Changes in renal function over time in patients with cardiac resynchronisation therapy

QUESTION UNDER STUDY: Cardiac resynchronisation therapy (CRT) with defibrillator back-up (CRT-D) is widely used in selected patients with moderate/severe heart failure. Renal failure is common in these patients. Data on the impact of CRT on renal function are controversial and limited by short follow-up. The aim of this study was to describe changes in glomerular filtration rate (GFR) from baseline compared with 1 and 2 years after CRT implantation. METHODS: A total of 284 CRT-D patients with creatinine levels at baseline and after 1 year were identified in two prospective registries. In 149 patients, levels after 2 years were available. GFR in ml/min/1.73 m2 was estimated with the Modification Diet in Renal Disease equation and patients stratified into GFR stages 1 to 4. RESULTS: The population was predominantly male (75%), mean (± standard deviation) age was 61 ± 7 years and ejection fraction 24% ± 8 %. GFR was 63 ± 24 ml/min/1.73 m2 at implantation and 60 ± 24 ml/min/1.73 m2 after 1 year (p = 0.26). At the 2-year follow-up, GFR had decreased from 60 ± 21 to 56 ± 21 ml/min/1.73 m2 (p = 0.04). Mean GFR decreased in stages 1 and 2, remained stable in stage 3 and improved in stage 4 patients. After 2 years, GFR had decreased ≥10 ml/min/1.73 m2 in 42%, but improved in only 15% (p = 0.04). CONCLUSIONS: Overall, mean GFR in CRT-D patients decreases at 1 and 2 years after implantation, depending in part on the initial degree of renal function. However, the chance of further substantial deterioration (≥10 ml/min/1.73 m2) is considerable.