The myocardial phenotype of Fabry disease pre-hypertrophy and pre-detectable storage

Background

Cardiac involvement in Fabry Disease (FD) occurs prior to left ventricular hypertrophy (LVH) and is characterized by low myocardial native T1 with storage reflected by cardiovascular magnetic resonance (CMR) and ECG changes.

Objectives

We hypothesize that a pre-storage myocardial phenotype might occur even earlier, prior to T1 lowering.

Methods

FD patients and age, sex and heart rate matched healthy controls underwent same-day ECG with advanced analysis and multiparametric CMR (cines, global longitudinal strain [GLS], T1 and T2 mapping, stress perfusion [myocardial blood flow, MBF] and late gadolinium enhancement [LGE]).

Results

114 Fabry patients (46±13 years, 61% female) and 76 controls (49±15 years, 50% female) were included. In pre-LVH FD (n=72, 63%), a low T1 (n=32/72, 44%) was associated with a constellation of ECG and functional abnormalities compared to normal T1 FD patients and controls. However, pre-LVH FD with normal T1 (n=40/72, 56%) also had abnormalities compared to controls: reduced GLS (−18±2 vs −20±2%, P<0.001), microvascular changes (lower MBF 2.5±0.7 vs 3.0±0.8mL/g/min, P=0.028), subtle T2 elevation (50±4 vs 48±2ms, p=0.027) and limited LGE (%LGE 0.3±1.1 vs 0%, P=0.004). ECG abnormalities included shorter P wave duration (88±12 vs 94±15ms, P=0.010) and T wave peak time (Tonset–Tpeak; 104±28 vs 115±20ms, P=0.015), resulting in a more symmetric T wave with lower T wave time ratio (Tonset–Tpeak)/(Tpeak–Tend) (1.5±0.4 vs 1.8±0.4, P<0.001) compared to controls.

Conclusions

FD has a measurable myocardial phenotype pre-LVH and pre-detectable myocyte storage with microvascular dysfunction, subtly impaired GLS and altered atrial depolarization and ventricular repolarization intervals.

Proposed stages of cardiac involvement

Funding Acknowledgement

Type of funding source: None

623 Short-term reversed remodeling post aortic valve intervention

Background

LV remodeling in AS can cause LV hypertrophy, interstitial fibrosis and reduced contractility. SAVR or TAVI are the mainstay treatment for symptomatic severe AS. Speckle tracking has the potential to detect early signs of reverse cardiac remodeling but such LV deformation data post-SAVR/TAVI is currently lacking.

Aim

To assess the early impact of LV unloading post-TAVR/SAVR using STE.

Methods

This prospective single-center study recruited 122 patients with varying degrees of AS who underwent resting transthoracic echocardiography with offline speckle-tracking. During the follow-up period, 50 patients underwent TAVI and 15 had SAVR.

Results

Patients were followed-up for a period of 4 ± 2 weeks post-intervention. Table 1 summaries the echocardiographic findings of patients pre- and post-intervention. AV peak velocity and mean pressure gradient dropped significantly immediately after intervention in both groups. AV intervention resulted in early improvements in all myocardial deformation parameters (Figure 1). There was a significant improvement in GLS and GRS irrespective of the intervention type. While SAVR led to a significant early improvement in GCS.

Conclusion

AV Intervention in severe symptomatic AS translates into an immediate and measurable improvement in LV deformation parameters. To our knowledge this is the first echocardiographic evidence of reverse remodeling early after SAVR and TAVI.

