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

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.

Inclusion Criteria: 1. Written informed consent obtained prior to any study procedure. 2. Age ≥18 years. 3. Left ventricular systolic dysfunction (LVEF \