How myocardial work could be relevant in patients with an aortic valve stenosis?

Funding Acknowledgements

Type of funding sources: None.

Background

Speckle tracking based myocardial work calculation is an attractive method to assess left ventricular (LV) myocardial function. In case of aortic stenosis (AS), assessment of work indices is challenging because it requires an accurate evaluation of LV-pressure curves. Therefore, we sought to evaluate the performances of two distinct methods for the estimation of myocardial work indices and to provide a quantitative comparison with invasively measured data.

Methods

Model-based and template-based methods were defined and applied for the evaluation of LV pressures on 67 AS patients. Global Constructive (GCW), Wasted (GWW), Positive (GPW), Negative (GNW) myocardial work and Global Work Efficiency (GWE) and Index (GWI) parameters were calculated using the available software computing the indices using brachial blood pressure and trans-aortic mean pressure gradient for estimating the LV pressures versus using a model-based and homemade software. A complete comparison was performed with invasive measurements.

Results

Patients were characterized by mean pressure gradient of 49.8 ± 14.8 mmHg, LV ejection fraction of 59 ± 8%, the global longitudinal strain was -15.0 ± 4.04%, GCW was 2107 ± 800mmHg.% (model-based method) and 2483 ± 1068mmHg.% (template-based method). The root mean square error (RMSE) and correlation were calculated for each patient and for each pressure estimation methods. The mean RMSE are 33.9mmHg and 40.4mmHg and the mean correlation coefficients are 0.81 and 0.72 for the model-based and template-based methods respectively. Correlation coefficient and Bland-Altman analysis were performed for the six work indices. The two methods present correlation coefficient r2 > 0.75 for almost all the indices.

Conclusion

The two non-invasive methods of LV pressure estimation and the work indices computation correlate with invasive measurements and computations for AS patients. Although the model-based approach requires less information and is associated with slightly better performances, the implementation of template-based method is easier and seems more appropriate in a clinical practice. Abstract Figure. SUMMARY

Prognostic value of diastolic function assessment in patients undergoing cardiac resynchronization therapy

Funding Acknowledgements

Type of funding sources: None.

Objective

The best modality to assess diastolic function in CRT-candidates is an object of debate and the relationship between diastolic function, CRT-response and survival are not

clearly understood.

Purpose of the study: to assess diastolic patterns in patients undergoing CRT according to the 2016 recommendations of the American Society of Echocardiography/European Association of Cardiovascular Imaging and to evaluate the prognostic value of diastolic dysfunction (DD) in CRT candidates.

Methods

193 patients (age: 67 ± 11 years, QRS width: 167 ± 21 ms) were included in this multicentre prospective study. Patients were stratified according to DD grades (grade I

to III). CRT-response was defined as a reduction of left ventricular (LV) end-systolic volume >15% at 6-month follow-up (FU). The primary endpoint was defined as a

composite of heart transplantation, LV assisted device implantation or all-cause death during FU.

Results

During FU, 132 (68%) patients were CRT-responders. CRT delivery was associated with diastolic function degradation in non-responders. Grade I DD was able to predict

CRT-response with a sensitivity, specificity and accuracy of 70%, 65%, and 63%, respectively. After a median period of 35 months, the primary endpoint occurred in 29

(15%) patients. Grade I DD was associated with a better outcome [HR 0.26 95% CI: (0.10-0.66)], independently from ischemic cardiomyopathy, LV dyssynchrony and CRT-response (Table 1). Non-responders with grade II or grade III DD had the worse prognosis (HR 4.36, 95%CI: 2.10-9.06) Figure 1.

Conclusions

Grade I DD is associated with LV remodelling after CRT and is an independent predictor of prognosis in CRT candidates.

Abstract Figure.

Comparison of two methods to predict CRT-response

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): Hospital university of Rennes INSERM - LTSI

Background

Non-invasive estimation of myocardial work by trans-thoracic echocardiography is a novel tool to analyze myocardial contraction efficiency during systole. Two methods are described, on using Left ventricular (LV) strain and a LV pressure estimation, and another with only LV strain integrals. The present study analyzes their utility in prediction of CRT-response.

