Myth Busters Episode 1...Recent negative angiogram makes ACS unlikely

You are presented with a 54 year old man, who has a 6 hour history of central chest pain at rest, very similar to his exertional angina. He has no risk factors for coronary artery disease (aside from having a heart - don't get me started on risk factors - a rant for another time...). A recent angio from a year ago showed no imminently threatening stenoses of his major vessels. He is clinically well, and is pain free by the time you examine him. You try to refer to cardiology, but the resident / registrar reassuringly tells you that a single troponin is sufficient given his recent normal angio...

Reasons why this is really not the case...

1) Angiography of the coronary vessels  focuses on stenoses of the relatively larger epicardial vessels, not the branches. Management of stenoses in these much smaller vessels is medical rather than interventional, and therefore they may not be routinely described in the report.

2) Diabetics have microvascular disease - these vessels cannot be visualised at all.

3) Vasospasm cannot be predicted by prior angiography

4) Studies have shown that lesions can progress by up to 20% a year. That non critical stenosis may look very different after 6 months...

5) Considering the pathophysiology of STEMI - most are caused by plaque rupture, which further down-stream, may occlude a 50% stenosed vessel, which was previously described as non-flow limiting. It is with Vulcan like logic that one may sumise that the size of the ruptured plaque cannot possibly be predicted on prior angiography.

So, normal recent angio does not exclude the risk of new acute coronary syndrome for the patient in front of you, and if the history sounds like it could be ischaemia / infarction, treat the patient accordingly... 

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