Mechanical Effects on Right Ventricular Function From Left Bundle Branch Block and Cardiac Resynchronization Therapy

Pressure overload is associated with right ventricular dyssynchrony in heart failure with reduced ejection fraction

AIMS

The determinants and relevance of right ventricular (RV) mechanical dyssynchrony in heart failure with reduced ejection fraction (HFrEF) are poorly understood. We hypothesized that increased afterload may adversely affect the synchrony of RV contraction.

METHODS AND RESULTS

A total of 148 patients with HFrEF and 36 controls underwent echocardiography, right heart catheterization, and gated single-photon emission computed tomography to measure RV chamber volumes and mechanical dyssynchrony (phase standard deviation of systolic displacement timing). Exams were repeated after preload (N = 135) and afterload (N = 15) modulation. Patients with HFrEF showed higher RV dyssynchrony compared with controls (40.6 ± 17.5° vs. 27.8 ± 9.1°, P < 0.001). The magnitude of RV dyssynchrony in HFrEF correlated with larger RV and left ventricular (LV) volumes, lower RV ejection fraction (RVEF) and LV ejection fraction, reduced intrinsic contractility, increased heart rate, higher pulmonary artery (PA) load, and impaired RV-PA coupling (all P ≤ 0.01). Low RVEF was the strongest predictor of RV dyssynchrony. Left bundle branch block (BBB) was associated with greater RV dyssynchrony than right BBB, regardless of QRS duration. RV afterload reduction by sildenafil improved RV dyssynchrony (P = 0.004), whereas preload change with passive leg raise had modest effect. Patients in the highest tertiles of RV dyssynchrony had an increased risk of adverse clinical events compared with those in the lower tertile [T2/T3 vs. T1: hazard ratio 1.98 (95% confidence interval 1.20-3.24), P = 0.007].

CONCLUSIONS

RV dyssynchrony is associated with RV remodelling, dysfunction, adverse haemodynamics, and greater risk for adverse clinical events. RV dyssynchrony is mitigated by acute RV afterload reduction and could be a potential therapeutic target to improve RV performance in HFrEF.

Right Ventricular Response to Cardiac Resynchronization Therapy: A Three-Dimensional and Speckle Tracking Echocardiographic Study

Cardiac resynchronization therapy (CRT) induces left ventricle reverse remodeling; however, its effects on right ventricular (RV) volumes and function were not well described. This study aimed to assess the effects of CRT on RV. Of 112 patients, 63 enrolled with a mean age of 62.77 ± 7.23 years, including 40 males (63.5%). All patients met criteria for CRT implantation and were followed at 3-month and 6-month intervals. Standard 2-dimensional/3-dimensional (3D) echocardiography and speckle-tracking analyses were conducted for assessment of LV and left atrium (LA). RV maximum diameters, tricuspid lateral annular systolic velocity, tricuspid annular plane systolic excursion, fractional area change, RV global (RV 4-chamber strain (RV4CSL), and RV free wall strain (RVFWSL), in addition to 3D echocardiographic assessment of RV, were done before CRT implantation and at follow-up visits. Mean follow-up period was 6.76 ± 1.25 months. A total of 48 patients (76.2%) were LV responders (LVR) whereas the rest were nonresponders (LVNR). Both groups had similar baseline characteristics, risk factors, device implantation, and programming values. Only LVR had significant reduction in RV basal diameter, together with significant improvement of RV systolic performance: systolic velocity, fractional area change, RV4CSL, RVFWSL, and 3D-derived RV volumes and ejection fraction, compared with baseline values. In addition, pulmonary arterial systolic pressure decreased in LVR with reduction of tricuspid regurgitation severity. LV response, percentage change of RV4CSL, LA end-systolic volume index, and LA emptying fraction at 3-month follow-up were the most independent predictors of RV response by multivariate analysis. Reduced left ventricular end-systolic volume >13.5% had 92.3% sensitivity and 81.8% specificity. In conclusion, CRT-induced RV reverse remodeling and improved RV-arterial coupling. These effects were associated with left side response to CRT.

