Atrial Pacing Negatively Affects Left Atrial Morphological and Functional Parameters Similarly to Atrioventricular Dyssynchrony.

Background and Objectives: Atrioventricular (AV) dyssynchrony as well as atrial and ventricular pacing affect left atrial (LA) function. We conducted a study evaluating the effect of atrial and ventricular pacing on LA morphological and functional changes after dual-chamber pacemaker implantation. Materials and Methods: The study prospectively enrolled 121 subjects who had a dual-chamber pacemaker implanted due to sinus node disease (SND) or atrioventricular block (AVB). Subjects were divided into three groups based on indication and pacemaker programming: (1) SND DDDR 60; (2) AVB DDD 60 and (3) AVB DDD 40. Subjects were invited to one- and three-month follow-up visits. Three subsets based on pacing burden were analyzed: (1) high atrial (A) low ventricular (V); (2) high A, high V and (3) low A, high V. LA function was assessed from volumetric parameters and measured strains from echocardiography. Results: The high A, low V group consisted of 38 subjects; while high A, high V had 26 and low A, high V had 23. A significant decrease in reservoir and contractile LA strain parameters were only observed in the high A, low V pacing group after three months (reservoir 25.9 ± 10.3% vs. 21.1 ± 9.9%, p = 0.003, contractile -14.0 ± 9.0% vs. -11.1 ± 7.8, p = 0.018). While the re-established atrioventricular synchrony in the low A, high V group maintained reservoir LA strain at the baseline level after three months (21.4 ± 10.4% vs. 22.5 ± 10.4%, p = 0.975); in the high A, high V group, a further trend to decrease was noted (20.3 ± 8.9% vs. 18.7 ± 8.3%, p = 0.231). Conclusions: High atrial pacing burden independently of atrioventricular dyssynchrony and ventricular pacing impairs LA functional and morphological parameters. Changes appear soon after pacemaker implantation and are maintained.

Atrial Pacing Affects Left Atrial Morphological and Functional Parameters Early after Pacemaker Implantation.

Background and Objectives: Chronic atrial stimulation might impair left atrial (LA) function. We aimed to assess the impact of atrial pacing burden on LA volumetric and functional parameters after implantation of a dual-chamber pacemaker. Materials and Methods: The prospective study included 121 subjects with sinus node disease (SND) or atrioventricular block (AVB) that received a dual-chamber pacemaker. After device implantation, the subjects were divided into three groups: (1) SND with a lower rate (LR) set to 60 bpm and rate response enabled; (2) AVB with an LR set to 60 bpm and no rate response; and (3) AVB with an LR set to 40 bpm and no rate response. Subjects were followed at one and three months. Two subsets of patients with high and low atrial pacing burdens accompanied by low ventricular pacing percentage were analyzed. LA function was evaluated with volumetric and strain parameters from transthoracic echocardiography. Results: The high atrial low ventricular pacing group consisted of 38 subjects, and the low atrial low ventricular group consisted of 22 subjects. When looking at the change in volumetric parameters, we observed a tendency for volumes to increase in both groups; however, only minimal LA volume reached statistical significance at three months in the high atrial pacing group. A trend towards the lowering of an active emptying fraction at one month (p = 0.076) became significant at three months (p = 0.043), and was also only observed in the same group. Moreover, a decrease in the tendency to reach statistical significance at three months for reservoir and contractile strain parameters and stiffness index was only observed in the high atrial pacing group. Meanwhile, in the low atrial pacing burden group, all parameters remained significantly unchanged. Conclusions: The burden of right atrial pacing in patients with preserved left ventricular function negatively influences functional and morphologic LA parameters. Moreover, negative effects take place soon after pacemaker implantation and appear to be sustained.

Dobutamine-stress echocardiography speckle-tracking imaging in the assessment of hemodynamic significance of coronary artery stenosis in patients with moderate and high probability of coronary artery disease.

