64 years old man implanted with a triple chamber defibrillator Concerto II CRT-D for ischemic cardiomyopathy with left bundle branch block ; symptomatic phrenic nerve stimulation; pacing output set at 1.5 Volts/0.4 ms with a minimal margin on the pacing threshold but with no phrenic nerve stimulation ; Follow-up by telemonitoring ; reception of an EGM tracing in the context of an optivol alert, statistical report indicating a permanent biventricular pacing;
In the absence of any alert, a remote telemonitored consultation is performed every 3 months; asymptomatic patient;
Succession of AS-BV cycles;
The physician missed the diagnosis; a few days later, an Optivol alert triggered a new remote consultation:
This tracing demonstrates the interest but also the difficulty of the remote monitoring in CRT patients. The programming of this patient was initially very precise and allowed for an effective and permanent LV capture (with only a small margin over the threshold of 1.25 V / 0.5 ms) without any phrenic stimulation (phrenic stimulation threshold 2 V / 0.5 ms). The first tracing was received during a programmed remote consultation where data and electrograms were transmitted. Rapid analysis of tracing did not recognize the intermittent loss of left ventricular capture. A few days later, the loss of LV capture became permanent and was associated with the occurrence of congestive signs and an increase in the pulmonary overload index. A second tracing is transmitted as a part of the Optivol alert. The analysis of this second tracing shows the persistent loss of LV capture despite a permanent biventricular pacing. This patient was convened before the onset of major symptoms and received a diuretic therapy. LV tests confirmed the diagnosis. A change in the left ventricular pacing configuration allowed for recovering an effective LV capture with no phrenic stimulation and with normalization of thoracic impedance.
This case illustrates the importance of early diagnosis of loss of LV capture. It also illustrates the importance of analyzing, in detail, the information transmitted.
