Impaired myocardial oxygen metabolism and energy efficiency in patients with dilated cardiomyopathy.

BACKGROUND

Myocardial oxygen metabolism and mechano-energetic efficiency are key determinants of cardiac function and clinical outcomes, but their status in dilated cardiomyopathy (DCM) remains incompletely understood. This study applied a non-contrast cardiovascular magnetic resonance (CMR) technique to assess myocardial oxygenation, cardiac work, and energy efficiency in DCM.

METHODS

We enrolled 49 DCM patients and 23 age- and sex- matched controls. All subjects underwent cine CMR imaging for left ventricular ejection fraction (LVEF) and global longitudinal strain (LVGLS), pre- and post-contrast T1 mapping for extracellular volume (ECV), and first-pass perfusion imaging for semi-quantification of myocardial blood flow (MBF). A non-contrast CMR technique was applied to quantify myocardial oxygen extraction fraction (mOEF). Semi-quantitative myocardial oxygen consumption (MVO₂), external work (EW), and myocardial external efficiency (MEE) were derived for analysis.

RESULTS

Compared with controls, DCM patients exhibited significantly lower mOEF (50.3 [47.9, 53.9] % vs. 57.6 [56.2, 60.4] %, p < 0.001), MVO2 per gram tissue (0.07 ± 0.01 vs. 0.08 ± 0.01, p = 0.027), EW (248.38 ± 97.87 vs. 341.88 ± 86.98mmHg×mL/min×103, p < 0.001), and MEE (22.88 ± 10.62% vs. 45.95 ± 10.53%, p < 0.001), but higher total MVO₂ (7.99 ± 2.58 vs. 5.30 ± 1.48, p < 0.001). Resting mOEF showed no significant association with LVEF and LVGLS, whereas total MVO₂ and MEE correlated significantly with both LVEF and LVGLS. Female DCM patients exhibited higher LVEF (31.30 ± 10.18% vs. 22.47 ± 9.74%, p = 0.006), absolute LVGLS (9.81 ± 3.55% vs. 7.24 ± 2.86%, p = 0.011) and MEE (27.29 ± 11.87% vs. 20.74 ± 9.43%, p = 0.049) compared with males.

CONCLUSION

This feasibility study demonstrates the potential of this non-contrast CMR technique for noninvasive assessment of myocardial oxygen metabolism and mechano-energetic coupling in DCM. Patients with DCM showed impaired resting myocardial oxygen metabolism and reduced energy efficiency.