Vascular calcifications in chronic kidney disease: are there new treatments?

Cardiovascular disease is extremely common in patients with end-stage renal disease (ESRD) and accounts for at least 50% of deaths among these patients. Vascular calcifications (VC) have been recently implicated as a possible cause of this excess cardiovascular mortality. Medial calcification is a striking feature of vascular disease in patients with ESRD. The traditional view that VC is a degenerative and passive process has been seriously challenged, based on strong evidence suggesting that VC is an active and highly regulated process similar to bone formation. Different data support the notion that elevated levels of phosphorus and/or other uremic toxins may play an important role by transforming vascular smooth muscle cells into osteoblast-like cells, which can produce bone matrix proteins. This nidus can then mineralize if the balance of pro-mineralizing factors outweighs inhibitory factors. The advent of newer noninvasive screening tests have generated great interest for screening patients with ESRD for vascular calcifications. Control of serum phosphorus with sevelamer, a recently developed non-calcium, non-aluminum phosphate binder, have attenuated or arrested progression of coronary artery and aortic calcifications compared to treatment with calcium-based binders. Amino bisphosphonates, have shown to completely inhibit soft tissue calcifications, calciphylaxis and prevent death in animal models. The first generation bisphosphonate, etidronate, reduces the progression of coronary artery calcifications patients receiving long-term hemodialysis and intravenous pamidronate has produced a rapid improvement of calciphylaxis. In conclusion, VC is a widespread phenomenon in patients with ESRD with important cardiovascular consequences. A better understanding of the processes of VC is leading to therapies to retard or improve this phenomenon and will probably have an important impact on patient mortality.