Assessment of atrial conduction times in patients with frequent premature ventricular complex

Abstract Background Premature ventricular complex (PVC) is a frequent finding in the general population. The atrial conduction time (ACT) is the period between the electrocardiographic P wave and the atrial mechanical contraction, and its prolongation indicates an atrial electromechanical delay (EMD). In our study, we compared atrial conduction parameters by echocardiographic methods between patients with frequent PVC and healthy control subjects. Methods The study included 54 patients with PVC and 54 healthy volunteers. Atrial conduction parameters were measured with echocardiographic examination. The time difference between the p wave and the Am wave was measured in the septal, lateral, and tricuspid annulus regions. The interatrial EMD, left atrial intra‐atrial delay, and the right atrial intra‐atrial delay were calculated from these measurements. The groups were compared for demographic and electrocardiographic features and echocardiographic parameters. Results Left intra‐atrial EMD, right intra‐atrial EMD, and interatrial EMD were significantly longer in the patient group (p = .001, p < .001, p < .001, respectively). PA lateral, PA septal, and PA tricuspid durations were significantly prolonged in the patient group (all p < .001). All ACT parameters were significantly prolonged in patients with PVC QRS duration of 150 ms and above (all p < .001). All ACT parameters were prolonged in PVCs of right ventricular origin than those of left ventricular origin (all p < .001). ACT parameters were prolonged in patients with a coupling interval time below 485 ms (all p < .001). Conclusions Atrial conduction times are prolonged in patients with frequent PVC.


| INTRODUC TI ON
Premature ventricular complex (PVC) is quite common and is detected in the majority of individuals with long-term ambulatory rhythm monitoring. While the pathophysiological mechanisms of PVCs remain mostly unknown, potential mechanisms include triggered activity, increased automaticity, and reentry. Advanced age, a taller height, a history of coronary heart disease, arterial hypertension, smoking, and decreased physical activity each predict a greater PVC frequency. A higher PVC frequency is associated with an increased risk of cardiovascular death, cardiomyopathy, and ischemic stroke. [1][2][3] PVC most frequently affects ventricular function in structurally normal heart. PVC can also cause retrograde ventriculoatrial conduction. These retrograde atrial activations can affect cardiac conduction systems like atrial ectopies. Increased PVC frequency correlates with increased left atrial (LA) maximum volume. [4][5][6][7] The atrial conduction time (ACT) represents the period between the electrocardiographic P wave and atrial mechanical contraction.
The prolongation of ACT is termed the atrial electromechanical delay (EMD). Interatrial conduction times can be measured without invasive methods using Doppler and tissue Doppler imaging (TDI) in echocardiography. [8][9][10] Prolonged ACT is associated with increased LA diameter and reduced LA function. It has been shown that left atrium negative remodeling may develop and LA diameter may increase in patients with frequent PVCs. Therefore prolonged ACT may be expected in patients with frequent PVCs. [12][13][14][15][16][17][18] In this study, we compared atrial conduction parameters by echocardiographic methods between patients with frequent PVC and healthy control subjects.

| Study population
Fifty-four patients with more than 10 000 PVC observed over 24 h of ambulatory rhythm Holter monitoring and 54 healthy volunteers with comparable demographic characteristics were included in the study. Twenty-four hours of ambulatory rhythm Holter monitoring revealed no arrhythmia in the control group. Patients with coronary artery disease reduced left ventricle ejection fraction (LVEF 50%), other arrhythmias (such as supraventricular tachycardia and atrial flutter), moderate and severe valvular heart disease, significant congenital heart disease, or left ventricle (LV) hypertrophy were excluded from the study. Since current literature does not suggest a cutoff value for frequent premature atrial contractions (PAC), we considered frequent PAC to be present similar to frequent PVC which was defined as more than 30 PVC in an hour. 19,20 Patients with a PAC of 30 or more per hour were not included in the study.
Patients with any type of chronic systemic or inflammatory illness or any form of malignancy that may impair the structure and function of the cardiovascular structure were also excluded from the study.
The local ethics committee approved of the research. All individuals provided informed permission before participating in the study.

| Electrocardiography
We assessed resting electrocardiograms. PVCs were analyzed regarding the QRS duration, amplitude, and morphology. PVCs are classified with respect to the presumed chamber of origin. In general, the left bundle branch block (LBBB) morphology of PVCs originates from the right ventricle (RV) and RVOT, however, PVCs originating from the septal left ventricular outflow tract (LVOT) or aortic cusp may also have LBBB morphology. Right bundle branch block (RBBB) morphology represents left ventricular origin. To distinguish right ventricular outflow tract (RVOT) versus LVOT origin we used precordial transition of R wave (late vs. early). A QRS transition in the precordial leads later than that in sinus rhythm suggests an RVOT exit (and vice versa). If the QRS transition in both PVC and sinus beats is at V3, the "R wave transition ratio" can provide further guidance. When comparing the PVC R-wave amplitude in V2 with that in sinus rhythm, a ratio ≥0.6 predicts a left-sided origin. A coupling interval is defined as the interval measured from the onset of the R wave of the previous sinus beat to the onset of the PVC.

| Echocardiography
All participants were evaluated using the GE Vivid E95 system (GE Healthcare). Echocardiographic examination was performed within the first 24 h after rhythm Holter recordings were obtained. Single lead electrocardiography recording was acquired from all participants during echocardiographic assessment. The diameters of the left atrium (LA) and the LV were measured in accordance with the guidelines of the American Society of Echocardiography. 11 The Simpson technique was utilized to determine LVEF. The TAPSE was measured using M mode from the apical four-chamber view. 11 The TAPSE was measured using M mode from the apical four-chamber view. E wave, A wave, E/A ratio, isovolumic relaxation time, and E-

| RE SULTS
In the study, there were 54 patients (mean age 45.9 ± 13.6 years and 40.7% male) and 54 control subjects (mean age 41.6 ± 10.4 years and 61.1% male) included. Table 1

| CON CLUS IONS
Atrial conduction times are prolonged in patients with frequent PVC.

CO N FLI C T O F I NTE R E S T
The work will be presented at the "European Society of Cardiology (ESC) Congress 2022, Barcelona" as an oral moderated poster presentation and will be published as an abstract in the supplement of the European Heart Journal.

DATA AVA I L A B I L I T Y S TAT E M E N T
The authors confirm that the data supporting the findings of this study are available within the article.

PATI ENT CO N S ENT
All participants provided informed consent before participating in the study.