When this happens ...
What be your response?
Happily the plumber fixes it. He explains that this is a problem with blockage in the pipes that he had to clear.

You tell your neighbour about your lucky escape with your life.
A few months later, your neighbour starts to notice his sink being slow to drain. He realises that this too is caused by clogging up of the pipes, although not a catastrophic complete blockage.

What should he do?
First few answers are 100% correct.

Same problem, but less drastic version.

Same solution, but less urgent.
When you have chest pain at rest, we have now trained the world to call 911 to get a stent put in to clear the blockage.

That is completely correct.
Since the right treatment of acute coronary syndrome is

"urgently go to hospital to get a stent",

then any sensible person (general physician or patient) will, default to assuming the right treatment of chronic stable angina is

"non-urgently go to hospital to get a stent".
Who is responsible for pointing out that this is not the case?
To put it in the words of Alex Nowbar and Chris Rajkumar (rcpjournals.org/content/clinme…)
You can't blame us for thinking that "ischemia kills". There is lots of observational evidence for it.

e.g. from CASS registry: Mortality versus number of diseased vessels
Many people have found it difficult to understand how the above graph can be true, and yet resolving ischaemia not dramatically slash mortality.

Here is the Nowbar-Rajkumar explanation.
I no longer mock those who stumble on this trap of logic.

It is a VERY easy trap to fall into.

Here is a document whose origin I will not state, other than to say it was written and/or approved by over 100 named signatories.

One year after ISCHEMIA reported.

See highlight.
At a meeting I showed this slide and asked some of the authors:

(a) Is the y axis cumulative or instantaneous? And if it is cumulative, why does it have bumps that go up and then down?
(b) What revascularisation strategy halves the rate of CV events compared with chronic stable disease?
(c) Most poignantly, what form of revascularisation causes the NON-revascularised arm to have a step up in events at time zero?

They were very angry. This surprised me, because they presumably they hadn't been so angry when the signed the document.


(a) They refused to be pinned down on whether it is cumulative or instantaneous. "It's just to give the feeling." (!)
(b) They refuse to suggest what form of procedural intervention halves the event rate chronically from day 1.

I offered the suggestion that perhaps the diagram shows a statin tablet, not a balloon?

Oddly this generously-offered escape route did not resolve their frowns.
(c) "We don't have to have a reason for the vertical positioning at the beginning".
So Figure 1 of the paper is one where:

- they don't know what the Y axis is
- they don't feel responsible for the relative slopes
- they don't feel responsible for the vertical positioning
Some people are excited that thallium scanning predicts CV events.

But the same is true for exercise testing.

And Stress Echo

And Stress MRI

Let's face it, the same is true for asking patients their age, or just seeing if they look bald.
Here are a few graphs. I can't be bothered telling you which one is which modality.
It's Exercise testing, stress echo and thallium
Or maybe

Exercise stress Echo,
Smoking status and
Baldness quotient
If you are really bored you can read the paper and work out which is which, but I wouldn't bother. It's not a good use of your time.
Francis's First Law of Prognostic Markers

Obviously, Duh."
So why would having INDUCIBLE ischaemia make you die?
I think all are plausible answers. It is entirely plausible that having episodes of ischaemia kill you.

Just like having episodes of asthma, even if they are not fatal, might gradually cause some sort of injury to the lung (inflammatory cells and whatnot), who knows? Plausible.
And even the argument "If god had meant us to have ischaemia, he would have given us all ischaemia" carries weight with me.

I have difficulty believing it is beneficial to acquire inducible ischaemia (although I know some people argue the point with preconditioning etc).
In the Nowbar-Rajkumar thesis:
A summary of COURAGE and its biggest flaw:
With the confirmed safety in the COURAGE cohort, ISCHEMIA could take the very difficult next step to prevent that flaw.
COURAGE and ISCHEMIA revealed our glistening edifice to be less solid than we had assumed.

Time to retreat.
Time to retreat!

"Take the outer city, we don't care! It's just some rubbish buildings we never liked anyway."

"We never believed revascularisation would improve prognosis! (even though we still secretly do: just look at the green bar graphs! look at Mystery Figure 1!)"
We can barricade ourselves into the inner sanctum of the citadel, for the last stand.


"At least the damn things stops you getting angina!
We know that for 100% certain. Don't we?"
What happened next?

I won't spoil your fun.

Read the whole story here:


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More from @ProfDFrancis

23 Dec 20
Tony Blair is (for once) right that the most efficient use of the limited vaccine supplies would be to give everyone (who wants it) one dose, and once that is all done, and more vaccine is available, go back for 2nd doses.
HOWEVER, much as I love to kick the government, I can see fully why they are NOT doing this.

If I was the head of my village in Outer Francisia, and I had only n vaccine doses for my n people, I would give them all 1 each. (If I had less, I would give to the most at-risk)
... based on this startling graph
Read 49 tweets
15 Dec 20
Very interesting question. People do still seem to misunderstand that creatures need to have an aim in mind when they do things.

The beauty of life was that it needs no more explanation than a ball rolling down a hill.
You could say that the ball "wants" to go lower if possible. But ultimately it is being dragged that way by gravity.

We can use the term "want" loosely, when describing inanimate objects:

"The heat in this oven wants to spread out evenly"

But we know it is only shorthand
The mistake that leads people to think that viruses and other creatures particularly want to spread, is that Darwin's principle is often quoted as "Survival of the fittest", and we often misunderstand that as "Survival of the fittest creature".
Read 22 tweets
9 Dec 20
Because of the 0.3%, i.e. 180,000 who die, and the few million who end up ill in hospital.

1. Because despite having lived cosseted lives where everything is provided for us from cradle to grave, be it food, security, education, healthcare, or law and order,

SOMEHOW many young people I come across seem to have a higher sense of civic virtue than you...
Read 13 tweets
8 Dec 20
Yes that sentence made me laugh.

Of course it can't be "stenosis per se" because there is no single index of "stenosis per se" for a patient.
If you had a high resolution map of everything what would you use?

How about tightest percent stenosis anywhere in coro?
If you thought it was great then you are going to rate a person with an isolated 75% stenosis of the distal RCA worse than a person with five 70%ish stenoses of each of the LAD, CX, RCA, Om1 and D1.
Read 19 tweets
8 Dec 20
Suppose you motor-bike to work every day. @rallamee nags you, "Why don't you wear a crash helmet, it is safer, blah blah blah."

If you wear a crash helmet today (ONLY), how will it improve your survival curve?

(Hazard = death risk on a particular day)
That baffled people, sorry. This isn't supposed to be the hard bit.

Wearing a crash helmet TODAY makes my motorcycle riding safer for me TODAY.

I go back to no-helmet from tomorrow onwards. Does the fact that I had worn a helmet today, make tomorrows ride safer?
Being a non-smoker today helps me not die today.

Does whether I smoke today have any influence on the probability of me surviving through the whole of 8 Dec 2030, GIVEN THAT I survive up to the end of 7 Dec 2030?

i.e. can smoking today cause _future_ death?
Read 23 tweets

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