Rate control in atrial fibrillation

This thesis demonstrates that high ventricular heart rates during AF are common, particularly in patients with paroxysmal atrial fibrillation (AF). Continuous heart rate monitoring with implantable loop recorders revealed that many patients paroxysmal AF spent a large proportion of AF episodes with heart rates above the guideline-recommended threshold of 110 beats per minute. Importantly, rate-control therapy was adjusted in only a minority of these patients, highlighting the practical challenges of achieving adequate rate control, especially due to the risk of bradycardia during sinus rhythm. In patients with newly diagnosed AF, more than one third presented with heart rates above 110 beats per minute at baseline. These patients reported more severe AF-related symptoms. Early rhythm control did not significantly reduce symptoms compared with usual care, suggesting that heart rate during AF is a key determinant of symptom burden. Meta analyses of rate-control medications showed that non-dihydropyridine calcium channel blockers and beta-blockers are similarly effective in lowering heart rate during AF. In retrospective analyses preformed in this thesis calcium channel blockers were associated with a significantly lower incidence of bradycardia during sinus rhythm. Furthermore, patients treated with calcium channel blockers showed signals of reduced AF progression, better exercise tolerance, and higher maximal heart rates during physical activity. Overall, this thesis demonstrates that rate control is often suboptimal in paroxysmal AF and that the choice of rate-control medication may have clinically meaningful implications, supporting a more individualized approach to AF management.