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.