The assessment of prognosis in patients with atrial fibrillation (AF) has been performed in the clinical course of heart failure (HF). AF is believed to share pathophysiologic associations with hypertension and HF, although no definite etiology has been determined. Regarding the outcomes of HF, the concomitant presence of AF could be used to identify high-risk patients to prevent subsequent hospital admissions. In patients with AF, left ventricular (LV) diastolic or systolic dysfunction is frequently encountered, leading to left atrial (LA) enlargement and pressure elevation. The electromechanical features of AF may impair ventricular filling and cause irregular contraction with poor ventricular rate control, resulting in a cardiomyopathy that is common in the left ventricle but may also be seen in right ventricle. Consequently, AF commonly has adverse hemodynamic effects on both the left and right ventricles, causing right ventricular (RV) dysfunction or HF.

RV function is also considered to be an independent predictor of clinical events in HF, irrespective of LV functional severity. Furthermore, Doppler tissue imaging (DTI) of the tricuspid valve (TV) annulus has been found to provide information about RV longitudinal function in previous studies. Interestingly, systolic myocardial velocity as determined from the TV annulus could be a significant predictor of RV function and has proven to be a useful index in the prognosis of RV infarction. However, few studies in the literature have examined DTI of the TV annulus in patients with HF with AF, although DTI is easily used for LV evaluation. In addition, patients with nonsinus rhythms such as AF have been usually excluded from echocardiographic studies. Despite the prognostic significance of AF in terms of HF, AF has not shown a consistent impact for prognosis in patients with HF, but rather, its impact might be dependent on the severity of HF. Importantly, the association of TV DTI with AF has not been evaluated or focused in studies of HF. Therefore, we hypothesized that TV DTI would be as important as mitral valve (MV) DTI for clinical outcomes, particularly in the setting of clinical AF. The goals of the present study were to quantify RV dysfunction and to assess the relationship between TV DTI and the prognosis of HF with AF compared with MV DTI.

Methods

Study Population

This was a prospective observational study of consecutive patients with AF who were referred to our echocardiography laboratory between June 2008 and December 2009 for cardiac evaluation for symptoms or signs of HF in this study. At the time of enrollment, all patients who were clinically stable underwent transthoracic echocardiography. Patients aged ≥ 18 years were eligible for inclusion if they showed chronic permanent AF and symptomatic HF with New York Heart Association (NYHA) functional classes II to IV. Permanent AF was defined as AF that was refractory to cardioversion and did not convert to sinus rhythm for a period > 6 months. HF was defined according to the criteria of the European Society of Cardiology. The exclusion criteria were paroxysmal or persistent AF; acute coronary syndromes or coronary revascularization within the past 3 months; significant valvular heart disease (moderate or severe grade) or prosthetic valve replacement; advanced liver, renal, and lung disease; and congenital heart disease. Blood samples were obtained at enrollment for measurement of routine blood chemistry, including hemoglobin and renal functional parameters. Baseline, clinical, and echocardiographic data were recorded. The study protocol was approved by the hospital’s institutional review boards, and written informed consent was obtained from all patients.

Echocardiography

Echocardiographic examinations were performed using the cardiac ultrasound machine Vivid 7 with a 3.5-MHz transducer (GE Vingmed Ultrasound AS, Horten, Norway). Images were taken while patients were in the left lateral decubitus position. Conventional echocardiographic studies including DTI were performed according to the recommendations of the American Society of Echocardiography. LV end-systolic and end-diastolic dimensions, interventricular septal and posterior wall thicknesses, and LA anteroposterior diameter were determined from two-dimensional imaging. Ejection fraction (EF) was calculated using the biplane Simpson’s method. Additionally, LA volume was obtained using the formula for the biplane area-length method. Mitral inflow was recorded on apical four-chamber view, and its peak early velocity and deceleration time were measured. Pulsed-wave tissue Doppler recordings were obtained in the apical four-chamber view, and a sample volume of pulsed-wave Doppler was positioned on the lateral and septal sides of the MV annulus. In addition, tissue Doppler was also performed by placing the sample volume at the lateral side of the TV annulus. Care was taken to ensure that the Doppler beam was aligned parallel to the LV lateral and septal and RV lateral walls. We tried to obtain high–frame rate images, and gain settings were adjusted to avoid background noise and to obtain clear DTI tracings. From the spectral signals of both MV and TV annuli, we measured the peak systolic (s′) and early diastolic (e′) mitral (at both septal and lateral sides) and tricuspid annular velocities ( Figure 1 ). A mean of five consecutive beats were measured for all Doppler measurements at a sweep speed of 50 mm/sec, and all values were averaged.

Representative DTI at the tricuspid and septal annuli in patients without (A,C) and with (B,D) events. Both tricuspid s′ and septal e′ were severely reduced in patients with event.

Study Follow-Up

With regard to the adverse clinical outcomes of HF with AF, patients were followed up in the outpatient clinic as well as by telephone. The clinical primary end point was a composite of cardiac death and worsening HF requiring hospitalization.

Statistic Analysis

Data analyses were performed using SPSS for Windows version 12.0 (SPSS, Inc., Chicago, IL). All values are presented as mean ± SD for continuous variables and as frequencies for discrete variables. Categorical variables were analyzed using χ ² tests and continuous variables using Student’s t tests. Receiver operating characteristic curves and the areas under the curves were obtained to compare the predictive value of echocardiographic parameters. Univariate and multivariate Cox proportional regression analysis was performed, and cumulative survival curves were constituted using the Kaplan-Meier method. The log-rank test was used to evaluate event-free survival according to the cutoff value for DTI. To address the independent contribution of DTI and to determine the incremental prognostic value over conventional data, a sequential Cox model analysis was performed, and a global χ ² value was obtained. Two-sided P values < .05 were considered statistically significant.