The presence of contractile reserve has no predictive value for the evolution of left ventricular function following atrio-ventricular node ablation in patients with permanent atrial fibrillation

Aims: Transcatheter ablation of the atrio-ventricular (AV) node followed by ventricular pacing has been shown to improve symptoms and quality of life (QOL) of patients with permanent atrial fibrillation (AF). In a considerable number of patients, cardiac function deteriorates after AV node ablation. We aimed to determine whether the absence of contractile reserve assessed by low dose dobutamine stress echocardiography (LDDSE) could identify those patients whose left ventricular (LV) function deteriorates after AV node ablation. Methods: All 25 patients studied had permanent AF for at least 12 months. LVEF was determined 6 days and 3 months after AV node ablation by radionuclide ventriculography (RNV), at a paced rate of 80 beats/min. Deterioration in cardiac function was defined as a decrease in LVEF >5%. LDSE was performed in all patients before and after ablation. The presence of contractile reserve was defined as an improvement in regional function of ≥1 grade at low dose dobutamine in at least 4 segments. QOL measurements were taken using Minnesota, NHBP and MPWB questionnaires. Results: LVEF showed no improvement in the overall group (52.8 ± 11.1% vs. 51.8 ± 9.8%, p = NS). QOL showed significant improvement in all questionnaires (Minnesota: 4.1 ± 2.1 vs. 2.5 ± 2, p = 0.001; NHBP: 54.8 ± 43.3 vs. 34.2 ± 34.3, p = 0.002; MPWB: 22.2 ± 4.6 vs. 19.4 ± 6.2, p = 0.03). There was no significant difference in change of LVEF between patients with and without contractile reserve (-0.4 ± 8.7 vs. 1.6 ± 11.3, p = NS). However, patients with a preserved LVEF at baseline showed more frequently a reduced LVEF after AV node ablation (62.2 ± 10.4% vs. 47.5 ± 7.6%, p = 0.001). Conclusions: (1) The absence of contractile reserve does not predict deterioration of cardiac function after AV node ablation. (2) AV node ablation results in a significant improvement in QOL, which is not necessarily associated with improvement of LVEF. (3) Higher baseline LVEF predicts deterioration of cardiac function. These data suggest that although AV node ablation is an excellent way of controlling symptoms, it should be avoided in patients with normal LV function.

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