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,