Impact of baseline right ventricular function on the response to cardiac resynchronization therapy - A meta-analysis

Baseline right ventricular (RV) function potentially determines the response to Cardiac Resynchronization Therapy (CRT) but is not included in the current selection criteria. In this meta-analysis, we examined the value of echocardiographic indices of RV function as potential predictors of CRT outcomes in patients with standard indications for CRT. Baseline tricuspid annular plane systolic excursion was consistently higher in CRT responders, and this association appears independent of age, sex, ischemic etiology of heart failure, and baseline left ventricular ejection fraction. This proof-of-concept meta-analysis of observational data may justify a more detailed assessment of RV function as an additional component in the selection process of CRT candidates.

Role of Strauss ECG criteria as predictor of response in patients undergoing cardiac resynchronization therapy

Background

Cardiac resynchronization therapy (CRT) is a standard treatment in patients with heart failure; however, approximately 20–40% of recipients of (CRT) do not respond to it based on the current patients’ selection criteria. The purpose of this study was to identify the baseline parameters that predict the CRT response and how the ECG morphology can affect the outcome. The study aimed to evaluate the Strauss ECG criteria as a predictor of response in patients undergoing cardiac resynchronization therapy.

Results

Out of 70 patients, 3 patients missed the 6-month follow-up after CRT implantation, so the study enrolled 67 patients that have been classified according to ECG morphology of LBBB to 37 patients with non-Strauss ECG criteria—one of whom died after 4 months—and 30 patients with Strauss ECG criteria. The number of responders in the study was 50 patients with percentage 75.8%; 52% of CRT responder (26 patients) had non-Strauss ECG criteria, while 48% of CRT responders (24 patients) had Strauss ECG criteria with P value = 0.463. While there was no statistical significance of overall CRT response nor 6-month hospitalization and mortality between patients of Strauss and non-Strauss ECG criteria, there was a significant improvement in NYHA class, EF assessed by biplane Simpson’s, end-systolic volume, global longitudinal strain and global circumferential strain by speckle tracking echocardiography in patients with Strauss ECG criteria of LBBB.

Conclusions

There is no statistical significance in overall CRT response nor the 6-month hospitalization and mortality after 6 months of follow-up between patients with Strauss and non-Strauss ECG criteria of LBBB; however, patients with Strauss ECG criteria have better improvement in NYHA class, echocardiographic parameters such as EF and ESV and speckle tracking parameters (GLS and GCS).

Lateral Wall Dysfunction Signals Onset of Progressive Heart Failure in Left Bundle Branch Block

OBJECTIVES

This study sought to investigate if contractile asymmetry between septum and left ventricular (LV) lateral wall drives heart failure development in patients with left bundle branch block (LBBB) and whether the presence of lateral wall dysfunction affects potential for recovery of LV function with cardiac resynchronization therapy (CRT).

BACKGROUND

LBBB may induce or aggravate heart failure. Understanding the underlying mechanisms is important to optimize timing of CRT.

METHODS

In 76 nonischemic patients with LBBB and 11 controls, we measured strain using speckle-tracking echocardiography and regional work using pressure-strain analysis. Patients with LBBB were stratified according to LV ejection fraction (EF) ≥50% (EF_preserved), 36% to 49% (EF_mid), and ≤35% (EF_low). Sixty-four patients underwent CRT and were re-examined after 6 months.

RESULTS

Septal work was successively reduced from controls, through EF_preserved, EF_mid, and EF_low (all p < 0.005), and showed a strong correlation to left ventricular ejection fraction (LVEF; r = 0.84; p < 0.005). In contrast, LV lateral wall work was numerically increased in EF_preserved and EF_mid versus controls, and did not significantly correlate with LVEF in these groups. In EF_low, however, LV lateral wall work was substantially reduced (p < 0.005). There was a moderate overall correlation between LV lateral wall work and LVEF (r = 0.58; p < 0.005). In CRT recipients, LVEF was normalized (≥50%) in 54% of patients with preserved LV lateral wall work, but only in 13% of patients with reduced LV lateral wall work (p < 0.005).

