QRS Width: Easily Obtained but Overlooked Parameter in Monitoring
Algorithms in Implantable Devices
Introduction We describe the progressive increase in the QRS
durations (QRSd) and the subsequent decrease in the left ventricular
ejection fractions (LVEF) of two patients post pacemaker implantation.
We aim to highlight the need for contemporary cardiac implantable
electronic devices (CIEDs) to include QRSd monitoring in the standard
device data capture. This would ultimately allow for early interventions
to be made to prevent chronic heart failure (CHF) hospitalizations.
Methods The echocardiographic studies of two patients (pre and
post pacemaker implantation) were analyzed, in order to determine
changes in QRSd and LVEF data leading up to CHF hospitalization events.
Results Patient 1 had a QRSd of 66 msec in June of 2018, one
month before pacemaker implantation. Six months after implantation,
Patient 1 had an increased QRSd of 156 msec. This was accompanied with a
stark decrease in LVEF, from 55% at the time of implantation to below
35% in October of 2020. Patient 2 had a QRSd of 160 msec and a LVEF of
43% prior to the implantation of a pacemaker in 2016. Patient 2
similarly showed a progressive increase in their QRSd and was found to
have a significantly decreased LVEF of 17% when hospitalized for
decompensated heart failure around 5 years after pacemaker insertion.
Conclusion Chronic RV apical pacing can be associated with
adverse effects, leading to compromised cardiac function and resulting
in pacing-induced cardiomyopathy (PICM). Progressive paced QRS widening
can be indicative of CHF development and correlates with a decline in
ejection fraction. The addition of device based QRS width monitoring to
the current trend toolkit in implantable devices could alert
electrophysiologists and patients of the potential for PICM, in the
absence of serial 12 lead comparisons. This pre-emptive alert is
essential in an era where remedy in the form of cardiac
resynchronization and physiological pacing therapy is readily available.