BACKGROUND AND OBJECTIVE: Myocardial deformation indices are considered as sensitive markers of ischemia and may be useful in the quantification of hemodynamic significance of coronary artery disease (CAD). We sought to determine the diagnostic value of speckle-tracking echocardiography derived myocardial deformation parameters at rest and during stress to determine hemodynamically significance coronary artery stenosis in patients with moderate and high probability of CAD. MATERIALS AND METHODS: In 81 patients (mean age, 64±8.6 years) with stable CAD inducible myocardial ischemia was evaluated by dobutamine stress echocardiography (DSE) and adenosine magnetic resonance imaging (AMRI). Based on AMRI patients were divided into two groups: nonpathologic (n=41) and pathologic (n=40). Strain and strain rate (SR) parameters and their changes from the rest (BASE) to low stress (MIN), peak stress (MAX), and recovery (REC) were analyzed using 2D speckle-tracking imaging (STI). RESULTS: In the nonpathologic group, systolic longitudinal and circumferential strain increased significantly from BASE to MIN, as well as systolic SR from BASE to MIN and from MIN to MAX in longitudinal plane. In contrast, in the pathologic group, insignificant longitudinal systolic SR increase and radial and circumferential systolic SR decrease from MIN to MAX was observed. Discriminant function analysis revealed that select STI derived parameters best classify patients into predefined AMRI groups (pathologic and nonpathologic) with the accuracy respectively 90.9% and 83.3%. According to ROC analysis these myocardial deformation parameters had the greatest predictive value of significant coronary artery stenoses: longitudinal strain at high dose (AUC 0.811, sensitivity 89.4%, specificity 64.7%), longitudinal strain rate at high dose (AUC 0.855, sensitivity 88.1%, specificity 71.0% at high doses). The sensitivity and specificity of inducible wall motion abnormalities were 74.0% and 85.0% (AUC 0.798) and was lower compared with the diagnostic value of longitudinal myocardial deformation parameters. CONCLUSIONS: Left ventricular strain and strain rate analyses during DSE can be used in the assessment of hemodynamic significance of coronary artery stenosis in patients with moderate and high risk for CAD.

Early and late diastolic strain rate vs global longitudinal strain at rest and during dobutamine stress for the assessment of significant coronary artery stenosis in patients with a moderate and high probability of coronary artery disease.

BACKGROUND: The aim of this prospective study was to assess the usefulness of global longitudinal strain (GLS), regional diastolic and systolic strain, strain rate (SR) parameters at rest and during dobutamine stress echocardiography for detecting significant coronary artery stenosis in patients with a moderate or high probability of coronary artery disease (CAD). METHODS: Dobutamine stress echocardiography and adenosine magnetic resonance imaging (AMRI) were performed on 127 patients with a moderate and high probability of CAD and left ventricle ejection fraction ≥55%. CAD was defined as ≥70% diameter stenosis on coronary angiography validated as hemodynamically significant by AMRI. Patients were grouped according to coronary angiography and AMRI results: CAD (-) n=67 (52.8%) vs CAD (+) n=60 (47.2%). RESULTS: There were no significant differences of clinical characteristics, conventional echocardiography, and deformation parameters between the two groups at rest except that GLS was higher in the CAD (-) group (-21.5±2.4% vs -16.2±2.1%, P=.00). GLS at high dobutamine doses had the highest area under the ROC curve (AUC) (AUC 0.955, sensitivity 94%, specificity 92%). Radial late diastolic SR at low doses performed best out of all diastolic parameters with an AUC of 0.789, sensitivity 76.7%, specificity 91.7%. Other deformation parameters including visual assessment were inferior. CONCLUSIONS: Global longitudinal strain is highly sensitive and specific in detecting hemodynamically significant coronary artery stenosis in moderate- to high-risk patients without known CAD. This is the first study showing that GLS is more sensitive and specific compared with early and late diastolic SR parameters or visual assessment in detecting CAD.