Reliability of resting heart rate measurements in atrial fibrillation.

BACKGROUND

Heart rate (HR) control in atrial fibrillation (AF) is commonly guided by resting HR measurements, usually with 12‑lead ECG or in-office pulse palpation.

OBJECTIVES

We aimed to assess the reliability of resting HR measurements in AF patients with long-term ambulatory ECG and activity monitoring.

METHODS

We included patients who had recorded a full-disclosure ambulatory ECG with a mobile cardiac telemetry device equipped with an accelerometer (PocketECG, MEDICALgorithmics, Poland), with at least 95% AF. Resting HR samples (≤20 per individual/day) were collected as 10-s daytime (8 am to 8 pm) measurements after ≥10 min of rest. These samples were compared to each individual's mean daytime resting HR.

RESULTS

In 832 patients (median age 77 (interquartile range (IQR) 69-83) years, 42% women) with a median registration duration of 13 days (IQR 7-22), the population mean daytime resting HR was 85 (±15) beats per minute (bpm). A single resting HR differed from the mean daytime resting HR by a mean of ±10.4% (IQR 3.6-14.4%). When the mean daytime resting HR was ≥110 bpm, 29% of resting HR samples were < 110 bpm, and when the mean daytime resting HR was 80-109 bpm,11% of samples were ≥ 110 bpm. Resting HR measurement variability decreased to 5.3% (IQR 1.9-7.5%) when four resting HR samples were averaged.

CONCLUSION

In patients with AF, a single resting HR measurement often differs substantially from the mean daytime resting HR. When a precise measurement is clinically relevant, repeated resting HR sampling or ambulatory monitoring can address this measurement imprecision.