Cardiac resynchronization therapy in patients with heart failure and atrial fibrillation: importance of new-onset atrial fibrillation and total atrial conduction time.

Aims: Cardiac resynchronization therapy (CRT) is an established therapy for patients with heart failure and sinus rhythm (SR), but its value in atrial fibrillation (AF) remains unclear. Furthermore, response to CRT may be difficult to predict in these patients. The aim of our study was to investigate whether predictors for CRT success differ between patients with AF and SR and to study the influence of present or developing AF on response to CRT.
Methods and Results: We examined consecutive patients in whom CRT was implanted disregarding the atrial rhythm. Atrial fibrillation was defined as either current or earlier AF, response to CRT was defined as a decrease in the left ventricular end-systolic volume of > or = 10% after 6 months. Total atrial conduction time (TACT), a measure to predict the risk of developing AF, was determined by echocardiography. We included 114 patients, of whom 56 (49%) were known with AF (23 current AF and 33 earlier AF). The other 58 patients had no history of AF. After 6 months, response in current and earlier AF and that in SR patients was comparable (56, 58 and 55%, respectively). In AF patients, multivariate analysis revealed a shorter TACT at baseline [odds ratio (OR) 16.7 (1.5-185.3), P = 0.02] and an interventricular mechanical delay (IVMD) > 40 ms [OR 10.4 (1.0-110.9), P = 0.05] as predictors for response. Non-responders more frequently suffered from new-onset AF (P = 0.02).
Conclusion: Failure to CRT is associated with new-onset AF. Total atrial activation time may be a parameter to predict response in AF patients.