Background
Implantable loop recorders (ILR) are increasingly utilised in the evaluation of unexplained
syncope. However, they are expensive and do not protect against future syncope.
Objectives
To compare patients requiring permanent pacemaker (PPM) implantation during ILR follow-up
with those without abnormalities detected on ILR in order to identify potential predictors
of benefit from upfront pacing.
Methods
We analysed 100 consecutive patients receiving ILR: Group 1 (n=50) underwent PPM insertion
due to bradyarrhythmias detected on ILR; Group 2 (n=50) had no arrhythmias detected
on ILR over >3 years follow-up. Baseline clinical characteristics, syncope history,
electrocardiographic and echocardiographic parameters were assessed to identify predictors
of ultimate requirement for pacing.
Results
Group 1 (64% male, median age 70.8 years; IQR 65.5–78.8) were older than Group 2 (58%
male, median 60.2 years; IQR 44.0–73.0 p=0.001) and were less likely to have related
historical factors such as overheating, posture and exercise (98% vs 70% p<0.001).
PR interval was also longer in Group 1 (192±51 vs 169±23 p=0.006) with greater prevalence
of distal conduction system disease (30% vs 4.3% p=0.002). Significant univariate
predictors for PPM insertion were distal conduction disease (p=0.007), first degree
atrioventricular (AV) block (p=0.003), absence of precipitating factors (p=0.004),
and age >65 years (p=0.001). Injury sustained, recurrent syncope, history of atrial
fibrillation (AF) or heart failure, left atrial (LA) size and left ventricular ejection
fraction (LVEF) were not predictive. These significant predictors were incorporated
into the DROP score1 (0–4). Using time-to-event analysis, no patients with a score of 0 progressed to
pacing, while higher scores (3–4) strongly predicted pacing requirement (log-rank
p<0.001).
Conclusion
The DROP score may be helpful in identifying patients likely to benefit from upfront
permanent pacemaker (PPM) insertion following unexplained syncope. Larger prospective
studies are required to validate this tool.
Keywords
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Article info
Publication history
Published online: March 31, 2022
Accepted:
March 4,
2022
Received in revised form:
January 18,
2022
Received:
November 5,
2021
Footnotes
1Distal conduction disease, Related historical predisposing or precipitating factors absent, Older age >65 years and PR interval prolongation.
Identification
Copyright
© 2022 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.