Table 1 TAVI (n = 50) SAVR (n = 15) Variables Pre Post P* value Pre Post P* value P value┼ AV vel.(m/s) 4.4 ± 0.8 2.2 ± 0.5 <0.001 4.5 ± 0.8 2.2 ± 0.5 <0.001 NS AV mPG (mmHg) 44.3 ± 16.2 9.7 ± 3.9 <0.001 44.6 ± 19.2 9.8 ± 4.8 <0.001 NS GLS (%) -10.9 ± 3.6 -13.9 ± 3.1 <0.001 -13.7 ± 4.5 -17.7 ± 3.9 0.002 NS GCS (%) -29.2 ± 9.1 -32 ± 9.5 NS -28.6 ± 9.8 -34.9 ± 5.1 0.032 NS GRS (%) 42.0 ± 15.1 47.2 ± 13 0.024 34.7 ± 12.5 41.4 ± 9.9 0.04 NS EDV (ml) 87.29 ± 55.3 89.8 ± 38.6 NS 104.3 ± 25.1 83.2 ± 41.9 NS NS ESV (ml) 45.1 ± 39.4 36.6 ± 29.1 NS 42.8 ± 17.7 28.6 ± 18.6 0.03 NS SV (ml) 59.7 ± 23.6 55 ± 19.3 NS 65.5 ± 17.9 57.2 ± 22.7 NS NS SVi (ml/m2) 33.1 ± 12.7 30.4 ± 9.6 NS 34.1 ± 8.3 29.8 ± 11.1 NS NS LV mass (g) 185.7 ± 53.6 183.3 ± 48. NS 177.5 ± 48.4 169.5 ± 52.2 NS NS LVMi (g/m2) 103.6 ± 30 102.1 ± 25.9 NS 93.8 ± 29.9 89.4 ± 24.2 NS NS Biplane EF (%) 58 ± 15 62 ± 13 0.013 60 ± 9 66 ± 6 <0.05 NS AV: Aortic valve; EDV: end diastolic volume; EF: ejection fraction; ESV: end systolic volume; GCS: Global circumferential strain; GLS: Global longitudinal strain; GRS: Global radial strain; LV: left ventricle; LVMi: left ventricular mass index; mPG: mean pressure gradient; SV: stroke volume; SVi: stroke volume index; Vel: velocity Data are expressed as mean ± SD. Comparisons were performed using paired Student"s t tests(parametric) or Wilcoxon paired test (non-parametric). *Pre and post intervention. ┼Comparison of pre/post-intervention measurement difference between the two intervention groups done using unpaired t-test

Abstract 623 Figure.

P307 Trajectories of Myocardial Strain Across the Spectrum of Aortic Stenosis

Introduction

Optimal timing of intervention in aortic stenosis (AS) is key. Left ventricular deformation parameters are sensitive markers of myocardial wellbeing in AS, but data is sparse so strain does not currently feature in the clinical decision-making process governing timing of AS intervention. We explore the trajectory of myocardial strain in AS of varying severity to potentially identify the most sensitive periods for valve intervention.

Methods

50 patients from across the spectrum of isolated AS were prospectively recruited: mild AS n = 10; moderate AS n = 10; and severe AS n = 30 of which n = 10 in each of 3 ejection fraction (EF) groups: EF > 50%, EF = 40-49% and EF < 35%. Longitudinal, circumferential, and radial strain were measured by speckle tracking echocardiography (STE) using TomTec software.

Results

Strain parameters and EF were not significantly different between mild and moderate AS groups but almost all parameters (except for global circumferential strain (GCS)) showed significant deterioration with progression to severe AS, even in spite of preserved EF (>50%; Table1). In patients with severe AS, strain parameters showed no significant differences between hearts with EF > 50% and EF 40-49%, but they continued to deteriorate significantly (p < 0.05) as hearts transitioned from 40-49% to <35% (Figure 1, a&b).

Conclusion

The heart can maintain its deformation and global systolic function throughout mild and moderate AS but strain deteriorates significantly in severe AS, irrespective of EF. Tracking the precise timings of strain deterioration in severe AS could help refine optimal timings of AS intervention.

LVEF and strain in varying AS severity Left ventricle ejection fraction and strain values in varying severity of AS Mild (n = 10) Moderate (n = 10) Severe (n = 10) P-value Mean (SD) Mean (SD) Mean (SD) EF (%) 65.4 (6.1) 65.8 (9.0) 60.4 (3.6)*§ 0.15 GLS (%) -14.2 (2.1) -13.6 (2.3) -11.8 (2.9)* 0.09 GCS (%) -30.3 (9.1) -31.0 (11.4) -26.5 (8.2) 0.55 GRS (%) 55.9 (15.5) 52.6 (24.0) 35.9 (13.5)*§ 0.05 EF: ejection fraction; GLS: global longitudinal strain; GCS: global circumferential strain; GRS: global radial strain; SD: standard deviation. Severe (n = 10): Severe AS with preserved EF >50%. P-value: ANOVA-single factor; comparison in-between groups was performed using unpaired t-test (parametric) and Mann Whitney test (non-parametric). *significant difference P < 0.05 mild vs severe. §significant difference P < 0.05 moderate vs severe.

Abstract P307 Figure.