Methods and results: 243 patients implanted by a CRT according to current recommendations were retrospectively included in hospital university of Rennes. All patients had a complete trans-thoracic echocardiography at implantation and at 6-moths follow-up. Responders were defined as having a 15% decrease in indexed LV end-systolic volume at follow-up compared to baseline. Baseline characteristics are described in table 1. 25.1% were non-responders. In this group, there were more men, more ischemic cardiomyopathies with more dilated LV. Strain signals ware analyzed only in the most informative loop, the apical 4 cavities. Myocardial work estimation with LV pressure estimation was previously described. The 3 different integral of strain signal were represented in figure 1. According to ROC curves, myocardial work (particularly wasted work in septal wall with AUC = 0.718 ± 0.04) estimated with LV pressure estimation is better than strain integrals to predict LV positive remodeling (best AUC 0.631 ± 0.040) after CRT-implantation.

Conclusion

Left ventricular pressure estimation give useful information on top of strain curves for prediction for CRT-response.

Table 1 Responders n = 182 Non-responders n = 61 Men (%) 109 (59.9%) 52 (85%) Ischemic cardiomyopathy (%) 42 (23.1%) 34 (55.7%) LVEF (%) 28 ± 6 28 ± 7 GLS (%) -9 ± 3 -7 ± 3 LVEDD (mm) 62 ± 8 67 ± 7 LVEDVi (ml/m2) 85 ± 34 88 ± 30 LVEF Left ventricular ejection fraction; GLS: global longitudinal strain; LVEDD: left ventricular end-diastolic diameter; LVEDVi: left ventricular end diastolic volume index Abstract Figure 1

Prospective validation of a non-invasive method to estimate myocardial work in aortic stenosis

Funding Acknowledgements

Type of funding sources: Public hospital(s). Main funding source(s): ANR - Maestro project

Background

Stratification of aortic stenosis patients remains challenging and robust indices are required. Myocardial work assessment is a new afterload independent alternative to evaluate left ventricular function. Although, this method was developed in patients with normal aortic valve. We previously developed an integrated cardiovascular system simulated by a computational model to estimate non-invasively myocardial work in aortic stenosis patients* (figure 1A). In the present study, we tested our model in a prospective population of AS patients.

Method and results

9 patients with severe AS (aortic valve area < 1cm2) were included. A complete trans-thoracic echocardiography with a non-invasive blood pressure by brachial artery cuff were realized immediately before a left heart catheterization to have an invasive left ventricular pressure. Myocardial work is then calculated with non-invasive and invasive LV pressure combined to LV strain curves. For constructive and wasted work, root mean squared between invasive and estimated measures were respectively r2 = 0.92 and r2 = 0.94 (figure 1B)

Conclusion

The proposed model is efficient to estimate non-invasively myocardial work indices in AS-patients. These afterload independent indices could permit in future to better stratify this population. 

*Owashi KP, Hubert A and al. Model-based estimation of left ventricular pressure and myocardial work in aortic stenosis. PlosOne 2020. Mar 3;15(3):e0229609

Abstract Figure 1

Importance of systematic right ventricular assessment in cardiac resynchronization therapy candidates: a machine-learning approach

Funding Acknowledgements

Type of funding sources: None.

Background

Despite having all a systolic heart failure and broad QRS, patients proposed for cardiac resynchronization therapy (CRT) are highly heterogeneous and it remains extremely complicated to predict the impact of the device on left ventricular (LV) function and outcomes.

Objectives

We sought to evaluate the relative impact of clinical, electrocardiographic, and echocardiographic data on the left ventricular (LV) remodeling and prognosis of CRT-candidates by the application of machine learning (ML) approaches.

Methods

193 patients with systolic heart failure undergoing CRT according to current recommendations were prospectively included in this multicentre study. We used a combination of the Boruta algorithm and random forest methods to identify features predicting both CRT volumetric response and prognosis (Figure 1). The model performance was tested by the area under the receiver operating curve (AUC). We also applied the K-medoid method to identify clusters of phenotypically-similar patients.

Results

From 28 clinical, electrocardiographic, and echocardiographic-derived variables, 16 features were predictive of CRT-response; 11 features were predictive of prognosis.

Among the predictors of CRT-response, 7 variables (44%) pertained to right ventricular (RV) size or function. Tricuspid annular plane systolic excursion was the main feature associated with prognosis. The selected features were associated with a very good prediction of both CRT response (AUC 0.81, 95% CI: 0.74-0.87) and outcomes (AUC 0.84, 95% CI: 0.75-0.93) (Figure 1, Supervised Machine Learning Panel). An unsupervised ML approach allowed the identifications of two phenogroups of patients who differed significantly in clinical and parameters, biventricular size and RV function. The two phenogroups had significant different prognosis (HR 4.70, 95% CI: 2.1-10.0, p < 0.0001; log –rank p < 0.0001; Figure 1, Unsupervised Machine Learning Panel).

