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Background <p>Coronary microvascular dysfunction (CMD) can exacerbate myocardial fibrosis, which may further impair microvascular function. However, the relationship between CMD and the extracellular volume fraction (ECV) in patients with ischemia with no obstructive coronary artery disease (INOCA) who are late gadolinium enhancement (LGE)-negative remains undetermined. We used T1 mapping and ECV to assess diffuse myocardial tissue abnormalities and extracellular compartment expansion in LGE-negative patients with CMD. We then investigated how these markers correlate with global myocardial flow reserve (MFR).</p> Methods <p>Between August 2024 and May 2026, we prospectively enrolled 86 LGE-negative patients with INOCA from a single center who underwent a positron emission tomography−magnetic resonance imaging (PET-MRI) protocol. Patients with significant epicardial stenosis (stenosis on coronary angiogram or computed tomography ≥ 50%), prior history of revascularization, known myocardial infarction, or heart failure were excluded. MFR and ECV were derived from PET perfusion imaging and pre- and post-T1 mapping, respectively. CMD was defined as PET-derived MFR of &lt; 2.0 in at least one major coronary artery territory.</p> Results <p>Among the 86 patients included, 39 (45.3%) were diagnosed with CMD. ECV was substantially higher in the CMD group (31.22 [29.93, 33.25]% vs. 26.66 [25.85, 27.55]%, <i>P</i> &lt; 0.001), with a more modest but statistically significant elevation in native T1 (1225 ± 25 ms vs. 1212 ± 21 ms, <i>P</i> = 0.012). Multivariable linear regression revealed that only global MFR (β [95% confidence interval] = − 1.905 [− 2.489, − 1.321], <i>P</i> &lt; 0.001) was an independent predictor of ECV in LGE-negative CMD patients. In the overall cohort, resting myocardial blood flow (MBF) (<i>r</i> = 0.539, <i>P</i> &lt; 0.001) and global MFR (<i>r</i> = − 0.741, <i>P</i> &lt; 0.001) were positively and negatively correlated with ECV, respectively. When participants were stratified into ECV tertiles, global MFR showed a progressive decrease (2.92 vs. 2.48 vs. 1.78; <i>P</i> &lt; 0.001 for trend) with increasing ECV values.</p> Conclusions <p>In patients with INOCA with CMD, prolonged native T1 and elevated ECV indicate diffuse interstitial expansion, consistent with early tissue remodeling, even when LGE is absent on CMR. These findings suggest that native T1 and ECV may hold promise as adjunctive tissue markers to support risk stratification, though their role in clinical management requires further validation in larger cohorts.</p>

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Early detection of myocardial fibrosis in patients with coronary microvascular dysfunction in the absence of late enhancement: role of T1 mapping and extracellular volume analysis

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月22日

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  • Runze Wen,
  • Qiang Xie,
  • Bo Pan,
  • Xingxing Zhu,
  • Dan Li,
  • Xuemei Wang

摘要

Background

Coronary microvascular dysfunction (CMD) can exacerbate myocardial fibrosis, which may further impair microvascular function. However, the relationship between CMD and the extracellular volume fraction (ECV) in patients with ischemia with no obstructive coronary artery disease (INOCA) who are late gadolinium enhancement (LGE)-negative remains undetermined. We used T1 mapping and ECV to assess diffuse myocardial tissue abnormalities and extracellular compartment expansion in LGE-negative patients with CMD. We then investigated how these markers correlate with global myocardial flow reserve (MFR).

Methods

Between August 2024 and May 2026, we prospectively enrolled 86 LGE-negative patients with INOCA from a single center who underwent a positron emission tomography−magnetic resonance imaging (PET-MRI) protocol. Patients with significant epicardial stenosis (stenosis on coronary angiogram or computed tomography ≥ 50%), prior history of revascularization, known myocardial infarction, or heart failure were excluded. MFR and ECV were derived from PET perfusion imaging and pre- and post-T1 mapping, respectively. CMD was defined as PET-derived MFR of < 2.0 in at least one major coronary artery territory.

Results

Among the 86 patients included, 39 (45.3%) were diagnosed with CMD. ECV was substantially higher in the CMD group (31.22 [29.93, 33.25]% vs. 26.66 [25.85, 27.55]%, P < 0.001), with a more modest but statistically significant elevation in native T1 (1225 ± 25 ms vs. 1212 ± 21 ms, P = 0.012). Multivariable linear regression revealed that only global MFR (β [95% confidence interval] = − 1.905 [− 2.489, − 1.321], P < 0.001) was an independent predictor of ECV in LGE-negative CMD patients. In the overall cohort, resting myocardial blood flow (MBF) (r = 0.539, P < 0.001) and global MFR (r = − 0.741, P < 0.001) were positively and negatively correlated with ECV, respectively. When participants were stratified into ECV tertiles, global MFR showed a progressive decrease (2.92 vs. 2.48 vs. 1.78; P < 0.001 for trend) with increasing ECV values.

Conclusions

In patients with INOCA with CMD, prolonged native T1 and elevated ECV indicate diffuse interstitial expansion, consistent with early tissue remodeling, even when LGE is absent on CMR. These findings suggest that native T1 and ECV may hold promise as adjunctive tissue markers to support risk stratification, though their role in clinical management requires further validation in larger cohorts.