Introduction Hypocalcemia (HC), without an underlying myocardial disease, is a relatively uncommon but reversible cause of congestive heart failure.

Objective We studied the cardiac functions (heart rate, blood pressure, ECG and Echocardiographic parameters (Fractional shortening (FR), left ventricular end diastolic diameter (LVEDD) of 14 children who presented with hypocalcaemia due to VDD before and 2-4 weeks after treatment with an IM dose of vitamin D 3 (VD) (10,000 IU/kg).

Results Correction of HC and VDD was associated with marked improvement of the LVEDDSDS (3.2 ± 4.4 to 1.1 ± 2.8) and slowing of the heart rate (from 101 ± 34 to 94.7 ± 30/min). The FS and QTc did not change. The LVEDDSDS was negatively correlated with serum calcium level (r =-0.46, p = 0.03) and PTH concentrations (r = 0.44, p = 0.032) but not with 25OHD level (r= -0.2, p = 0.2).

Discussion Improvement of the recorded changes in the heart rate and LVEDD after VD therapy implements an important role of VD through its effect on the concentration of the extracellular calcium ion that could modify the strength of the myocardial contraction through excitation-contraction coupling.

Conclusion These data strongly indicate that the maintenance of an optimal vitamin D status may be a promising approach for the prevention and/or therapy of myocardial diseases and in countries with high prevalence of VDD, vitamin D supplementation can prevent this risk of cardiac dysfunction.