Abstract 13147: Non-invasive Identification of Carditis in Acute Rheumatic Fever and Rheumatic Heart Disease

Background: The pathogenesis of acute rheumatic fever (ARF) and its evolution into rheumatic heart disease (RHD) is poorly understood. We aimed to identify carditis in patients with ARF and RHD using cardiac magnetic resonance (CMR) tissue characterisation with T1 mapping. We hypothesised that prolonged native T1 time on CMR, would be present in ARF and RHD patients. Methods: We prospectively recruited 62 patients. We recruited 16 patients fulfilling the Jones Criteria for the diagnosis of ARF, 15 controls with an inflammatory condition and 10 healthy controls. We also recruited 11 patients with echocardiographic evidence of RHD and 10 matched controls. All patients underwent CMR with assessment of non-contrast myocardial T1 mapping. The myocardial T1 time, as an index of myocardial inflammation from carditis, was compared between the groups. All T1 times were converted to Z-scores, to enable comparison with different CMR systems. Findings: Patients with ARF had evidence of carditis demonstrated by markedly elevated mean myocardial T1 times. The mean Z score was 2.76(95% CI 1.34-4.17) for patients with ARF compared to 0.32(95% CI -0.25-0.88) for those with non-cardiac inflammatory conditions and 0.00(95% CI -0.72-0.72) for healthy controls, P=0.004. A myocardial T1 Z score greater than 1.4 showed excellent diagnostic performance as a single test for the diagnosis of ARF (AUC = 0.85[0.67-0.99], P=0.001, sensitivity = 82 %, specificity = 92%, Youden’s J = 0.74). Patients with RHD also demonstrated significantly elevated native T1 time compared to matched controls. The mean Z score for RHD patients was 2.79(95% CI 1.3-4.3) compared to 0.00(95% CI -0.72-0.72) in controls, P=0.002. Interpretation: Patients with ARF and RHD have markedly elevated myocardial T1 Z-scores on CMR, consistent with carditis. Incorporating CMR T1 mapping into the diagnostic algorithm for ARF may improve diagnostic certainty and lead to more effective delivery of secondary penicillin prophylaxis.

Native T1 time of right ventricular insertion points by cardiac magnetic resonance: relation with invasive haemodynamics and outcome in heart failure with preserved ejection fraction

Aims Increased afterload to the right ventricle (RV) has been shown to induce myocardial fibrosis at the RV insertion points (RVIPs). Such changes can be discrete but potentially detected by cardiac magnetic resonance (CMR) T1-mapping. Whether RVIP fibrosis is associated with prognosis in heart failure with preserved ejection fraction (HFpEF) is unknown. Methods and results We prospectively investigated 167 consecutive HFpEF patients, a population frequently suffering from post-capillary pulmonary hypertension, who underwent CMR including T1-mapping. About 92.8% also underwent right heart catheterization for haemodynamic assessment. Native T1 times were 995 ± 73 ms at the anterior and 1040 ± 90 ms at the inferior RVIP. By Spearman’s rank order testing, RVIP T1 times were significantly correlated with pulmonary artery pressure (mean PAP, r = 0.313 and 0.311 for anterior and inferior RVIP), pulmonary artery wedge pressure (r = 0.301 and 0.251) and right atrial pressure (r = 0.245 and 0.185; P for all <0.05). During a mean follow-up of 43.2 ± 22.6 months, 30 (18.0%) subjects died. By multivariable Cox regression, NTproBNP [Hazard ratio (HR) 2.105, 95% confidence interval (CI) 1.332–3.328; P = 0.001], systolic PAP (HR 1.618, 95% CI 1.175–2.230; P = 0.003), and native T1 time of the anterior RVIP (HR 1.659, 95% CI 1.125–2.445; P = 0.011) were significantly associated with outcome. Also, by Kaplan–Meier analysis, T1 times at the anterior RVIPs had a significant effect on survival (log-rank, P = 0.002). Conclusion Interstitial expansion of the anterior RVIP as detected by CMR T1-mapping reflects haemodynamic alterations, and is independently related with prognosis in HFpEF.

