FACTORS
● ETHIC GROUP
Limitations of Risk Scoring system
This system for prediction of CHD is based upon follow - up data from the Framingham Heart Study in USA in a white population.
It is possible that the presence and the extent of the relations between Framingham risk factors and the future development of CHD may be different in other populations and ethic groups, the risk scoring system may not accurately predict CHD in these populations.
Furthermore, the scoring, system does not take into consideration the presence of emerging, conditional and predisposing risk factors.
adjustment for positive family history and at the presence of a very high risk factor have been referred to in previous sections.
Implications
The most important practical implication of cardiovascular risk assessment is to define the need for initiating pharmacologic intervention in the asymptomatic patient.
A simple approach is to define the risk category of the individual as recommended by the Third Report of the National Cholesterol Education Program.
Based upon the probability of developing CHD (myocardial infarction, unstable angina or coronary death) in the next ten years three risk categories can be identified, high, moderate and low.
Patients with CHD, or CHD risk equivalents belong to the high risk category where the risk exceeds 20%.

Patients with clinically manifest CHD or other atherosclerotic disease have already declared themselves to be at high risk of further coronary or other vascular events.
CHD risk equivalents include patients with diaibetes mellitus, clinical atherosclerotic disease e.g. abdominal artic aneurysm, carotid artery disease and individual with multiple risk factors who have according to their risk score a CHD risk in ten years more than 20%.
In this high risk group drug therapy in addition to life style modification should be initiated with aggressive risk factors reduction , Individuals in the moderate risk category carry a CHD risk in the next ten years between 10 and 20%.
In this risk group are individuals with multiple risk factors.
Clinical judgment should be used in this moderate risk category before starting drug treatment taking into consideration the cost-effectiveness of pharmacologic therapy , sometimes non invasive testing to detect myocardial ischemia or subclinical atherosclerosis is needed.
Individuals with no or only a single risk factor are at low risk of CHD less than 10%.
There is no need for risk scoring in this group, but one should know that simply being a male is a risk factor.
An example of the practical impllications of this approach is the definition of LDC- cholesterol goal.
In the high risk category i.e. CHD and CHD risk equivalent, the goal is less than100mg/dl, in the moderate risk. (two or more risk factors) the goal is less than 130mg/dl, in the low risk category (0-1 risk factor), the LDC goal is less than 160mg/dl.
Initiation of drug therapy in the low risk group (0-1 risk factor) will
depend upon the severity of the
single risk factor and the presence or absence of multiple conditional and predisposing risk factors.
An LDL-C equals or greater than 190mg/dl, a SBP greater than 180 mmHg and DBP greater than 110 mmHg are indications for drug therapy in the absence of other risk factors.
When LDL-C is in the range of 160-189mg/dl and SBP between 160 to 180mmHg, DBP between 100-110 mmHg, one has to consider other risk factors and the probability of CHD risk in ten years before initiating drug therapy.
Individuals with an absolute CHD risk as low as 15% (equivalent of cardiovascular risk of 20%) over ten years do benefit from blood pressure and lipid lowering therapies that reduce coronary and cardiovascular morbidity and mortality, but the cost at the population level will
be considerable.
As a minimum all individuals with an absolute CHD risk of 30%
or more over ten years should receive aggressive therapy with intensive risk factors reduction.
NO LONG-TERM BACK PAIN FROM EPIDURAL DURING LABOUR
Epidural analgesia given during labor does not result in higher incidences of long-term low back pain, disability, or movement restriction compared with other methods of pain relief.
Although epidural analgesia is given to some 100,000 British women each year during labour, little is known on long-term effects. Anecdotal reports or case series have concentrated on more severe side effects, such as extremely rare neurological complications, and earlier studies into back pain and epidural analgesia have produced inconsistent results.
In light of the great human, medical, and economic costs of chronic low back pain, Dr. Charlotte Howell, anaesthetist, and colleagues at the Academic Department of Obstetrics and
Gynaecology, North Staffordshire Hospital, Stoke on Trent, England carried out a comparative, randomised, controlled trial.
in the study, 123 women in labour received epidural anesthesia and 133 received non-epidural pain relief. There were no significant demographic or other differences between the groups.
At follow-up at a mean of 26 months, clinicians assessed self-reported low back pain, disability, and limitation of movement through individual interviews between patients and physiotherapists, a questionnaire on back pain and disability, and physical measurements of spinal mobility.
Results showed that about 33 percent of patients in each group reported pain in the week before interview, but there were no significant differences in the onset or duration of low back pain, self-reported measures of disability in activities of daily living, or measurements of spinal mobility