RESUMEN
PURPOSE: Guidelines recommend stress only (SO) myocardial perfusion imaging (MPI) without follow-up rest imaging if perfusion and left ventricular ejection fraction (LVEF) are normal. However additional rest imaging may show transient ischaemic dilation (TID) and/or impaired LVEF reserve (iLVEFr) suggestive of 'balanced ischemia'. Concurrent coronary artery calcium (CAC) scoring helps to identify subclinical atherosclerosis. The safety of SO MPI when CAC is elevated is unclear. We aim to assess the incidence and outcomes of TID and iLVEFr amongst stress/rest MPIs with normal SO images and elevated CAC. METHODS: Retrospective analysis of normal stress/rest MPIs performed between 1 March 2016 to 31 January 2017 with concurrently measured CAC >300. Cases were stratified by presence of TID and/or iLVEFr. Major adverse cardiac events (MACE, defined as cardiac death, non-fatal myocardial infarction and revascularization) within 24 months were compared. RESULTS: There were 230 cases included of which 43 (18.7%) had TID and/or iLVEFr. Presence of TID and/or iLVEFr was associated with higher 24-month MACE (23.3 vs. 8.6%, p = 0.013), driven by more elective revascularizations (18.6 vs. 4.3%, p = 0.001). Cardiac death and non-fatal myocardial infarction rates were similar. TID and/or iLVEFr significantly predicted overall MACE after multivariate analysis (OR 2.933 [1.214 - 7.087], p = 0.017). CONCLUSIONS: TID and/or iLVEFr is seen in the minority of normal stress MPI with elevated CAC, and is associated with higher 24-month MACE, driven by higher elective revascularizations. Overall cardiac death and non-fatal myocardial infarction rates were low and not significantly different between both groups.