Reduced cardiac index is not the primary driver for renal dysfunction among patients hospitalized for heart failure (HF), according to results of a recent study published in the Journal of the American College of Cardiology.
While these findings support evidence reported, previous studies did not test nonlinear or threshold effects or examine subgroups of patients where lower cardiac output might be an important cause of renal dysfunction.
Therefore, researchers used a multicenter population of HF patients who underwent pulmonary artery catheterization (PAC) to determine the relationship between cardiac index and renal function.
The study included 575 patients undergoing PAC from either the ESCAPE (Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness) trial or ESCAPE registry. Researchers evaluated the associations between cardiac index and renal function across multiple subgroups and assessed the nonlinear, threshold, and longitudinal relationships.
They discovered a weak but significant inverse association between cardiac index and estimated glomerular filtration rate (eGFR). Higher cardiac index was paradoxically associated with worsened eGFR (r= -0.12; P=.02).
Cardiac index was not associated with blood urea nitrogen (BUN) or the BUN to creatinine ratio, and there were also no associations between cardiac index and improved renal function across multiple subgroups with PAC or hemodynamic, laboratory, or demographic parameters.
Among patients with serial assessments of renal function and cardiac index, there were no observed associations within each patient between change in cardiac index and eGFR.
“This lack of association persisted across multiple patient subgroups, different metrics of renal function, and the spectrum of cardiac indices,” the authors wrote. “Overall, these results argue that low cardiac output is not the predominant driver for renal dysfunction in patients presenting with decompensated HF.”
Researchers concluded that neither cardiac index nor change in cardiac index were lower in patients developing worsening renal function (P≥.28).
They also noted that the lack of positive association was not due to threshold effects and that additional analyses for nonlinear effects did not reveal any positive associations between cardiac index and renal function.
“Although these data do not provide a specific recommendation for how we should treat patients with HF and renal dysfunction, they should motivate us to entertain alternative diagnostic and therapeutic approaches before instituting these interventions that carry significant risk,” the authors stated.
Future research should aim to identify the factors responsible for renal impairment that commonly occurs in HF patients as well as the influence of cardiac output on other parameters of renal function.
Hanber JS, Sury K, Wilson FP, et al. Reduced cardiac index is not the dominant driver of renal dysfunction in heart failure. J Am Coll Cardiol. 2016;67(19):2199-2208. doi: 10.1016/j.jacc.2016.02.058.