Conclusions

Machine learning can reliably identify clinical and echocardiographic features associated with CRT-response and prognosis. The evaluation of both RV-size and function parameters has pivotal importance for the risk stratification of CRT-candidates and should be systematically assessed in patients undergoing CRT.

Abstract Figure 1

Prognostic utility of the assessment of diastolic function in patients undergoing cardiac resynchronization therapy

Conflicting data exist about the relationship between cardiac resynchronization therapy (CRT) and diastolic function. Aims of the study are to assess diastolic patterns in patients undergoing CRT according to the 2016 recommendations of the American Society of Echocardiography/European Association of Cardiovascular Imaging and to evaluate the prognostic value of diastolic dysfunction (DD) in CRT candidates. METHODS AND RESULTS: One-hundred ninety-three patients (age: 67 ± 11 years, QRS width: 167 ± 21 ms) were included in this multicentre prospective study. Mitral filling pattern, mitral tissue Doppler velocity, tricuspid regurgitation velocity, and indexed left atrial volume were used to classify DD from grade I to III. CRT-response, defined as a reduction of left ventricular (LV) end-systolic volume > 15% at 6-month follow-up (FU), occurred in 132 (68%) patients. The primary endpoint was a composite of heart transplantation, LV assisted device implantation, or all-cause death during FU and occurred in 29 (15%) patients. CRT was associated with a degradation of DD in non-responders. At multivariable analysis corrected for clinical variables, QRS duration, mitral regurgitation, CRT-response and LV dyssynchrony, grade I DD was associated with a better outcome (HR 0.37, 95% CI: 0.14-0.96). Non-responders with grade II-III DD had the worse prognosis (HR 4.36, 95%CI: 2.10-9.06). CONCLUSIONS: The evaluation of DD in CRT candidates allows the prognostic stratification of patients, independently from CRT-response.

Non-invasive estimation of myocardial work in aortic stenosis from modelling approach

Background

The noninvasive assessment of myocardial work by pressure-strain loops (PSL) analysis is a recently introduced tool to estimate myocardial performance. PSL analysis cannot be applied to patients having an obstacle to LV ejection, as in the case of aortic stenosis (AS), because of the difficulty to estimate left ventricular (LV) pressure.

The purpose of this work is to propose a non-invasive model-based estimation of the left ventricular pressure curve in AS patients in order to evaluate myocardial work indices.

Methods

Twelve patients with moderate-to-severe AS underwent cardiac catheterization to acquire the LV pressure (Pexp-LV). All patients underwent a standard trans-thoracic echocardiography to extract regional myocardial strain curves and estimate the aortic valve area (AVA). Systolic and diastolic arterial pressures were also measured. The proposed cardiovascular system (CVS) model is composed of four main coupled sub-models simulating: i) cardiac electrical activities, ii) cardiac cavity, iii) the systemic and pulmonary circulation, and iv) cardiac valves (Figure 1, upper panel). A 2-step parameter identification strategy, based evolutionary algorithms, was implemented to learn LV parameters from Pexp-LV and to estimate patient-specific model-based LV pressure curves (Pmodel-LV) starting from parameters obtained from non-invasive hemodynamics. Global myocardial constructive work (GCW) and myocardial wasted work (GWW) were calculated using Pexp-LV and Pmodel-LV.

Results

A close match was observed between Pexp-LV and Pmodel-LV, with a mean total relative error of 12.27% (range 5.9% to 17.40%). When considering GCW and GWW, global correlation was equal to 0.92 (p<0.0001). In BA analysis, mean bias was −2.9 mmHg.%, which corresponds to relative bias equal to 0.11% with respect to the mean value of work indices (Figure 1, lower panel).

Conclusions

A model-based approach can be used to estimate LV pressure and myocardial work indices in patients with AS, and be provide a promising tool for the assessment of myocardial performance in patients with AS

Funding Acknowledgement

Type of funding source: None

Model-based analysis of myocardial strain in left bundle branch block patients

Background

Although patients with typical left bundle branch block (LBBB) show greater efficacy of cardiac resynchronization therapy (CRT), there is a wide range of responses to CRT with a subset of patients showing little or no improvement. Recently, it has been shown that combination of echo-based parameters of LV dyssynchrony and QRS duration helped to improve the prediction of the response to CRT. However, the interpretation of features extracted from echocardiography could be difficult due the complexity of mechanisms involved in cardiac contraction. Computational modelling could help to improve the interpretation of myocardial strains in LBBB patients before implantation.

