Abstract 14153: Hypertrophic Cardiomyopathy Patients Have Increased Diffuse Interstitial Myocardial Fibrosis Measured by T1 Mapping Correlating With Left Ventricular Systolic and Diastolic Dysfunction
Introduction: Diffuse interstitial myocardial fibrosis (IMF) is associated with worse clinical outcomes in hypertrophic cardiomyopathy (HCM). T1 mapping, a novel magnetic resonance (MRI) technique, has recently been developed to quantify IMF noninvasively. We hypothesized that 1) T1 mapping-derived IMF will be higher in HCM patients than controls; and 2) IMF will inversely correlate with systolic and diastolic function in HCM.
Methods: T1 mapping with a Look-Locker sequence was performed in a 3 Tesla MRI 9±3 minutes after the infusion of 0.2 mmol/Kg of gadolinium in 90 patients with suspected HCM. 61 patients were diagnosed with HCM by independent cardiologists, and the remaining 29 patients without HCM served as controls. T1 mapping was performed with previously validated in-house custom-made software and post-contrast T1 relaxation time was used as a surrogate of IMF. Feature tracking-derived longitudinal strain (FT-LS) and circumferential strain (FT-CS) were analyzed from the MRI cine images. Diastolic function was assessed by echocardiography.
Results: There were no differences in age or gender between both groups. As expected, HCM patients had larger LV mass (171±68 vs 116±37 g, p<0.01) and maximum wall thickness (11.4±1.3 vs 19.8±5.4 mm, p<0.01) than controls. LL-derived postcontrast T1 time was shorter in HCM patients (408±47 vs 472±39ms, p<0.01), suggesting a higher degree of IMF in HCM. A T1 time < 444 ms had a sensitivity of 89% and specific of 78% to diagnose HCM (area under the curve 0.89). Additionally, in HCM patients, we found shorter T1 times in hypertrophic than in non-hypertrophic segments (385±60 vs 420±50 ms). In HCM patients, T1 time correlated with measures of diastolic dysfunction: E′ (r=0.45, p<0.05), E/E′ (r =-0.48, p < 0.05) and left atrial size (r=-0.43, p<0.05). Importantly, while overall LVEF and T1 times did not correlate, there was a significant correlation between T1 values and the more sensitive parameters of LV systolic dysfunction FT-LS (r=-0.51, p<0.05) and FT-CS (r=-0.49, p<0.05).
Conclusions: HCM patients show a greater amount of IMF, as assessed by shorter post-contrast relaxationT1 time, than controls. T1 mapping-detected IMF correlates with and probably contributes to systolic and diastolic dysfunction in HCM.
- © 2013 by American Heart Association, Inc.