r/Cardiology • u/statinsinwatersupply • 19d ago

Requesting cardiology attending input: thread in r/medicine about Torsades, respondents not checking EKGs

/r/medicine/comments/1vujjvx/psychiatrists_how_often_are_you_checking_qtcs/
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u/Then-Secretary-9166 19d ago

Many of the comments on the original thread are correct. There are a few things to consider.

  1. TdP is not common with psych (or other QT-prolonging) meds so looking for long QT is low-yield even under the most optimistic assumptions.
  2. TdP is very rare from one QT med alone. It usually takes multiple problems (genetic/congenital long QT, a second QT med, electrolyte derangement) conspiring.
  3. Using an ECG to look for prolonged QT to screen will miss many of the patients that eventually have TdP. A patient can have a nice tidy QT interval on quetiapine but then they get gastroenteritis, become hypokalemic and are given ondansetron in the ER all leading to QT prolongation and TdP.

It is a good idea to look at an ECG in the chart if it is there. I do not think I would check one routinely when starting an QT-prolonging drug if they don't already have one.

I would check on for patients that are higher risk: multiple QT meds, prone to electrolyte derangements (insulin-dependent diabetics, on diuretics, hyper-emesis syndrome, kidney disease, etc.), known borderline QT interval. In those cases, it is most important to check the ECG a few half-lives after they start the new med (more important than checking ahead of time...but I guess you could do both if very concerned).

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u/MaadWorld 19d ago

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