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NBME 24 Answers

nbme24/Block 4/Question#43 (reveal difficulty score)
A 72-year-old woman with coronary artery ...
Neointima formation in the right coronary stent ๐Ÿ” / ๐Ÿ“บ / ๐ŸŒณ / ๐Ÿ“–
tags: vascular

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 +39  upvote downvote
submitted by โˆ—xxabi(293)
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Stent thrombosis vs re-stenosis. Stent thrombosis is an acute occlusion of a coronary artery stent, which often results in acute coronary syndrome. Can be prevented by dual antiplatelet therapy or drug-eluting stents. Re-stenosis is the gradual narrowing of the stent lumen due to neointimal proliferation, resulting in anginal symptoms.

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sunshinesweetheart  so just to clarify - it's the "symptom-free for 3 months" that rules out thrombosis? +9
hpsbwz  It's moreso that at rest there's no changes, but during exercise there is. Like the pathophys of stable angina. +8
suckitnbme  I think it's more because of the 2-month history of PROGRESSIVE angina sx with exertion. This points to a chronic process rather than an acute event. +
alienfever  Drug-eluting stents prevent re-stenosis (rather than thrombosis) by releasing sirolimus which by blocking cell proliferation. +3



 +8  upvote downvote
submitted by โˆ—sweetmed(157)
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Stent Restenosis occurs from scar tissue grows over stent causing โ€œneointimal hyperplasiaโ€ and narrowing, ischemia symptoms return Tx: prevent by using drig eluting stents eg. Sirolimus. Thrombosis Post stenosis is Acute, stent serves as nidus for thrombus formation usually 2/2 missing mediation. Tx: prevent by using dual antiplatelet treatment [aspirin+clopidogrel/ticagrelor]. After 1 year, endothelization of stent occurs and there is a lower risk of thrombus, Tx lowered to just aspirin.

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 +5  upvote downvote
submitted by โˆ—hungrybox(1277)
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Section on Endovascular Stenting from BIG ROBBINS (for people like me who need more context):

https://i.imgur.com/mhRrpwl.png

https://i.imgur.com/e9mO0Nz.png

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 +2  upvote downvote
submitted by medschooler1(2)
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I think the key here is that this patient already had a stent placed, was symptom free for a few months, and now has angina with exertion. Angina with exertion is describing "Stable angina", the angina is due to "demand ischemia". The most common cause of stable angina is atherosclerosis/atherosclerotic plaque build up and a very common adverse effect of stents is neointima formation/ forming a new plaque on the stent.... a thrombosis would cause angina at both rest and with exercise, due to "supply ischemia", and it would be more acute, not progressive like the question stem describes

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 -1  upvote downvote
submitted by โˆ—an_improved_me(91)
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Another thing to note: they could have made this question even trickier by asking whether or not you know which leads are associated with which arteries. This person had LAD and RCA stent placement. That means that they could have given you leads II, III, aVF (for RCA probs) or V1-V6, I, aVL (for LAD probs) and make you choose based on that.

This question was easier since all answers are regarding the RCA.

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