Additional value of the coronary artery calcium score in patients for whom myocardial perfusion imaging is challenging

Background: Determination of prognosis based on ischemia detection, using single‑photon emission computed tomography myocardial perfusion imaging (SPECT‑MPI), can be challenging in patients with multiple affected coronary arteries. Aims: The aim of the study was to examine the outcomes of SPECT‑MPI combined with the coronary artery calcium score (CACS) to identify predictors of adverse cardiac events (ACEs) in patients for whom ischemia detection may be difficult using SPECT‑MPI. Methods: The study group included 195 patients with a history of chronic kidney disease, suspected ischemic cardiomyopathy, or left bundle branch block. All patients underwent SPECT‑MPI and CACS evaluation. During the follow‑up, ACEs were recorded. Perfusion and functional parameters as well as the CACS were analyzed to find the predictors of ACEs. Results: The ACEs were recorded in 58 individuals (29.7%) and were significantly associated with ischemia (P < 0.001), abnormal functional parameters (P = 0.04), and higher CACSs (P < 0.001). The optimal cutoff value of the CACS to predict an ACE was 530. Cox proportional hazards models revealed that age, mild and severe ischemia, functional abnormalities, and a CACS of 530 or higher were significant predictors of ACEs. In the subgroup of individuals without ischemia, a CACS of 530 or higher was significantly associated with poor outcome, while we recorded only 3 ACEs in these patients when the CACS was lower than 530. Conclusions: The addition of the CACS to SPECT‑MPI improves the identification of patients at higher risk for ACEs, even in individuals for whom SPECT‑MPI is challenging