Prognostic Value of Ultrafast Myocardila Perfusion Spect Imaging Using an Intergrated Stress-first And Stress-Only Approach

Background: Most previous studies demonstrating the prognostic value of myocardial perfusion SPECT imaging (MPI) involved conventional technology and high stress radiation-doses. This study assessed the prognostic value of one-day stress-first and stress-only ultrafast MPI using low stress radiation-doses.

Methods and Results: We determined all-cause mortality, myocardial infarction (MI) and late revascularization among 7,259 patients who underwent ultrafast stress-first Tc-99m sestamibi MPI using ultrafast CZT camera, and a very low stress-dose. Of these, 2,429 (33.5%) with normal stress MPI underwent low-dose stress-only testing. Mean follow-up time was 1.97±0.57 years. Median stress and per-patient effective doses were 2.6 and 7.7 mSv, respectively. Multivariate Cox-regression demonstrated that stress perfusion deficit (stress-PD) was highly predictive of death, and of composite endpoints of death and cardiac evnts. Risk stratification by ischemia demonstrated that mild ischemia (ischemic-PD 5-10%) was associated with a 2.5 fold increase in death and death+MI rates vs. ischemic-PD=0% (2.05 vs. 0.82 %/year and 2.51 vs. 1.03 %/year, respectively, log rank p ≤0.005). Ischemic-PD 5%-10% and ≥10% independently predicted higher risk of death+MI+ late revascularization (Hazard ratio 1.84 and 2.39, respectively, p<0.001). Patients who underwent stress-only MPI had very low death, death+MI and death+MI+ revascularization rates (0.46, 0.56 and 1.03 %/year, respectively).

Conclusions: Ultrafast stress-first MPI using a low stress-dose and conversion to stress-only after normal stress imaging provided high prognostic value at reduced effective-radiation. Ischemic burden ≥5% of the left ventricular myocardium identified patients at moderate-high risk of death and cardiac events, while those who underwent a stress-only MPI had excellent outcome.