Characterization of Atrial Substrate to Predict the Success of Pulmonary Vein Isolation: The Prospective, Multicenter MASH‐AF II (Multipolar Atrial Substrate High Density Mapping in Atrial Fibrillation) Study

Abstract

Background Left atrial substrate may have mechanistic relevance for ablation of atrial fibrillation (AF). We sought to analyze the relationship between low‐voltage zones (LVZs), transition zones, and AF recurrence in patients undergoing pulmonary vein isolation. Methods and Results We conducted a prospective multicenter study on consecutive patients undergoing pulmonary vein isolation‐only approach. LVZs and transition zones (0.5–1 mV) were analyzed offline on high‐density electroanatomical maps collected before pulmonary vein isolation. Overall, 262 patients (61±11 years, 31% female) with paroxysmal (130 pts) or persistent (132 pts) AF were included. After 28 months of follow‐up, 73 (28%) patients experienced recurrence. An extension of more than 5% LVZ in paroxysmal AF and more than 15% in persistent AF was associated with recurrence (hazard ratio [HR], 4.4 [95% CI, 2.0–9.8], P <0.001 and HR, 1.9 [95% CI, 1.1–3.7], P =0.04, respectively). Significant association was found between LVZs and transition zones and between LVZs and left atrial volume index (LAVI) (both P <0.001). Thirty percent of patients had significantly increased LAVI without LVZs. Eight percent of patients had LVZs despite normal LAVI. Older age, female sex, oncological history, and increased AF recurrence characterized the latter subgroup. Conclusions In patients undergoing first pulmonary vein isolation, the impact of LVZs on outcomes occurs with lower burden in paroxysmal than persistent AF, suggesting that not all LVZs have equal prognostic implications. A proportional area of moderately decreased voltages accompanies LVZs, suggesting a continuous substrate instead of the dichotomous division of healthy or diseased tissue. LAVI generally correlates with LVZs, but a small subgroup of patients may present with disproportionate atrial remodeling, despite normal LAVI.

Clinical impact of left atrial remodeling pattern in patients with atrial fibrillation: Comparison of volumetric, electrical, and combined remodeling

“…Similar patient backgrounds corresponding to types of atrial remodeling have also been reported by Bergonti et al 6 …”

“…LA enlargement has been frequently associated with AF recurrence, 1,2 and is considered one of the most clinically used predictors. The presence and extension of LVAs have also been shown to predict AF recurrence 4–6 . The novelty of this study is that either type of remodeling can develop in populations with different backgrounds, and is associated with AF recurrence.…”

“…The presence and extension of LVAs have also been shown to predict AF recurrence. [4][5][6] The novelty of this study is that either type of remodeling can develop in populations with different backgrounds, and is associated with AF recurrence. In addition, patients with combined remodeling had even worse rhythm outcomes than those with either remodeling, possibly because the combination of volumetric and electrical remodeling suggests more advanced LA remodeling.…”

“…Both the presence and extent of LVAs correlate well with AF recurrence after AF ablation. [4][5][6] In the clinical setting, the progression of LA enlargement and extension of LVAs are not necessarily parallel, and the relative predominance of the two varies from case to case. Nevertheless, information about the distribution, patient background, and prognostic impact of the different types of atrial remodeling is scarce.…”

“…On the other hand, LA electrical remodeling including the presence of low‐voltage areas (LVAs) reportedly indicates the presence of myocardial histological degeneration such as fibrosis, 3 and may be used as surrogate markers of histological degeneration. Both the presence and extent of LVAs correlate well with AF recurrence after AF ablation 4–6 …”