Assessment of Cardiac Involvement in Fabry Disease (FD) with Native T1 Mapping

Purpose Fabry disease (FD) is an X-linked multi-organ disorder of lysosomal metabolism with cardiac disease being the leading cause of death. Identifying early FD-specific pathologies is important in the context of maximum therapeutic benefit in these stages. Therefore, the aim of this study was to investigate the value of quantitative cardiac T1 mapping as a potential disease-specific surrogate. Methods 16 consecutive FD patients (9 female, 7 male; median age: 54 years, IQR 17) and 16 control patients (9 female, 7 male; median age: 52 years, IQR 20) were investigated at 1.5 Tesla. Native T1 mapping was performed using a modified look locker inversion recovery sequence (MOLLI) and native T1 times were measured within the septal myocardium at the midventricular short-axis section. Also functional parameters, left ventricular morphology, presence of late-gadolinium enhancement, cTnI- and Lyso-Gb3-Levels were evaluated. Results The median native septal T1 time for FD was 889.0 ms and 950.6 ms for controls (p < 0.003). LGE and positive cTnI values (0.26 ± 0.21) were present in 5 FD patients (31.25 %), and left ventricular hypertrophy (LVH) was present in 4 FD patients (25.00 %). The 4 cTnI and 8 Lyso-Gb3 positive FD patients had significantly lower native T1 values (p < 0.05, respectively p < 0.01). Assuming a T1 cut-off value of 900 ms for the identification of increased cardiac lipid deposit, 9 patients with FD (56.25 %) had pathologic values (4 patients cTnI and 8 patients Lyso-Gb3 positive). Moreover, native septal T1 showed a good negative correlation to Lyso-Gb3 (r = – 0.582; p = 0.018). Conclusion A pathologic cardiac native T1 time obviously reflects cardiac involvement in the scope of FD at tissue level. In the future native T1 mapping as an imaging biomarker might allow identification of early stages of cardiac involvement in FD before morphological changes are obvious. Key Points: Citation Format

Abstract 14783: Relationship Between Native Papillary Muscle T1 Time and Severity of Functional Mitral Regurgitation in Patients With Non-ischemic Dilated Cardiomyopathy

Introduction: Functional mitral regurgitation is one of the severe complications of non-ischemic dilated cardiomyopathy (DCM). Non-contrast native T1 mapping has emerged as a non-invasive method to evaluate myocardial fibrosis. Hypothesis: We hypothesized that papillary muscle native T1 time is correlated with severity of functional mitral regurgitation in DCM patients. Methods: Forty DCM patients (55±13 years) and 20 healthy adult control subjects (54±13 years) were studied. Native T1 mapping was performed using a slice interleaved T1 mapping sequence (STONE) which enables acquisition of 5 slices in the short-axis plane within a 90 sec free-breathing scan. We measured papillary muscle diameter, length and shortening. DCM patients were allocated into 2 groups based on the presence or absence of functional mitral regurgitation. Results: Papillary muscle T1 time was significantly elevated in DCM patients with mitral regurgitation (n=22) in comparison to those without mitral regurgitation (n=18) (anterior papillary muscle: 1127±36 msec vs 1063±16 msec, p<0.001; posterior papillary muscle: 1124±30 msec vs 1062±19 msec, p<0.001), but LV T1 time was similar (1129±38 msec vs 1134±58 msec, p=0.93). Multivariate linear regression analysis showed that papillary muscle native T1 time (β=0.109, 95%CI: 0.048-0.170, p=0.001) and tenting height (β=1.334, 95%CI: 0.434-2.234, p=0.005) are significantly correlated with mitral regurgitant fraction. Elevated papillary muscle T1 time was associated with larger diameter, longer length and decreased papillary muscle shortening (all p values <0.05). Conclusions: In DCM, papillary muscle native T1 time is significantly elevated and related to mitral regurgitant fraction. These results suggest that papillary muscle diffuse fibrosis might be associated with severity of mitral regurgitation in this population.

Abstract 15137: Detection of Diffuse Myocardial Fibrosis using Multi-slice T1 Mapping by Slice Interleaved T1 (STONE) Sequence in Patients With Hypertrophic Cardiomyopathy

Introduction: In hypertrophic cardiomyopathy (HCM), there are significant variations in left ventricular (LV) wall thickness and fibrosis, which necessitates a volumetric coverage. Slice-interleaved T1 (STONE) mapping sequence allows for the assessment of native T1 time with complete coverage of LV myocardium. Hypothesis: We hypothesized that STONE sequence is useful for the assessment of regional native T1 time abnormality in HCM patients. Methods: Twenty-four septal HCM patients (56±16 years) and 10 healthy adult control subjects (57±15 years) were studied. Native T1 mapping was performed using STONE sequence which enables acquisition of 5 slices in the short-axis plane within a 90 sec free-breathing scan. We measured LV native T1 time and maximum LV wall thickness in each 16 segments from 3 slices (basal-, mid- and apical-slice) and evaluated the relationship between LV native T1 time and wall thickness. Late gadolinium enhanced (LGE) MRI was acquired to assess presence of myocardial enhancement. Results: In HCM patients, LV native T1 time was significantly elevated compared to healthy controls, regardless of presence or absence of LGE (mean native T1 time; LGE (+) segments (n=27), 1139±55 msec; LGE (-) segments (n=351), 1118±55 msec; healthy control (n=160),1065±35 msec; p<0.001 by one-way ANOVA, 6 segments were excluded from analysis due to artifacts). Among 351 segments without LGE, native LV T1 time was diffusely elevated over the 16 segments (Figure). Significant positive correlation was found between LV wall thickness and native LV T1 time (y=1013+8.7x, p<0.001). Conclusions: In HCM, substantial number of segments without LGE showed elevated native T1 time, and native T1 time was correlated with LV wall thickness. Multi-slice T1 mapping by using STONE sequence could be advantageous to overcome limited cardiac coverage of conventional single-slice T1 mapping technique and to accurately detect the diffuse myocardial fibrosis in HCM patients.