SPC365

Diagnostic yield of implantable loop recorders in routine clinical practice – a 10-year single-center experience

Session: Sessão de Posters 09 - Síncope, ILR e cardioneuromodulação
Speaker: Adriana Vazão

Congress: CPC 2026
Topic: C. Arrhythmias and Device Therapy
Theme: 04. Arrhythmias, General
Subtheme: 04.3 Arrhythmias, General – Diagnostic Methods
Session Type: Posters Eletrónicos
FP Number: ---
Authors: Adriana Vazão; André Martins; Joana Reis Pereira; Mónica Amado; Carolina Esteves; João Filipe Carvalho; Davide Severino; Hélia Martins; David Durão

<p style="text-align:justify"><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000"><strong>Background</strong></span></span></span><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000">: Implantable loop recorders (ILRs) are widely used in the evaluation of syncope, palpitations, and cryptogenic stroke, but real-world data on their diagnostic yield remain limited.</span></span></span></p>

<p style="text-align:justify"><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000"><strong>Objective</strong></span></span></span><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000">: To evaluate the diagnostic yield of ILRs in a real-world population from a local health unit in Portugal.&nbsp;</span></span></span></p>

<p style="text-align:justify"><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000"><strong>Methods</strong>: Single-center retrospective cohort of&nbsp;patients (pts)&nbsp;who underwent ILR monitoring (Dec&nbsp;2014-Dec&nbsp;2024). Baseline clinical, electrocardiographic and echocardiographic variables and outcomes (all-cause mortality, cardiovascular (CV) mortality, heart failure (HF) hospitalization and urgent pacemaker (PM) implantation) were collected. Diagnostic findings included symptomatic sinus node disease (SND), atrioventricular (AV) node disease (high-grade AV block; complete AV block), new-onset atrial fibrillation (AF), slow AF (symptomatic ventricular pause &gt;3s) and sustained supraventricular (SVT) or ventricular tachycardia (VT).&nbsp;</span></span></span></p>

<p style="text-align:justify"><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000"><strong>Results</strong></span></span></span><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000">: A total of 340 ILRs were implanted. Annual implant numbers increased over time, peaking at 64 in 2023 (Figure 1). Syncope was the main indication (n=274, 80.6%), followed by palpitations (n=35, 10.3%) and cryptogenic stroke (n=18, 5.3%). Patients were predominantly male (50.6%), with a mean age of 64.9&plusmn;15.6 years. Baseline electrocardiograms revealed sinus rhythm in 65% and bundle branch block (BBB) in 12.8%. The median left ventricular ejection fraction was 60%. The overall diagnostic yield was 34.1%, with a median time to diagnosis of 6 months. Among syncope pts, the diagnostic yield was 37.9%; 66 pts (72.5%) subsequently received a cardiac implantable electronic device (16 for complete AV block, 35 for SND, 7 for high-grade AV block, 3 for bradycardia-tachycardia syndrome, 3 for slow AF) and 2 received an implantable cardioverter-defibrillator (ICD) for VT. Among pts monitored for cryptogenic stroke the yield was lower (16.7%), with the diagnosis of AF in 2 pts and sustained asymptomatic VT in another patient, although the findings led to therapeutic changes in 2/3 of cases. In the palpitation&rsquo;s subgroup, the diagnostic yield was 48.6%, mainly SVT, with targeted treatment in 47% of diagnosed cases (Figure 2). Diagnostic yield declined markedly after the first year (Figure 3). Pts were followed for a median of 23 months [IQR 9-38]. During follow-up, 38 pts experienced adverse outcomes: 11 required urgent admission for syncope with PM implantation, 2 were admitted for HF, 4 had a non-fatal stroke and 2 had non-fatal AMI. Overall, 23 pts died (6.8%), including 3 CV deaths.&nbsp;</span></span></span></p>

<p><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000"><strong>Conclusion</strong></span></span></span><span style="font-size:12pt"><span style="font-family:'Times New Roman',serif"><span style="color:#000000">: ILRs are a highly valuable diagnostic tool for the evaluation of syncope, cryptogenic stroke and palpitations. In this real-world cohort, ILRs demonstrated a good diagnostic performance, with a diagnostic yield of 34%, and most diagnoses occurring withing the first year after implantation.&nbsp; </span></span></span></p>