AIC Genotyping Study

INCLUSION: AIC (Cases): * Age ≥18 * Persistent AF before index catheter ablation or cardioversion * LVEF ≤40% during rate-controlled (resting HR \<100bpm, mean HR on 24-hour Holter \<100bpm) AF prior to index catheter ablation or cardioversion * LVEF normalisation (LVEF ≥55%) in SR, post-catheter ablation or cardioversion (≥3 months post-catheter ablation or cardioversion), no AF (\>30 seconds of continuous AF) detected outside blanking period (8 weeks post-catheter ablation), and with no new introduction of any new or increased dose of heart failure guideline-directed medical therapy (GDMT) (renin-angiotensin-aldosterone system inhibitors (RAASi), Sodium Glucose Co-transporter 2 (SLGT2) inhibitors, increased dose of beta-blocker (BB), mineralocorticoid receptor antagonist (MRA)) AF-pEF (Negative controls): * Age ≥18 * Persistent AF before index catheter ablation or cardioversion * LVEF ≥55% during rate-controlled (resting HR \<100bpm) AF. AIC-genotyping study, v1.7, 27.01.26 Page 13 of 28 AF/HF non-responders (Positive controls) * Age ≥18 * Persistent AF before index catheter ablation or cardioversion * LVEF ≤40% during rate-controlled (resting HR \<100bpm) AF before index catheter ablation or cardioversion. * Persistent LVSD (LVEF ≤40%) in SR, post-catheter ablation or cardioversion (≥3 months post-catheter ablation or cardioversion), no AF (\>30 seconds of continuous AF) detected outside blanking period (8 weeks post-catheter ablation) and with no change in heart failure GDMT (RAASi, SGLT2 inhibitors, increased dose of BB, MRA). EXCLUSION: AIC (Cases). * No alternative cause for LVSD (ischemic cardiomyopathy/non-ischaemic cardiomyopathy before AF diagnosis, primary valve disease, inherited cardiomyopathy * Any pregnancy during AF or in the 12 months preceding LVSD onset. * Alcohol intake \>21 units/week * Any history of cardiotoxic chemotherapy AF-pEF (Negative controls) * No known cause for LVSD (ischemic cardiomyopathy/non-ischaemic cardiomyopathy before AF diagnosis, primary valve disease, inherited cardiomyopathy). * Any pregnancy during AF or in the 12 months preceding LVSD onset. * Alcohol intake \>21 units/week. * Any history of cardiotoxic chemotherapy. AF/HF non-responders (Positive controls) * No alternative cause for LVSD (ischemic cardiomyopathy/non-ischaemic cardiomyopathy before AF diagnosis, primary valve disease, inherited cardiomyopathy). * Any pregnancy during AF or in the 12 months preceding LVSD onset. * Alcohol intake \>21 units/week. * Any history of cardiotoxic chemotherapy.