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. 2025 Jan 17;6(4):519-527.
doi: 10.1016/j.hroo.2025.01.006. eCollection 2025 Apr.

Simple electrocardiographic index for A4-wave amplitude of the VDD leadless pacemaker

Takafumi Oka  1 , Koki Tanabiki  2 , Takayuki Sekihara  1 , Akira Yoshida  1 , Kentaro Ozu  3 , Tomoaki Nakano  1 , Hibiki Mima  1 , Yasuhiro Akazawa  1 , Fusako Sera  1 , Shigetaka Kusumoto  2 , Masaki Takashina  2 , Tomohito Ohtani  1 , Yasushi Sakata  1
Affiliations

Simple electrocardiographic index for A4-wave amplitude of the VDD leadless pacemaker

Takafumi Oka et al. Heart Rhythm O2. .

Abstract

Background: A4-wave amplitude (A4-amplitude) is a crucial factor determining the percentage of atrioventricular synchrony (%AVS) in a mechanical sensing-based VDD leadless pacemaker (VDD-LP). We hypothesized that 12-lead electrocardiographic (ECG) parameters related to right atrial (RA) excitation could predict A4-amplitude.

Objectives: We aimed to investigate the relationship between A4-amplitude and 12-lead ECG parameters reflecting RA excitation and assess its predictive power for achieving an appropriate A4-amplitude associated with high %AVS.

Methods: This single-center, retrospective, observational study enrolled consecutive patients undergoing VDD-LP implantation. The relationship between A4-amplitude and the positive peak amplitude of the P wave in lead II (P2), the positive peak amplitude of the P wave in lead V1 (V1P), and the sum of P2 and V1P (V1PP2) were assessed.

Results: Of the 67 patients undergoing VDD-LP implantation, 46 without atrial fibrillation bradycardia were enrolled. They had a data set of manual atrial mechanical sensing tests and 12-lead ECG. Among P2, V1P, and V1PP2, only V1PP2 was correlated with A4-amplitude (R 2=0.10; P=.029). In 30 patients in VDD pacing mode, the median %AVS was 67.8%. The A4-amplitude cutoff for %AVS ≥ 67.8% was 3.2 m/s2 (area under the curve [AUC] 0.81; P=.002). For A4-amplitude ≥ 3.2 m/s2, V1PP2 had moderate predictive power (AUC 0.72; P=.007). In 30 patients without sick sinus syndrome, the predictive power of V1PP2 for A4-amplitude ≥ 3.2 m/s2 was increased (AUC 0.80; cutoff value 110 μV; sensitivity 83%; specificity 71%; P=.011).

Conclusion: V1PP2, reflecting RA excitation, was related to A4-amplitude and had moderate predictive power. Notably, its predictive power increased when limited to patients without sick sinus syndrome. V1PP2 is a simple ECG predictor of A4-amplitude.

Keywords: 12-Lead electrocardiogram; Atrioventricular block; Atrioventricular synchrony; Leadless pacemaker; P-wave; Sick sinus syndrome.

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Figures

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Graphical abstract
Figure 1
Figure 1
Study flowchart. Sixty-seven patients who undergo VDD leadless pacemaker implantation at Osaka University Hospital are retrospectively enrolled in this study. After excluding 21 patients, 46 are included. AF = atrial fibrillation; MAM = manual atrial mechanical.
Figure 2
Figure 2
Measurement method of the P-wave positive amplitude in leads II and V1. A: Standard 12-lead electrocardiogram with 1.0 mV/10 mm voltage calibration. B: Leads II and V1 with 1.0 mV/40 mm voltage calibration. C: P-wave positive amplitude (positive peak to isoelectric line) is manually measured with an electric caliper.
Figure 3
Figure 3
Distribution of A4-amplitude and P-wave positive peak amplitude in leads II and V1. A: Distribution of A4-amplitude (m/s2). B: Distributions of V1PP2, P2, and V1P. C: Correlation between P2 and A4-amplitude. D: Correlation between V1P and A4-amplitude. E: Correlation between P2 and V1P. F: Correlation between V1PP2 and A4-amplitude. The blue line represents the regression line; the light blue curve represents the 95% confidence interval; and the orange curve represents the 95% prediction interval. A4-amplitude = A4-wave amplitude; P2 = positive P-wave amplitude in lead II; V1P = positive P-wave peak amplitude in lead V1; V1PP2 = positive P-wave amplitude in lead II plus positive P-wave peak amplitude in lead V1.
Figure 4
Figure 4
Predictive power of V1PP2 for A4-amplitude. A: ROC analysis (n = 21) of A4-amplitude for high %AVS ≥ 67.8%, which was the median %AVS in the 21 patients. B: ROC analysis of V1PP2 for A4-amplitude ≥ 3.2 m/s2. C: Comparison of V1PP2 between patients with and without sick sinus syndrome. D: ROC curves of V1PP2 for 3.2 m/s2 of A4-amplitude in patients without sick sinus syndrome (n = 21). A4-amplitude = A4-wave amplitude; AUC = area under the curve; %AVS = percentage of atrioventricular synchrony; P2 = positive P-wave amplitude in lead II; ROC = receiver operating characteristic; V1P = positive P-wave peak amplitude in lead V1; V1PP2 = positive P-wave amplitude in lead II plus positive P-wave peak amplitude in lead V1.
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