title: Longer Ambulatory ECG Monitoring Increases Identification of Clinically Significant Ectopy.
abstract: Frequent premature ventricular contractions (PVCs) can cause a reversible reduction in systolic function. Most studies use 24-hour ambulatory electrocardiograms (AECGs) to assess PVC burden; however, PVC counts vary across 24-hour periods. We hypothesized that extended AECG monitoring would better identify clinically significant ectopy.
  
  
  
  All 14-day AECGs performed at the San Francisco Veterans Affairs Medical Center between 2012 and 2015 (N = 694) were reviewed, and individuals with PVC counts ≥1.0% of total heartbeats were included (N = 101). Daily PVC counts and the range of these values across 24-hour periods were assessed. Median time for these ranges to cross clinically significant thresholds (PVCs ≥ 10%, 15%, or 20% of total heartbeats) was determined.
  
  
  
  Median PVC burden was 2.6% of total heartbeats (interquartile range [IQR]: 1.6-5.4%) and the median range across 24-hour periods was 3.6% (IQR: 2.0-9.1%). Individual ranges of daily PVC burden crossed thresholds of 10%, 15%, and 20% of total heartbeats in 26.7%, 16.8%, and 6.9% of patients, respectively. Median time to detecting an individual's maximum PVC burden was 6 days (IQR: 2-11 days). While 75% of those who reached the 20% threshold did so on day one of monitoring, only 53% of those reaching the 10% threshold did similarly, with a continually increasing yield throughout the 14-day monitoring period.
  
  
  
  PVC burden varies widely from day-to-day. While most patients with PVC burdens ≥20% were detected with 24 hours of monitoring, extended monitoring nearly doubled the identification of those reaching the 10% threshold.
authors.affiliation: Department of Medicine, University of California San Francisco, California, San Francisco.
authors.forename: Zak
authors.initials: Z
authors.lastname: Loring
authors.affiliation: Department of Medicine, University of California San Francisco, California, San Francisco.
authors.forename: Peter
authors.initials: P
authors.lastname: Hanna
authors.affiliation: Department of Medicine, University of California San Francisco, California, San Francisco.|Department of Cardiology, Veterans Affairs Medical Center, California, San Francisco.
authors.forename: Cara N
authors.initials: CN
authors.lastname: Pellegrini
mesh_terms: D000368:Aged; D015716:Electrocardiography, Ambulatory / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D013997:Time Factors; D018879:Ventricular Premature Complexes / Q000175:diagnosis*
keywords: ambulatory monitoring; cardiomyopathy; electrocardiography; premature ventricular contractions