Pre-Operative Masseter Area is an Independent Predictor of Long-Term Survival after Carotid Endarterectomy

Abstract

Objective/background: Sarcopenia is a predictor of mortality in elderly patients. Masseter area (MA) reflects sarcopenia in trauma patients. It was hypothesised that MA and Masseter density (MD) could be evaluated reliably from pre-operative computed tomography angiography (CTA) scans and that they predict post-operative survival in carotid endarterectomy (CEA) patients.

Methods: This was an observational registry study. Patients (n = 242) were operated on for asymptomatic stenosis (n = 32; 13.2%), amaurosis fugax (n = 41; 16.9%), transient ischaemic attack (n = 85; 35.1%), or ischaemic stroke (n = 84; 34.7%). Internal carotid artery stenoses were graded angiographically. Intraclass correlation coefficient (ICC) was used to analyse measurement reliability by three independent observers. Cox regression analysis was used to study the effect of MA and MD on survival (hazard ratio [HR]).

Results: Median patient age was 71.0 years (interquartile range [IQR] 13.0) and follow up time was 68.5 months (range 3-163 months); at the end of follow up (1 October 2017), 104 (43.0%) patients had died according to the National Population Register. The average MA (MAavg, the mean of left and right MA [median 394.0 mm²; IQR 110.1 mm²]) and MD (MDavg, the mean of left and right MD [median 53.5 HU; IQR 16.5 HU]) could be measured with excellent reliability (ICC > 0.865, p < .001 for all). In multivariable analyses only body surface area (BSA) (p < .001) and dental status were associated with MAavg (p = .021). Increased MAavg predicted lower mortality (HR 0.76, 95% confidence interval [CI] 0.61-0.96; p = .023) independent of age (HR 1.05, 95% CI 1.02-1.07; p = 0.001), female sex, body mass index, renal insufficiency, ipsilateral stenosis, indication category, and presence of teeth. MDavg was not associated with mortality. After further adjustment, BSA (the most significant determinant of MAavg) did not alter the association between MAavg and mortality (0.75, 95% CI 0.58-0.97; p = .031).

Conclusion: Average MA but not MD measured from the pre-operative CTA scan provides a reliable estimate of post-operative long-term survival in CEA patients independent of other risk factors, anthropometric measurements, and dental status.

Keywords: Carotid endarterectomy; Cerebrovascular disease; Computed tomography angiography; Muscle.