Long-term atrioventricular-synchronous leadless pacing with micra AV: stable AV synchrony up to 4 years follow-up

Background

Micra AV enables AV-synchronous pacing by sensing atrial mechanical contraction (A4) via an accelerometer. Short-term studies report high AV synchrony (AVS), but durability beyond the first year is unclear.

Purpose

To evaluate long-term AVS with Micra AV after early atrial-sensing optimization, and to identify clinical/device factors associated with sustained AVS.

Methods

Within the OPTIVALL cohort, we identified patients implanted with a first-generation Micra AV (June 2020–February 2024) who remained in sinus rhythm and programmed in VDD for ≥1 year. Device-derived AVS was collected annually (Tracking Index and total AVS = AM-VP + AM-VS) up to 4 years. A4 amplitude was recorded at each visit. A subgroup underwent 24-h Holter-ECG to assess ambulatory AVS at long-term follow-up. . Atrial sensing had been optimized early after implant in all patients.

Longitudinal trends were assessed with repeated-measures ANOVA and linear mixed-effects models; predictors of long-term ambulatory AVS were analyzed using multivariable regression.

Results

Of 54 implants, 44 patients met criteria. Device-derived total AVS remained stable: 88.1 ± 9.6%, 86.4 ± 11.2%, 85.7 ± 10.2%, and 88.4 ± 5.3% at 1-, 2-, 3-, and 4-year follow-up, respectively (no time effect) (Figure 1A). Tracking index showed a similar pattern: 92.4±5.7%, 90.8±8.4%, 88.1±11.5%, 89.6±5.4% at 1-, 2-, 3-, and 4-year follow-up, respectively (Figure 1B). A4 amplitude was preserved (3.5±1.5, 3.7±1.5, 3.4±1.8, 3.9±1.5 m/s² at 1-, 2-, 3-, and 4-year follow-up, respectively; no time effect), supporting durable atrial mechanical sensing (Figure 1C). In 20 patients with 24-h Holter-ECG at 2.7±1.1 years, median ambulatory AVS was 85.5% (IQR 80.0–90.7). Average AVS remained >80% across all heart rate ranges up to 110 bpm. Mean ambulatory AVS at long-term follow-up was comparable to that observed at short-term evaluation, indicating stability over time (83.9 ± 8.8% vs 84.3 ± 10.4%, respectively; p = 0.843) (Figure 2). On multivariable analysis, lower E/A ratio (β = -0.533, p = 0.016), the use of a combined vector including vector 2 (β = -0.401, p = 0.047), and an A3/A4 ratio < 1 (β =0.450, p = 0.028) remained independently associated with greater ambulatory AVS.

Conclusions

After early optimization, Micra AV provides high and stable AV synchrony for up to 4 years with preserved A4 amplitude. Simple echocardiographic markers (E/A) and specific sensing configurations (A3/A4 <1 and vectors including 2) help identify patients most likely to maintain durable AV-synchronous leadless pacing.Figure 1Figure 2.