Cardiac resynchronization therapy improves renal function in human heart failure with reduced glomerular filtration rate

Background: Renal dysfunction is an important independent prognostic factor in heart failure (HF). Cardiac resynchronization therapy (CRT) improves functional status and left ventricular (LV) function in HF patients with ventricular dyssynchrony, but the impact of CRT on renal function is less defined. We hypothesized that CRT would improve glomerular filtration rate as estimated by the abbreviated Modification of Diet in Renal Disease equation (eGFR). Methods and Results: The Multicenter InSync Randomized Clinical Evaluation (MIRACLE) study evaluated CRT in HF patients with NYHA Class III-IV, ejection fraction <= 35%, and QRS >= 130 ms. Patients were evaluated before and 6 months after randomization to control (n = 225) or CRT (it = 228). Patients were categorized according to their baseline eGFR: >= 90 (category A), 60 <= eGFR < 90 (category B), and 30 <= eGFR < 60 (category C) mL/min per 1.73 m(2). CRT improved LV function in all categories. Compared with control, CRT increased eGFR (-2.4 +/- 1.2 vs. +2.7 +/- 1.2 mL/min per 1.73 m(2); P = .003) and reduced blood urea nitrogen (+6.4 +/- 2.4 vs. -1.1 +/- 1.5 mg/mL; P = .008) in category C, whereas no differences were observed in categories A and B. Conclusions: CRT increased eGFR and reduced blood urea nitrogen in HF patients with moderately reduced baseline eGFR. By improving cardiac function, CRT can indirectly improve renal function, underscoring the importance of cardiorenal interaction and providing another mechanism for the beneficial effects of CRT.