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NBME 21 Answers

nbme21/Block 3/Question#11

A 50-year-old man is found dead in bed at home. His ...

Arrhythmia

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 +7  upvote downvote
submitted by cantaloupe5(35),

Histology showed coagulative necrosis (preserved architecture of myocardial fibers) with neutrophil infiltration which hinted that the MI was within 24 hours. Most likely cause of death within first 24 hours of MI is arrhythmia. Myocardial rupture would also be visible on gross appearance of the heart, which they described in the stem.

bighead478  in FA it shows softening of the myocardium to happen at 3-14 days. Do you think this was overly misleading people (like me) into choosing myocardial rupture? I understand the histo features are consistent with < 24 hours, but the stem should also match this in every detail +3  
sbryant6  Myocardial rupture would not happen until 3-14 days. Since this shows signs of <24 hrs, the answer is arrythmia. +1  
hello  @bighead478 You have to look at the whole picture. Histo shows preserved architecture, which indicates coagulative necrosis -- coagulative necrosis is a histo finding only in the first 24h. The most common causes of MI-related sudden death are: arrythmia > cardiogenic shock (heart pump problem) > rupture. +  




 +5  upvote downvote
submitted by hungrybox(232),

/u/cantaloupe5 had a great explanation.

Here's an image of the different stages following myocardial infarction. Note the "contraction bands" are what define coagulative necrosis.





 +0  upvote downvote
submitted by frimmy_11(0),

Mottling and softening of anterior wall on autopsy suggests it was not older than 24 hrs. Death from fatal arrhythmia like V-fib most commonly occurs within one day of the MI. That said, once scar has formed in myocardial tissue it, too, can cause arrhythmia.

bighead478  in FA it shows softening of the myocardium to happen at 3-14 days. Do you think this was overly misleading people (like me) into choosing myocardial rupture? I understand the histo features are consistent with < 24 hours, but the stem should also match this in every detail +  




 +0  upvote downvote
submitted by volcanobuns(0),

MI sudden death -> arrhythmia. The order of commonness is arrhythmia > cardiogenic shock > rupture.





 +0  upvote downvote
submitted by zpatel(6),

https://webpath.med.utah.edu/CVHTML/CV127.html

check this out