Electrocardiographic predictors of atrial mechanical sensing in leadless pacemakers

Background: Leadless pacemakers (LPs) capable of VDD pacing allow for atrioventricular synchrony through mechanical sensing of atrial contraction. However, mechanical sensing is less reliable and less predictable than electrical sensing.

Objective: The purpose of this study was to evaluate P-wave amplitude during sinus rhythm from preoperative 12-lead electrocardiograms (ECGs) as a predictor for atrial mechanical sensing in patients undergoing VDD LP implantation.

Methods: Consecutive patients undergoing VDD LP implantation were included in this 2-center prospective cohort study. ECG parameters were evaluated separately and in combination for association with the signal amplitude of atrial mechanical contraction (A4).

Results: Eighty patients (median age 82 years; female 55%; mean body mass index [BMI] 25.8 kg/m²) were included in the study and 61 patients in the A4 signal analysis (19 patients in VVI mode during follow-up). Absolute (aVL, aVF, V₁, V₂) and BMI-adjusted (I, II, aVL, aVF, aVR, V₁, V₂) P-wave amplitudes from baseline ECGs demonstrated a statistically significant positive correlation with A4 signal amplitude (all P <.05). A combined P-wave signal amplitude of at least 0.2 mV in V₁ and aVL was predictive, with specificity of 83% (95% confidence interval 67%-100%) for A4 signal ≥1 m/s². We found a significant correlation of A4 signal amplitude and overall atrioventricular synchrony (P = .013).

Conclusion: P-wave amplitudes in ECG leads aVL and V₁ can predict A4 signal amplitude in patients with VDD LP and therefore the probability of successful AV synchronous pacing.