The 'Happy Ending Problem' of cardiac pacing? Cardiac resynchronization therapy for patients with atrial fibrillation and heart failure after atrioventricular junction ablation

The ‘Happy Ending Problem’ in mathematics is the following statement: Any set of five points in the plane in a general position has a subset of four points that form the vertices of a convex quadrilateral .A particular analogy can be drawn between this so-called unsolved problem in mathematics and the still unsolved problem of treatment of patients with heart failure (HF) associated with atrial fibrillation. Patients with HF and atrial fibrillation represent a subgroup of patients that encounters additional difficulties when compared with patients in sinus rhythm (SR). Most available studies, which include this subgroup of patients, suggest a beneficial effect of cardiac resynchronization therapy (CRT) on the outcome ( Table 1 ).1–8 However, most studies in the field of CRT excluded this particular patient population. Moreover, studies until now have contained 95% of the patients in SR. Despite this, a few well-conducted studies have addressed this problem. Unfortunately, some studies have caused a certain amount of confusion because of controversial data. This controversy arises as a result of errors in the study design, interpretation, and the low inclusion rates. The above-mentioned analogy in mathematics clearly points out another difficulty in decision-making in this multifactorial problem. The five points in this geometrical problem can represent at least five independent factors, which could influence future recommendations. Furthermore, these factors could have a potential effect on the outcome: the effect of atrioventricular (AV) node ablation and pacing, the effect of the pacing site on cardiac function, a diminished atrial function (lack of atrial kick), the effect of rhythm regularization, and the presence … *Corresponding author. Tel: +31 104633991; fax: +36 12151220 ext. 413. E-mail address : t.szilitorok{at}erasmusmc.nl