June 2019

A remote alert for AT/AF daily burden exceeding threshold

Jason Collinson – Chief Cardiac Physiologist
Essex Cardiothoracic Centre, Basildon and Thurrock University Hospital


A remote alert was received from an 80 year old male with a Medtronic CRT-pacemaker for AT/AF daily burden exceeding threshold a few weeks after handing out home monitoring. There were 73 episodes of AT/AF recorded since his last follow up (approx. 2 weeks) with the most recent episode having lasted more than 6 hours. No previous atrial arrhythmias had been documented. The presenting EGM (figure 1) and device settings are displayed below.

Mode: DDD
LR/UR: 60/130 bpm.
Paced/Sensed AV delay: 130/100 ms
PVAB: 150 ms
PVAB method: Partial +
Mode switch: On
Sensitivity thresholds: Atrial 0.3 mV, Ventricular 2.5 mV

Figure 1
Presenting EGM – Channel 1 shows the atrial tip to ring EGM. Channel 2 the RV tip to RV ring EGM. Below these are the A-A interval, marker and V-V interval channels.


A) What is the cause of the AT/AF episodes?

  • Atrial bigeminy
  • Far field R wave oversensing
  • Atrial undersensing
  • Atrial tachycardia

B) Which two programming options should be considered to correct the problem?

  • Increase the PVAB
  • Shorten the PVAB
  • Decrease atrial sensitivity
  • Increase atrial sensitivity
  • Change the PVAB method