A novel diagnostic tool to identify atrial endo-epicardial asynchrony using signal fingerprinting

OBJECTIVE

Patients with persistent atrial fibrillation (AF) have more electrical endo-epicardial asynchrony (EEA) during sinus rhythm (SR) than patients without AF. Prior mapping studies indicated that particularly unipolar, endo- and/or epicardial electrogram (EGM) morphology may be indicators of EEA. This study aim to develop a novel method for estimating the degree of EEA by using unipolar EGM characteristics recorded from either the endo- and/or epicardium.

METHODS

Simultaneous endo-epicardial mapping during sinus rhythm was performed in 86 patients. EGM characteristics, including unipolar voltages, low-voltage areas (LVAs), potential types (single, short/long double and fractionated potentials: SP, SDP, LDP and FP) and fractionation duration (FD) of double potentials (DP) and FP were compared between EEA and non-EEA areas. Asynchrony Fingerprinting Scores (AFS) containing quantified EGM characteristics were constructed to estimate the degree of EEA.

RESULTS

Endo- and epicardial sites of EEA areas are characterized by lower unipolar voltages, a higher number of LDPs and FPs and longer DP and FP durations. Patients with AF have lower potential voltages in EEA areas, along with alterations in the potential types. The EE-AFS, containing the proportion of endocardial LVAs and FD of epicardial DPs, had the highest predictive value for determining the degree of EEA (AUC: 0.913). Endo- and epi-AFS separately also showed good predictive values (AUC: 0.901 and 0.830 respectively).

CONCLUSIONS

EGM characteristics can be used to identify EEA areas. AFS can be utilized as a novel diagnostic tool for accurately estimating the degree of EEA. These characteristics potentially indicate AF related arrhythmogenic substrates.

Left atrial total emptying fraction measured by cardiovascular magnetic resonance imaging predicts low-voltage areas detected during electroanatomical mapping

AIMS

Low-voltage areas (LVAs) found during left atrial (LA) electroanatomical mapping are increasingly targeted by radiofrequency catheter ablation (RFCA) on top of pulmonary vein isolation to improve arrhythmia-free survival in patients with atrial fibrillation (AF). However, pre-procedural prediction of LVAs remains challenging. The purpose of the present study was to describe the association between parameters of LA function and dimensions, respectively, derived from pre-procedural cardiovascular magnetic resonance (CMR) imaging, and the presence of LVAs on LA voltage mapping.

METHODS AND RESULTS

Patients who underwent first-time RFCA for paroxysmal or persistent AF and who were in stable sinus rhythm during pre-procedural CMR imaging were included in this study. Cardiovascular magnetic resonance-derived parameters of LA function and dimensions were calculated. Low-voltage areas were defined as areas with bipolar voltage amplitudes of ≤0.5 mV on electroanatomical mapping. In total, 259 consecutive patients were included in this analysis. Low-voltage areas were found in 25 of 259 patients (9.7%). Compared with those without LVAs, patients with LVAs were significantly older, were more likely to be female, had a higher CHA2DS2-VASc score, had larger LA volumes, and had a lower LA total emptying fraction (TEF). In multivariate analysis, only LA TEF [odds ratio (OR) 0.885, 95% confidence interval (CI) 0.846-0.926, P < 0.001] and the CHA2DS2-VASc score (OR 1.507, 95% CI 1.115-2.038, P = 0.008) remained independently associated with the presence of LVAs.

CONCLUSION

Left atrial TEF and the CHA2DS2-VASc score were independently associated with the presence of LVAs found during LA electroanatomical mapping. These findings may help to improve pre-procedural prediction of pro-arrhythmogenic LVAs and to improve peri-procedural patient management.

Atrial extrasystoles enhance low-voltage fractionation electrograms in patients with atrial fibrillation

BACKGROUND AND AIMS

Atrial extrasystoles (AES) provoke conduction disorders and may trigger episodes of atrial fibrillation (AF). However, the direction- and rate-dependency of electrophysiological tissue properties on epicardial unipolar electrogram (EGM) morphology is unknown. Therefore, this study examined the impact of spontaneous AES on potential amplitude, -fractionation, -duration, and low-voltage areas (LVAs), and correlated these differences with various degrees of prematurity and aberrancy.

