Key result
CZT-SPECT global myocardial flow reserve yields a modest 0.80 AUC for identifying CMD in INOCA.
Why the study?
The diagnostic value and optimal cut-off values of CZT-SPECT-derived sMBF and MFR for coronary microvascular dysfunction in INOCA patients remained unclear.
Does CZT-SPECT-derived sMBF and MFR accurately identify coronary microvascular dysfunction in INOCA patients compared to caIMR?
Cross-Sectional (n=56)
Does CZT-SPECT-derived sMBF and MFR accurately identify coronary microvascular dysfunction in INOCA patients compared to caIMR?
CZT-SPECT-derived global sMBF and MFR provide modest diagnostic accuracy for identifying coronary microvascular dysfunction in INOCA patients, offering a potential non-invasive alternative to invasive assessment.
Should not change INOCA management yet; leaves open CZT-SPECT diagnostic role pending validation.
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/.
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Fei et al. (2026) conducted a cross-sectional in Ischemia and non-obstructive coronary artery disease (INOCA) (n=56). CZT-SPECT-derived global sMBF and MFR vs. caIMR was evaluated on Diagnostic accuracy for identifying coronary microvascular dysfunction (CMD) (AUC 0.80, 95% CI 0.68-0.90, p=<0.01). CZT-SPECT-derived global myocardial flow reserve provided modest diagnostic accuracy for identifying coronary microvascular dysfunction in INOCA patients (AUC 0.80; 95% CI 0.68-0.90; p<0.01).
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