An interventional study of Closed-Loop Stimulation and Accelerometer-Based VVIR Pacing in Block Complete Heart, Atrial Fibrillation (AF) and Chronotropic Incompetence, sponsored by Bartlomiej Wrobel. Completed at 1 site in Poland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-10.
Sponsored by Bartlomiej Wrobel · Not applicable, Interventional, and Treatment
This prospective, single-center, crossover study evaluated the effects of closed-loop stimulation (CLS) compared with conventional accelerometer-based rate-adaptive pacing (VVIR) in patients with permanent atrial fibrillation undergoing left bundle branch area pacing (LBBAP). Chronotropic responses were evaluated during standardized mental and physical stress testing. Heart rate distribution during daily activity, functional capacity, quality of life, and device-related parameters were also assessed.
Exclusion Criteria:
Participants received closed-loop stimulation (CLS) during the first study period, followed by accelerometer-based VVIR pacing during the second study period.
Device: Closed-Loop Stimulation · Device: Accelerometer-Based VVIR Pacing
Participants received accelerometer-based VVIR pacing during the first study period, followed by closed-loop stimulation (CLS) during the second study period.
Device: Closed-Loop Stimulation · Device: Accelerometer-Based VVIR Pacing
The pacemaker was programmed to closed-loop stimulation (CLS), an impedance-based rate-adaptive pacing algorithm that adjusts the pacing rate in response to changes in intracardiac impedance associated with cardiac contractile dynamics.
The pacemaker was programmed to VVIR mode with accelerometer-based rate-adaptive pacing. The pacing rate was adjusted according to physical activity detected by the device's accelerometer.
Change in Heart Rate During Mental Stress
Change in heart rate (ΔHR) during the Paced Auditory Serial Addition Test (PASAT), calculated as the peak heart rate recorded during the test minus the baseline heart rate. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing and expressed in beats per minute (bpm).
Time frame: At the end of each 1-month pacing period
Change in Heart Rate During Isometric Handgrip
Change in heart rate (ΔHR) during the 5-minute isometric handgrip test performed at 30% of maximal voluntary contraction, calculated as the peak heart rate recorded during the test minus the baseline heart rate. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing and expressed in beats per minute (bpm).
Time frame: At the end of each 1-month pacing period
Change in Heart Rate During Treadmill Exercise
Change in heart rate (ΔHR) during the symptom-limited treadmill exercise test using the modified Bruce protocol, calculated as the peak heart rate achieved during exercise minus the baseline heart rate. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing and expressed in beats per minute (bpm).
Time frame: At the end of each 1-month pacing period
Exercise Duration During Treadmill Testing
Total exercise duration during the symptom-limited treadmill exercise test performed using the modified Bruce protocol. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing and expressed in seconds.
Time frame: At the end of each 1-month pacing period
Metabolic Equivalents Achieved During Treadmill Testing
Exercise capacity during the symptom-limited treadmill exercise test using the modified Bruce protocol, expressed as metabolic equivalents (METs) achieved during the test. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing.
Time frame: At the end of each 1-month pacing period
Heart Rate Score During Daily Activity
Heart Rate Score (HRS), defined as the percentage of all sensed and paced ventricular beats occurring in the most populated 10-beats-per-minute heart rate histogram bin. HRS was assessed from pacemaker-derived heart rate histograms under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing. Higher HRS values indicate a more concentrated heart rate distribution and less heart rate variation across histogram bins. The score ranges from 0% to 100%.
Time frame: At the end of each 1-month pacing period
Health-Related Quality of Life Assessed With the EQ-5D-5L Index
Health-related quality of life was assessed using the EuroQol 5-Dimension 5-Level (EQ-5D-5L) descriptive system. Responses were converted to an EQ-5D-5L index value using the Polish value set. Index values range from -0.590 to 1.000, with higher values indicating better health-related quality of life. A value of 1 represents full health, 0 represents a health state equivalent to death, and negative values represent health states valued as worse than death. The outcome was compared between closed-loop stimulation (CLS) and accelerometer-based VVIR pacing.
Time frame: At the end of each 1-month pacing period
Self-Rated Health Assessed With the EQ VAS
Self-rated health was assessed using the EuroQol Visual Analogue Scale (EQ VAS), ranging from 0 to 100, where 0 represents the worst health the participant can imagine and 100 represents the best health the participant can imagine. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing.
Time frame: At the end of each 1-month pacing period
Patient-Reported Pacing-Mode Preference
At the end of the study, participants were asked during which of the two pacing periods they experienced better overall subjective well-being, or whether they had no preference. Responses were subsequently categorized according to the pacing mode programmed during the preferred period as preference for closed-loop stimulation (CLS), preference for accelerometer-based VVIR pacing, or no preference.
Time frame: At the end of the study, after completion of both 1-month pacing periods
Ventricular Pacing Percentage
Ventricular pacing percentage was obtained from pacemaker interrogation and defined as the proportion of ventricular events that were paced during each study period. The outcome was assessed under both closed-loop stimulation (CLS) and accelerometer-based VVIR pacing and expressed as a percentage from 0% to 100%.
Time frame: At the end of each 1-month pacing period
Plan to share: No — There is currently no plan to make individual participant data publicly available.
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