Effect of atrial radiofrequency ablation designed to cure atrial fibrillation on atrial mechanical function

Introduction: The effects of linear radiofrequency lesions in the atria for cure of atrial fibrillation on atrial contraction have not previously been quantified. Methods and Results: Atrial function was measured before and 30 +/- 24 days after a biatrial ablation procedure designed to cure atrial fibrillation i n eight dogs and after a sham procedure in three dogs. Atrial mechanical fu nction was assessed using Doppler diastolic blood flow velocities, atrial s ystolic pressure wave amplitude, and assessment of atrial contribution to c ardiac output estimated by comparison of AV sequential pacing to ventricula r pacing at the same heart rate. The mitral Doppler A/E velocity ratio was 1.03 +/- 0.45 before and 0.72 +/- 0.43 after ablation (P = 0.048). The tric uspid A/E ratio was 0.88 +/- 0.17 before and 0.71 +/- 0.12 after ablation ( P = 0.04). The estimated atrial contribution to cardiac output was 18% +/- 9% before and 5% +/- 4% after ablation (P < 0.01). The left atrial systolic pressure wave amplitude was 2.8 +/- 1.5 mmHg before and 1.7 +/- 1.0 mmHg a fter ablation (P = 0.1). These changes were not observed in control dogs. L esions covered 25% +/- 6% of the atrial endocardial surface. Conclusion: Multiple linear radiofrequency lesions in the atria designed to cure atrial fibrillation may impair atrial contractility. Reduced atrial f unction is partly due to loss of atrial myocardial mass, but regional delay s in atrial activation and splinting of the atria by scarring also may cont ribute.