Value of Index Beat in Evaluating Left Ventricular Systolic and Diastolic Function in Patients with Atrial Fibrillation: A Dual Pulsed-Wave Doppler Study

Evaluation of left atrial and ventricular remodeling in atrial fibrillation subtype by using speckle tracking echocardiography

Background

Atrial fibrillation (AF) is associated with cardiac structural and functional remodeling. We investigated the left atrial (LA) and left ventricular (LV) changes in AF subtypes by using two-dimensional echocardiography strain techniques.

Methods

The study population consisted of 102 subjects with sinus rhythm (control group) and 463 patients with AF, among which 284 patients had paroxysmal AF (PAF) and 179 patients had persistent AF (PerAF). A speckle tracking automatic functional imaging software was used to perform the strain analysis.

Results

Patients with AF had dilated LA maximum and minimum volume, decreased LA reservoir strain, lower LV ejection fraction (LVEF), and impaired global longitudinal strain (GLS) compared to those of the sinus rhythm control group. In patients with PerAF, the LA maximum and minimum volumes were larger, and the LA reservoir strain [PAF vs. PerAF, 28% (21,33) vs. 19% (14, 28), P < 0.05], LVEF, and absolute GLS value (PAF vs. PerAF, -16.9 ± 3.3 vs. -14.1 ± 3.5%) were lower than those in patients with PAF. Patients with AF regardless of LA enlargement had decreased LA reservoir strain and lower LVEF and absolute GLS value than those in the sinus rhythm control group.

Conclusion

Compared with those with normal sinus rhythm, patients with AF had dilated LA volume and impaired LA function, which were further worsened in patients with PerAF than those in patients with PAF. LA functional impairment occurred before LA enlargement. Left atrioventricular remodeling happened across different stages of AF development.

Validation of E/e' Using the Index-Beat Method as an Estimate of Left Atrial Pressure in Patients with Atrial Fibrillation

INTRODUCTION

Echocardiographic assessment of diastolic function during atrial fibrillation (AF) remains challenging due to the irregular cardiac cycle length. We sought to assess whether the index-beat method, the beat following two preceding cardiac cycles of equal duration, could provide a more reliable measurement of E/e' (mitral E wave/diastolic tissue Doppler velocity) than the conventional averaging of consecutive beats and hence facilitate the noninvasive estimation of elevated left atrial pressure (LAP) in patients with AF.

METHODS

We prospectively studied 35 patients with persistent AF who had preserved left ventricular ejection fraction and underwent radiofrequency ablation. LAP was measured in conjunction with transseptal puncture during catheter ablation. Echocardiography was performed 24 h before ablation and E/e' was determined using the recommended averaging of 10 beats and the index-beat method, with the observers blinded to the clinical details and LAP measurements.

RESULTS

Correlation analysis showed a strong positive correlation between two methods in terms of both septal E/e' (r = 0.841, p < 0.001) and lateral E/e' (r = 0.930, p < 0.001). Bland-Altman analysis also showed a good agreement between the two measurement methods in terms of E/e'. E/e' determined using both conventional averaging and the index-beat method was significantly correlated with LAP (p < 0.05). After Fisher Z transformation, we found that the index-beat septal E/e' had a better correlation with LAP than did the conventional averaging E/e' (r = 0.736 vs. r = 0.392, Zr = -2.110, p = 0.035). Furthermore, the index-beat method took significantly less time to measure E/e' (mean 33.6 s; 95% confidence intervals [CIs]: 32.1 s-36.2 s) than did conventional averaging method (mean 96.2 s; 95% CI: 90.2 s-102.3 s; p < 0.001). Receiver operating characteristic curve analysis revealed that the optimal cut-off for predicting mean LAP >12 mm Hg was 11 (sensitivity 100%; specificity 77.3%) for index-beat septal E/e' and 16 (sensitivity 61.5%; specificity 95.5%) for index-beat lateral E/e'.

CONCLUSIONS

Good correlations were found between E/e' and LAP in patients with AF, particularly with the index-beat method. Moreover, the index-beat method can easily measure E/e' at an accuracy similar to that for the conventional averaging of consecutive beats, which can therefore be applied to assess the diastolic dysfunction and potentially improve the diagnosis of heart failure in patients with AF.

