Phase entropy of gated SPECT-MPI for predicting major adverse cardiovascular events: incremental prognostic value beyond perfusion and function.

Gated SPECT myocardial perfusion imaging (MPI) phase analysis provides a quantitative assessment of left ventricular mechanical synchrony, enabling cardiovascular risk stratification. Phase entropy, a derived imaging biomarker, reflects the spatiotemporal heterogeneity of myocardial contraction. However, its prognostic significance and clinically applicable threshold values have not been rigorously validated. This study aimed to determine the independent prognostic value of phase entropy for predicting major adverse cardiovascular events (MACE). Among 1,674 coronary artery disease patients (median age 62.0 years, 66.2% male) followed for a median 36.6 months, an U-shaped association between phase entropy and major adverse cardiovascular events was identified (P = 0.005). Patients with abnormal phase entropy (>53% or ≤31%) exhibited significantly lower survival than those with normal values (31%-53%, P < 0.001). After multivariable adjustment, phase entropy remained an independent major adverse cardiovascular events predictor, and its addition to a model including total perfusion deficit (TPD) and left ventricular ejection fraction (LVEF) improved major adverse cardiovascular events prediction (P < 0.05). Phase entropy ≤31% or >53% correlates with reduced survival. This biomarker independently predicts major adverse cardiovascular events and provides incremental prognostic value beyond TPD and LVEF, with ≤31% identifying a high-risk subgroup that merits intensified clinical monitoring.