The relationship between ventricular ectopic beat frequency and heart rate.

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Abstract
We examined the relationship between the frequency of premature ventricle complexes (PVCs) and underlying heart rate in 24 patients with frequent PVCs using 24-hour ambulatory ECG recordings. Plots of PVC frequency vs heart rate were made at 1-beat/min intervals for all heart rates that were recorded for at least 5 minutes of the 24 hours. Heart rates during 24 hours ranged from 56 +/- 10.0 to 102.2 +/- 15.4 beats/min. Twenty-three of the 24 patients had a distinct relationship between PVC frequency and heart rate. Patterns included an approximate log-linear increase in PVCs at higher heart rates in 12 patients, a log-linear decrease (overdrive suppression) in one patient, flat curves in three patients, and a complex relationship (e.g., more PVCs at low rates and suppression at high rates) in seven patients. Patterns were reproducible in 21 of the 24 patients on repeat ambulatory ECG monitorings done 1 day to 2 months later. We conclude that most patients with frequent PVCs have a characteristic relationship between PVC frequency and heart rate over the range of heart rates achieved during routine daily activity. The most frequent relationship is a marked increase in PVC frequency with increasing heart rate. These observations may in part explain such phenomena as "spontaneous" variability of PVC frequency, sleep suppression of PVCs and suppression of PVCs by beta-blocking drugs.