Utility of stress parameters to determine prognosis following normal exercise SPECT myocardial perfusion imaging.

Exercise parameters achieved during an exercise stress myocardial perfusion imaging (MPI) with single-photon emission computed tomography (SPECT) study may help to predict clinical outcomes. The aim of our study was to compare different exercise stress parameters to determine their prognostic utility following a normal rest- exercise stress MPI. We performed a retrospective cohort study on 3290 consecutive patients who had undergone rest-exercise-stress MPI from 2017 to 2024. 1020 patients had normal perfusion images and were included in the analysis. The primary endpoint of the study was a composite of all-cause mortality, non-fatal myocardial infarction and coronary revascularization. Using multivariable survival analysis, we evaluated the incremental prognostic risks of exercise and clinical factors to predict the primary end point. 58% of the cohort were male, the mean age was 59 ± 10 years. During a follow-up of 55 ± 22 months, 44 primary events occurred. On univariable and multivariable survival analysis achieving < 85% of the maximum age predicted heart rate (APHRmax) was not associated with an increase in risk. In patients who achieved a maximal heart rate and stress systolic blood pressure product (rate pressure product, RPPstress) of < 25,000, the risk of the primary end point was increased (HR 2.03 (1.08-3.83), p = 0.028). RPPstress and not APHRmax had incremental prognostic risk following normal rest-exercise-stress MPI SPECT. RPPstress might be considered as an additional parameter to be included in SPECT-MPI reporting to assist clinicians in risk stratification.