Prognostic value of D-SPECT-derived myocardial flow reserve in detecting coronary microvascular disease and predicting outcomes after complete revascularization: a two-center pilot study.

PURPOSE: This two-center prospective study sought to evaluate whether D-SPECT-derived myocardial flow reserve (MFR) can identify coronary microvascular disease (CMD) and predict major adverse cardiac events (MACE) in patients who had undergone complete revascularization by percutaneous coronary intervention (PCI).

METHODS

We enrolled 174 patients with angiographically confirmed complete revascularization post-PCI. Global and regional MFR were quantified using dynamic D-SPECT at rest and during pharmacological stress. CMD was defined as global or territorial MFR < 2.0 in the absence of > 50% epicardial stenosis. The primary endpoint was major adverse cardiac events (MACE), defined as a composite of all-cause death, myocardial infarction, unscheduled coronary revascularization, stroke, heart failure hospitalization, and rehospitalization for angina pectoris. Multivariable Cox regression and reclassification analyses (NRI/IDI) were used to assess prognostic value.

RESULTS

Over a median follow-up of 12 months (interquartile range, IQR 7-21 months), 42 patients (24.1%) experienced MACE. Patients with CMD had significantly higher MACE rates (log-rank χ²=11.375, P = 0.001). After multivariate adjustment for cardiovascular risk factors and abnormal myocardial perfusion imaging, CMD remained an independent predictor of MACE (HR = 2.46; 95%CI: 1.27-4.76; P = 0.007). Regional MFR provided significant incremental prognostic value over global MFR (NRI = 0.524, 95%CI: 0.202-0.821; IDI = 0.036, 95%CI 0.007-0.067). The association between CMD and MACE was consistent across all prespecified subgroups.

CONCLUSION

In this two-center cohort of patients with complete revascularization after PCI, D-SPECT-derived CMD is associated with a > 2-fold increased risk of future MACE, independent of traditional risk factors and perfusion abnormalities. Regional MFR provides incremental prognostic value beyond global MFR. These findings are exploratory and warrant validation in multi-center studies with longer follow-up and comparisons with invasive measurements.