Prognostic role of cardiac magnetic resonance in left ventricular non compaction

Introduction

Left ventricular non compaction (LVNC) is a heterogeneous entity with uncertain prognosis. Cardiac magnetic resonance (CMR) is widely used in the diagnosis of LVNC. However, its role in risk stratification has not been well established.

Purpose

Therefore, the aim of our study was to identify prognostic CMR variables in LVNC.

Methods

We conducted a retrospective longitudinal multicentre cohort study of consecutive patients fulfilling CMR LVNC criteria. The endpoints were heart failure (HF), ventricular arrhythmias (VA), systemic embolisms (SE) and all-cause mortality. Biventricular volumes, ejection fraction (LVEF and RVEF) as well as late gadolinium enhancement (LGE) were analysed.

Results

A total of 310 patients were included: age was 44.4±19 and 43% female. LVEF was 47% ± 15%, RVEF was 48±12 and 28 patients (9%) presented LGE. After a median follow-up of 3.8 2.5 years, 40 patients (13%) presented HF, 31 (10%) had VA, SE occurred in 6 (2%) and 3 patients (1%) died. Baseline characteristics of patients with and without HF and VA are described in Table 1.

In univariate analysis, LVEF, LV volumes, LGE, and RVEF were associated with both HF and VA risk. In multivariate analysis, LVEF was the only variable independently associated with HF (HR 0.932, CI 95% 0.88–0.97, p 0.003). Patients with an LVEF >35% were at very low risk of HF (Figure 1A). With regards to VA, LGE was the only independent predictor (HR 2.64, IC 95% 1.059–6.61, p 0.003) (Figure 1B). In LGE negative patients, the arrhythmic risk was higher among those with an LVEF <35% (HR 2.81, 95% CI 1.02–8.12, p 0.047).

Conclusions

In a large multicentre retrospective LVNC study, left ventricular ejection fraction and late gadolinium enhancement were the main predictors of cardiovascular events. Patients with an LVEF <35% and with LGE were at markedly increased risk. Therefore, we suggest that these variables should be combined to enhance risk stratification in LVNC.

Funding Acknowledgement

Type of funding sources: None.

Prognostic value of left ventricular hemodynamic forces in patients with left ventricular noncompaction

Introduction

Left ventricular noncompaction (LVNC) is a poorly defined entity with LV ejection fraction (LVEF) being the main predictor of major adverse cardiovascular events (MACE). Left ventricular hemodynamic forces (LVHDF) have been recently demonstrated to be promising markers of sub-clinical dysfunction and potential predictors of disease outcome.

Purpose

To determine in a large cohort of LNVC the LVHDF parameters and its long-term prognostic value.

Methods

Retrospective, longitudinal, multicentre cohort study including consecutive patients with LVNC from 2000 to 2018. CMR was performed at 1.5T and LVHDF were analyzed with a prototype software (Medis Suite Qstrain). Systolic LVHDF were decomposed into “apex-base” (long-LVHDF) and “lateral-septal” (radial-LVHDF). MACE was defined as a composite of heart failure (HF), ventricular arrhythmias (VA), systemic embolisms (SE) and/or all-cause mortality.

Results

A total of 158 patients were included, age was 53±4.3y and 85 (53.8%) were men. Median LVEF was 44 (IQR 34–55)%, with 61.4% having a LVEF <50%. During a median follow-up of 3.7 (IQR 1.4–5.9) years, MACE occurred in 49 (31%) patients with an unadjusted incidence rate of 8.05 (95% CI 6.0–10.6) events per 100 person-years: 36 HF, 15 VA, 5 SE and 2 deaths. Patients with MACE had significantly worse LVHDF parameters (Table 1). LV-HDF parameters showed no significant variation with age or gender. Spearman coefficient confirmed an inverse correlation between LVEF and long-LVHDF (r=0.478, p<0.0001) and radial-LVHDF (r=0.414, p<0.001). Patients with LVEF <50% (53% vs 78%, p logrank = 0.028) and long-LVHDF <11% (38% vs 84%, p logrank <0.001) had an increased risk of MACE. LVEF (HR 0.97, 95% CI 0.95–0.99, p=0.016), long-LVHDF<11% (HR 5.18, 95% CI 1.1–13.1, p=0.001) and age (HR 1.16, 95% CI 1.06–1.26, p=0.002) were the only variables independently associated with MACE on multivariate analysis. Among patients with LVEF >50%, on univariate regression long-LVHDF <11% (HR 3.32, 95% CI 1.00–11.01, p=0.050) was independently associated with MACE, while LVEF was not (HR 1.04, 95% CI 0.97–1.10, p=0.200). In patients with LVEF <50%, long-LVHDF <11% (HR 7.70, 95% CI 2.40 25.21, p=0.001),and LVEF (HR 0.93,95% CI 0.90–0.95, p<0.001) were independent predictors of outcome on univariate analysis.

Conclusions

LVHDF in patients LVNC were quantified for the first time, with an adequate correlation with LVEF. Both radial and longitudinal LVHDF were significantly reduced in patients with MACE, however, only misalignment of systolic longitudinal-LVHDF predicted outcomes. In patients with LVEF >50%, reduced longitudinal-LVHDF was associated with prognosis, while LVEF was not, and may serve as an additional tool for risk stratification.

Funding Acknowledgement

Type of funding sources: None.

