Background <p>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.</p> Methods <p>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 &gt; 25 U. Bonferroni correction was applied for multiple comparisons of regional coronary physiological parameters.</p> Results <p>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 &lt; 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 &lt; 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 &lt; 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). <i>Conclusions</i> 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/.</p>

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The value of myocardial perfusion CZT-SPECT in the assessment of coronary microvascular dysfunction in INOCA patients: a comparative study with caIMR

  • Mengyu Fei,
  • Federico Caobelli,
  • Hengbin Zhang,
  • Kaitao Wang,
  • Chong Xu,
  • Wenliang Che,
  • Fei Yu,
  • Han Zhang

摘要

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/.