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Updated: Apr 12, 2026
Author Spotlight: Investigating HR-Dependent Cardiac Function in Mouse Models Through a Novel Atrial-Pacing Approach
Published on: July 21, 2023
Effect of heart rate on the intrinsic and the ventricular-paced QRS duration
John Chiladakis1, Andreas Kalogeropoulos1, Fani Zagkli1
1Cardiology Department, Patras University Hospital, 26500 Rion, Patras, Greece.
Background:
We evaluated the effect of heart rate on the intrinsic and the ventricular-paced QRS duration in implanted device recipients with normal or reduced left ventricular ejection fraction (EF).
Methods:
We studied 239 outpatients with preserved intrinsic ventricular activation and normal (n=92) or reduced (n=147) EF who had apical (RVA) or mid-septal (RVS) right ventricular lead position. The QRS duration was measured at baseline and during atrial-based pacing at increased heart rate to ensure intrinsic or ventricular-paced QRS activation.
Results:
The heart rate increase shortened the intrinsic QRS only in patients with normal EF, and further prolonged the ventricular-paced QRS in patients with reduced EF and either narrow or wide QRS (p<0.001), irrespective of RVA or RVS pacing (p<0.01).
Conclusion:
Heart rate increase is associated with further QRS prolongation in patients with reduced EF, regardless of RVA or RVS pacing site.
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