Introduction:Heart failure (HF) nurse practitioners (NP) are part of the HF specialist workforce and to date their impact on improving patient outcomes is untested. The aim of this study was to determine the cost effectiveness of a HF NP inpatient service compared to current practice of no HF NP service from a health system perspective.Methods:A post-hoc analysis was undertaken from pre-existing data of a pre and post intervention study of a HF NP inpatient service. A total of 500 patients admitted to a single center with acute decompensated HF (250 patients in the historical control and 250 in the prospective HF NP group) were enrolled and followed up for 12 months post-discharge. Patients were matched on five-year age groups. Using a Markov model, costs, effects and cost-effectiveness were estimated for patients in the HF NP group compared to usual care. Annual discount rate of 3% was applied. Transition probabilities and utilities were derived from published studies. Costs during hospitalization and health service resource utilization were derived from hospital clinical costing and governmental pharmaceutical costs. US dollars reported.Results:Overall the mean age was 77.7 +11years (SD). At 12 months post-discharge, 73.7% of patients in the HF NP group were readmitted compared to 81.7% in the usual care group (p=0.03). In the base case, HF NP group compared to no HF NP, was more costly ($19688 vs $19067) but more effective (1.97 vs 1.93). Cost of hospital readmissions over 12 months was $15479 in the HF NP group compared to usual care of $21058. The cost of outpatient and community services were similar (outpatient: $1429 vs $1371 respectively; community: $882 vs $874 respectively). The incremental cost effectiveness ratio for the HF NP versus usual care was $9630 per QALY gained at 12 months and $9770 per QALY gained at three years. The HF NP was estimated to have a 100% chance of being cost-effective at a willingness-to-pay threshold of $30000.Conclusion:This study shows that a HF NP service is likely to be cost-effective at a willingness-to-pay of $30000. The main cost driver was hospital readmissions with the HF NP group experiencing a significantly lower rate of readmissions. More robust evidence is required with an economic evaluation alongside a multicentre RCT.