The prevalence and prognostic impact of low voltage zone in patients with cardiomyopathy after catheter ablation for atrial fibrillation
Authors: Oka T , Ozu K , Sekihara T , Nakano T , Yasumura K , Mima H , Akazawa Y , Nakamura D , Sera F , Mizote I , Ohtani T , Sakata Y 
Published: October 2024

Abstract

Background
The low voltage zone (LVZ) in left atrium (LA) was observed in 20-30% of patients undergoing catheter ablation of atrial fibrillation (AF). Furthermore, LVZ was associated with not only AF recurrence but also prognosis. However, the prevalence and prognostic impact of LVZ in patients diagnosed with cardiomyopathy remained unclear.

Purpose
In this study, we focused on the patients with cardiomyopathy after AF ablation and investigated the prevalence and prognostic impact of LVZ after AF ablation.

Methods
This study is a single-center retrospective observational study. We enrolled 125 patients diagnosed with cardiomyopathy. All patients underwent voltage mapping after pulmonary vein isolation. LVZ was defined as regions where bipolar peak-to-peak voltage was &lt;0.5mV. We set 5 cm² as the cutoff of the presence of LVZ. The etiology of cardiomyopathy was divided into arrhythmia-induced cardiomyopathy (AICM) and non-AICM consisting of idiopathic dilated cardiomyopathy (iDCM), hypertrophic cardiomyopathy (HCM), ischemic cardiomyopathy (ICM), transthyretin amyloidosis wild type (ATTRwt) and others (1 Fabry disease, 1 cardiac sarcoidosis, 1 restrictive cardiomyopathy). AICM was defined as patient whose LVEF was recovered above 50% after maintenance of sinus rhythm. We investigated the proportion of LVZ by etiology, and the association between LVZ and the composite endpoint consisting of all cause death, heart failure hospitalization, ventricular assisting device implantation, ventricular arrhythmia and stroke.

Results
Out of 125 patients [age 68 (58-73), female 32 (25%), LVEF 34.0 (25-43)], 51 (41%) had LVZ. Sixty-four patients were AICM etiology (LVEF pre to post: 30.7±10.7% to 61.1±6.7% ) and 61 was Non-AICM etiology (LVEF: 40.7 ± 18.1 to 44.7±15.7, P=0.0062). The presence of LVZ was lower in AICM than in non-AICM group (20.3% vs. 62.3%, P&lt;0.0001). The etiology of non-AICM was consisting of 26 iDCM, 18 HCM, 7 ICM, 7 ATRRwt and 3 other etiology. The prevalence of LVZ was lower in AICM than in non-AICM (20.3 vs. 62.3%, P&lt;0.0001). Detail is shown in Figure 1. Next, the incidence of composite endpoint was higher in patients with LVZ than in those without (HR 4.6, 95%CI 2.1-10.0, P=0.0001) (Figure 2A). Among 4 groups stratified by AICM/non-AICM and with/without LVZ, there was significant difference in the incidence of the composite endpoint (Figure 2B, P&lt;0.0001). After adjusted with age, gender, Non-AICM, LVZ, LVZ tended to have association with composite endpoint (2.21, 0.87-5.65, P=0.097) and Non-AICM showed strong association (5.58, 1.55-20.12, P=0.0086). LVZ was associated with HF hospitalization (4.35, 1.21-15.61, P=0.024).

Conclusions
The prevalence of LVZ was 60% in Non-AICM, while it was 20% in AICM. LVZ tended to be associated with poor prognosis of cardiomyopathy after AF ablation. LVZ was associated with HF hospitalization in patients with cardiomyopathy. LVZ might be the marker for poor prognosis in cardiomyopathy cohort.