1. Director, Lipid Research Center The Johns Hopkins Medical Institutions
CRC 2012 What Is Role of LDL and HDL Subfractions in the Evaluation of Patients with CVD: Quantity Versus Quality
Peter O Kwiterovich, MD
Director, Lipid Research Center
The Johns Hopkins Medical Institutions

2. Peter O Kwiterovich, MD Research Grants Merck Pfizer Abbott
GlaxoSmithKline
Advisory Boards
Lipo Science

4. Observational Epidemiology
LDL cholesterol
HDL cholesterol
The original total cholesterol association has been refined to show that:
higher plasma LDL-C and TG increases risk for MI whereas higher HDL-C decreases risk for MI
Emerging Risk Factors Collaboration, JAMA 2009; 302:

5. HDL Cholesterol Level - An Epidemiological Risk Factor: Causal or Not?
Two Possible Major Approaches

6. Mendelian randomisation Random allocation of alleles
Approaches to help judge HDL causality
Drug interventions
Mendelian randomisation
Population
Random allocation of alleles
Genotype aa
Genotype AA
Biomarker
higher
lower
CV event
rate lower
rate higher
Genetics
RCT
Sample
Randomisation
Intervention
Control
Biomarker
higher
Biomarker
lower
CV event
rate lower
CV event
rate higher
Slide courtesy of John Danesh
Hingorani et al, Lancet 2005

7. PCSK9 R46L, Plasma LDL- C, and MI Risk
Theoretically predicted
Observed
LDL Difference
Odds Ratio for MI:
0.54 (0.40 – 0.72)
P=2x10-5
N=3490 cases,
3497 controls
OR = 0.84
OR = 0.54
(0.40 – 0.72)
3490 MI cases,
3497 controls
46L carriers have
16 mg/dl lower LDL
P<10-8
Kathiresan, N Engl J Med 2008a
Kathiresan, N Engl J Med 2008b

8. HDL: Endothelial Lipase Asn396Ser
1 in 67 people carry Serine allele
higher HDL-C
No effect on other lipid fractions
No effect on other MI risk factors
Edmondson, J Clin Invest 2009

9. LIPG N396S, Plasma HDL-C, and MI risk
Theoretically predicted
Observed
HDL Difference
Odds Ratio for MI:
0.54 (0.40 – 0.72)
P=2x10-5
N=3490 cases,
3497 controls
396S carriers have
5.5 mg/dl higher HDL
HR = 0.84
( )
HR = 1.12
(0.91 – 1.36)
Voight, in press

10. Effect of Lifestyle Modifications on HDL-C Levels and HDL Components
Singh, I. M. et al. JAMA 2007;298:
Copyright restrictions may apply.

12. Plasma Lipoproteins Characterized by Their Density and Size
Chylo-
microns
Plasma Lipoproteins Characterized by Their Density and Size
0.95
VLDL
Chylomicron
Remnants
1.006
IDL
Density (g/ml)
1.02
LDL
1.06
Lipoprotein particles have historically been segregated into groups based on common physical size (abscissa), density (ordinate), core cholesterol and triglyceride content, and surface apolipoproteins present. The most common class groupings appear above. The lower the hydrated density, the greater the core lipid content and size, and the lower the content of apolipoproteins. The triglyceride-rich lipoproteins chylomicrons and VLDL are large particles that are catabolized into smaller remnant particles, chylomicron remnants and VLDL remnants, such as IDL. Once most of triglyceride has been removed from the triglyceride-rich particles, the cholesterol- rich LDL remains. LDL also has subclasses that vary in size from large, medium and small. The smaller, cholesterol-rich HDL exist as at least two subclasses, HDL2 and HDL3. Lp (a) is an LDL molecule to which is attached apo (a).
Each lipoprotein class is therefore composed of a continuum of individual lipoprotein particles, which span a defined range of size or density. The number of individual lipoprotein particles present within a class varies not only from one patient to another, but, can be affected in the same patient over time by development or expression of co-morbidities, diet, activity, or medication.
Conventional lipid assays determine the amount of cholesterol or triglyceride carried by all particles within a lipoprotein class. While this approach allows for a generalized assessment about the lipoproteins involved in lipid transport, it does not allow for quantification of the number or characterization of the size of individual lipoprotein particles present. Methods such as nuclear magnetic resonance spectroscopy do provide an assessment of the number and size of the lipoprotein subclasses.
HDL2
Lp(a)
1.10
HDL3
1.20 5 10 20 40 60 80
1000
Diameter (nm)

13. Framingham Offspring Study (n=3,066)
CHD Event Associations of LDL-P versus LDL-C
Framingham Offspring Study (n=3,066)
Years of Follow-up
Event-Free Survival
Low LDL-C
High LDL-P
(n=282)
High LDL-C
Low LDL-P
(n=284)
Better survival
Lower risk
Worse survival
Higher risk
(n=1,249)
(n=1,251)
Concordant
Discordant
Cromwell WC et al. J Clin Lipidology 2007;1(6):

14. Population Equivalent Cut points for Alternate LDL Measures
(LDL-C, Measured Apo B and NMR LDL-P)
Biomarker
Population
Percentile Equivalent Concentration
< 5th
20th
50th
80th
LDL-C (mg/dL)
Framingham1
< 70
100
130
160
Measured Apo B
(mg/dL)
< 60 80
120
NMR LDL-P (nmol/L)
< 850
1100
1400
1800
MESA2
< 700
1000
1300
1600
1 Contois, et al. Clinical Chemistry 2009;55:
2 Mora S, et al. AHA/ADA Met Syn/Met Risks, San Francisco, May 3-5, 2006

15. Lipoprotein Particle Subclasses as Predictors of CHD Events
***
*** **
*** **
*** *
Adjusted for treatment, age, diabetes, hypertension, smoking, and BMI
*p< **p< ***p<0.001
Otvos JD, et al. Circulation 2006;113: 15

16. HDL-C and HDL-P are Affected Differently by Most (All?) Interventions
Cholesterol per particle decreases with:
statins
ezetimibe
fibrates
Cholesterol per particle increases with:
niacin
glitazones
omega 3 FAs
CETP inhibitors
exercise
HDL-P more than HDL-C
HDL-P less than HDL-C

17. On-Trial LDL Particle Subclasses as Predictors of CHD Events in VA-HIT
Adjusted values were from a model containing all LDL, and HDL subclasses together, adjusted additionally for treatment group, age, hypertension, smoking, body mass index, and diabetes.
Otvos JD, et al. Circulation 2006;113: 17

22. Abnormal Metabolism of Deficient HDL in Atherogenic Dyslipidemia
Kontush A and Chapman MJ Pharmacol Rev 2006; 58:

24. Summary and Interpretation
1. Increasing amounts of a physiologically normal HDL-C decreases risk for CAD in the general population but the explanation for this relationship is complex and involves both environmental and presumably genetic factors that have yet to be identified.
2. A threshold may exist, where the generation of oxidative molecules disrupts the structure and metabolism of HDL rendering it dysfunctional and atherogenic.
3. The aggressive treatment of LDL-C has been unequivocally shown to decrease risk of both primary and secondary CAD. Subsets of patients exist who have increased LDL-P out of proportion to LDL-C who should be identified and treated accordingly.
4. It remains to be determined if increasing HDL-C or HDL-P per se will decrease risk of CAD.
5. In the meantime decreasing the atherogenic and oxidative milieu particularly in patients with diabetes, the metabolic syndrome and the dyslipidemic triad (increased LDL-P and triglycerides and low and possibly dysfunctional HDL) and with other risk factors is a reasonable therapeutic option.