"Long QT" after droperidol

A patient presented to the ED with intractable hiccups.  He also had "ongoing GERD symptoms with heartburn......but no chest pain"  (Whatever that means).  He was treated with droperidol and benadryl and this decreased his symptoms and he was discharged.  No ECG was recorded (!).

Later, the patient returned with altered mental status and reports of falls.

He had an ECG recorded:

The QT was 504 ms
The computerized QTc (Hodges correction) was listed as 530 ms.
Bazett correction would be 563 ms
The providers were worried that the droperidol had resulted in a long QT.
What do you think?
See below for explanation.

There are huge U-waves, best seen in V1-V3.  These are almost always due to hypokalemia.  Some overdoses can cause this:

Cole JB, Stellpflug SJ, Smith SW: Refractory Hypotension and “Ventricular Fibrillation” With Large U Waves After Overdose (this is a great full text online case of hydroxycholorquine overdose)

Here I have drawn lines at the beginning and end of the U-waves in V1-V3
Then I draw them down to lead II across the bottom
Then I go to sections that are under I-III, aVR-aVF, and V4-V6.
Then I draw the line up through those leads to show where the U-wave is in those leads.
And you can see how what may appear to be a T-wave and a long QT is really a U-wave.
V4-V6 in particular show only one wave which appears to be a T-wave only.  But by showing from other leads where the U-wave vs. T-wave is, we can see that this apparent T-wave is really a U-wave.

Whether it is a long QT or a QU, it may be equally prone to ventricular tachycardia and VF.
However, the etiology of U-waves is different is different from the etiology of long QT.
This would not be drug effect due to droperidol, but more likely hypokalemia.

The K was measured and was 1.7 mEq/L

Learning Points:

1.  When the QT seems impossibly long, consider that it might be U-waves which are mimicking long QT (often with a long QU interval)

The etiologies of long QT and large U-waves are different, even if they both may have the same dysrhythmic consequences.  Therefore, the treatment will be different.

2. Also, patients with intractable hiccups, or who have what they call "heartburn", should usually get at least an ECG, as ischemia could be underlying both of these.