AV timing in pacemaker patients with first-degree AV block: which is preferable, intrinsic AV conduction or pacing?

Analysis of the Independent Risk Factors of second-Degree Atrioventricular Block in Patients with Atrial Fibrillation and the Diagnostic Efficacy of Dynamic Electrocardiogram

Objective

Exploring the independent risk factors of second-degree atrioventricular block (II AVB) in patients with atrial fibrillation (AF), and to evaluate the clinical value of 24-hour dynamic electrocardiogram (DCG) in its diagnosis.

Methods

A prospective cohort study was conducted on 947 patients with AF diagnosed and treated in our hospital from January 1, 2021 to December 31, 2021. These patients were divided into combined group (98 cases) and uncombined group (849 cases) according to whether they were accompanied by. The clinicopathological data of the patients were collected, and Multivariate logistic regression analysis was used to analyze the independent risk factors. Patients in combined group were further evenly divided into the study group (underwent 24-hour DCG) and the control group (underwent routine ECG) based on the detection methods. The diagnostic value was valued and the positive detection rate was calculated by ROC curve.

Results

The smoking history, left atrial internal diameter (LAD), R-R interval and ventricular rate of patients in two groups had significant differences (P<0.001). Smoking history (HR=1.531, 95% CI 1.150-2.038, P<0.001), LAD>35.88 mm (HR=1.941, 95% CI 1.301-2.895, P<0.001), R-R interval>2.50 s (HR=2.282, 95% CI 1.231-4.229, P=0.014) were independent risk factors for AF combined with II AVB, while ventricular rate≤70 beats/min (HR=0.506, 95% CI 0.293-0.873, P=0.014) were independent protective factors for AF combined with II AVB. The mean ventricular rate (70.03±5.40 beats/min vs 83.11±8.05 beats/min, P<0.001) and R-R interval (2.82±0.26s vs 2.37±0.14s, P<0.001) in the study group were longer than the control group. The diagnostic positive rate of DCG (97.96% vs 85.71%, χ²=4.900, P=0.027) was higher than that of conventional ECG.

Conclusion

Smoking history, LAD, R-R interval and ventricular rate were influential factors for AF combined with II AVB. 24-h DCG had potential diagnostic value in the occurrence of AF combined with II AVB.

Characteristics of successful termination of atrial fibrillation by atrial antitachycardia pacing in patients with cardiac implantable electronic devices

Asymptomatic paroxysmal atrial fibrillation (AF) is often found in patients implanted with cardiac implantable electronic devices (CIEDs). Second-generation atrial antitachycardia pacing (A-ATP) is effective in managing AF in patients implanted with CIEDs. The purpose of this study was to evaluate the efficacy and safety of A-ATP in patients implanted with CIEDs. This was a single-center retrospective study involving 91 patients (male 46 patients, mean age 74 ± 9 years) implanted with Reactive A-ATP equipped devices (84 patients with pacemakers, 6 with ICDs, and 1 with a CRT-D). The AF burden, rate of AF termination, and details of the activation of the A-ATP were analyzed in each patient. During a mean follow-up period of 21 ± 13 months, A-ATP was activated in 45 of 91 patients (49.5%). No patients had adverse events. Although the efficacy of the A-ATP varied among the patients, the median rate of AF termination was 44%. In comparison to the A-ATP start time, "0 min" had a higher AF termination rate by the A-ATP (39.4% vs. 24.4%, P = 0.011). The rate of termination by the A-ATP was high for AF with a long cycle length and a relatively regular rhythm. A-ATP successfully terminated AF episodes in some patients implanted with CIEDs. The optimal settings of the A-ATP will be determined in future studies.

Improvement of myocardial contractility with leadless endocardial single-lead atrial sensing ventricular pacing in patients with prolonged PQ interval

Aim: Micra AV represents a leadless endocardial pacing system able to detect atrial contractions providing atrioventricular synchrony. A reduction of myocardial contractility may be detected in case of first-degree atrioventricular block (AVB). Materials & methods: In six patients with first-degree AVB (PQ interval ≥220 msec) was evaluated the left ventricle global longitudinal strain (LV GLS) by speckle tracking (ST) echocardiography during single-lead atrial sensing ventricular pacing (VDD) stimulation as compared with spontaneous rhythm (SR), 24-48 h after Micra AV implantation. Results: A statistically significant difference between the two modalities was observed (LV GLS during SR: -14.7% [interquartile range (IQR) 5.5], LV GLS during VDD pacing: -16.1% [IQR 5.2]; p value = 0.041). Conclusion: Our preliminary results suggest an improvement of myocardial contractility with VDD pacing as compared with SR.