Here
are some important information for your kind consideration, which will give
you additional information to diagnose
1.
Coronary
Heart Disease (CAD)
2.
Ischemic
heart disease (IHD)
3.
Assessment
of the effectiveness of pharmacological treatment
with lipid lowering Drugs
using
latest diagnostic techniques available in laboratory
medicine.
The information provided will be useful for your reference.
Diagnostic
Relevance of Apo A1 and Apo B Measurement:
·
Apolipoproteins
A1
is the major protein of HDL and Apolipoprotein
B
is the main part of LDL, but also present on VLDL and Intermediate Density
Lipoproteins (IDL). Each of the
three particle classes LDL, IDL and VLDL carries exactly one molecule of Apo
B
per particle, the latter is a measure for the total number of LDL, IDL and
VLDL.
·
The
liver secrets a Triglyceride rich lipoprotein, VLDL, which by the removal of
the most of its Triglycerides is converted to a smaller Cholesterol rich
Lipoprotein, LDL. The biological
Half Life of an LDL particle is at least 9 times longer than that of a VLDL
particle and, therefore, there are always 9 times more LDL particles than VLDL
particles. Because each
VLDL and LDL particles contains one molecule of Apo
B,
measuring plasma Apo
B
measures exactly the total number of VLDL and LDL particles, that is 90%
of which is LDL.
·
As
LDL particles differ substantially from one another in the amount of
cholesterol they contain, Total and LDL cholesterol are imprecise measure the
number of Apo
B
particles. Therefore measuring Apo
B,
provides a direct estimate of the total number of atherogenic particles
·
Apo
B
measurement can be performed on non-fasting samples.
·
Elevated
Apo
B
levels were associated with an increased risk, independent of the LDL particle
size as per the study conducted by Dr. Benoit Lamarche, Dr.Ande Tchernof
and Dr. Bernard Cantin on 2103
men initially free of IHD, among whom 114developed IHD during a 5 years follow
up period. These 114 case
patients were matched with health control subjects for age, body mass index,
smoking habits and alcohol intake. The
study found that individuals having both elevated Apo
B
levels and Small LDL particles showed the increase in IHD risk by 6 folds. The
study found that among lipids, lipoproteins and apolipoprotein variables, Apo
B
individually and Apo B:Apo A1 ratio is the best and only significant
predictor of IHD.
·
The
Quebec Cardiovascular study found that Apo
B
concentration was the best metabolic predictor of IHD risk.
·
The
study suggests that prevention and treatment of IHD should only be focused on
reducing the number of LDL+VLDL+IDL particles, that is Apo
B
concentration rather than altering the size of the particles.
·
The
study by Dr. Judith F Lynch and Dr. Michella D Marshell in Australian
children, of 6992 (3501 boys and 3491 girls) aged 5-13 years, between
1991-1995 showed that Indian children had the highest levels of Apo
B
and Apo B:Apo A1 ratio. This
suggests that, when the food habits and life style is altered or changes the Apo
B
gets elevated and Indians are prone to retain additional Cholesterol in their
body.
·
As
per Dr. N. Sahi and Dr. G. S. Salinani, Apo
A1
and Apo
B
ratio has emerged as a better predictor of angiographically assessed coronary
artery disease. In 17.3% of
cardiac population, the levels of HDL cholesterol and LDL cholesterol were
considered to be normal, the Apo B:ApoA1 ratio was increased, as per
the study conducted in Jeslok Hospital, Mumbai.
Suggestions:
1.
Why
should we not measure Apo
A1
and Apo
B
in routine practice if it improves the prediction of risk and the outcome?
2.
If
statin therapy is chosen, the evidence described, suggests that only Apo B
need to be measured in follow up. That
is, care would be simpler for the patient, in that, fasting is not necessary
and simpler for the physician in that only one result, and not all the 5, need
to be considered and tested on. Simpler
care would translate into more cost effective care.
3.
Please
note, we would emphasize that we are proposing
modification, not abolition,
of the present system. Apo A1 and
Apo B should not be the only parameter measured in the initial assessment of
the risk of disease due too lipids.
Conclusion:
Given the importance that has been assigned to Cholesterol, change will
not be easy in the initial periods. But
however, we shall have the regular Cholesterol testing for a period of time
with Apo A1 and Apo B in the lipid profile.
Change is the price of progress.
Given the potential for benefit for our patients and our society, we
hope the Apo A1 and Apo B testing will prove the case.
How
to introduce these tests for your patients?
a
Apo
A1 and Apo B testing reagents costs only Rs 20/- each in your Hospital’s
Laboratory.
a
You
shall ask your laboratory to add Rs 100/- extra for the lipoid profile and ask
your laboratory to do Apo A1 and Apo B in the lipid profile.
That
is: If the charges for Lipid Profile is Rs 350/- you shall make it to Rs
450/- including Apo A1 and Apo B.
Your
Hospital Laboratory, as you are very much aware, is fully equipped to include
these tests for your patients.
Please
leave your comments below, about the change – the progress – you believe
to make and mail back to [email protected]