CONCLUSIONS

In early stages, LBBB-induced heart failure is associated with impaired septal function but preserved lateral wall function. The advent of LV lateral wall dysfunction may be an optimal time-point for CRT.

Ratio between Right Ventricular Longitudinal Strain and Pulmonary Arterial Systolic Pressure: Novel Prognostic Parameter in Patients Undergoing Cardiac Resynchronization Therapy

BACKGROUND

We aimed to evaluate whether right ventricle (RV) longitudinal strain indexed to pulmonary arterial systolic pressure (PASP) has prognostic significance in patients undergoing cardiac resynchronization therapy (CRT).

METHODS

Patients undergoing CRT were prospectively included. The primary endpoint was adverse cardiovascular events (death and HF-related hospitalizations). RV global longitudinal strain (RVGLS) and RV free wall strain (RVfwS) were measured by speckle tracking and indexed to echocardiographic estimated PASP.

RESULTS

A total of 54 patients (64.0 ± 13.8 years; 58% male) were included. After 33 ± 12.9 months, the primary endpoint occurred in 18 patients. Baseline RVGLS/PASP and RVfwS/PASP showed good discriminative ability for response to CRT (AUC = 0.88, 95% CI (0.74-1) and AUC = 0.87, 95% CI (0.77-1)). RVGLS/PASP and RVfwS/PASP were significantly associated with high risk of events at univariate analysis (HR 0.039, 95% CI (0.001-0.8) p < 0.05, respectively HR = 0.049, 95% CI (0.0033-0.72), p < 0.05). Upon multivariate Cox regression analysis, RVGLS/PASP and RVfwS/PASP remained associated with high risk of events (HR 0.018, 95% CI (0.0005-0.64), p = 0.02 and HR 0.015, 95% CI (0.0004-0.524), p = 0.01) after correction for gender, etiology, QRS duration and morphology. Conclusions: Indexing RV longitudinal strain (global and free wall) by PASP provides a parameter, which independently identifies patients with high risk of cardiovascular events and predicts non-response to CRT.

Right ventricular-arterial coupling - A new perspective for right ventricle evaluation in heart failure patients undergoing cardiac resynchronization therapy

BACKGROUND

Right ventricular - arterial (RV-PA) coupling can be estimated by echocardiography using the ratio between (TAPSE) and pulmonary arterial systolic pressure (PASP). TAPSE/PASP ratio proved to be a prognostic parameter in patients with heart failure and reduced ejection fraction (HFrEF).

OBJECTIVE

To evaluate the significance of RV-PA coupling in patients with HFrEF undergoing cardiac resynchronization therapy (CRT).

METHODS

Patients undergoing CRT in our center between January 2017 and November 2019 were eligible. Response to CRT was defined by a reduction of more than 15% of left ventricle systolic volume (LVESV) one year after CRT. Primary endpoint was a composite of HF hospitalizations and death during follow-up.

RESULTS

54 patients (Age 64.0 ± 13.8 years; 58% male; left ventricular ejection fraction (LVEF) 28.4 ± 1.3%) were prospectively included. After a mean follow-up of 31 ± 12.9months, the primary endpoint had occurred in 18 (33.3%) patients. A lower TAPSE/PASP ratio was associated with baseline worse HF symptoms, lower LVEF and long-term less LV reverse remodeling (P < .05). After one year CRT improved RV systolic function (TAPSE, RV global longitudinal strain, P < .05), but not TAPSE/PASP ratio (P = .4). The ratio TAPSE/PASP (AUC=0.834) ≥ 0.58 mm/mm Hg showed good sensitivity (90%) and specificity (81.8%) for predicting response to CRT while a ratio <0.58 mm/mm Hg was associated with a higher risk of death and HF hospitalizations during the follow-up (HR 5.37 95%CI [1.6-18], P < .001).

