Incremental prognostic value of myocardial strain in patients with coronary slow flow

Although coronary slow flow (CSF) was associated with adverse cardiac outcomes, the prognostic value of myocardial strain (MS) for major adverse cardiovascular events (MACEs) in CSF is not well established. We aimed to examine the longitudinal association between MS and MACEs in this population. Medical records from 336 patients with CSF (January 2019 to June 2022) were analyzed retrospectively. All patients underwent comprehensive echocardiography with MS quantified via speckle tracking echocardiography (STE), including left ventricular global longitudinal strain (LVGLS) and circumferential strain (LVGCS). MACEs were defined as the primary endpoint. Multivariable Cox regression analysis was performed to evaluate the association between MS and MACEs. During a median follow-up of 19 months (range: 6–51 months), MACEs occurred in 37.8% (127/336). LVGCS was independently associated with MACEs (HR = 1.794, 95% CI 1.307–2.462, P < 0.001) after adjusting for conventional risk factors and may provide incremental prognostic value beyond conventional risk factors (C statistics increased from 0.790 to 0.885; IDI = 0.172, P < 0.001; NRI = 0.790, P < 0.001). LVGCS was independently associated with MACEs in CSF patients. Adding LVGCS to conventional risk factors may provide incremental prognostic information, suggesting its potential utility for improving risk stratification.