Beyond PVI in the setting of heart failure
The vast majority of AF in patients with concurrent LV dysfunction is persistent, and the proportion seen in this study (71%) mirrors that in other large studies8, 17. Given its nature, cryoablation usually entails a PVI only approach to AF ablation. The findings of this study suggests that a PVI-alone approach is an effective ablation strategy in this setting, and that additional index substrate-based ablation may not be necessary to achieve the anti-heart failure treatment effect of catheter ablation. This finding is consistent with that published by Voskoboinik et al which showed that an index PVI only based approach (with either RF based or cryoablation) in patients with persistent AF (albeit in the absence of structural heart disease) was associated with a 12-month arrhythmia free survival rate of 66.7%18. This is similar to the results seen in other studies19, 20. Additionally, the improvement in ventricular function despite these modest ‘success’ rates of 40-60%, highlights the important fact that standard measures of recurrence (AF/AT > 30 secs) may be of little relevance when evaluating the long-term effect of catheter ablation upon improving ventricular function. In this regard, AF burden may be a more useful measure21. Thus, arguably, any improved freedom from AF potentially attributable to additional ablation beyond PVI from an RF based approach may not be necessary to achieve the heart failure benefit of catheter ablation. Importantly, repeat procedures were uncommon (9%) and where performed, PV re-isolation alone was the ablation strategy in the large majority (71%) of patients. It should be noted that to date, no substrate modification strategy in persistent AF has shown to benefit outcomes when evaluated in a prospective randomised fashion22. This is consistent with the results of a recent meta-analysis suggesting that outcomes of a PVI approach were no different to an approach incorporating linear lesions and ablation of fractionated electrograms5,