Catheter Ablation Improves Ventilatory Efficiency in Atrial Fibrillation-Mediated Cardiomyopathy

Background

Exercise Oscillatory Ventilation (EOV) and a steep ventilatory efficiency (VE/VCO2) slope are features of ventilatory inefficiency on cardiopulmonary exercise testing (CPET), both associated with poor prognosis in patients with heart failure (HF). The prevalence in patients with co-existent atrial fibrillation (AF) and the impact of catheter ablation (CA) is unknown.

Objectives

To characterize ventilatory inefficiency in patients with persistent AF and Left Ventricular Systolic Dysfunction (LVSD) and assess the impact of CA.

Methods

Patients with persistent AF and Left Ventricular Ejection Fraction (LVEF) < 50% undergoing first-time CA were prospectively enrolled. Echocardiography and CPET were performed at baseline and 6 months post-CA. EOV was defined using the Kremser–Corrà criteria, and VE/VCO2 slope gradient > 30 was considered abnormal.

Results

A total of 53 participants were enrolled (mean LVEF of 34 ± 9%). A total of 10 (19.2%) exhibited EOV at baseline. These patients had larger indexed left atrial (41.6 ± 13.1 mL/m² vs. 33.3 ± 9.3 mL/m², p = 0.03) and ventricular volumes [65.7 mL/m² (57.1, 89.0) vs. 46.7 mL/m² (39.8, 61.4), p = 0.03]. The partial pressure of end-tidal carbon dioxide (P_ETCO₂) at peak exercise increased (33.7 ± 6.1 mmHg to 41.2 ± 5.8 mmHg, p < 0.001) and correlated with improvement in HF symptoms (p = −0.003) and objective HF markers. A total of 25 (48.1%) had an abnormal VE/VCO2 gradient. The EOV pattern resolved in eight (80%) participants due to a reduction in EOV burden (71.1 ± 11.9% vs. 48.8 ± 14.8%, p = 0.006) and the component amplitude of minute ventilation cycles (2.6 L/min (2.5,3.2) vs 2.2 L/min (1.8,2.6), p = 0.028). Fewer patients had an abnormal VE/VCO2 gradient after CA [25 (48.1%) vs. 16 (34.0%), p = 0.004].

Conclusions

Ventilatory inefficiency is common in patients with AF and LVSD. CA improves both EOV and VE/VCO2 in AF-induced cardiomyopathy. Improvement in P_ETCO₂ is also seen and correlates with HF symptom burden.