So how should we all use that evidence without simply testing everyone? Here's Professor Rick Boddy.

Hi, today we're going to be talking about when to order a troponin in your patient with chest pain.

I still remember what it was like when I first started and i wasn't really quite sure about when to order a troponin test was i being over cautious under cautious i certainly didn't want to miss anything and i've seen lots of doctors take very different approaches to this with very different risk thresholds let's go through some of the evidence to help us guide which patients with chest pain might need a troponin test this is going to surprise you so bear with me on this one Now, this is an issue that's very close to my heart.

I felt it's been very relevant to my clinical practice all the way through my career.

And when I did a PhD, I really wanted to gather some evidence to help me answer this question.

So I made it a chapter of my PhD to have a look at the value of symptoms and signs for diagnosing myocardial infarction.

Basically what we did is we recruited a cohort of over 800 patients.

Well, here's your answer.

A really welcome back to him talking us through the fifth universal definition of myocardial infarction.

The fifth universal definition of myocardial infarction is now out.

I'm going to take you through what's new, what's changed and what it means for your practice.

So the biggest single change in the fifth universal definition compared with the fourth is to the terminology.

We say goodbye to type 1 type 2 type 3 type 4 and type 5 myocardial infarction with all of those complicated subgroups and we've got much simpler terminology now so it's simply primary secondary and procedure related that's a welcome simplification now there are some nuances to this as well that we need to understand primary myocardial infarction includes all of your primary coronary pathology this happens spontaneously so if you've got an atherosclerotic plaque in your coronary artery and it ruptures and you develop a troponin rise with signs of ischemia that's a primary myocardial infarction if you have a coronary artery dissection you also now fit into that group if you've got coronary vasospasm you fit into this group or an embolism to your coronary arteries that also fits under primary myocardial infarction Under secondary myocardial infarction, we've got a supply and demand imbalance of oxygen to the myocardium.

So it's just like the old type two myocardial infarction with a few differences.

Obviously, some of those causes have now moved into primary myocardial infarction, like coronary artery dissection.