Purpose

Purpose of the study is to propose a patient-specific model-based approach in order to assist the analysis of myocardial strains and to improve the interpretability of echo-based parameters.

Methods

The proposed model of the cardiovascular system integrates four main sub-models: 1) cardiac electrical system, 2) right and left atrium, 3) multi-segment right and left ventricles and 4) systemic and pulmonary circulations. Patient-specific simulations of myocardial strains were obtained by coupling the computational model and the clinical data to a parameter identification algorithm (Figure 1, upper panel). The proposed approach was evaluated on data obtained from 10 LBBB patients, including ischaemic (n=5) and non-ischaemic (n=5) cardiomyopathy. The localisation of scar was determined by cardiac MRI. Bull's-eye representations of the electrical activation time and contractility levels were analysed.

Results

The comparison between simulated and experimental strains for the 10 subjects reflects a satisfying adaptation of the model to different strain morphologies. The mean errors between real and synthesized signals are equal to 3.72±0.91. The lower panel of Figure 1 presents simulated (black line) and experimental (red line) myocardial strain signals for selected LBBB patients with a lateral ischaemia, anterior ischaemia and non-ischaemia. The bull's-eye representations of electrical activation delay and contractility levels, estimated from the model-based approach, for ischemic and non-ischemic LBBB is included in the figure. Contractility bull's-eye results allow ischaemic and non-ischaemic cases distinction, where low levels of contractility could be associated with damaged tissues.

Conclusion

Identified parameters show significant electrical conduction, mechanical activation delays for the LBBB patient. Hypocontractile myocardial segments were successfully localized from the model-based approach in both ischemic and non-ischemic patients.

Funding Acknowledgement

Type of funding source: None

New expectations for diastolic function assessment in TTE based on a semi-automated computing of strain-volume loops

Background

Early diagnosis of heart failure with preserved ejection fraction (HFpEF) by determination of diastolic dysfunction is challenging. Strain-volume loop (SVL) is a new tool to analyze left ventricular function.

Purpose

We propose a new semi-automated method to calculate SVL area and explore the added value of this index for diastolic function assessment.

Methods

50 patients (25 amyloidosis, 25 HFpEF) were included in the study and compared with 25 healthy control subjects. All patients underwent standard echocardiography. SVL area were also assessed.

Results

Left ventricular ejection fraction was preserved and similar between groups. Classical indices of diastolic function were pathological in HFpEF and amyloidosis groups with greater left atrial volume index, greater mitral average E/e' ratio, faster tricuspid regurgitation (p<0.0001 compared with controls). SVL analysis demonstrated a significant difference of the global area between groups, with the smaller area in amyloidosis group, the greater in controls and a mid-range value in HFpEF group (37 vs 120 vs 72 ml.%, respectively, p<0.0001) (Table 1). Applying a Linear Discriminant Analysis (LDA) classifier, results show a mean area under the curve (AUC) of 0.89 for the comparison between HFpEF and amyloidosis groups (Figure 1).

Conclusion

Strain-volume loops area is efficient to identify patients with a diastolic dysfunction. This new semi-automated tool is very promising for future development of automated diagnosis with machine-learning algorithms.

Figure 1

Funding Acknowledgement

Type of funding source: None

101 Semi-automated volume-strain loops: a new tool in TTE to assess diastolic dysfunction

AIM

This work aims to evaluate a novel semi-automatic tool for the assessment of volume-strain loops by transthoracic echocardiography (TTE).

