Short QTc in Diltiezam Overdose

Report:

Junctional rhythm 56/min

Short QT interval 0.36”

QTc 0.35”

Lead V2 missing

Possible old inferior infarction.

Comment:

The cause of QT interval shortening is iatrogenic32 hypercalcæmia induced by calcium infusion for diltiezam overdose hypotension. Serum calcium peaked at 3.44 mmol/L.

The patient had a known inferior MI, but its evidence had dissipated over the years. This happens to at least 1/3 inferior MIs in time. Looking harder, there are puny q waves in 2 and aVF, with a QS in 3 - not exactly a proof. What supports the diagnosis is small voltage in the inferior leads and concordant T wave inversion in 3.

The inferior MI was well documented. The patient had CABGs to the left circumflex and left anterior descending arteries a year previously.

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