Coffee Use, Physical Activity and Symptomatic Ventricular Arrhythmias in Patients With Left Ventricular Dysfunction and an ICD

• Questionnaire (Other): Caffeine Consumption Questionnaire

Primary outcomes

• Burden of premature ventricular contractions (PVCs) [12 months]: 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 (%).

Secondary outcomes

• Non-sustained ventricular tachycardia (NSVT): occurrence (%) [12 months]: 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).
• Non-sustained ventricular tachycardia (NSVT): rate [12 months]: 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).
• Non-sustained ventricular tachycardia (NSVT): distribution [12 months]: 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.
• Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): occurrence (%) [12 months]: 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).
• Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): rate [12 months]: 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).
• Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): median episode duration (seconds) [12 months]: 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).
• Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): mode of termination [12 months]: 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).
• Sustained monomorphic (SMVT) and polymorphic ventricular tachycardia (PVT/VF): mean cycle length (ms) [12 months]: 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).
• Physical activity (hours per day) [12 months]: 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.
• Physical activity: mean daily activity expressed as a z-score [12 months]: 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.

Sex: All, ages: 18 Years to any

Inclusion Criteria:

1. Written informed consent obtained prior to any study procedure.
2. Age ≥18 years.
3. Left ventricular systolic dysfunction (LVEF <50%), i.e. HFrEF or HFmrEF, documented on the most recent available transthoracic echocardiogram.
4. Presence of a transvenous implantable cardioverter-defibrillator (ICD), including cardiac resynchronization therapy defibrillators (CRT-D), implanted at least 12 months before the caffeine questionnaire.

Exclusion Criteria:

1. Presence of channelopathies.
2. Subcutaneous implantable cardioverter-defibrillator (S-ICD), which does not provide ventricular ectopic beat counters, accelerometer-derived physical activity data or antitachycardia pacing, and therefore cannot generate the primary outcome measure.
3. Inability to complete the study questionnaire on coffee and caffeinated product consumption.