RESUMEN
BACKGROUND: Vitamin D deficiency has been associated with a poor outcome in patients with heart failure (HF). We examined the role of vitamin D in the response of HF patients to cardiac resynchronization therapy (CRT). METHODS: The study comprised 50 patients (30 men and 20 women) with HF undergoing CRT implantation who were prospectively enrolled. Response to CRT was defined as a combination of ≥15% reduction in left ventricular end-systolic volume (LVESV) and ≥10% improvement in the 6Minute Walk Test within 6 months. Patients were grouped based on their levels of vitamin D prior to CRT implantation. Clinical and echocardiographic examinations were performed prior to and 6 months after the procedure. RESULTS: Of the patients, 11 (22%) failed to respond to CRT; two patients died within 6 months and an additional nine patients showed no improvement in the 6Minute Walk Test and no reduction in their baseline LVESV. A comparison was made between 25 patients with sufficient levels of vitamin D and 25 patients with insufficient levels. Nine patients (36%) in the "insufficient" group and two patients (8%) in the "sufficient" group failed to respond to CRT implantation (p = 0.037). CONCLUSION: Adequate serum concentrations of vitamin D play a significant role in improving the functional status of patients with systolic HF following CRT implantation.