Right and left ventricular function and flow quantification in pediatric patients with repaired tetralogy of Fallot using four-dimensional flow magnetic resonance imaging

Background To assess the accuracy and reproducibility of right ventricular (RV) and left ventricular (LV) function and flow measurements in children with repaired tetralogy of Fallot (rTOF) using four-dimensional (4D) flow, compared with conventional two-dimensional (2D) magnetic resonance imaging (MRI) sequences. Methods Thirty pediatric patients with rTOF were retrospectively enrolled to undergo 2D balanced steady-state free precession cine (2D b-SSFP cine), 2D phase contrast (PC), and 4D flow cardiac MRI. LV and RV volumes and flow in the ascending aorta (AAO) and main pulmonary artery (MPA) were quantified. Pearson’s or Spearman’s correlation tests, paired t-tests, the Wilcoxon signed-rank test, Bland–Altman analysis, and intraclass correlation coefficients (ICC) were performed. Results The 4D flow scan time was shorter compared with 2D sequences (P < 0.001). The biventricular volumes between 4D flow and 2D b-SSFP cine had no significant differences (P > 0.05), and showed strong correlations (r > 0.90, P < 0.001) and good consistency. The flow measurements of the AAO and MPA between 4D flow and 2D PC showed moderate to good correlations (r > 0.60, P < 0.001). There was good internal consistency in cardiac output. There was good intraobserver and interobserver biventricular function agreement (ICC > 0.85). Conclusions RV and LV function and flow quantification in pediatric patients with rTOF using 4D flow MRI can be measured accurately and reproducibly compared to those with conventional 2D sequences.

Altered left atrial 4D flow characteristics in patients with paroxysmal atrial fibrillation in the absence of apparent remodeling

The pathophysiology behind thrombus formation in paroxysmal atrial fibrillation (AF) patients is very complex. This can be due to left atrial (LA) flow changes, remodeling, or both. We investigated differences for cardiovascular magnetic resonance (CMR)-derived LA 4D flow and remodeling characteristics between paroxysmal AF patients and patients without cardiac disease. In this proof-of-concept study, the 4D flow data were acquired in 10 patients with paroxysmal AF (age = 61 ± 8 years) and 5 age/gender matched controls (age = 56 ± 1 years) during sinus rhythm. The following LA and LA appendage flow parameters were obtained: flow velocity (mean, peak), stasis defined as the relative volume with velocities < 10 cm/s, and kinetic energy (KE). Furthermore, LA global strain values were derived from b-SSFP cine images using dedicated CMR feature-tracking software. Even in sinus rhythm, LA mean and peak flow velocities over the entire cardiac cycle were significantly lower in paroxysmal AF patients compared to controls [(13.1 ± 2.4 cm/s vs. 16.7 ± 2.1 cm/s, p = 0.01) and (19.3 ± 4.7 cm/s vs. 26.8 ± 5.5 cm/s, p = 0.02), respectively]. Moreover, paroxysmal AF patients expressed more stasis of blood than controls both in the LA (43.2 ± 10.8% vs. 27.8 ± 7.9%, p = 0.01) and in the LA appendage (73.3 ± 5.7% vs. 52.8 ± 16.2%, p = 0.04). With respect to energetics, paroxysmal AF patients demonstrated lower mean and peak KE values (indexed to maximum LA volume) than controls. No significant differences were observed for LA volume, function, and strain parameters between the groups. Global LA flow dynamics in paroxysmal AF patients appear to be impaired including mean/peak flow velocity, stasis fraction, and KE, partly independent of LA remodeling. This pathophysiological flow pattern may be of clinical value to explain the increased incidence of thromboembolic events in paroxysmal AF patients, in the absence of actual AF or LA remodeling.

Abstract 17275: The SGLT2 Inhibitor Empagliflozin Ameliorates Left Atrial Dilatation in Non-Diabetic Patients With Heart Failure With Reduced Ejection Fraction: A Secondary Analysis of the EMPATROPISM Trial

Background: SGLT2 inhibitors (SGLT2i) improve prognosis in HFrEF patients. We recently demonstrated in a porcine model of non-diabetic HFrEF that empagliflozin (EMPA) ameliorates adverse cardiac remodeling and improves LV systolic function. However, the effect of EMPA on left atrial (LA) dilatation has not yet been studied Hypothesis:: Empagliflozin ameliorates left atrial dilatation in non-diabetic HFrEF patients Methods: The EMPATROPISM clinical trial investigated the efficacy and safety of EMPA in non-diabetic HFrEF patients. 84 patients were randomized to EMPA 10mg daily for 6 months or placebo on top of optimal medical treatment, and were evaluated with cardiac magnetic resonance (CMR). LA Volumes were quantified by CMR using the Simpson method (the number of slices in the usual short axis SSFP cine sequence was increased to cover both LV and the whole of LA. The primary endpoint was change in LVEDV. Prespecified secondary endpoints were changes in maximal and minimal LA volumes (ΔMax LA Vol and ΔMin LA Vol) at the end of 6 months between both arms Results: 80 patients completed the follow up period. There were no differences at baseline in LVEDV (220±75 vs 209±68mL for EMPA vs placebo, p=0.5) or LVEF (36±8 vs 37±8%, p=0.7). There were no differences at baseline in both groups in either maximal or minimal LA volume (Table). In the primary endpoint, EMPA-treated patients showed decrease in LVEDV and increase in LVEF (ΔLVEDV -25±25 vs -1±25mL, p<0.001; and ΔLVEF 6±4 vs 0±4%, p<0.001 for EMPA vs placebo). EMPA-treated patients exhibited a reduction of both maximal LA volume (ΔMax LA Vol -16.2±17.8 vs 11.4±25.9mL for EMPA vs placebo, p<0.001) and minimal LA volume (ΔMin LA Vol -11.3±13.3 vs 6.4±19.3mL for EMPA vs control, p<0.001) Conclusions: In HFrEF patients without diabetes, treatment with empagliflozin ameliorates left atrial dilatation. As LA volume is a surrogate for chronic filling pressures, this reduced LA volume suggest improved diastolic function with EMPA

