Cardiac resynchronisation therapy in atrial fibrillation: the importance of AV node ablation

Vienna, Austria, 3 September 2007:

Cardiac resynchronization therapy (CRT) is an effective therapy in symptomatic, drug-refractory heart failure (HF) patients with prolonged QRS and low ejection fraction (EF). Long-term results of CRT on exercise tolerance and disease progression as evaluated by reversal of maladaptive remodeling process are rather limited, and mostly reported in patients with sinus rhythm (SR). Permanent atrial fibrillation (AF) is a rather common supraventricular arrhythmia in heart failure patients and is associated with increased morbidity and mortality. Some studies have reported significant acute benefits but short-term data of CRT in AF patients are conflicting. The importance of atrio-ventricular junction (AVJ) ablation in order to optimize CRT in patients with permanent AF has been investigated at minimum extent. This approach appears to maximize CRT delivery yielding a “pure” resynchronization effect which translates into significant long-term improvements of both ejection fraction and reversal of maladaptive remodeling; such reversal remodeling effect has been previously correlated with improved survival in HF patients with normal sinus rhythm. Recent ESC guidelines on cardiac resychronization therapy and pacing did not address the appropriate management of CRT delivery in this important subgroup of HF patients.

The purpose of the present study was two fold: first to investigate the effect of CRT on long-term survival in HF patients with permanent AF compared to SR patients; second to evaluate within an ample AF population treated with CRT the impact of AV junction ablation on long-term survival.

The question was addressed using data included into the Multicenter Longitudinal Observational Study

(MILOS). This registry included, using a prospectively pre-defined registry protocol, 1305 consecutive patients undergoing CRT pacemaker (CRT-P) or CRT defibrillator (CRT-D) device implant between August 1st 1995 and August 1st 2004 from 2 centers in Italy and 2 in Germany (22).

Long-term survival data of the entire population have been published in the American Journal of Cardiology (Auricchio et al. Am J Cardiol 2007; 99: 232 -238). In the Clinical Seminar Session entitled “Cardiac resynchronisation therapy: what is the hot news?” of this ESC meeting results referring to the importance of AV node ablation in CRT patients will be reported.

The MILOS results show for the first time the importance of AVJ ablation on long-term survival in AF patients treated with CRT. In our large multi-center series the long-term overall survival of drug-refractory heart failure patients with permanent AF and left ventricular conduction delay treated with CRT was similar to that of SR patients. However, in HF patients with permanent AF, AVJ ablation in addition to CRT significantly improves long-term overall mortality, compared to CRT alone, primarily by reducing HF death. AVJ ablation appears to be of paramount relevance in order to ensure adequate CRT delivery and thus reducing mortality in patients with permanent AF.

The clinical implication of our findings are large and may lead to an expansion of currently available ESC guidelines, indicating that AF patients may benefit from CRT but that a very aggressive treatment strategy, including ablation of the AV junction, should be performed in order to maximize the clinical and survival benefit of these patients.