Combination of CZT SPECT stress myocardial blood flow (MBF) and coronary artery calcium (CAC) scoring - opportunity for stress-first/stress-only protocol

Abstract Introduction Typical dynamic CZT SPECT protocol (rest – stress) enables absolute quantification of MBF and coronary flow reserve (CFR = stress MBF/rest MBF). However, its great disadvantage is a complexity. Stress-first protocol enabling stress-only MBF can significantly reduce time, cost and a radiation dose. Purpose To assess the prognostic significance of stress MBF, CFR, and CAC scoring. Methods Retrospective analysis of 73 patients (26 men, 66±9 years) examined with rest-stress dynamic myocardial SPECT and CAC scoring. The adverse cardiac event (CE) defined as sudden cardiac death, myocardial infarction, situations requiring coronary revascularization, and hospitalization for heart failure with reduced ejection fraction, were recorded. Results We observed 12 CE during a mean follow-up of 13±8 months. Patients with CE had higher CAC score (1035±1121 vs 205±445), comparable rest MBF (1.27±0.44 vs 1.23±0.47 ml/min/g) but significantly lower stress MBF (2.01±1.11 vs 2.83±0.98 ml/min/g) and a lower CFR (1.58±0.61 vs 2.47±0.88). A cut-off value for the prediction of CE were: CAC score 230,2 (sensitivity of 91 % and a specificity of 82 %), stress MBF 2.29 ml/min/g (sensitivity of 83 % and a specificity of 70 %), and CFR 1.94 (sensitivity of 75 % and a specificity of 77 %), respectively. There was no superiority of CFR over stress MBF in the identification of CE (P = NS). No CE occurred in patients with the combination of stress MBF ≥ 2.29 ml/min/g and CAC score < 230.2. Conclusion We can predict CE by a combination of stress MBF and CAC scoring. A simplification of dynamic SPECT protocol (stress-first/stress-only) enables expansion of the MBF quantification for a larger number of patients.