Use of an intracardiac electrogram eliminates the need for a surface ECG during implantable cardioverter-defibrillator follow-up.
BACKGROUND
A surface electrocardiogram (SECG) for pacing threshold measurements during routine implantable cardioverter-defibrillator (ICD) follow-up can be cumbersome. This study evaluated the use of an intrathoracic far-field electrogram (EGM) derived between the Can and superior vena cava (SVC) electrode -- the Leadless electrocardiogram (LLECG), in dual chamber ICDs in performing pacing threshold tests.


METHODS
The LLECG was evaluated prospectively during atrial and ventricular pacing threshold testing as a substudy of the Comparison of Empiric to Physician-Tailored Programming of Implantable Cardioverter-Defibrillators trial (EMPIRIC) in which dual chamber ICDs were implanted in 888 patients. Threshold tests were conducted at 1 volt by decrementing the pulse width. Follow-up at three months compared pacing thresholds measured using LLECG with those using Lead I of the surface ECG (SECG). The timesaving afforded by LLECG was assessed by a questionnaire.


RESULTS
The median threshold difference between LLECG and SECG measurements for both atrial (0.00 ms, P = 0.90) and ventricular (0.00 ms, P = 0.34) threshold tests were not significant. Ninety percent of atrial and ventricular threshold differences were bounded by +/- 0.10 ms and -0.10 to +0.04 ms, respectively. We found that 99% of atrial and ventricular thresholds tests at six and 12 months attempted using LLECG were successfully completed. The questionnaire indicated that 65% of healthcare professionals found LLECG to afford at least some timesaving during device follow-ups.


CONCLUSIONS
Routine follow-up can be performed reliably and expeditiously in dual chamber Medtronic (Minneapolis, MN, USA) ICDs using LLECG alone, resulting in overall timesaving.
Michael
Kevin A
KA
Wessex Cardiothoracic Centre, Southampton University Hospital Trusts, Southampton, UK.
Peterson
Brett J
BJ
Yue
Arthur M
AM
Wilson
Ryan D
RD
Wang
Li
L
Ousdigian
Kevin
K
Wilkoff
Bruce
B
Sterns
Laurence
L
Morgan
John M
JM
D001145:Arrhythmias, Cardiac / Q000503:physiopathology / Q000628:therapy*; D017147:Defibrillators, Implantable; D004562:Electrocardiography / Q000295:instrumentation*; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies