Cardiac resynchronization therapy in patients with intermittent atrial arrhythmias: will cardiac resynchronization therapy be good for all?

Cardiac resynchronization therapy (CRT) is an established treatment for symptomatic patients with heart failure (HF), a prolonged QRS duration, and reduced ejection fraction (EF). The latest 2013 European Society of Cardiology Guidelines on cardiac pacing and cardiac resynchronization therapy [(1