Efficacy of Indocyanine Green Angiography for Predicting Subclinical Intraoperative Thrombosis During Head and Neck Microvascular Free Tissue Transfer.

[BACKGROUND] Traditional intraoperative flap assessments like capillary refill and distal bleeding can provide insight on flap viability and circulation; however, it is difficult to assess the cause of the vascular compromise or detect early "subclinical" thrombosis. This study was designed to determine the sensitivity and specificity of indocyanine green angiography (ICGA) in detecting subclinical intraoperative thrombosis during HN-MFTT.

[METHODS] A retrospective cohort study was performed on HN-MFTT cases at a single institution. Flaps where ICGA was employed after completing the anastomosis were reviewed. The frequency of subclinical intraoperative thrombosis was compared between cases with normal and abnormal ICGA prompting vessel exploration.

[RESULTS] A total of 67 patients who had intraoperative ICGA were included (male, 55 [82.1%]; median age, 64 [interquartile range, 56-72]). Most underwent anterolateral thigh (n = 56, 83.6%), fibula (n = 13, 19.4%), or radial forearm (n = 12, 17.9%) reconstruction. Of the flaps included, 11 (16.5%) had abnormal ICGA and 9 (13.4%) had subclinical thrombosis. For predicting subclinical thrombosis, abnormal ICGA had a sensitivity of 100% (95% CI: 66.4-100), specificity of 96.6% (95% CI: 88.1-99.6), positive predictive value of 81.8% (95% CI: 48.2-97.7), and negative predictive value of 100% (95% CI: 93.6-100). There was no significant difference in takebacks, flap loss, and complications between those with normal and abnormal ICGA (p > 0.05 for all tests).

[CONCLUSION] ICGA is a sensitive and specific technique for detecting intraoperative, subclinical thrombosis during HN-MFTT in properly selected patients. This warrants future research to define indications for ICGA use and evaluate how this technology affects clinical outcomes.