The goal of this observational study is to learn whether caffeine consumption is associated with ventricular arrhythmias and physical activity in adults with heart failure, reduced left ventricular ejection fraction, and an implantable cardioverter-defibrillator (ICD). The main questions it aims to answer are: Is caffeine consumption associated with the burden of premature ventricular contractions (PVCs)? Is caffeine consumption associated with the occurrence of ventricular arrhythmias, including non-sustained ventricular tachycardia (NSVT), sustained monomorphic ventricular tachycardia (SMVT), and ventricular fibrillation (VF)? Is caffeine consumption associated with the level of daily physical activity recorded by the ICD? Participants will: Complete a one-time questionnaire about their consumption of coffee and other caffeine-containing products during the previous 7 days. Allow researchers to collect relevant information from their medical records. Allow researchers to use data already collected during the routine follow-up of their ICD, including information on heart rhythm abnormalities, heart rate, and physical activity. No additional hospital visits, medical examinations, blood tests, or changes to treatment are required as part of this study.
Study Type
OBSERVATIONAL
Enrollment
170
Caffeine Consumption Questionnaire
AZ Sint-Jan Brugge
Bruges, Belgium
Burden of premature ventricular contractions (PVCs)
Burden of premature ventricular contractions (PVCs), expressed as the percentage of total recorded ventricular beats represented by PVCs (%PVC burden), as provided by the device's remote monitoring software, assessed over the 12 months immediately preceding the date of the caffeine questionnaire, averaged across all monitored days. Unit: percent (%).
Time frame: 12 months
Non-sustained ventricular tachycardia (NSVT): occurrence (%)
Non-sustained ventricular tachycardia (NSVT). Untreated episodes of at least three consecutive ventricular beats above the programmed detection cut-off, lasting less than 30 seconds. For each episode, the device-assigned date and time will be recorded. Reported as occurrence (percentage of participants).
Time frame: 12 months
Non-sustained ventricular tachycardia (NSVT): rate
Non-sustained ventricular tachycardia (NSVT). Untreated episodes of at least three consecutive ventricular beats above the programmed detection cut-off, lasting less than 30 seconds. For each episode, the device-assigned date and time will be recorded. Reported as rate (episodes per 100 monitored days).
Time frame: 12 months
Non-sustained ventricular tachycardia (NSVT): distribution
Non-sustained ventricular tachycardia (NSVT). Untreated episodes of at least three consecutive ventricular beats above the programmed detection cut-off, lasting less than 30 seconds. For each episode, the device-assigned date and time will be recorded. Reported as the distribution of episodes across time.
Time frame: 12 months
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): occurrence (%)
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF). Episodes lasting at least 30 seconds or terminated by device therapy. Reported as occurrence (percentage of participants).
Time frame: 12 months
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): rate
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF). Episodes lasting at least 30 seconds or terminated by device therapy. Reported as rate (episodes per 100 monitored days).
Time frame: 12 months
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): median episode duration (seconds)
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF). Episodes lasting at least 30 seconds or terminated by device therapy. Reported as median episode duration (seconds).
Time frame: 12 months
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): mode of termination
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF). Episodes lasting at least 30 seconds or terminated by device therapy. Reported as mode of termination (percentage of episodes terminating spontaneously, by antitachycardia pacing, or by shock).
Time frame: 12 months
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): mean cycle length (ms)
Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF). Episodes lasting at least 30 seconds or terminated by device therapy. Reported as mean cycle length (milliseconds).
Time frame: 12 months
Physical activity (hours per day)
Physical activity, absolute. Daily physical activity recorded by the ICD accelerometer and reported by the remote monitoring platform, averaged across monitored days; platforms reporting activity as a proportion of the day are converted by multiplying by 24. Unit: hours per day.
Time frame: 12 months
Physical activity: mean daily activity expressed as a z-score
Physical activity, manufacturer-standardised. Each participant's mean daily activity expressed as a z-score relative to the mean and standard deviation of all study participants monitored on the same platform. Unit: standard deviation units.
Time frame: 12 months
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