Cardiac resynchronization therapy in patients with and without atrial fibrillation

Background: Cardiac resynchronization therapy (CRT) has emerged as an effective option in selected heart failure (HF) patients with electro-mechanical dyssynchrony. Several prospective, randomized controlled trials have proven its safety and clinical efficacy. However, most of these trials only enrolled patients in sinus rhythm (SR). The benefits of CRT in patients with atrial fibrillation (AF) are not yet well evaluated. Methods: Fifty-six patients who received CRT between 2002 and 2008 were divided into two groups, SR and AF. Baseline characteristics were collected at the time of implantation. Echocardiographic examinations were performed in every patient within 2 days before and 6 months after device implantation. Echocardiographic parameters, tissue velocity, and strain images were analyzed. Results: Forty patients were in SR and 16 had either persistent or permanent AF at the time of CRT implantation. Pre-CRT parameters showed no statistical difference between the two groups. Both groups had similar rates of clinical and echocardiographic responders. Six months after CRT, left ventricular ejection fraction of both groups had improved (26 ± 7% to 38 ± 15% in SR, p < 0.001; 27 ± 7% to 34 ± 11% in AF, p < 0.004). Indices of synchronicity (QRS duration, septal-posterior wall motion delay, standard deviation of time to peak tissue velocity, all p < 0.001) were improved in both groups. Conclusion: Both patients in SR and AF showed similar responses to CRT. CRT therapy should be considered in AF patients with persistent HF symptoms and electro-mechanical dyssynchrony after optimal medical therapy.