Response to Letter Regarding Article, “New-Onset Heart Failure Due to Heart Muscle Disease in Childhood: A Prospective Study in the United Kingdom and Ireland”
We thank Dr Sane for his comments on our article. We agree that vitamin D deficiency is an underdiagnosed cause of cardiomyopathy in infants. However, our documentation of vitamin D–associated cardiomyopathy in this series is noteworthy because the recent large North American series of >900 cases of pediatric cardiomyopathy1 did not reveal any cases. It is likely that screening for this problem is not widespread; however, it is only relatively recently that it has become recognized as a serious problem. One of our authors was also on the other recent article referred to by Dr Sane.2 That article describes the first substantial case series of infant heart failure in association with hypocalcaemia and vitamin D deficiency. All of the infants were dark skinned and had been breast fed. Exactly how many cases are caused by this problem could be very crudely estimated by combining the UK articles. Approximately 17% of cases of infant cardiomyopathy with heart failure in London may be caused by vitamin D deficiency, and vitamin D deficiency may conceivably be the most common cause of heart failure from dilated cardiomyopathy in breast-fed, dark-skinned infants. The children reported had overt and very severe heart failure, but there may be many more cases of undetected, subclinical, but potentially important cardiomyopathy associated with vitamin D deficiency. Profound heart failure from this cause is unlikely to be such a problem outside of infancy, because severe hypocalcaemia is less common in older children with vitamin D deficiency. Clearly, it is important to remember that this is an entirely preventable form of infant heart failure. We agree with Dr Sane that screening for vitamin D deficiency of at-risk infants with heart failure is necessary, but, equally important, the provision of vitamin D supplementation to pregnant women and children at risk of vitamin D deficiency should become universal.