Abstract 11065: Stress T1 Mapping Demonstrates Coronary Microcirculatory Dysfunction in Both Nonhypertrophied and Hypertrophied Myocardium of Hypertrophic Cardiomyopathy

Abstract

Introduction: Coronary microcirculatory dysfunction (CMD) in hypertrophic cardiomyopathy (HCM) is associated with clinical deterioration. We have shown that stress T1 mapping could detect CMD of hypertrophied interventricular septum (IVS). However, CMD in nonhypertrophied left ventricular free wall (LVFW) has not been fully elucidated. Hypothesis: We assessed the hypothesis that regional CMD in LVFW of HCM can be detected using stress T1 mapping. Methods: We evaluated 36 consecutive subjects (26 HCM patients and 10 control subjects, mean age: 61±3 years) who underwent CMR at 3T. Cine imaging, rest and adenosine stress T1 mapping, late gadolinium enhancement (LGE) and phase-contrast imaging of coronary sinus flow were performed. The T1 values at rest and after adenosine stress were measured as an averaged T values of 3 short-axis slices of LV myocardium and T1 reactivity (ΔT1) was calculated as follows: ΔT1 (%) = (T1stress - T1rest)/T1rest х 100. Coronary flow reserve (CFR) was measured coronary sinus blood flow during adenosine stress divided by that at rest. Results: The T1 values at rest were significantly higher in HCM than control (1245±9ms vs. 1196±11ms, p=0.0027), and the T1 values after adenosine stress significantly increased in both groups (HCM: 1285±10ms, p=0.0018 vs. rest, control: 1244±9ms, p=0.0128 vs. rest, Figure 1). Both IVS and LVFW demonstrated significantly lower ΔT1 in HCM than control (IVS: 3.95±0.35% vs. 5.68±0.41%, p=0.0163, LVFW: 4.80±0.39% vs. 6.75±0.65%, p=0.0163, Figure 2). CFR in HCM significantly decreased than that in control (2.48±0.40 % vs. 5.97±1.31 %, p=0.0051). Multiple regression analysis revealed that ΔT1 of both IVS and LVFW was correlated with CFR (β=0.527, p=0.0026, β=0.445, p=0.0325). Conclusions: T1 reactivity significantly decreased in both nonhypertrophied and hypertrophied myocardium of HCM compared to control. Stress T1 mapping have the advantage of being able to estimate regional CMD in addition to global CMD.