How to work out the risk of one or more complications from an ablation (or any other medical procedure).

As I may have to have an ablation, I wanted to work out the risk of having one or more complications from the procedure. Information on some of the complications can be found on Royal Brompton’s website.o

I am just posting this her in case anyone finds it useful. I’m not suggesting that anyone needs to use it. Also, I’m not 100% sure about the accuracy of the calculation. Criticisms welcome.

First, I have assumed that the complications are independent (that is, one complication doesn’t influence another complication- that may not be correct, I am not medically knowledgeable enough to know).

Procedure:

1. Find (1-prob) for each complication independently.

2. The probability of NO complication is obtained by multiplying these results (ie the probabilities of no complication).

3. The probability of 1or more complications= the number just calculated.

Example

Suppose there are 3 complications (there are actually many more, this is just for illustrative purposes): their probabilities are 0.01, 0.02 and 0.05.

[if you wished, you could just use the probabilities of the complications you are most worried about]

1-0.01=0.99

1-0.02=0.98

1-0.05=0.95

0.99x0.98x0.95=0.92169

1-0.92169=0.07831

So the risk of one or more complications is nearly 8%.

This is a made up example , not related to the actual procedure.

[BobD Volunteer]

You do love your formulae ! Firstly is it my beleif that most risks are explained to prevent legal action against the doctors and hospital concerened rather than for the patient's comfort.

Secondly many risks depend an awful lot on the physiology of the patient. For examaple if a person had very thin heart walls then the risk of tamponade may be considerably higher yet be unknown prior to the procedure. Similarly damage to the oesophagus or vagus or phrenic nerves would have higher risk if these ran very close to the heart. None of these can be calculated and are luck of the draw. The risk ratio given is merely the result of comparison of cases over time not a mathematical certainty.

Add in Sodt's Law that some of us will attract disasters just because we are who we are and it is really a waste of time trying to ascertain if anything bad will happen. I once had a listed side effect to a procedure (not ablation by the way) which was most unusual. I once asked a leading professor in the field if he had every known it and in fifty years he had not although he did say that it was in the text books. One also signs the consent form listing this possibility!!

When I first met my EP at RBHT he told me all the bad things that might happen including death so I asked him when he last killed somebody. Shocked he said he never had so I asked him to put me on the list for the week after he did so i know he would be more careful.

[Hidden in reply to BobD]

“You do love your formulae ! Firstly is it my beleif that most risks are explained to prevent legal action against the doctors and hospital concerened rather than for the patient's comfort.”

I would agree that preventing legal action is a consideration, but I think it is also to provide patients with information on which to base a decision.

“Secondly many risks depend an awful lot on the physiology of the patient. For examaple if a person had very thin heart walls then the risk of tamponade may be considerably higher yet be unknown prior to the procedure. “

Absolutely. The Royal Brompton website just gives the generic risks, but these might be greater for some patients (or perhaps less in some cases). If that’s the case the doctor should inform the patient during the assessment if they are known.

“Similarly damage to the oesophagus or vagus or phrenic nerves would have higher risk if these ran very close to the heart. None of these can be calculated and are luck of the draw. “

Yes, they cannot be calculated with precision in every case; but I would argue that it is informative to be told something like “assuming you don’t have any nerves running close to heart the risk is x.” The doctor could also say how likely it is that a patient would have a nerve running close to the heart.

“The risk ratio given is merely the result of comparison of cases over time not a mathematical certainty”

The result is a probability, so there is no claim of certainty.

“Add in Sodt's Law that some of us will attract disasters just because we are who we are and it is really a waste of time trying to ascertain if anything bad will happen. “

Here I don’t agreee. I think that for most patients it is useful to be given a probability, or a range of probabilities. For example, I have already been told that the chance of success on a first ablation is 60-70% with PAF. Now that has been questioned by one study which says it may only be 28%. But at least I have a starting point for discussion when I go for the assessment. I can ask the EP to justify the 60-70% figure (assuming he adheres to it). Then I can evaluate how convincing his argument is. If it is 28% I wouldn’t go ahead with it.

“I once had a listed side effect to a procedure (not ablation by the way) which was most unusual. I once asked a leading professor in the field if he had every known it and in fifty years he had not although he did say that it was in the text books. One also signs the consent form listing this possibility!! When I first met my EP at RBHT he told me all the bad things that might happen including death so I asked him when he last kiled somebody. Shocked he said he never had so I asked him to put me on the list for the week after he did so i know he would be more careful.”

It’s an important question to ask. I was told by a friend who knows a retired cardiologist that the track record of the person (or team) doing the ablation matters a lot, and that ideally you want someone who has done the procedure hundreds of times with a high success rate.

[BobD Volunteer in reply to Hidden]

That is precisely why results in USA differ so widely from those here in UK I was told by a leading UK EP. We have less new kids on the block.

[Hidden in reply to BobD]

I didn’t know there was a difference. You mean the procedure is less or more successful there?

[Buffafly]

Clearly you are not ready for an ablation. I had an offer of an op to straighten and support my spine, can't remember the stats quoted to me but they weren't good, included paralysis or death and the surgeon was more anxious than I was. I decided very quickly that with my pain, deformity and disability and a life of more of the same that the risk was worth it. Absolutely was! When you are ready for an ablation you won't care about the stats, hopefully it won't be too late for a successful result.

[Hidden in reply to Buffafly]

The letter from the consultant has not yet reached my GP so I don’t know when the assessment will be. It could be weeks or months, I guess. At the moment I’m just planning to go to the assessment and ask a lot of questions. If it’s said the ablation is really needed then I will go along with that. If it can safely be left for a while then I’d prefer that.

All that I know at the moment is that I have had PAF since June of this year, with some episodes every 3 or 4 weeks, that the left (ventricle?) is slightly enlarged and that the Sotalol is suppressing but not eliminating the PAF . The consulatant also said that this would or could change to the point where the symptoms become much more pronounced and the heart becomes larger. He didn’t give a time scale for this (I should have asked ). The referral letter will provide some clue- of its urgent then the GP will presumably say so and make a quick referral.

[Buffafly in reply to Hidden]

You might want to read NJ47's post as well......