METHODS AND RESULTS

Intra-operative high-resolution epicardial mapping of the right and left atrium, Bachmann's Bundle, and pulmonary vein area was performed during sinus rhythm (SR) in 287 patients (60 with AF). AES were categorized according to their prematurity index (>25% shortening) and degree of aberrancy (none, mild/opposite, moderate and severe). In total, 837 unique AES (457 premature; 58 mild/opposite, 355 moderate, and 154 severe aberrant) were included. The average prematurity index was 28% [12-45]. Comparing SR and AES, average voltage decreased (-1.1 [-1.2, -0.9] mV, P < 0.001) at all atrial regions, whereas the amount of LVAs and fractionation increased (respectively, +3.4 [2.7, 4.1] % and +3.2 [2.6, 3.7] %, P < 0.001). Only weak or moderate correlations were found between EGM morphology parameters and prematurity indices (R2 < 0.299, P < 0.001). All parameters were, however, most severely affected by either mild/opposite or severely aberrant AES, in which the effect was more pronounced in AF patients. Also, there were considerable regional differences in effects provoked by AES.

CONCLUSION

Unipolar EGM characteristics during spontaneous AES are mainly directional-dependent and not rate-dependent. AF patients have more direction-dependent conduction disorders, indicating enhanced non-uniform anisotropy that is uncovered by spontaneous AES.

Left Atrial Localized Low-Voltage Areas Indicate Whole Left Atrial Electrophysiological Degeneration in Atrial Fibrillation Patients

BACKGROUND

The efficacy of ablation targeting low-voltage areas (LVAs) is controversial, although LVA presence is well known to be associated with atrial fibrillation (AF) recurrence after ablation. AF substrate may not localize within LVAs.Methods and Results:This observational study enrolled 405 consecutive patients who underwent an initial AF ablation procedure. The left atrial (LA) voltage map was obtained after pulmonary vein isolation. LVAs were defined as areas with voltage <0.5 mV. To estimate whole LA electrophysiological degeneration, mean regional voltage at each of the 6 regions and LA total conduction velocity were measured. LVAs existed in 143 of 405 (35.3%) patients. Patients with LVAs demonstrated lower mean regional voltages throughout all 6 regions compared to those without LVAs (1.3 [1.8, 0.8] vs. 0.6 [1.0, 0.2] mV for the anterior wall, P<0.001). In contrast, LA conduction velocity was lower in patients with LVAs than in those without (0.89 [1.01, 0.74] vs. 0.93 [1.03, 0.87] m/s, P<0.001). Multivariate analysis revealed that low LA total conduction velocity and a higher number of regions with mean voltage reduction were independently associated with AF recurrence, although LVA presence was not.

CONCLUSIONS

Patients with localized LA LVAs were characterized by whole LA electrophysiological degeneration as assessed by mean regional voltage and conduction velocity. In addition, whole LA electrophysiological degeneration parameters were well associated with AF recurrence.

Prediction of low-voltage areas using modified APPLE score

AIMS

The presence of low-voltage areas (LVAs) in patients with atrial fibrillation (AF) reflects left atrial (LA) electroanatomical substrate, which is essential for individualized AF management. However, echocardiographic anteroposterior LA diameter included into previous LVAs prediction scores does not mirror LA size accurately and impaired left ventricular ejection fraction (LV-EF) is not directly associated with atrial myopathy. Therefore, we aimed to compare a modified (m)APPLE score, which included LA volume (LAV) and LA emptying fraction (LA-EF) with the regular APPLE score for the prediction of LVAs.

METHODS AND RESULTS

In patients undergoing first AF catheter ablation, LVAs were determined peri-interventionally using high-density maps and defined as signal amplitude <0.5 mV. All patients underwent cardiovascular magnetic resonance imaging before intervention. The APPLE (one point for Age ≥ 65 years, Persistent AF, imPaired eGFR ≤ 60 mL/min/1.73 m2, LA diameter ≥ 43 mm, and LVEF < 50%) and (m)APPLE (last two variables changed by LAV ≥ 39 mL/m2, and LA-EF < 31%) scores were calculated at baseline. The study population included 219 patients [median age 65 (interquartile range 57-72) years, 41% females, 59% persistent AF, 25% LVAs]. Both scores were significantly associated with LVAs [OR 1.817, 95% CI 1.376-2.399 for APPLE and 2.288, 95% CI 1.650-3.172 for (m)APPLE]. Using receiver operating characteristic curves analysis, the (m)APPLE score [area under the curve (AUC) 0.779, 95% CI 0.702-0.855] showed better LVAs prediction than the APPLE score (AUC 0.704, 95% CI 0.623-0.784), however, without statistically significant difference (P = 0.233).

CONCLUSION

The modified (m)APPLE score demonstrated good prognostic value for LVAs prediction and was comparable with the regular APPLE score.

