Left atrium in cardiac resynchronization therapy: Active participant or innocent bystander

Predictors of Higher Frequency of Atrial Fibrillation in Patients with Cardiac Resynchronization Therapy

Background and Objectives: Cardiac resynchronization therapy (CRT) is one of the effective therapeutic options in the treatment of systolic heart failure (HF) with persistent symptoms. This prospective study was designed to determine whether CRT with biventricular pacing would reduce the risk of development of atrial fibrillation (AF) and to identify predictors for AF occurrence. Materials and Methods: The study population consisted of 126 patients, with a mean age of 63.8 ± 9.1 years, who were eligible for CRT with biventricular pacing. Inclusion criteria were left ventricular ejection fraction (LVEF) ≤ 35%, QRS duration ≥ 130 msec, and persistent HF symptoms of New York Heart Association (NYHA) II or III, despite optimal drug therapy. Patients were followed for a period of 24 months and were evaluated through clinical, electrocardiographic, and echocardiographic examination at baseline (prior to CRT implantation), as well as at 6 and 24 months post-implantation. At the end of follow-up, patients were divided into clinical responders and non-responders based on the following criteria: decrease in NYHA class ≥ I, increase in LVEF ≥ 10%, and reduction in QRS duration ≥ 20 msec. Results: At follow-up, CRT was associated with a significant increase in LVEF (20.6 ± 6.9% pre-implantation, 32.9 ± 9.3% 24 months after implantation; p < 0.001), reduction in left ventricular end-diastolic and end-systolic diameters, and decrease in QRS duration (167.6 ± 14.3 msec pre-implantation, 131.7 ± 11.7 msec 24 months after implantation; p < 0.001), while left atrial (LA) diameter was slightly increased (p = 0.070). The frequency of AF occurrence increased after two years of follow-up (52.4% to 56.9%, p < 0.001). Significant predictors of AF occurrence in our study population were response to CRT-AF more frequent in non-responders (B = 8.134; p < 0.001), LA diameter-AF more frequent with larger LA diameter (B = 0.813; p < 0.001), and coronary sinus (CS) lead position-AF more frequent with posterolateral in comparison with lateral CS lead position (B = 5.159; p = 0.005). Conclusions: The results of our study provide new data on AF predictors in patients with HF subjected to CRT. There remains a permanent need for new predictors, which might help in patient selection and improvement in response rate.

Cardiac Resynchronization Therapy and Left Atrial Remodeling: A Novel Insight?

Cardiac resynchronization therapy (CRT) restores ventricular dyssynchrony, improving left ventricle (LV) systolic function, symptoms, and outcome in patients with heart failure, systolic dysfunction, and prolonged QRS interval. The left atrium (LA) plays tremendous roles in maintaining cardiac function, being often inflicted in various cardiovascular diseases. LA remodeling implies structural-dilation, functional-altered phasic functions, and strain and electrical-atrial fibrillation remodeling. Until now, several important studies have approached the relationship between LA and CRT. LA volumes can predict responsiveness to CRT, being also associated with improved outcome in these patients. LA function and strain parameters have been shown to improve after CRT, especially in those who were positive responders to it. Further studies still need to be conducted to comprehensively characterize the impact of CRT on LA phasic function and strain, and, also, in conjunction with its impact on functional mitral regurgitation and LV diastolic dysfunction. The aim of this review was to provide an overview of current available data regarding the relation between CRT and LA remodeling.

Left atrial volume index predicts response to cardiac resynchronisation therapy: a systematic review and meta-analysis

INTRODUCTION

In responders, cardiac resynchronisation therapy (CRT) results in improved left ventricular (LV) function and reduced atrial arrhythmia. The aim of this meta-analysis was to assess the potential relationship between the left atrium (LA) volume and CRT response.

MATERIAL AND METHODS

We systematically searched all electronic databases up to August 2018 in order to select clinical trials and observational studies that assessed the predictive value of LA volume index (LAVI) of CRT response. Left ventricular end-systolic volume (LVESV) reduction ≥ 15 ml and/or LV ejection fraction (EF) increase ≥ 10% were the documented criteria for positive CRT response.

RESULTS

A total of 2191 patients recruited in 10 studies with mean follow-up duration of 10.5 months were included in this meta-analysis. The pooled analysis showed that CRT responders had lower baseline LAVI compared to non-responders, with a weighted mean difference (WMD) of -5.89% (95% CI: -9.47 to -3.22, p < 0.001). At follow-up, LAVI fell in the CRT responders (WMD -4.36%, 95% CI: -3.54 to -5.17, p < 0.001) compared to non-responders (WMD 1.45 %, 95% CI: -0.75 to 3.65, p = 0.20). The mean change of LAVI in the CRT responders was related to the fall in LVESV, β = -1.02 (-1.46 to -0.58), p < 0.001 and the increase in LVEF, β = 2.02 (1.86 to 4.58), p = 0.001. A baseline LAVI < 34 ml/m² predicted CRT response with summary sensitivity 0.80% (0.53-0.95), specificity 0.74% (0.53-0.89), and odds ratio > 11.

CONCLUSIONS

Baseline LAVI predicts CRT response, and its reduction reflects devise-related LA remodelling. These results emphasis the role of LAVI assessment as an integral part of cardiac function response to CRT.

