Improvement of NYHA class and specified adverse events (hyperkalaemia, renal function, hypotension, and gynaecomastia) were also considered to be important for decision-making. Evidence was identified for all outcomes except for hypotension. Quality of the clinical evidence The evidence for the critical outcome of all-cause mortality (measured as time to event) was moderate quality, though the confidence intervals around the absolute effect were imprecise, ranging from 34 fewer deaths to 12 more deaths per 1000 individuals. Time to event data could not be extracted from the smaller included study, so dichotomous data was extracted instead, which was very low quality due to risk of bias and very serious imprecision (no events occurred in the placebo arm and only one event in the intervention arm). The evidence for the critical outcome of quality of life ranged from moderate to low quality due to risk of bias stemming from the reporting of the data. The evidence on all-cause hospitalisation (measured as a count rate number of events) was high quality, while the evidence from the second smaller study was reported as number of participants with events and was moderate quality due to imprecision. The evidence was of moderate quality for the important outcomes of hyperkalaemia and worsening renal function (due to risk of bias caused by likely underestimation of the frequency of events) and was of low quality for Chronic Heart Failure Treating Heart Failure NICE 2018. All rights reserved. Subject to Notice of rights. ISBN: 978-1-4731-3093-7 Research recommendation No recommendation gynaecomastia (due to risk of bias and indirectness again due to likely underestimation of the incidence of events). Evidence quality was very low for improvement in NYHA class (due to risk of bias, indirectness and imprecision), meaning that the committee placed little weight on this outcome in their decision making. 