Abstract 10016: Potential of Stress T1 Mapping for Detection of Microvascular Dysfunction Without Contrast Agents

Abstract

Introduction: Ischemia of hypertrophic myocardium due to microvascular dysfunction is related to worse prognosis in hypertrophic cardiomyopathy (HCM). Stress T1 mapping is a novel cardiac magnetic resonance (CMR) method without contrast agents to be able to assess myocardial blood flow. Hypothesis: We assessed the hypothesis that stress T1 mapping can detect microvascular dysfunction in HCM patients. Methods: Forty-one consecutive subjects without history of coronary artery disease (mean age : 60±3 years, 25 HCM patients, 10 concentric left ventricular hypertrophy (LVH) patients and 6 control subjects) underwent CMR at 3T including cine imaging, rest and adenosine stress T1 mapping, and late gadolinium enhancement (LGE). Native and stress T1 values were measured as an averaged T1 values in the septum of 3 short-axis slices of base-to-apex left ventricle myocardium and T1 reactivity (ΔT1) was calculated as follows: ΔT1 (%) = (T1stress - T1rest)/T1rest х 100. Thirteen HCM patients underwent phase-contrast imaging of coronary sinus flow during rest and adenosine stress to assess coronary flow reserve (CFR). Results: Native T1 values in HCM patients (1271±12ms) showed no significant differences compared with LVH (1225±13ms, p=0.0877) and control subjects (1243±8ms, p=0.534), but ΔT1 in HCM patients (4.00±0.36%) was significantly lower than that in control subjects (5.97±0.41%, p=0.0272), but not in LVH patients (4.95±0.29%, p=0.265, Figure 1). In HCM patients, native T1 values and ΔT1 showed no significant differences between LGE-positive (n=19) and LGE-negative (n=6) groups (native T1: 1274±15ms vs. 1260±20ms, p=0.632, ΔT1: 4.55±0.79% vs. 3.82±0.41%, p=0.394). A moderate positive correlation between ΔT1 and CFR was seen (β=0.697, p=0.0398). Conclusions: T1 reactivity (ΔT1) was reduced in HCM patients compared to control subjects. Stress T1 mapping is a promising CMR method for the assessment of microvascular dysfunction without contrast agents.