Do ECG abnormalities, degree of sternal displacement or troponin level influence outcomes following sternal fracture?

BACKGROUND: Sternal fractures are critical indicators of significant blunt chest trauma, with reported mortality rates ranging from 4.3% to 32%. While associations between sternal fractures and mortality have been noted, the specific factors influencing outcomes remain incompletely understood.

OBJECTIVE: To analyze potential factors influencing clinical outcomes in patients with sternal fractures, specifically examining the relationship between mortality risk and degree of sternal displacement, troponin levels, and ECG changes.

METHODS: This retrospective cohort study analyzed data obtained from clinical audit. There were 245 patients with documented sternal fractures presenting to a Level 1 Trauma Centre in Adelaide, South Australia from November 2020 to March 2024. Demographic information, clinical data including ECG changes, troponin levels, degree of sternal fracture displacement, and outcome data were extracted from a departmental clinical audit.

RESULTS: The study population had a 9% mortality rate (22/245). Significant associations were found between mortality and sternal displacement severity (Fisher's exact test, p = 0.022), with moderate/complete displacement showing higher mortality (36%) compared to no/mild displacement (8%). High-sensitivity initial troponin T levels exceeding 17.5 ng/L (a post-hoc cut-point) were associated with 20% mortality (17/84), compared to 2% (3/143) at lower levels. Delta troponin T levels were significantly higher in non-survivors (20.5 ng/L, IQR 8.0-154.0) than in survivors (1.0 ng/L, IQR -1.0-4.0; Mann-Whitney U test, p < 0.001). ECG abnormalities were significantly associated with mortality (Fisher-Freeman-Halton exact test, p = 0.001), with mortality rates increasing progressively from normal sinus rhythm (1%) to conduction abnormalities (33%).

CONCLUSION: Degree of sternal fracture displacement, elevated troponin levels, ECG abnormalities, age and injury severity are significant univariate predictors of mortality in patients with sternal fractures. A moderate or severely displaced sternal fracture and/or troponin T level exceeding 17.5 ng/L should serve as red flags for significantly increased mortality risk, warranting heightened clinical vigilance and potentially more aggressive management.