109 Anderson Fabry disease in CMR: twins by traditional tissue characterization, different by parametric mapping

Anderson Fabry disease (AFD) is an X-linked recessive lysosomal storage disease, caused by intracellular accumulation of glycosphingolipids due to deficiency of the enzyme α-galactosidase. The cardiac involvement carries a worse prognosis. Myocardial hypertrophy is the most common manifestation due to the intracellular accumulation of glycosphingolipids in myocytes. With disease progression the deposits are replaced by fibrosis although recent data suggest a chronic inflammation also independently to glycosphingolipids accumulation. Cardiac magnetic resonance (CMR) by tissue characterization using parametric mapping is a unique technique in evaluating AFD progression and in determining enzyme treatment indications and evolution under therapy. Heterozygous females are not asymptomatic carriers of the AFD mutation, they have a variable clinical presentation; disease expression in females is the result of random inactivation of the X chromosome. Female patients have a . This case provides an example of Fabry disease in a couple of sisters with a third sister with a diagnosis of AFD with cardiac, hepatic, and renal involvement. The youngest sister with a positive genetic test was symptomatic for chest pain, without any significant coronary arteries disease by coro CT. The ECG showed atrial fibrillation and sign for LVH confirmed by echocardiography. The traditional CMR study by SSFP cine images and LGE technique showed an increased thickness in the basal infero-lateral wall (15 mm) and the anterior interventricular septum (14 mm) with midwall fibrosis in the basal infero-lateral wall (Fig. 1 A, B). The oldest sister with a positive genetic test was asyntomatic in AF. ECG and ECOC were aspecific. The traditional CMR study by SSFP cine images and LGE technique showed the same finding of the youngest sister (Fig. 2 A, B) By T1 mapping based on the normal cut off values of the Lab the older sister reported a short T1 global value (915 ms) and short T1 values in all segment with exception of lateral wall, mid and distal inferior segments and distal septum (Figure 1 C). Despite the presence of positive LGE in the basal infero-lateral wall the T1 value was normal in this segment due to a pseudo normalization related to the sphingolipid accumulation. Based on the CMR report she started the enzyme replacement therapy and the CMR follow was planned at 1 year. Conversely, the younger woman reported a long T1 value only in the basal infero-lateral wall with normal T1 value in all the other segments (Figure 2 C). The positive LGE in the basal infero-later segment (oedema/fibrosis) justifies the long T1 value in this no thickness segment. Based on the CMR report she did not start enzyme replacement therapy. Conclusion The case of this family show how quantitative parametric mapping could be a unique tool for the clinicians to adjust the therapy and plan the follow up of patients affected by AFD with cardiac involvement. Abstract 109 Figure.

In Vivo Quantification of Regional Circumferential Green Strain in the Thoracic and Abdominal Aorta by Two-Dimensional Spiral Cine DENSE MRI

Regional tissue mechanics play a fundamental role in the patient-specific function and remodeling of the cardiovascular system. Nevertheless, regional in vivo assessments of aortic kinematics remain lacking due to the challenge of imaging the thin aortic wall. Herein, we present a novel application of displacement encoding with stimulated echoes (DENSE) magnetic resonance imaging (MRI) to quantify the regional displacement and circumferential Green strain of the thoracic and abdominal aorta. Two-dimensional (2D) spiral cine DENSE and steady-state free procession (SSFP) cine images were acquired at 3T at either the infrarenal abdominal aorta (IAA), descending thoracic aorta (DTA), or distal aortic arch (DAA) in a pilot study of six healthy volunteers (22–59 y.o., 4 females). DENSE data were processed with multiple custom noise reduction techniques including time-smoothing, displacement vector smoothing, sectorized spatial smoothing, and reference point averaging to calculate circumferential Green strain across 16 equispaced sectors around the aorta. Each volunteer was scanned twice to evaluate interstudy repeatability. Circumferential Green strain was heterogeneously distributed in all volunteers and locations. The mean spatial heterogeneity index (standard deviation of all sector values divided by the mean strain) was 0.37 in the IAA, 0.28 in the DTA, and 0.59 in the DAA. Mean (homogenized) peak strain by DENSE for each cross section was consistent with the homogenized linearized strain estimated from SSFP cine. The mean difference in peak strain across all sectors following repeat imaging was −0.1±2.3%, with a mean absolute difference of 1.7%. Aortic cine DENSE MRI is a viable noninvasive technique for quantifying heterogeneous regional aortic wall strain and has significant potential to improve patient-specific clinical assessments of numerous aortopathies, as well as to provide the lacking spatiotemporal data required to refine patient-specific computational models of aortic growth and remodeling.