Segmental evaluation of myocardial ischemia in stable coronary artery disease using native T1 mapping.

Objective: To evaluate the myocardial ischemic segments and related factors in stable coronary artery disease (SCAD) patients by native T1 mapping.

Methods: 316 SCAD patients and 30 healthy controls (all right coronary dominant) underwent CMR native T1 mapping within 90 days of CCTA. Segmental native T1 values were measured using AHA 16-segment model. Patients were grouped by number of diseased coronary arteries (DCA (Mozaffarian et al., 2016; Neumann et al., 2019; Gräni et al., 2020 [1-3])) with the largest diameter stenosis (DS [< or ≥ 50 %]) and culprit coronary artery (CCA [LAD, LCX, RCA]), or number of coronary artery stenosis ≥50 % (CAS [0-4]), respectively. Ischemic segments were defined as native T1 values significantly elevated versus controls. Multivariable generalized estimating equations (GEE) model was used to identify independent factors.

Results: Single-vessel disease showed localized native T1 increases in corresponding perfusion territories, while multi-vessel disease exhibited complex ischemia patterns. Anterior and anteroseptal segments had significantly higher native T1 values in groups CAS 2 and 3 than CAS 0 and 1 (Bonferroni-adjusted P < 0.05). GEE model identified DCA (two-vessel disease: β = 13.6 ms, P = 0.010), CAS (1-3: β = 10.5, 34.4 and 57.2 ms, P < 0.05, respectively), and coronary artery calcium (CAC) score 4 and 5 (β = 12.2 and 14.5 ms, P < 0.05), LAD-fractional flow reserves (LAD-FFR) (β = -47.3 ms, P = 0.010) and CCA (LCX: β = -9.5 ms, P = 0.019) as independent factors.

Conclusion: Native T1 mapping reveals spatially heterogenous ischemia in SCAD and is independently associated with both anatomical and functional parameters, supporting its value in personalized evaluation and management.