OBJECTIVES: Transient Loss of Consciousness (T-LOC), or “blackout”, remains challenging; possible diagnoses include syncope (most common), epilepsy and psychological conditions. Studies showed that 26.8% of T-LOC patients will remain undiagnosed after comprehensive evaluation. Lack of diagnosis hampers attempts at appropriate management and opportunity to decrease future episodes. Healthcare utilisation associated with these patients can become very significant, since every subsequent T-LOC can lead to hospitalisation and repetition of diagnostic tests. Furthermore, each T-LOC episode carries a 29-68.11% injury risk. Implantable Loop Recorders (ILRs) significantly increase the probability of recording a physiological variable (heart rhythm) during T-LOC and hence in obtaining a diagnosis. This could allow patients to receive treatment faster than conventional diagnostics. We sought to quantify the potential cost-offsets associated with ILR use in the diagnostic pathway, under the UK NHS setting. These offsets stem from reducing unnecessary diagnostic testing, preventing recurrent blackouts and the serious injuries associated with them. METHODS: Markov Model in Excel used to compare the costs between two diagnostic strategies, in which patients run through the model until diagnosed and treated, or dead. Literature reviews used for blackout recurrence, yield of diagnostics tests, arrhythmia prevalence and injury risk. Neither Life Years gained, nor QoL benefits were included. NHS Reference Costs 2007-2008 used. Costs discounted at 3.5% p.a. RESULTS: ILRs proved significantly cost-saving. Base case diagnosis and treatment costs per patient were reduced by 60.57% (£9262.70 without ILR vs. £5768.69 with ILR), or £3494.23 saved per ILR implanted. The model proved sensitive to risk and cost of injury. CONCLUSIONS: ILRs can be significantly cost-saving, because future cost-offsets exceed initial device costs. Our study is the first to incorporate injuries and extrapolate potential savings to patient lifetime. More research is needed to examine outcome-related benefits such as reducing debilitating injuries and improving patient survival – thus providing comprehensive evaluation.