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Updated: Jun 25, 2026
Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Importance of heart rate during exercise for response to cardiac resynchronization therapy
Alexander H Maass1, Sandra Buck, Wybe Nieuwland
1Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
Background:
Cardiac resynchronization therapy (CRT) is an established therapy for patients with severe heart failure and mechanical dyssynchrony. Response is only achieved in 60-70% of patients.
Objectives:
To study exercise-related factors predicting response to CRT.
Methods:
We retrospectively examined consecutive patients in whom a CRT device was implanted. All underwent cardiopulmonary exercise testing prior to implantation and after 6 months. The occurrence of chronotropic incompetence and heart rates exceeding the upper rate of the device, thereby compromising biventricular stimulation, was studied. Response was defined as a decrease in LVESV of 10% or more after 6 months.
Results:
We included 144 patients. After 6 months 86 (60%) patients were responders. Peak VO2 significantly increased in responders. Chronotropic incompetence was more frequently seen in nonresponders (21 [36%] vs 9 [10%], P = 0.03), mostly in patients in SR. At moderate exercise, defined as 25% of the maximal exercise tolerance, that is, comparable to daily life exercise, nonresponders more frequently went above the upper rate of the device (13 [22%] vs 2 [3%], P < 0.0001), most of whom were patients in permanent AF. Multivariate analysis revealed heart rates not exceeding the upper rate of the device during moderate exercise (OR 15.8 [3.3-76.5], P = 0.001) and nonischemic cardiomyopathy (OR 2.4 [1.0-5.7], P = 0.04) as predictive for response.
Conclusions:
Heart rate exceeding the upper rate during moderate exercise is an independent predictor for nonresponse to CRT in patients with AF, whereas chronotropic incompetence is a predictor for patients in SR.
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