The effects of Vitamin K2 supplementation on the progression of Coronary Artery Calcification

Coronary Artery Calcification (CAC) is a strong predictor of cardiovascular
events. Not only CAC in itself, but also its annual progression is
independently associated with cardiovascular events and mortality. There is
increasing evidence that arterial calcification in atherosclerotic disease is
not merely a passive epiphenomenon of atherosclerosis, but actually plays an
active role in further atherogenesis and plaque-stability. The development of
arterial calcification results from imbalance between calcification-promoting
and inhibiting factors. An important inhibitor of calcification is Matrix Gla
Protein (MGP), a protein present in the vascular wall where it is synthesized
by Vascular Smooth Muscle Cells (VSMC). MGP requires Vitamin K-mediated
carboxylation to function properly. Deficiency of Vitamin K has been
demonstrated to cause arterial calcification and in observational studies, a
diet containing large amounts of Vitamin K2 was associated with lower CAC and
cardiovascular risk. In animal studies, active supplementation of Vitamin K2
caused regression of existing arterial calcification. To date, no controlled
trials with Vitamin K2 have been performed in humans.

The primary objective of this study is to determine whether daily oral
supplementation of Vitamin K2 will slow down or arrest CAC-progression after 12
and 24 months in comparison to placebo in patients with established CAC.
Secondary, we wish to determine whether oral vitamin K2 supplementation will
inhibit the development of new calcified coronary lesions, alter parameters of
arterial stiffness, such as the carotid-femoral Pulse-Wave Velocity (PWV) and
central Aortic blood-pressure and parameters of non-coronary atherosclerosis
such as the carotid Intima Media Thickness. Finally, we will study the effects
of Vitamin K2 supplementation on the blood-concentrations of Osteocalcin and
MGP and assess whether changes in MGP concentrations are correlated with
changes in CAC-progression

Randomized, placebo-controlled, double-blind clinical trial. Subjects will be
followed-up for 24 months with measurements of the primary and secondary
outcomes at 0, 12 and 24 months.

Daily oral capsule containing 360 micrograms of menaquinone-7 (Vitamin K2) or a
daily placebo-capsule that is identical to the other intervention except for
the presence of menaquinone-7.

The most important risks and disadvantages of this study are:
- Radiation exposure due to CT-scanning
- Possibly adverse reaction to iodine-contrast agents
- Blood-sampling by venipuncture
- The requirement to take one capsule per day
- Time-investment for follow-up visits.

The radiation-exposure per CT-scan varies between 2 and 6 mSv. Since we aim to
use dose-reduction techniques, the mean effective radiation dose is estimated
to be 1- 3 mSv per CT-scan. We estimate that we can apply these
reduction-techniques in 90% of all study-participants. In total, two CT-scans
will be made for the purpose of this study (after 12 and 24 months of
follow-up). The first follow-up scan will only consist of calcium scoring (0.9
mSv) In a study on the lifetime attributable risk on cancer after a standard
64-slice coronary CT-scan, the risk was 0.35% and 0.22% for a 40-year-old and a
80-year-old woman respectively (Einstein et al.). The mean effective dose was 9
* 29 mSv and no dose-reduction techniques have been applied in this study. In
our proposed study, the effective radiation-dose will therefore be 7 to 23 mSv
lower than in the study mentioned above.
We will use iodine-contrast in our study. In rare cases (0.1%), an allergic
reaction may occur after administration of iodine contrast. Since we will not
include patients with renal insufficiency, we estimate the risk of
contrast-induced nephropathy to be very low.

In all subjects, 25 ml of blood will be obtained three times by venipuncture.
This possibly may cause a small hematoma.
Finally, we will require participants to take a capsule every day for 24 months
and to visit the hospital every six months for follow-up. On the first visit
and after 12 and 24 months, the visit will consist of physical examination,
ultrasonography, blood-sampling and the follow-up CT-scan (at 12 and 24
months). These investigations will take approximately 2 hours. The remaining
follow-up visits after 6 and 18 months will only take 15 * 20 minutes and
consist of a short interview about the study and medication, measurement of the
blood-pressure and providing the capsules for the next period.

In our opinion, this study can be justified with regards to risks and burdens
because this study may lead to a new (additional) therapy for calcified
coronary atherosclerotic disease; a condition that is associated with a high
morbidity and mortality. In addition, the role of calcification in
atherosclerosis and plaque-stability is not yet fully understood. This study
will provide more insight into these matters.