CONCLUSION

RV-PA coupling evaluation using TAPSE/PASP ratio predicts CRT response. A lower TAPSE/PASP ratio is associated with a higher risk of adverse cardiovascular events.

Evaluation of cardiac function and systolic dyssynchrony of fetuses exposed to maternal autoimmune diseases using speckle tracking echocardiography

OBJECTIVES

To compare cardiac function and systolic dyssynchrony of fetuses not exposed to and those exposed to maternal autoimmune antibodies using two-dimensional speckle tracking echocardiography (2DSTE).

METHODS

An observational study of 52 fetuses, 18 from mothers with autoimmune antibodies (anti-SSA/Ro60, anti-Ro52 or/and anti-SSB/La) and 34 from healthy mothers without antibodies, was conducted. Maternal baseline characteristics, fetoplacental Doppler parameters, and conventional echocardiographic data were prospectively collected. Systolic global and regional longitudinal strain of left and right ventricle (LV and RV) and the time to peak strain of regional myocardium were measured using 2DSTE. We also calculated the differences in time to peak strain between the LV free wall and RV free wall (two-chamber dyssynchrony, 2C-DYS) and the LV dyssynchrony between the septum and LV free wall (one-chamber dyssynchrony, 1C-DYS).

RESULTS

There were no significant differences in conventional systolic and diastolic functional parameters for the LV and RV. No effect modification was demonstrated in a myocardial deformation analysis. However, 1C-DYS was significantly more prolonged in the maternal autoimmune disease group (19.50 [8.00 to 29.25] vs. 28.50 [13.50 to 39.25], P = 0.042).

CONCLUSIONS

LV systolic mechanical dyssynchrony in fetuses of mothers with autoimmune antibodies suggests in-utero subclinical damage of the cardiac conduction system. Key points • The left ventricular systolic dyssynchrony was significantly more prolonged in the maternal autoimmune disease (AD) fetuses. • Subclinical damage to the left ventricular conduction system of the fetal heart in maternal AD was observed. • Systolic and diastolic functional of the left and right ventricle were preserved in fetuses exposed to maternal autoimmune disease.

Importance of Systematic Right Ventricular Assessment in Cardiac Resynchronization Therapy Candidates: A Machine Learning Approach

BACKGROUND

Despite all having systolic heart failure and broad QRS intervals, patients screened for cardiac resynchronization therapy (CRT) are highly heterogeneous, and it remains extremely challenging to predict the impact of CRT devices on left ventricular function and outcomes. The aim of this study was to evaluate the relative impact of clinical, electrocardiographic, and echocardiographic data on the left ventricular remodeling and prognosis of CRT candidates by the application of machine learning approaches.

METHODS

One hundred ninety-three patients with systolic heart failure receiving CRT according to current recommendations were prospectively included in this multicenter study. A combination of the Boruta algorithm and random forest methods was used to identify features predicting both CRT volumetric response and prognosis. Model performance was tested using the area under the receiver operating characteristic curve. The k-medoid method was also applied to identify clusters of phenotypically similar patients.

RESULTS

From 28 clinical, electrocardiographic, and echocardiographic variables, 16 features were predictive of CRT response, and 11 features were predictive of prognosis. Among the predictors of CRT response, eight variables (50%) pertained to right ventricular size or function. Tricuspid annular plane systolic excursion was the main feature associated with prognosis. The selected features were associated with particularly good prediction of both CRT response (area under the curve, 0.81; 95% CI, 0.74-0.87) and outcomes (area under the curve, 0.84; 95% CI, 0.75-0.93). An unsupervised machine learning approach allowed the identification of two phenogroups of patients who differed significantly in clinical variables and parameters of biventricular size and right ventricular function. The two phenogroups had significantly different prognosis (hazard ratio, 4.70; 95% CI, 2.1-10.0; P < .0001; log-rank P < .0001).

CONCLUSIONS

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