Stress-induced Worsening Diastolic Function in Patients with Coronary Slow Flow: A Study from G-SPECT Imaging

Background: Gated 99m Tc-sestamibi myocardial perfusion single-photon emission computed tomography (G-SPECT) is a non-invasive imaging technique that offers accurate evaluation of myocardial perfusion and resting left ventricular diastolic function in patients with coronary slow flow (CSF). However, it’s uses to estimate the diastolic function during stress is still not well determined. Objective: To evaluate the left ventricular diastolic function at rest and during stress in CSF patients using G-SPECT and to determine the association between the clinical variables and the rest-stress changes in diastolic function. Methods: We identified 18 angiographically proven CSF patients (56 ± 8.9 years, 12 male), from January 2017 through October 2018, who underwent a 2-day 99m Tc-t sestamibi adenosine/exercise stress test along with rest protocols. The cardiac diastolic function parameters, including peak filling rate (PFR), time to peak filling (TTPF), and peak filling rate normalized to EDV (end diastolic volume) (PFR/EDV) were obtained using G‑SPECT. Then, the association between the diastolic function parameter changes (Δ stress-rest) and cardiovascular risk factors were analyzed. Results: Compared with rest, summed stress scores were significantly higher ( P  = 0.01). TTPF, PFR, and PFR adjusted by EDV(PFR/EDV) alone showed no significant difference between rest and stress as diastolic dysfunction was present in both states. There was progressive decrease in TTPF, PFR and PFR/EDV with stress. In stepwise regression model, total cholesterol was significantly associated with the difference of summed scores (ΔStress-Rest) (β = 0.518, P  = 0.028). In the same model, uric acid was found inversely associated with the difference in TTPF (ΔStress-Rest) and PFR/EDV (ΔStress-Rest) (β= -0.516, P  = 0.028 and β= -0.560, P  = 0.015, respectively). Conclusion: Uric acid is significantly associated with the diastolic function worsening during stress in CSF patients. It may be a potential predictor and possible therapeutic target to attenuate the early diastolic function deterioration in these patients.