METHOD

17 patients with proved cardiac amyloidosis and 18 patients with heart failure with preserved ejection fraction (HFpEF) were compared to 19 controls, from a local database. All TTE were performed using Vivid E95 ultrasound system (General Electrics Healthcare, Horten, Norway). The complete method includes several steps: 1) extraction of LV strain full traces from apical 4 and 2 cavities views, 2) estimation of LV volume from these two traces by spline interpolations, 3) resampling of LV strain curves, determined for the same cardiac beat, (in apical 4-, 2- and 3- cavities views) as a function of pre-defined percentage increments of LV-volume and 4) calculation of the LV volume-strain loop area. (Figure 1, panel A)

RESULTS (Table 1): LVEF was similar between all groups whereas global longitudinal strain was significantly lower in amyloidosis group than controls (-14.4 vs -20.5%; p < 0.001). HFpEF and amyloidosis groups had a worse diastolic function than controls with a greater left atrial volume index , a faster tricuspid regurgitation, a greater E/e’ ratio with a p < 0.001 for all these indices. Simultaneously, the global area of volume-strain loop was significantly lower in HFpEF and amyloidosis group than controls (72 vs 36 vs 120.0 %.mL, respectively, p < 0.0001) with an intermediate profile of HFpEF(Figure 1, panel B, HFpEF in green). This area was better correlated with mean e’ (r = 0.650, p < 0.001) than all other indices.

CONCLUSION

LV volume-strain loop area appears a very promising new tool to assess semi-automatically diastolic function.

Main echocardiographic results Controls n = 19 HFpEF n = 18 Amyloidosis n = 17 p-value LVEDV (mL) 105 ± 15 103 ± 30 95 ± 93 0.476 LVEF (%) 65 ± 5 62 ± 7 62 ± 7 0.196 GLS (%) -20.5 ± 1.8 -18.4 ± 4.3 -14.4 ± 3.8 <0.0001 LAVi (ml.m-2) 22 ± 5 51 ± 14 51 ± 22 <0.0001 E/A ratio 2.1 ± 0.4 1.2 ± 0.7 1.7 ± 1.0 0.005 Mitral E/Ea average 5.9 ± 1.4 13.7 ± 5.8 17.3 ± 5.4 <0.0001 Vmax TR (m/s) 2.0 ± 0.3 3.1 ± 0.4 2.7 ± 0.5 <0.0001 V-S loop area (ml.%) 120 ± 54 72 ± 45 37 ± 21 <0.0001

Abstract 101 Figure 1

539 Optimized multiparametric analysis of cardiac dyssynchrony: machine learning and prediction of response to cardiac resynchronization therapy based of the apical 4-chamber view

Conclusion

The high number of important features indicate the relevance of the 4-chamber as unique view for applying machine learning approaches on strain curves. Optimizing selection of patients for CRT should be possible just on the dataset coming from one apical 4-chamber view.

Abstract 539 Figure. fig1

557 Left ventricular diastolic function is a predictor of volumetric response to cardiac resynchronization therapy

Background

Conflicting data exist about the effects of cardiac resynchronization therapy (CRT) on diastolic function (DF). Aims of the study are: 1) to assess diastolic patterns in patients undergoing CRT; 2) to evaluate the role of DF in predicting CRT-response.

Methods

193 patients (age: 67 ± 11 ms, QRS width: 167 ± 21 ms, LVEF 28 ± 8%) were prospectively included in this multicentric study. 2D-standard echocardiography was performed before CRT and at 6-month follow-up (FU). DF was assessed according to recommendations from grade I to III. In case of data in the "grey zone", DF was defined as "indeterminate". A reduction of left ventricular (LV) end-systolic volume >15% at FU identified CRT-responders (CRT-R).

Results

At 6-month FU, 132 patients (68%) were CRT-R. Figure 1 shows DF parameters in the overall population, CRT-R, and CRT-non responders (CRT-NR) before and after CRT. At multivariable analysis, grade I diastolic dysfunction at baseline was a significant independent predictor of CRT response (OR 3.02, p = 0.001) (Table 1). The addition of grade I diastolic dysfunction to a model including clinical (sex, NYHA class, ischemic cardiomyopathy) and echocardiographic parameters (LV size), significantly increase the model power for the prediction of CRT-response (χ2: 29 vs 44, p = 0.001).

Conclusions

Before CRT, DF parameters are significantly altered in CRT-NR with respect to CRT-R. Moreover, CRT-NR experience a significant deterioration of DF after CRT. In our population, grade I diastolic function at baseline was a significant independent predictor of positive response to CRT.

