Pectoralis major muscle index as an opportunistic predictor of mortality in acute stroke patients treated with intravenous thrombolysis.

Background: Premorbid sarcopenia in acute stroke indicates poor prognosis. Since formal sarcopenia tests cannot be performed, the muscle features imaged in diagnostic studies are opportunistically used as surrogates for sarcopenia in the acute period.

Methods: In 110 consecutive acute ischemic anterior circulation stroke patients treated with intravenous tissue plasminogen activator alone (mean age: 73±13 years, 55% women), the cross-sectional area (CSA) and attenuation of pectoralis major and minor muscles and mediastinal adipose tissue were measured at admission computed tomography (CT) angiography source images.

Results: Pectoralis major and minor muscle CSA (mm²) and indices (CSA/height(m)²) were significantly higher in patients with 3-month modified Rankin's scores of 0-1 (excellent outcome, 41%), 0-2 (good outcome, 54%), and in surviving patients (87%). In regression models adjusted for age and NIHSS, pectoralis major muscle CSA (partial r: -0.281, p = 0.027) and pectoralis major index (partial r: -0.332, p = 0.008) were independent predictors of mortality. The discriminatory value of the pectoralis major index for mortality was good (ROC-AUC 0.794, 95%CI: 0.676-0.885). The optimal threshold for survival of pectoralis major index was > 3316 mm²/m² with 0.607 Youden J index. No difference was found in muscle CT attenuation values, mediastinal adipose tissue area and radiodensity in deceased patients.

Conclusions: Our retrospective analysis documents that the pectoralis major index, a readily available CT anthropometry surrogate for sarcopenia, is an independent predictor of survival in patients with acute ischemic stroke undergoing systemic thrombolysis. It may suggest that the pectoralis major index could be included in the prognostic toolkit of acute ischemic stroke.