Limitations of routine long-term electrocardiographic monitoring to assess ventricular ectopic frequency.

TLDR

Routine 24‑hour ECG monitoring has limitations that must be considered in diagnosis and treatment decisions. The study assessed VPD frequency variability in 15 stable cardiac patients using three consecutive 24‑hour ECG recordings and analyzed the data with nested ANOVA. VPD frequencies varied widely (37–1,801 per hour) and showed substantial spontaneous day‑to‑day (23%), intra‑day (29%), and hourly (48%) fluctuations; detecting a true therapeutic reduction required >83% decrease with two 24‑hour recordings or >65% with two 72‑hour recordings.

Abstract

Variations in the frequency of ventricular premature depolarizations (VPDs) were evaluated with three consecutive 24-hour long-term electrocardiography monitor recordings from 15 clinically stable patients with various cardiac disorders. Mean hourly VPD frequencies ranged from 37--1,801 per hour. Data were subjected to 4 and 5 factor nested analyses of variance. The extent of spontaneous variation in arrhythmia frequency that occurred in individual patients from day to day was 23%, between 8-hour periods within days was 29%, and from hour to hour was 48%. In addition, the variability between repeated three-day monitoring periods over time was quantified in five patients and found to be 37%. This analysis determined that to distinguish a reduction in VPD frequency attributable to therapeutic intervention rather than biologic or spontaneous variation alone required a greater than 83% reduction in VPD frequency if only two-24-hour monitoring periods were compared, and greater than 65% reduction if two 72-hour periods were compared. The limitations of routine 24-hour electrocardiographic monitoring must be considered in diagnostic and therapeutic decision-making.