INTRODUCTION: Frailty is associated with mortality and functional outcome after cardiac arrest. Temporalis muscle thickness (TMT) is a measure of sarcopenia, which represents one dimension of frailty. We assessed the correlation between TMT, measured on head computed tomography (CT), and Clinical Frailty Scale (CFS) in patients resuscitated from cardiac arrest. METHODS: We enrolled adults resuscitated from cardiac arrest who had a head CT obtained within 48 hours of collapse. Study investigators prospectively obtained data to determine pre-arrest CFS and blinded investigators measured TMT. We calculated Spearman rank-order correlation to assess the relationship between TMT and CFS. We also performed multivariable regression adjusting for confounders of frailty and sarcopenia. RESULTS: We enrolled 50 subjects with median CFS 4 [IQR 2-6] and median TMT 6.6 [IQR 5.0-8.9] mm. There was a moderate, negative correlation between TMT and CFS (ρ = -0.52 (p <
0.001)). In linear regression, TMT (R CONCLUSIONS: We found that TMT exhibits a moderate negative correlation with the CFS, supporting TMT as a tool to measure frailty. Measuring TMT in patients with early head CTs after resuscitation from cardiac arrest may allow for characterization of sarcopenia as a dimension of pre-arrest frailty.