The Effect of Renal Denervation on Cardiac Diastolic Function in Patients with Hypertension and Paroxysmal Atrial Fibrillation

Objective

Renal artery denervation (RDN) can treat hypertension and paroxysmal atrial fibrillation (PAF). Hypertension and PAF can affect cardiac diastolic function. The study aimed to evaluate the effect of RDN on cardiac diastolic function in patients with refractory hypertension and PAF.

Methods

190 consecutive patients with hypertension and PAF were recruited. The levels of NT-proBNP and metrics of echocardiography were measured before and after RDN in patients with refractory hypertension and PAF. The 190 patients were divided into the decreasing HR and nondecreasing HR group, the decreasing MAP and nondecreasing MAP group, the HFPEF group, and the normal diastolic function group, respectively.

Results

Before RDN, the indices about cardiac diastolic function were out of the normal range. After RDN, the diastolic function improved in the indices of NT-proBNP, E/e′, e′. The diastolic function about the indices of NT-proBNP, E/e′, e′ was improved in the decreasing HR group, the decreasing mean arterial pressure (MAP) group, and the HFPEF group, correspondingly compared to the nondecreasing HR group, the non-decreasing MAP group, and the preoperative normal diastolic function group. In the multivariate analysis, the MAP and HR were the only two indicators significantly associated with the improvement of diastolic function.

Conclusion

RDN could improve the diastolic function in patients with refractory hypertension and PAF. Patients with HFPEF could receive benefits through RDN. It was speculated that RDN improved the diastolic function mainly through decreasing HR and MAP.

Improving the diagnosis of heart failure in patients with atrial fibrillation

OBJECTIVE

To improve the echocardiographic assessment of heart failure in patients with atrial fibrillation (AF) by comparing conventional averaging of consecutive beats with an index-beat approach, whereby measurements are taken after two cycles with similar R-R interval.

METHODS

Transthoracic echocardiography was performed using a standardised and blinded protocol in patients enrolled in the RATE-AF (RAte control Therapy Evaluation in permanent Atrial Fibrillation) randomised trial. We compared reproducibility of the index-beat and conventional consecutive-beat methods to calculate left ventricular ejection fraction (LVEF), global longitudinal strain (GLS) and E/e' (mitral E wave max/average diastolic tissue Doppler velocity), and assessed intraoperator/interoperator variability, time efficiency and validity against natriuretic peptides.

RESULTS

160 patients were included, 46% of whom were women, with a median age of 75 years (IQR 69-82) and a median heart rate of 100 beats per minute (IQR 86-112). The index-beat had the lowest within-beat coefficient of variation for LVEF (32%, vs 51% for 5 consecutive beats and 53% for 10 consecutive beats), GLS (26%, vs 43% and 42%) and E/e' (25%, vs 41% and 41%). Intraoperator (n=50) and interoperator (n=18) reproducibility were both superior for index-beats and this method was quicker to perform (p<0.001): 35.4 s to measure E/e' (95% CI 33.1 to 37.8) compared with 44.7 s for 5-beat (95% CI 41.8 to 47.5) and 98.1 s for 10-beat (95% CI 91.7 to 104.4) analyses. Using a single index-beat did not compromise the association of LVEF, GLS or E/e' with natriuretic peptide levels.

CONCLUSIONS

Compared with averaging of multiple beats in patients with AF, the index-beat approach improves reproducibility and saves time without a negative impact on validity, potentially improving the diagnosis and classification of heart failure in patients with AF.

Heart Failure in Atrial Fibrillation - An Update on Clinical and Echocardiographic Implications

Atrial fibrillation (AF) is the most common sustained arrhythmia in adults and has unfavorable consequences such as stroke, heart failure (HF), and death. HF is the most common adverse event following AF and the leading cause of death. Therefore, identifying the association between AF and HF is important to establish risk stratification for HF in AF. Recent studies suggested that left atrial and ventricular fibrosis is an important link between AF and HF, and the prognostic impact may differ with respect to HF subtype, stratified with left ventricular ejection fraction (EF). Mortality risk in patients with concurrent AF and HF with reduced EF (HFrEF) appears slightly higher compared with those with concurrent AF and HF with preserved EF (HFpEF). On the other hand, the prognostic impact of HF in AF is similar between HFrEF and HFpEF. Further, left atrial size, as well as left atrial and left ventricular functional assessment, are reported to be useful for the prediction of HF in AF, incremental to the conventional risk factors. In this review, we focus on the epidemiological, pathophysiological, and prognostic associations between AF and HF, and review the clinical and echocardiographic predictors for HF in AF.