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.

Heart rate variability after radiofrequency ablation of epicardial ganglionated plexuses on the ovine left atrium.

BACKGROUND: Ganglionated plexuses (GP) are terminal parts of cardiac autonomous nervous system (ANS). Radiofrequency ablation (RFA) for atrial fibrillation (AF) possibly affects GP. Changes in heart rate variability (HRV) after RFA can reflect ANS modulation. METHODS: Epicardial RFA of GP on the left atrium (LA) was performed under the general anesthesia in 15 mature Romanov sheep. HRV was used to assess the alterations in autonomic regulation of the heart. A 24 - hour ECG monitoring was performed before the ablation, 2 days after it and at each of the 12 following months. Ablation sites were evaluated histologically. RESULTS: There was an instant change in HRV parameters after the ablation. A standard deviation of all intervals between normal QRS (SDNN), a square root of the mean of the squared differences between successive normal QRS intervals (RMSSD) along with HRV triangular index (TI), low frequency (LF) power and high frequency (HF) power decreased, while LF/HF ratio increased. Both the SDNN, LF power and the HF power changes persisted throughout the 12 - month follow - up. Significant decrease in RMSSD persisted only for 3 months, HRV TI for 6 months and increase in LF/HF ratio for 7 months of the follow - up. Afterwards these three parameters were not different from the preprocedural values. CONCLUSIONS: Epicardial RFA of GP's on the ovine left atrium has lasting effect on the main HRV parameters (SDNN, HF power and LF power). The normalization of RMSSD, HRV TI and LF/HF suggests that HRV after epicardial RFA of GPs on the left atrium might restore over time.

Association of the genetic and traditional risk factors of ischaemic heart disease with STEMI and NSTEMI development.

INTRODUCTION: To evaluate the influence of traditional risk factors of ischaemic heart disease and genetic factors to predict different types of acute coronary syndromes. MATERIALS AND METHODS: Five hundred and twenty-three patients with acute coronary syndromes (393 with ST elevation myocardial infarction (STEMI) and 130 with non-ST elevation myocardial infarction (NSTEMI)) comprised the study group. The control group consisted of 645 subjects free from symptoms of ischaemic heart disease and stroke. Genetic polymorphisms of MMP-2 (-735) C/T, MMP-2 (-1306) C/T, MMP-3 (-1171) 5A/6A, MMP-9 (-1562) C/T and ACE I/D were evaluated using polymerase chain reaction. RESULTS: Patients with acute coronary syndromes more often had ID or II genotype than DD genotype of ACE ( P = 0.04) and 5A5A or 5A6A genotype than 6A6A genotype of MMP-3 ( P = 0.02) in comparison to the control group. The genotypes of other matrix metalloproteinase genes did not differ between the groups. 5A5A and 5A6A genotypes of MMP-3 (odds ratio (OR) 1.5; P = 0.021), II and ID genotypes of ACE (OR 1.7; P = 0.006) along with traditional ischaemic heart disease risk factors such as smoking (OR 4.9; P = 0.001), hypertension (OR 2.0; P = 0.001), diabetes mellitus (OR 2.9; P = 0.001) and dyslipidaemia (OR 2.1; P = 0.001) increased the risk of STEMI. However, the polymorphism of MMP-3 5A/6A and ACE I/D was not associated with the occurrence of NSTEMI. CONCLUSIONS: Genetic polymorphisms of MMP-3 5A/6A and ACE I/D along with conventional ischaemic heart disease risk factors increase the risk of the occurrence of STEMI, while having no influence on the pathogenesis of NSTEMI.

Evaluation of atrial fibrillation management and cardiovascular risk profile in atrial fibrillation patients: A cross-sectional survey.

OBJECTIVE: The aim of this study to investigate the most frequent risk factors of atrial fibrillation (AF), co-morbidities, complications associated with AF and the use of anticoagulants and other medications in patients who were referred to university hospitals in Lithuania. MATERIALS AND METHODS: This cross-sectional study enrolled consecutive inpatients and outpatients with AF presenting to cardiologists in the two biggest Lithuanian university hospitals from November 2013 to May 2014. AF diagnosis was confirmed by a 12-lead ECG or 24-h Holter with an episode duration of >30s. RESULTS: A total number of 575 patients were recruited, and complete data on clinical subtype were available for 515 patients (mean age of 70.7 years; 48.5% of women). Permanent AF was the most frequent type of AF (46.6%). Common comorbidities were hypertension (85.8%), heart failure (77.9%) and coronary artery disease (51.8%). Amiodarone was the most common antiarrhythmic agent used in 14.6% of the patients, while beta-blockers and digoxin were the most often used rate control drugs (59.6% and 10.7%, respectively). Oral anticoagulants were used by 53.3% of the patients; of them, 95.6% used vitamin K antagonists, while non-vitamin K antagonist were used by only 4.4%. The INR within a therapeutic range (2.0-3.0) was documented in 19.2% of the patients. Other antithrombotic drugs such as aspirin and clopidogrel were used in 13.7% and 2.0% of the patients, respectively; dual antiplatelet treatment was administered in 6.2% of the patients. Of the entire cohort, the mean CHA2DS2-VASc score was 3.97±1.6 and the mean HAS-BLED score was 2.25±1.0. CONCLUSIONS: Compliance with the treatment guidelines remains suboptimal and further patient education is needed.