Int J Cardiovasc Imaging. 2026 Jul 8. doi: 10.1007/s10554-026-03769-8. Online ahead of print.
ABSTRACT
BACKGROUND: In this exploratory diagnostic study, although our previous study demonstrated the strong prognostic value of CZT-SPECT-derived stress myocardial blood flow (sMBF) and myocardial flow reserve (MFR) in patients with ischemia and non-obstructive coronary artery disease (INOCA), their diagnostic value and optimal cut-off values for coronary microvascular dysfunction (CMD) remain unclear.
METHODS: We prospectively recruited 56 INOCA patients referred from cardiovascular medicine to nuclear medicine. Each underwent CZT-SPECT and coronary angiography-derived index of microcirculatory resistance (caIMR) within one week. CMD was defined as caIMR > 25 U. Bonferroni correction was applied for multiple comparisons of regional coronary physiological parameters.
RESULTS: Based on caIMR, CMD was present in 42 INOCA patients (75%). After correction, regional MFR (LAD: 2.9 ± 0.9 vs. 3.7 ± 0.7, p =0.02; LCX: 2.8 ± 1.0 vs. 4.0 ± 1.5, p = 0.02; RCA: 2.9 ± 1.1 vs. 3.9 ± 0.7, p = 0.04) and global MFR (3.0 ± 0.9 vs. 3.9 ± 0.8, p < 0.01) were significantly lower in the CMD group, while no significant difference was observed in regional sMBF. Only global sMBF (r=-0.43, p < 0.01) and global MFR (r=-0.32, p = 0.02) showed moderate inverse correlations with caIMR. The optimal diagnostic cut-offs were global sMBF ≤ 3.8 mL/min/g (AUC = 0.68, 95%CI 0.55-0.80, p = 0.02) and global MFR ≤ 2.9 (AUC = 0.80, 95%CI 0.68-0.90, p < 0.01). DeLong test showed no statistically significant difference in diagnostic efficacy between the two parameters (95%CI for AUC difference: -0.06 to 0.30, p = 0.19). Conclusions These preliminary results demonstrate that CZT-SPECT-derived global sMBF and MFR provide modest diagnostic accuracy for identifying CMD in INOCA patients. This non-invasive approach may support identification of CMD and help guide clinical decision-making.
TRIAL REGISTRATION: ChiCTR2000037112. Registered 27 August 2022, https://www.chictr.org.cn/.
PMID:42420743 | DOI:10.1007/s10554-026-03769-8
