Peak VO2 is associated with cardiac functional response and long-term survival in patients with heart failure and atrial fibrillation undergoing catheter ablation
Authors: Ahluwalia N , Zakeri R , Tinddale A , Omar F , Packer M , Khan H , Baker V , Honarbakhsh S , Jones D , Markides V , Earley M J , Sporton S , Schilling R J , Wong T , Hunter R J 
Published: October 2024

Abstract

Background
Contemporary guidelines recommend Catheter Ablation (CA) in patients with persistent Atrial Fibrillation (AF) with Heart Failure with reduced ejection fraction (HFrEF). It is challenging to prospectively predict who will respond. We have previously described the long-term survival outcomes of patients in this cohort.(1) However, the clinical characteristics associated with HF response and long-term clinical outcomes have not been reported.

Objective
To evaluate the association of HF parameters with cardiac functional response to CA and long-term survival after CA.

Methods
Post-hoc, long-term follow-up of mortality was undertaken in patients enrolled in the CAMTAF and ARC-HF RCTs. Both studies enrolled patients with persistent AF and HFrEF between 2005 and 2012 and randomised to first-time CA or medical therapy alone. Left ventricular ejection fraction (LVEF) and peak VO2 were measured in both studies at baseline and 12-month follow-up. The Universal Definition of HF response (LVEF improves by &gt;10% points or to an LVEF &gt;50%) was used.(2,3) Multi-variate logistic regression was used to determine features associated with HF response and Cox proportional hazards modelling for survival.

Results
102 patients underwent randomisation with 52 assigned to CA. The mean age was 60.2 ±10.7 years with 93 (91.2%) male. The mean Baseline LVEF was 31 ±11% and peak VO2 was 1815 ±642mlmin-1. Baseline LVEF did not correlate significantly with Minnesota Living with Heart Failure (MLWHF) score (r=-0.11, p=0.29) whereas baseline peak VO2 did (r=-0.28, p&lt;0.01).
In patients randomised to CA, the median (IQR) improvement in LVEF was +8.4% (0, 15%). 22/52 (42.3%) patients were classified as Responders based on the Universal Criteria. Responders were younger (54.7 ±10.6 years vs 61.8 ±11.4, p=0.03) and had a higher mean HR on baseline Holter monitoring (89 ±14bpm vs 79 ±11bpm p&lt;0.01) than non-responders. There was no significant difference in sex, baseline MLWHF scores, BNP levels or LVEF between groups (28±9% vs 31 ±9%, p=0.19). Responders had a significantly higher peak VO2 at baseline than Non-Responders (1972 ±668mlmin-1 vs 1556 ±580mlmin-1, p=0.03). On multivariate analysis, mean heart rate on Holter monitoring and peak VO2 were significantly associated with Responder status post-ablation. (Table 1a)
During a median follow-up of 7.8 (3.9 –9.9) years, 34 (33.3%) patients died, including 17 (32.7%) patients in the CA arm. On univariate analysis, baseline peak VO2 was significantly greater of survivors at 5 years (1867 ±624 mlmin-1 vs 1259 ±497 mlmin-1, p&lt;0.01). On multivariate Cox regression analysis, the peak VO2 at baseline was the only significant predictor of survival (Table 1b).

Conclusion
Peak VO2 at baseline was associated with baseline symptom status, the short-term LVEF response to CA and long-term survival and may be a useful stratification tool to aid patient selection for CA.1a. Regression for 6-month LVEF response1b. Regression for long-term mortality