Table 1 Univariable analysis Multivariable analysis Age 1.01 (0.99-1.05) 0.25 Males 0.36 (0.17-0.76) 0.008 0.57 (0.22-1.47) 0.25 CAD 0.21 (0.11-0.40) <0.001 0.31 (0.15-0.65) 0.002 NYHA 0.52 (0.31-0.88) 0.01 0.57 (0.22-1.47) 0.25 QRS 1.01 (0.99-1.02) 0.44 LVEDV 0.99 (0.99-1.00) 0.003 0.98 (0.97-1.01) 0.18 LVESV 0.99 (0.98-0.99) 0.005 1.01 (0.99-1.03) 0.28 LVEF 1.00 (0.97-1.05) 0.63 Grade I DD 4.13 (2.16-7.91) <0.0001 3.02 (1.26-7.23) 0.001 Grade II DD 0.57 (0.40-0.80) 0.001 0.87 (0.35-2.19) 0.79 Grade III DD 0.76 (0.58-1.02) 0.06

Abstract 557 Figure.

P1486Semi-automated volume-strain loops: a new tool in TTE to assess diastolic dysfunction

Aim

This work aims to evaluate a novel semi-automatic tool for the assessment of volume-strain loops by transthoracic echocardiography (TTE). The proposed method was evaluated on a typical model of left ventricular (LV) diastolic dysfunction: the cardiac amyloidosis.

Method

18 patients with proved cardiac amyloidosis were compared to 19 controls, from a local database. All TTE were performed using Vivid E9 or E95 ultrasound system. The complete method includes several steps: 1) extraction of LV strain full traces from apical 4 and 2 cavities views, 2) estimation of LV volume from these two traces by spline interpolations, 3) resampling of LV strain curves, determined for the same cardiac beat, (in apical 4-, 2- and 3- cavities views) as a function of pre-defined percentage increments of LV-volume and 4) calculation of the LV volume-strain loop area. (Figure 1, panel B)

Results

(Table 1): LVEF was similar between both groups whereas global longitudinal strain was significantly lower in amyloidosis group (−14.4 vs −20.5%; p<0.001). Amyloidosis group had a worse diastolic function with a greater left atrial volume index (51 vs 22ml/m2), a faster tricuspid regurgitation (2.7 vs 2.0 m/s), a greater E/e' ratio (17.3 vs 5.9) with a p<0.001 for all these indices. Simultaneously, the global area of volume-strain loop was significantly lower in amyloidosis group (36.5 vs 120.0%.mL). This area was better correlated with mean e' with r=0.734 (p<0.001) than all other indices (Figure 1, panel A).

Table 1 Amyloidosis (N=18) Controls (N=19) p Global strain-volume loop area (%.mL) 36.5±21.3 120.0±54.2 <0.001 Global longitudinal strain (%) −14.4±3.8 −20.5±1.8 <0.001 Left ventricular ejection fraction (%) 62±7 65±5 0.08 Left atrial volume index (ml/m2) 51±22 22±5 <0.001 E/A 1.72±0.97 2.07±0.45 0.17 Mean e' 5.5±1.3 14.4±2.8 <0.001 Mean E/e' 17.3±5.4 5.9±1.4 <0.001 Tricuspid regurgitation velocity (m/s) 2.7±3.8 2.0±0.3 <0.001

Figure 1

Conclusion

LV volume-strain loop area appears a very promising new tool to assess semi-automatically diastolic function. Future applications will concern the integration of LV volume-strain loop area as novel feature in machine-learning approach.

Heart rate differences between symptomatic and asymptomatic Brugada syndrome patients at night

OBJECTIVE

Ventricular arrhythmias in Brugada syndrome (BS) mainly occur at rest, especially during nighttime, suggesting that parasympathetic activity at night may play an important role in the arrhythmogenesis of the disease. This study examined and compared the autonomic function of symptomatic and asymptomatic BS patients overnight.

APPROACH

We analyzed various heart rate variability (HRV) and heart rate complexity (HRC) markers in a clinical series including 87 BS patients, where 23 were symptomatic.

MAIN RESULTS

Statistically significant differences were found in markers MIRR, SDNN, SDANN, [Formula: see text] and SampEn, suggesting that symptomatic patients may be related to lower heart rate variability and complexity values, as well as to greater circadian fluctuations overnight.

SIGNIFICANCE

The results provide further evidence for the role of autonomic imbalance in the pathophysiology of BS, highlighting the relevance of nighttime analysis to the unmasking of significant ANS changes. Based on these outcomes, the role of HRV and HRC assessment at night could be a step forward towards the understanding of BS and the risk for the occurrence of symptoms in these patients, with a potential future impact on therapeutic strategies.