618 Adaptive myocardial mechanics in aortic stenosis patients

Introduction

Left ventricular (LV) hypertrophy in aortic stenosis (AS) becomes maladaptive over time, leading first to a reduction in global longitudinal strain (GLS) and in a later stage a reduction in ejection fraction (EF). The myocardial state of impaired GLS but preserved EF is a key remodeling turning point in AS, yet little is known about the coping mechanics of the LV at or around this sensitive juncture.

Aim

1) To study the relationship between LV mass index (LVMi) increase and measures of LV function, including strain in AS; 2) To investigate whether augmentation of global myocardial radial and circumferential strain (GRS, GCS) compensates for the GLS reduction in AS patients with preserved EF.

Methods

One-hundred and eleven patients with varying degrees of AS, and 20 age- and gender-matched healthy volunteers were prospectively enrolled. transthoracic echocardiography with offline strain analysis was performed using TomTec software. Intra- and inter-observer variability of linear LV internal dimensions/thickness, EF and strain indices was tested on 20 randomly selected patients.

Results

Clinical and demographic characteristics of cases and controls are shown in Figure 1. GLS was impaired in AS patients compared to controls. In AS with preserved EF (>50%), as LVMi increased, GLS progressively improved up to a point, beyond which any further increase in LVMi appeared counter-productive with impairment of GLS (Figure 1). EF preservation in these AS patients was mediated by a compensatory supernormal augmentation of GRS and a smaller augmentation of GCS (Figure 1). We observed a significant inverse correlation between GRS and GLS (r = 0.3, p = 0.002), and a similar trend between GCS and GLS (r = 0.275, p = 0.004). Intraclass correlation coefficient was high for all measurements (0.7-0.9).

Conclusion

In patients with AS and preserved EF, progressive myocardial hypertrophy improves GLS up to a point beyond which GLS drops and GRS increase to compensate. This plasticity of myocardial mechanics, in particular the supranormal augmentation of GRS is what enables the pathologically hypertrophied AS ventricle to delay the otherwise inexorable decline in its global systolic function.

Abstract 618 Figure 1

P909Echocardiographic Assessment of Left Ventricular Function in Patients with Aortic Stenosis and the short-term effects after intervention

Introduction

Aortic stenosis (AS) is the most prevalent form of acquired valvular heart disease, it affects ∼2% of people aged over 75. Series of compensatory mechanisms occur, in order for LV to adapt to high pressure overload. Aortic valve replacement has been the mainstay AS treatment either surgically or percutaneously. The evaluation of myocardial strains after Transcatheter Aortic Valve Implantation (TAVI) and Surgical Aortic Valve Replacement (SAVR) is still underexplored and there is no single study to date scouting the difference between TAVI and SAVR.

Aim

To assess the impact of unloading LV after TAVI and SAVR on LV remodelling.

Methods

In this prospective study, we have recruited 111 patients (75±11 years, 63% were females) with varying degrees of aortic stenosis. Of the 111 patients, 43 patients and 11 patients underwent TAVI and SAVR respectively between November 2017 and May 2018. Demographics, clinical and echocardiographic measurements along with speckle tracking parameters were recorded for all participants and again 4±2 weeks after intervention.

Results

Pre-TAVI LV-GLS mean was −10.8±3.5% and after implantation of aortic prosthesis immediate improvement of the myocardial deformation to −13.98±2.9% was observed after one month of the intervention, mean difference of −3.16% following procedure. There was an evidence of significant improvement in LV-GRS after TAVI (44.86±12.9% to 49.77±10.8%, P value= 0.047). Per contra, when comparing pre and post TAVI LV-GCS, no statistical evidence was noted. However, a difference of −2.4% in GCS following the intervention might be clinically important, but no previous evidence can support this. This is attributed to the poor reproducibility and yet not available standardisation.

Table 1 Variables TAVI (n=43) SAVR (n=11) P value† Pre Post P* value Pre Post P* value GLS (%) −10.82±3.5 −13.98±2.9 <0.001 −12.75±4.3 −16.1±2 0.021 0.152 GCS (%) −30.1±8.1 −32.49±9.2 0.134 −27±9.8 −33.9±4.69 0.063 0.062 GRS (%) 44.86±12.9 49.77±10.8 0.047 36.6±13.3 44.97±4.9 0.074 0.058 Data are expressed as mean ± SD. Comparisons were performed using paired Student's t tests. *Pre and post intervention. †Post TAVI vs. post SAVR. Comparison done using unpaired t test of the differences.

Conclusion

Significant improvement was evident in myocardial deformation parameters – in particular GLS – after weeks of the intervention demonstrating a strong evidence of reversed remodelling following SAVR and TAVI.