Risk of corrected QT interval prolongation after pamidronate infusion in children.

BACKGROUND

Hypocalcemia carries a risk of cardiac conduction incidents and death. Hypocalcemia is a frequent adverse effect of pamidronate.

OBJECTIVE

The objective of this study was to investigate whether pamidronate infusion lengthens the ventricular repolarization in children.

DESIGN AND METHODS

Thirty-four children with cerebral palsy and severe osteoporosis were treated for approximately 1 yr with pamidronate (three times per year). Calcemia and corrected QT interval (QTc) (in which the QT interval is a measure between the Q and T waves in the electrical cycle of the heart) were measured before and after each cycle of intravenous infusions.

RESULTS

Pamidronate decreased calcemia in all patients from 2.40 to 2.21 mm (P<0.0001) and increased QTc from 390 to 403 ms (P<0.0001), with 7.4% of postinfusion QTc becoming longer than 440 ms. QTc at baseline was significantly correlated to final QTc (P<0.0001; r2=0.27).

CONCLUSIONS

Because we observed a lengthening in QTc after bisphosphonate infusion, we recommend that children treated with pamidronate should receive attention as to other possible risk factors of prolonged QT and have a preinfusion and postinfusion measurement of their QTc.