Diastolic J-Curve - Heart Disorders Message Board

Lenin · 08-09-2006, 06:11 AM

I wasn't sure about where to place this discussion but decided on the HEART forum.

From several of the studies of antihypertensive drugs, it seems to be emerging that there may be a J-curve phenomenon especially with diastolic BP lowering for those people with coronary artery disease.

The INVEST study pointed the problem out as did several other major well controlled studies.

Basically a J-curve phenomenon in diastolic is a decreasing incidence of death, MI, and stroke as diastolic pressure is lowered TO A POINT...then an increase in incidence of these unfrotunate events starts occurring with further lowereing. For diastolic that point may well be very close to 80 mm.Hg.

The effect is pronounced in those with CAD, the elderly and in those with isolated systolic that is treated with the unfortunate result of lowering a normal diastolic as well.

It's may not be just a slight effect:

Quote:

Looking for a J Curve, researchers analyzed data
from the INVEST trial, which compared two blood pressure
lowering therapies in 22,576 patients with high blood pressure
and CAD. Results showed J-shaped relationships between
both systolic and diastolic blood pressures and the primary
endpoint of all-cause death, nonfatal heart attack or nonfatal
stroke. However, the J curve was much clearer for diastolic
blood pressure.
THE HEAD RESEARCHER SAID THAT
WHEN DIASTOLIC PRESSURE IN THESE PATIENTS
WENT BELOW 70, MORTALITY DOUBLED; AND
WHEN IT DROPPED BELOW 60, MORTALITY
QUADRUPLED. This seems to only apply to people with
CAD, sometimes called CHD for coronary heart disease.

I have noticed that my diastolics very often go into the 60's and really average only 70 on my antihypertensive regimen. I think I may have to let my numbers drift higher. I can;t complain if the hand of god deals me a mortal or near mortal blow...but I certainly don't want to do it to myself because I am trying to conform to my doctors notion of healthy.

Any thoughts?

Beefsteak · 08-09-2006, 11:35 AM

Hi Lenin,
You have a fertile mind, but at the moment we are juggling as many marbles as we can! Medications and naturopathy especially are very confusing.

There is no straight answer on so many things.

Just mention Lipitor in the blood channel and you end up having to fend off complaints from all around. (I was surprised just how strong the "anti-Lipitor" movement is.) But I am beginning to feel people, many people, are affected badly by these drugs and I wonder is there a message that is just not getting through. That's another story for another day.
I think the answer to your J-curve question is we cannot do anything until we know the mechanism better - otherwise we just confuse cause and effect. Without knowing any details it seems possible that as the heart begins to fail, in a serious way, then the blood pressure would no longer be properly maintained throughout the body. This is simply saying that there might be a point where performance of the "pump" begins to drop as the pump itself is destroyed (not a nice word but...

). Is your J-curve a sort of cross-over point? With any reasonable data that should be pretty easy to work out.
Where does that place you then, if you decide to increase your diastolic BP?
At a guess I would say it's risky because your heart may already be working hard enough and pushing it harder may just increase the deteriorative processes. Those that win through are quite possibly the ones with the intrinsically strong hearts right from the start, and you cannot join that group by raising your BP to their level. A linear study of several groups with different starting BPs and continuing through to their later lives might answer this. So in essence I'm saying that those with greater mortality, and the lower average BPs, are just those who had physically weaker or flawed hearts from the start, and they failed earlier.
As a layman in this area that's the best I can do!
Beefy.

CircusSquirrel · 08-09-2006, 01:35 PM

My husband is in the Army's physician assistant program, and when I worry about my blood pressure he always tells me about studies similar to that. He said they've had cardiologists lecture on it. Guess what is driving the "lower the better" blood pressure attitude, though? Of course you know---the drug companies!