Vitamin D and heart structure and function in chronic kidney disease

Abstract

The relationship between vitamin D and heart structure and function is of crucial importance in chronic kidney disease (CKD) because cardiovascular events including sudden cardiac death are, beside cancer, the major cause of premature mortality in these patients. The vitamin D receptor (VDR) is expressed in the heart and the vessels, and experimental studies have documented various molecular effects of vitamin D that may protect against heart diseases. Epidemiological studies in CKD patients identified vitamin D deficiency as a risk marker for adverse cardiovascular outcomes. Randomized controlled trials (RCT) have shown that vitamin D treatment exerts beneficial effects on some cardiovascular risk factors such as parathyroid hormone and proteinuria, but there was no effect on myocardial hypertrophy. Whether vitamin D treatment can significantly reduce cardiovascular events in CKD patients is still unclear because available data are based on very few and relatively small RCTs. It should, however, be noted that some RCTs including one meta-analysis suggest that patients on active vitamin D treatment experience fewer cardiovascular events. Regarding clinical use of vitamin D in CKD patients, it must therefore be stressed that although patients on active vitamin D treatment are at increased risk of hypercalcemia, there is no clear indication that this potential adverse effect translates into higher cardiovascular risk. These safety considerations are of great importance when considering the clinical use of active vitamin D treatment, but further large RCTs are urgently needed to better characterize the cardiovascular effects of vitamin D treatment in CKD.