Prognostic implications of supraventricular ectopy
Authors: Fredriksson T , Stridh M , Friberg L , Svennberg E 
Published: November 2020

Abstract

Background
According to consensus atrial fibrillation (AF) is an irregular heart rhythm with absence of p-waves, lasting for at least 30 seconds. However, AF is most likely a continuous disease ranging from occasional bursts of AF-like activity to permanent AF, rather than a dichotomous condition. Regardless, the 30-second AF definition leaves cardiologists without clear guidelines on how to manage patients with shorter episodes of seemingly atrial fibrillation-like activity and/or an abundance of supraventricular ectopic beats.

Purpose
The aim of this study was to establish the prevalence and prognostic implication of frequent supraventricular ectopic beats, isolated, in bi- or trigeminy, and supraventricular tachycardias with different characteristics.

Methods
In the STROKESTOP I mass-screening study for AF in 75- and 76-year olds in Sweden, 7173 participants did 30-second intermittent ECG twice daily for two weeks. ECG-recordings from STROKESTOP I were re-evaluated using an automated algorithm to detect individuals with frequent supraventricular ectopic beats or runs. Detected episodes were manually re-examined to confirm the findings. The primary endpoint was atrial fibrillation as ascertained from the nationwide Swedish Patient register. Secondary endpoints were stroke and death. Median follow-up was 4.2 (3.8–4.4) years.

Results
Of the 6100 examined participants 85% were free of significant supraventricular arrhythmia. Frequent supraventricular ectopic beats were the most common arrhythmia, n=709 (11.6%), and irregular SVTs were more common than regular SVTs. During follow-up 387 participants developed AF, 161 had a stroke event and there were 354 deaths. Individuals with the most AF-like SVT, irregular and lacking p-waves, n=97 (1.6%), had the highest risk of developing AF (hazard ratio 4.3 (95% confidence interval 2.7–6.8), Figure 1. They also had an increased risk of death, 2.0 (1.1–3.8). We found no significant increase in stroke risk.

Conclusion
Progression of atrial arrhythmias from supraventricular ectopic beats to more organized arrhythmic episodes are associated with development of AF. Extended screening for AF should be considered in individuals with frequent supraventricular activity, especially in those with supraventricular tachycardias with AF characteristics.
Figure 1. Kaplan-Meier curve showing primary end-point event rate (atrial fibrillation) in participants with different arrhythmias.

Funding Acknowledgement
Type of funding source: Private grant(s) and/or Sponsorship. Main funding source(s): This study was supported by Stiftelsen Hjärtat, Boehringer Ingelheim, The Swedish Heart and Lung Association, Capio Forskningsstiftelse and Åke Wibergs Stiftelse. STROKESTOP I was founded by Stockholm County Council, the Swedish Heart & Lung Foundation, King Gustav V and Queen Victoria's Freemasons' Foundation, the Klebergska Foundation, the Tornspiran Foundation, the Scientific Council of Halland Region, the Southern Regional Healthcare Committee, the Swedish Stroke Fund, Boehringer-Ingelheim, Bayer and Pfizer. Emma Svennberg is supported by the Stockholm County Council (Clinical postdoctorial appointment) and has received research funding from the Swedish Society of Medicine.