Po-05-016 grade 1 diastolic dysfunction predicts micra av atrio-ventricular synchronous pacing

The Micra AV (Medtronic) is a leadless ventricular pacemaker offering atrioventricular synchronous pacing relying on the detection of mechanical atrial contraction using an accelerometer. We have previously reported that diastolic dysfunction improves atrial tracking with this device. The purpose of this study was to evaluate the relationship between grade 1 diastolic dysfunction and atrioventricular synchronous pacing in patients with a Micra leadless pacemaker. The effect of heart rate on atrial tracking was also assessed. We performed a retrospective cohort review of all patients who underwent AV Micra placement within Northwell Health over a one-year period. Contemporaneous echocardiograms of 186 patients as well as device report rate histograms documenting atrial tracking at 10 bpm heart rate intervals were obtained. The percentage of total pacing performed with atrioventricular synchrony was assessed. 75 (40.3%) patients had normal diastolic function, 71 (38.2%) patients had grade 1 diastolic dysfunction, and 40 (21.5%) patients had advanced (grade 2 or 3) diastolic dysfunction. The rate of synchronous pacing was significantly higher in patients with grade 1 diastolic dysfunction compared with patients with advanced diastolic dysfunction (72.6% vs. 50.5%, P<0.001) or normal diastolic function (72.6% vs. 59.5%, P<0.01). Average time spent in atrial tracking modes was highest between heart rates of 70-80 (51%) and 80-90 (52.7%), followed by 60 – 70 (47%), 50-60 (46%), and 90-100 (43%). Atrial tracking was poor at heart rates of 40-50 (21%) and 100-110 (22%). Tracking at heart rates above 110 was rare (<5%). In this analysis, grade 1 diastolic function was associated with better atrial tracking in the Micra AV leadless pacemaker relative to normal or advanced diastolic function. Ventricular filling becomes more dependent on atrial contraction in patients with early diastolic dysfunction relative to patients with normal diastolic function. In advanced diastolic dysfunction, the atrial contribution to filling diminishes. This property of grade 1 diastolic dysfunction may allow the Micra AV to more accurately track atrial activity. Tracking based on heart rate appears to be most effective between heart rates of 70 and 90, decreasing at higher and lower rates. With this in mind, the Micra AV may be better suited to older patients who tend to be less active and are more likely to have impaired myocardial relaxation.