Friday, 13 March 2015

Cardiology CIA

When you have blood-fat numbers like mine, stumbling on to heterozygous familial hypercholesterolaemia (HeFH) papers, that actually bother to look at something other than the lipids, can be a fascinating experience. I could be wrong, but they seem to be fairly rare and I’m often starved of some good confirmation bias.

In 1985, Sugrue et al ran some numbers on a small group of people with, what they defined as, HeFH. Without today’s genetic screening tools, the eligibility criteria was slightly more ambiguous, but the fact remains that they all had fairly high levels of cholesterol – dodgy LDL receptors or not.

Of the 61 people they studied, 32 had evidence of coronary heart disease and the other 29 did not.  

Without even looking at the rest of the paper, those numbers should be worth noting. The oldest heart-healthy person was 59. Why she/he wasn’t whisked off to the bowels of Cardiology CIA (c’mon, surely there is such a thing) to be studied and dissected will remain a mystery, because Sugrue certainly ain't telling.

Long story short – after comparing those with CHD and those without, coagulation factor VIII and fibrinogen were significantly greater in the CHD group.

“There were no significant differences in any lipid variables between the two groups”
I’m not for a second suggesting that such a small sample size is indicative of anything in terms of coagulation-CVD cause and effect, because I also found this interesting chapter of a PHD thesis – in which they found (sort of) the reverse, i.e. certain coagulation factors were decreased in those with CVD. 

I think the author was funded by pharma and the whole thing was pretty ugly to read, but there was one glaring consistency in both studies - this group of 106 HeFH ‘sufferers’ also had a proportion that were, according to the doctors, heart disease free. Or at least a group with no prior cardiovascular event. 

Can you guess what the “no CVD” percentage was? A quarter? A half?

Eighty one (76%) of the 106 HeFH patients did not have a previous CV event. 

The two groups had very similar lipids (total chol of about 10.4 mmol/l), but the CVD group were older, fatter and probably male. I suppose the CCIA would claim that the CVD percentage would rise to 100% given enough time.

Whether the coagulation factors are THE deciding factors in who does or doesn’t develop CVD remains to be proven - they most likely play a role. But one thing that seems fairly clear, in these two examples at least, is that it’s certainly not the lipids.

Just a side note on the second paper, I found this comment interesting - “After 6 months of high dose simvastatin therapy, the present study showed an increase (12%, p<0.0001) of fibrinogen.”

Of course they were pretty quick to conclude that “the increase of fibrinogen by simvastatin is not related to clinical outcome, but rather a ‘side-effect’ of statin treatment".

Ha. Well played, sir.
Katherine Gorge is pretty quiet this time of year