Electrocardiographic predictors of atrial mechanical sensing in leadless pacemakers

Background Leadless pacemakers (LP) capable of VDD pacing allow for atrioventricular synchrony through mechanical sensing of atrial contraction. Unfortunately, mechanical sensing is less reliable and less predictable than electrical sensing. Objective We evaluated the P wave amplitude during sinus rhythm from pre-operative 12-lead 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 two-center prospective cohort study. ECG parameters were evaluated separately and in combination for association with the signal amplitude of mechanical atrial contraction (A4). Results 80 patients (median age 82, female 55%, mean BMI 25.8 kg/m2) were included in the study, and 61 patients in the A4 signal analysis (19 patients were in VVI mode during follow up). Absolute (aVL, aVF, V1, V2) and BMI-adjusted (I, II, aVL, aVF, aVR, V1 and V2) P wave amplitudes from baseline ECGs demonstrated a statistically significant positive correlation with A4 signal amplitude (all p<0.05). A combined P wave signal amplitude of at least 0.2mV in V1 and aVL was predictive with a specificity of 83% (95%-CI 67-100%) for an A4 signal ≥1m/s2. We found a significant correlation of the A4 signal amplitude and overall atrioventricular synchrony (p=0.013). 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.