A Simple Predictive Marker in Cardiac Resynchronization Therapy Recipients: Prominent S-Wave in Right Precordial Leads

Background and objectives: Current guidelines criteria do not satisfactorily discriminate responders to cardiac resynchronization therapy (CRT). QRS amplitude is an established index to recognize the severity of myocardial disturbance and might be a key to optimal patient selection for CRT. Materials and Methods: (1) Initial R-wave amplitude, (2) S-wave amplitude, and (3) a summation of maximal R- or R′-wave amplitude and S-wave amplitude were measured at baseline. These parameters were averaged according to right (V1 to V3) or left (V4 to V6) precordial leads. The impact of these parameters on response to CRT, which was defined as a decrease in left ventricular end-systolic volume ≥15% at six-month follow-up, was investigated. Results: Among 47 patients (71 years old, 28 men) who received guideline-indicated CRT implantation, 25 (53%) achieved the definition of CRT responder. Among baseline electrocardiogram parameters, only the higher S-wave amplitude in right precordial leads was an independent predictor of CRT responders (odds ratio: 2.181, 95% confidence interval: 1.078–4.414, p = 0.030) at a cutoff of 1.44 mV. The cutoff was independently associated with cumulative incidence of heart failure readmission and appropriate electrical defibrillation following CRT implantation (p < 0.05, respectively). Conclusions: Prominent S-wave in right precordial leads might be a promising index to predict left ventricular reverse remodeling and greater clinical outcomes following CRT implantation.

Improved Left Atrial Function in CRT Responders: A Systematic Review and Meta-Analysis

Cardiac resynchronization therapy (CRT) is associated with reverse left atrial (LA) remodeling. The aim of this meta-analysis was to assess the relationship between clinical response to CRT and LA function changes. We conducted a systematic search of all electronic databases up to September 2019 which identified 488 patients from seven studies. At (mean) 6 months follow-up, LA systolic strain and emptying fraction (EF) were increased in CRT responders, with a -5.70% weighted mean difference (WMD) [95% confidence interval (CI) -8.37 to -3.04, p < 0.001 and a WMD of -8.98% [CI -15.1 to -2.84, p = 0.004], compared to non-responders. The increase in LA strain was associated with a fall in left ventricle (LV) end-systolic volume (LVESV) r = -0.56 (CI -0.68 to -0.40, p < 0.001) and an increase in the LV ejection fraction (LVEF) r = 0.58 (CI 0.42 to 0.69, p < 0.001). The increase in LA EF correlated with the fall in LVESV r = -0.51 (CI -0.63 to -0.36, p < 0.001) and the increase in the LVEF r = 0.48 (CI 0.33 to 0.61, p = 0.002). The increase in LA strain correlated with the increase in the LA EF, r = 0.57 (CI 0.43 to 0.70, p < 0.001). Thus, the improvement of LA function in CRT responders reflects LA reverse remodeling and is related to its ventricular counterpart.

Cardiac resynchronization therapy in patients with heart failure and moderately reduced ejection fraction: Could it trigger a super-response?

Background/Aim

Despite the well-established benefits of cardiac resynchronization therapy (CRT) in heart failure (HF) patients with left ventricular ejection fraction (LVEF) ≤35%, many patients with less reduced EF remain refractory to optimized medical treatment and at high risk of morbidity and mortality. The objective of the study is to evaluate the effects of CRT in optimally treated patients with New York Heart Association (NYHA) classes II–IV, LVEF of 36–45%, and left bundle branch (LBBB), including clinical, structural and biochemical response.

Methods

A selected group of HF patients have been implanted with CRT-P devices and were followed up for 6 months at 4, 12 and 24 weeks. Clinical assessment included NYHA class, quality of life and 6-min walk distance (6 MWD) test. Echocardiographic assessment included LV dimensions and function and left atrial volume. Serum N-terminal pro b-type natriuretic peptide (NT-ProBNP) was measured at the same intervals.

Results

This prospective single center study included 23 patients. NYHA functional class significantly improved after CRT-P (p < 0.0001), associated with improvement in QOL (p < 0.0001) and 6 MWD, which increased, from 145.7 ± 20.1 m to 219.5 ± 42.2 m (p < 0.0001). Mean QRS duration showed significant shortening from 164.4 ± 13.2 ms to 126.4 ± 13.6 ms (p < 0.0001). CRT induced reverse remodeling with reduction in both left ventricular end diastolic diameter (LVEDD) from 68.95 ± 5.05 mm to 62.8 ± 4.47 mm, p = 0.0002 and left ventricular end systolic diameter (LVESD) from 54.1 ± 4.5 mm to 46.5 ± 4.1 mm, p < 0.0001, and significant increase in LVEF (from 40.3 ± 2.8 to 48.3 ± 4.2 mm, p < 0.0001). The biochemical response to CRT showed significant reduction in serum NT-ProBNP from 1025.6 ± 363.1 pg/ml to 594.9 ± 263.5 pg/ml (p < 0.0001).

Conclusions

Symptomatic HF patients on maximal optimized medical treatment who have LBBB and baseline LVEF 35–45% appeared to derive significant clinical and structural benefit from CRT.