Atrial event, or is it?

Trace category: 
Boston Scientific

82 year old patient with a CRT-D device. 

This is an episode sent through telemonitoring because of a sensed atrial tachyarrhythmia.

But what's going on at the ventricular channel?


Thank you Marc for this intriguing tracing!

As you said, the EGM was stored as ATR onset. At the beginning of the tracing we see a ventricular asystole of +/- 3s, during which we observe an asynchronous LV pacing sequence at decremental output (0.5, then 0.4V). This cannot be an automatic test (PacSAfe VGAT): this algorithm provides a RVP support all along the test and does not allow loss of capture.
Therefore, it is a manual testing of the LV threshold. The test has been frozen with the RTA onset. This is a funny behavior of BS devices to store events which occured during the manual interrogation (see my comment on the last RHYTHM IQTM post).

Personally I don't go under 1V for a threshold testing in a dependant patient, since I won't program <2.5 anyway. This avoids to induce a prolonged asystole.

Don't hesitate to send your comments and EGMs!

S Ploux