Abstract
BACKGROUND: Recent studies have shown that high levels of serum phosphate are associated with adverse cardiovascular events. However, little is known about the relation between phosphate levels and improvement of cardiac function in chronic heart failure (CHF) patients who underwent cardiac resynchronization therapy (CRT). The purpose of this study was to examine whether serum phosphate levels were able to predict responders to CRT and adverse cardiac events. METHODS: The study population consisted of 30 CHF patients (24 males, mean age 65.7±8.5 years) who received CRT with defibrillator (CRT-D) implantation. Levels of serum phosphate were measured before, and 6 months after, CRT-D implantation. Left ventricular end-diastolic volume and end-systolic volume were assessed simultaneously by echocardiography. In addition, the rate of re-hospitalization due to worsening of heart failure was investigated. All patients were divided into 2 groups: responders (Group-R, n=18) and non-responders (Group-NR, n=12) to CRT-D. Responders were defined as patients who showed >15% reduction in left ventricular end-systolic volume. We compared these parameters between the 2 groups. RESULTS: Serum phosphate levels were significantly lower in Group-R than in Group-NR (3.3±0.2 vs. 3.7±0.4 mg/dL, p=0.01). The rate of re-hospitalization was lower in Group-R than in Group-NR (0% vs. 33%, p=0.018). Multivariate analysis showed that serum phosphate levels had a predictive power to determine responders to CRT (odds ratio 0.008, 95% confidence interval 0.000-0.348, p=0.015). CONCLUSIONS: These results suggest that serum phosphate levels might predict both responders to CRT, and adverse cardiac events, in CHF patients with CRT-D.