Circumferential wall shear stress predicts co-localized progressive dilation in bicuspid aortic valve patients

Background

Bicuspid aortic valve (BAV), a congenital heart defect, is associated with ascending aorta (AAo) dilation. Whether the high prevalence of dilation in BAV patients is related to alteration of aortic blood flow and thus in wall shear stress (WSS) [1,2], which have been associated with aortic wall degeneration [3], or intrinsic abnormalities of the aortic wall, such as altered aortic stiffness [4], has not been established. Recently, a technique for the semi-automatic quantification of progressive aortic dilation maps via image registration has been introduced [5].

Purpose

To test whether ascending aorta WSS predicts co-localized progressive dilation in BAV patients.

Methods

Forty BAV patients free from moderate and severe aortic valve regurgitation (regurgitant fraction <16%) and stenosis (maximum velocity at the aortic valve <3m/s), with no previous aortic or aortic valve surgery or replacement and included in a double-blind clinical trial (BICATOR, NCT02679261) were enrolled. All patients underwent a baseline 4D flow CMR study to assess aortic hemodynamics, followed by two contrast-enhanced computed tomography angiographies to quantify progressive dilation. WSS was computed at 64 pre-specified standardized ascending aortic regions, automatically obtained dividing the ascending aorta into 8 equidistant longitudinal sections which were further divided along the circumference into 8 equal regions (I = inner, L = left, O = outer and R = right) [2]. WSS was also projected into axial and circumferential directions, as previously described [1,2]. Progressive dilation was assessed in terms of growth rate (GR), i.e. increase in diameter divided by follow-up duration [mm/year], following a previously described methodology [5], at the same 64 pre-specified ascending aortic locations. A two-tailed p-value <0.05 was considered statistically significant.

Results

Demographic and clinical characteristics of the patients are shown in Table 1. WSS and growth rate maps are shown in Figure 1. Follow-up duration was 44.8±2.6 months. Growth rate (Figure 1A) was heterogeneously distributed, being highest (up to 0.26 mm/year) in the outer region of the mid AAo and in the inner region of the proximal-mid AAo. Circumferential WSS showed highest values in the outer region of the mid AAo (Figure 1C) while WSS (magnitude) and its axial component (Figure 1B and D) presented maximum values in the right region of the mid AAo. Maps of statistically significant association between GR and WSS values showed circumferential WSS to be correlated with GR in regions where progressive dilation was fastest, while WSS magnitude and its axial component resulted in limited associations with GR maps.

Conclusions

Circumferential wall shear stress predicts location-matched progressive dilation in bicuspid aortic valve patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This study has received funding from the Instituto de Salud Carlos III (PI17/00381). Guala A. has received funding from Spanish Ministry of Science, Innovation and Universities (IJC2018-037349-I). Table 1. DemographicsFigure 1. GR and WSS maps and correlations

Accurate and reproducible aortic growth rate mapping via registration of serial contrast-enhanced computed tomography angiograms

Introduction

Accurate assessment of aortic diameters and growth rates is key for clinical management of patients with aortic aneurysms [1]. Manual assessment on multiplanar reformatted views of computed tomography angiograms (CTA) is recommended [1], although its reproducibility in the assessment of growth rates has not been reported [2]. Image registration has been proposed to provide 3D maps of aortic diameters and growth [3], but its accuracy and reproducibility have not been established.

Purpose

To quantify accuracy and inter-observer reproducibility of aortic root and thoracic aorta diameters and growth rate by registration of serial CTAs compared to current standard.

Methods

Forty non-operated patients with ≥2 contrast-enhanced ECG-gated CTA acquired at least 6 months apart were included. Aortic diameters and growth rates were measured in the aortic root and thoracic aorta by two independent observers, both with the current standard and with the registration-based technique. To perform registration-based assessment, each observer semi-automatically segmented the aorta at baseline and located typical anatomical landmarks (Fig. 1A). Then, deformable image registration was used to map baseline and follow-up CT scans and deformation was applied to the baseline aortic surface points to obtain their location at follow-up (Fig. 1B). Finally, aortic root diameters and growth rate and 3D maps of thoracic aortic diameters and growth rate were automatically obtained (Fig. 1C). Agreement between techniques and their inter-observer reproducibility were calculated.

Results

Follow-up duration was 3.3±1.5 years (range 0.52–6.2). Compared with manual assessment, registration-based aortic diameters presented low bias and excellent agreement in the aortic root (0.42 mm, ICC=0.99) and the thoracic aorta (0.55 mm, ICC=0.99), and similar inter-observer reproducibility (ICC=0.99 for both). Compared with manual assessment, registration-based growth rates presented low bias and good agreement in the aortic root (0.12 mm/y, ICC=0.84) and the thoracic aorta (0.03 mm/y, ICC=0.77) (Fig. 2A), and much higher inter-observer reproducibility (ICC=0.96 vs 0.68 in the aortic root, ICC=0.96 vs 0.80 in the thoracic aorta) (Fig. 2B and C). Registration-based aortic growth rates reproducibility at 6 months follow-up was comparable to that obtained by manual assessment at 2.7 years (LoA = [−0.01, 0.33] and LoA = [−0.13, 0.21], respectively). Aortic diameters and growth rate 3D maps were highly reproducible (ICC>0.9) in the whole thoracic aorta.

Conclusions

Progressive aortic dilation assessment via registration of CTAs is accurate and more reproducible than the current standard even over follow-ups as short as 6 months, and further provides robust 3D mapping of aortic diameters and growth rates. Its application may provide new insights in aneurysms pathophysiology and improve the clinical management of these patients.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): This study has received funding from the Instituto de Salud Carlos III (PI17/00381). Guala A. has received funding from Spanish Ministry of Science, Innovation and Universities (IJC2018-037349-I). Figure 1. Methodology.Figure 2. Growth rate comparison.