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Optimisation of atrioventricular delay during exercise improves cardiac output in patients stabilised with cardiac resynchronisation therapy
  1. Jing Ping Sun1,2,
  2. Alex Pui-Wai Lee1,
  3. Richard A Grimm3,
  4. Ming-Jui Hung4,
  5. Xing Sheng Yang1,2,
  6. David DeLurgio2,
  7. Angel R Leon2,
  8. John D Merlino2,
  9. Cheuk-Man Yu1
  1. 1Division of Cardiology, S.H. Ho Cardiovascular Disease and Stroke Centre, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, Hong Kong
  2. 2Emory University Hospital Midtown, Emory University School of Medicine, Atlanta, Georgia, USA
  3. 3Cleveland Clinic Foundation, Cleveland, Ohio, USA
  4. 4Chang Gung Memorial Hospital at Keelung, Chang Gung University College of Medicine, Taiwan
  1. Correspondence to Professor Jing Ping Sun, Division of Cardiology, S.H. Ho Cardiovascular Disease and Stroke Centre, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, Hong Kong; jingpingsun6{at}yahoo.com

Abstract

Background Atrioventricular (AV) delay in cardiac resynchronisation therapy (CRT) recipients are typically optimised at rest. However, there are limited data on the impact of exercise-induced changes in heart rate on the optimal AV delay and left ventricular function.

Methods and results The authors serially programmed AV delays in 41 CRT patients with intrinsic sinus rhythm at rest and during two stages of supine bicycle exercise with heart rates at 20 bpm (stage I) and 40 bpm (stage II) above baseline. The optimal AV delay during exercise was determined by the iterative method to maximise cardiac output using Doppler echocardiography. Results were compared to physiological change in PR intervals in 56 normal controls during treadmill exercise. The optimal AV delay was progressively shortened (p<0.05) with escalating exercise level (baseline: 123±26 ms vs stage I: 102±24 ms vs stage II: 70±22 ms, p<0.05). AV delay optimisation led to a significantly higher cardiac output than without optimisation did during stage I (6.2±1.2 l/min vs 5.2±1.2 l/min, p<0.001) and stage II (6.8±1.6 l/min vs 5.9±1.3 l/min, p<0.001) exercise. A linear inverse relationship existed between optimal AV delays and heart rates in CRT patients (AV delay=241−1.61×heart rate, R2=0.639, p<0.001) and healthy controls (R2=0.646, p<0.001), but the slope of regression was significantly steeper in CRT patients (p<0.001).

Conclusions Haemodynamically optimal AV delay shortened progressively with increasing heart rate during exercise, which suggests the need for programming of rate-adaptive AV delay in CRT recipients.

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Footnotes

  • Funding This project is sponsored by Medtronic International Ltd.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval Ethics approval was provided by the Cleveland Clinic Foundation and Emory University School of Medicine.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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