Voltage during atrial fibrillation is superior to voltage during sinus rhythm in localizing areas of delayed enhancement on magnetic resonance imaging: An assessment of the posterior left atrium in patients with persistent atrial fibrillation

Abstract

Background Bipolar electrogram voltage during sinus rhythm (V SR ) has been used as a surrogate for atrial fibrosis in guiding catheter ablation of persistent atrial fibrillation (AF), but the fixed rate and wavefront characteristics present during sinus rhythm may not accurately reflect underlying functional vulnerabilities responsible for AF maintenance. Objective The purpose of this study was determine whether, given adequate temporal sampling, the spatial distribution of mean AF voltage (V mAF ) better correlates with delayed-enhancement magnetic resonance imaging (MRI-DE)–detected atrial fibrosis than V SR . Methods AF was mapped (8 seconds) during index ablation for persistent AF (20 patients) using a 20-pole catheter (660 ± 28 points/map). After cardioversion, V SR was mapped (557 ± 326 points/map). Electroanatomic and MRI-DE maps were co-registered in 14 patients. Results The time course of V mAF was assessed from 1–40 AF cycles (∼8 seconds) at 1113 locations. V mAF stabilized with sampling >4 seconds (mean voltage error 0.05 mV). Paired point analysis of V mAF from segments acquired 30 seconds apart (3667 sites; 15 patients) showed strong correlation (r = 0.95; P <.001). Delayed enhancement (DE) was assessed across the posterior left atrial (LA) wall, occupying 33% ± 13%. V mAF distributions were (median [IQR]) 0.21 [0.14–0.35] mV in DE vs 0.52 [0.34–0.77] mV in non-DE regions. V SR distributions were 1.34 [0.65–2.48] mV in DE vs 2.37 [1.27–3.97] mV in non-DE. V mAF threshold of 0.35 mV yielded sensitivity of 75% and specificity of 79% in detecting MRI-DE compared with 63% and 67%, respectively, for V SR (1.8-mV threshold) . Conclusion The correlation between low-voltage and posterior LA MRI-DE is significantly improved when acquired during AF vs sinus rhythm. With adequate sampling, mean AF voltage is a reproducible marker reflecting the functional response to the underlying persistent AF substrate.

The correlation between the mean voltage recorded during atrial fibrillation and sinus rhythm during substrate mapping of the atria

“…In our study the mean voltages recorded throughout the LA were lower during AF than SR which is in keeping with a recent study in which the voltage recorded during AF demonstrated a better correlation than SR when compared with a DE-MRI of the posterior wall of the LA. [5] This study also demonstrated that AF voltage recordings tend to stabilize after a period of 4 seconds. For the first time we have found a linear correlation between the voltage amplitude in SR and AF with adequate temporal sampling in the most common locations for substrate.…”

Substrate mapping of the left atrium in persistent atrial fibrillation: spatial correlation of localized complex conduction patterns in global charge-density maps to low-voltage areas in 3D contact bipolar voltage maps

“…Kalman et al [14] reported that, in patients with PsAF, variation in rate and directionality of the wave front produces both general and regional changes in voltage, conduction velocity, and complex fractionation, resulting in significant changes in the BVM. Lim, et al [15] described that the correlation between LVA and MRI-DE in the LA is significantly improved when acquired during PsAF vs SR. More specifically, they reported that, with adequate sampling, mean PsAF voltage is a reproducible marker reflecting the functional response to the underlying PsAF substrate. This represents a limitation of our study.…”

Do most patients with obesity or type 2 diabetes, and atrial fibrillation, also have undiagnosed heart failure? A critical conceptual framework for understanding mechanisms and improving diagnosis and treatment

“…Coronary microvascular dysfunction is exceptionally common in HFpEF and, when present, is associated with a two‐fold increase in the prevalence of AF . Cardiac magnetic resonance imaging (MRI) reveals meaningful myocardial fibrosis (in the LA and LV) in both patients with HFpEF and those with AF . Fibrosis is indicative of an underlying atrial and ventricular myopathy and may precede the clinical identification of AF or HFpEF …”

“…29,30 Cardiac magnetic resonance imaging (MRI) reveals meaningful myocardial fibrosis (in the LA and LV) in both patients with HFpEF 31-36 and those with AF. 37,38 Fibrosis is indicative of an underlying atrial and ventricular myopathy and may precede the clinical identification of AF or HFpEF. 32,39,40…”