Risk for atrial fibrillation in stroke patients with excessive supraventricular ectopic activity detected by prolonged Holter ECG - a subanalysis of the FIND-AFrandomised trial

S. Beimel (Leipzig)¹, E. Richter (Leipzig)¹, K. Wasser (Göttingen)², M. Weber-Krüger (Göttingen)³, K. Gröschel (Mainz)⁴, R. Wachter (Leipzig)¹, T. Uhe (Leipzig)^1
1Universitätsklinikum Leipzig Klinik und Poliklinik für Kardiologie Leipzig, Deutschland; ²Universitätsmedizin Göttingen Klinik für Neurologie Göttingen, Deutschland; ³Universitätsmedizin Göttingen Klinik für Palliativmedizin Göttingen, Deutschland; ⁴Universitätsmedizin Mainz Klinik für Neurologie Mainz, Deutschland

Background:
Excessive supraventricular ectopic activity (ESVEA) is associated with an increased risk of atrial fibrillation (AF). While AF risk based on ESVEA is usually stratified by means of 24-h Holter ECG, it remains uncertain whether prolonged Holter ECG identifies additional patients with high risk for AF. We aimed to characterise ESVEA during 10-day Holter ECG and assess its association with newly detected AF.

Methods:
This analysis is based on the baseline 10-day Holter ECG in the intervention group of the FIND-AF_randomised trial, a study which randomised patients with acute ischemic stroke to repetitive prolonged Holter ECGs or usual care. Patients without AF on the first day were included. ESVEA was defined as either ≥30 premature atrial contractions per hour x recorded hours (PAC/h) or at least one atrial run (AR) ≥20 beats per day. Follow-up for AF was 36 months. Categorial data were compared by Chi-square test or Fisher’s exact test, AF incidence by Kaplan-Meier curves and log-rank test. Hazard ratios were calculated by multivariable Cox regression.

Results:
A total of 185 of 200 patients were included in this analysis. Median age was 72 and 42% were female. ESVEA was detected in 38 (20%) patients on the first day of monitoring. During subsequent monitoring, ESVEA was identified in 40 (22%) additional patients, while 107 (58%) patients never had ESVEA. In patients with ESVEA on day 1, the ESVEA criterion was mainly fulfilled by PAC/h, while in those with ESVEA on any other day, PAC/h and AR contributed equally (Figure A). After 36 months of follow-up, AF occurred in 11 of 38 (29%) patients with ESVEA on day 1 of monitoring, in 8 of 40 (20%) patients with ESVEA on any other day and in 3 of 107 (3%) patients without ESVEA (Figure B). The AF detection rate did not differ significantly between patients with ESVEA on the first day and those with ESVEA on any other day (p=0.357). In contrast, patients with ESVEA, whether identified on day 1 or later, showed a significantly higher AF detection rate compared to those without ESVEA (ESVEA day 1 vs no ESVEA: p<0.001; ESVEA any other day vs no ESVEA: p=0.001). Adjusting for age and CHA₂DS_2-VA-Score, ESVEA detected on day 1 (HR 11.2, 95% CI 3.1 – 41.0, p<0.001) and ESVEA on any other day (HR 7.8, 95% CI 2.0 – 29.9, p=0.003) were both significantly associated with a higher risk of AF after 36 months.

Conclusion:
Prolonged Holter ECG identifies a similar number of patients with ESVEA on subsequent days compared to 24-h Holter ECG. These patients have a comparable risk for AF. Patients without ESVEA during the first 10 days of Holter ECG after ischemic stroke have a very low AF risk (3% in 3 years). Hence, analysis of supraventricular ectopy during 10-day Holter ECG may be used for referring or withholding patients from intensified rhythm monitoring.