Left and right atrial appendage functional features as predictors for voltage-defined left atrial remodelling in patients with long-standing persistent atrial fibrillation

It was hypothesised that left atrial (LA) fibrosis identified by the presence of low-voltage areas (LVA) may influence the mechanical and electrical function of the left (LAA) and right (RAA) atrial appendage among the long-standing persistent atrial fibrillation (LSPAF) population. 140 consecutive patients underwent voltage mapping of LA with a multielectrode catheter following pulmonary vein isolation and restoration of sinus rhythm with cardioversion. Echocardiography determined LAA peak outflow and inflow velocities and intracardiac catheter-based mean LAA and RAA AF cycle length (AFCL) were obtained during AF before ablation. The impact of flow velocities and AFCL on the prevalence and location of LVA was further evaluated. LVA were detected in 54% of the patients. 14% of the patients presented severe global LVA burden > 20% of the total LA surface area. 29% of the patients presented a disseminated pattern of remodelling as 3 out of 5 LA segments were affected. LAA AFCL, RAA AFCL, LAA flow velocities did not predict the absolute presence of LVA. However LAA AFCL > 155 ms predicted disseminated LVA pattern and LAA AFCL > 165 ms severe LVA incidence. LAA AFCL > 155 ms was predictive for existence of LVA within antero-septal LA segments whilst LAA emptying velocity ≤ 0.2 m/s within lateral wall. Moreover RAA AFCL > 165 ms was strongly related to the presence of LAA AFCL > 15 ms and > 165 ms. LAA and RAA functional assessment was predictive of the presence of advanced stages of voltage-defined LA fibrosis and its regional distribution among LSPAF population.

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

Purpose

This study aimed to investigate the spatial relationship between low-voltage areas (LVAs) in bipolar voltage mapping (BVM) and localized complex conduction (LCC)-cores in a global, non-contact, charge-density-based imaging, and mapping system (AcM).

Methods

Patients with history of index PVI for PsAF and scheduled for a repeat ablation procedure for recurrence of the same arrhythmia were enrolled between August 2018 and February 2020. All patients underwent both substrate mappings of the left atrium (LA) with the CARTO 3D map-ping system and with AcM.

Results

Ten patients where included in our analysis. All presented with persistency of PVI in all veins at the moment of repeat procedure. There was no linear relationship in BVM maps between SR and CSd (correlation coefficient 0.31 ± 0.15), SR and CSp (0.36 ± 0.12) and CSd and CSp (0.43 ± 0.10). The % overlap of localized irregular activation (LIA), localized rotational activation (LRA) and Focal (F) regions with LVA was lower at 0.2 mV compared to 0.5 mV (4.97 ± 7.39%, 3.27 ± 5.25%, 1.09 ± 1.92% and 12.59 ± 11.81%, 7.8 ± 9.20%, 4.62 ± 5.27%). Sensitivity and specificity are not significantly different when comparing composite maps with different LVA cut-offs. AURC was 0.46, 0.48, and 0.39 for LIA, LRA, and Focal, respectively.

Conclusion

Due to wave front direction dependency, LVAs mapped with BVM in sinus rhythm and during coronary sinus pacing only partially overlap in patients with PsAF. LCC-cores mapped during PsAF partially co-localize with LVAs.

High Brain Natriuretic Peptide Level Predicts The Prevalence Of Low-Voltage Areas And Poor Rhythm Outcome In Patients Undergoing Atrial Fibrillation Ablation

Backgrounds

The prevalence of residual left atrial low-voltage areas (LVAs) is associated with atrial fibrillation (AF) recurrence after pulmonary vein isolation. Brain natriuretic peptide (BNP) may be increased in AF patients and may raise AF recurrence risk after catheter ablation. We investigated the association between BNP and the prevalence of LVAs.

Methods

One hundred and eighty three consecutive AF cases were retrospectively enrolled that underwent initial ablation for AF (persistent AF, 82 [45%] patients). Serum BNP was measured before ablation and the natural logarithm of BNP (log-BNP) was calculated. Low-voltage points were defined as sites with left atrial electrogram amplitude <0.5 mV. LVAs were defined as regions with ≥5% low-voltage points across the total surface area of the left atrium.

Results

Of the 183 patients, 38 (21%) had LVAs. Patients with LVAs demonstrated higher log-BNP (4.8±0.9 vs. 3.9±1.2, P<0.001). The optimal cut-off value of log-BNP was 4.4, which was equivalent to 81 pg/mL of BNP. LVAs were more frequent in patients with higher log-BNP. In multivariate analysis, log-BNP >4.4 was an independent predictor of LVAs (odds ratio 2.7 [95% confidence interval 1.01-7.1], P=0.048). Freedom from AF recurrence was significantly lower in patients with than without high log-BNP (P=0.007).

Conclusions

BNP correlated with the prevalence of left atrial LVAs and AF recurrence in patients with AF undergoing catheter ablation.

Left atrial size and total atrial emptying fraction in atrial fibrillation progression

BACKGROUND

Left atrial (LA) size and low-voltage areas (LVA) mirror atrial fibrillation (AF) progression. Whether these factors are important for the impairment of total atrial emptying fraction is understudied.

OBJECTIVE

The aim of the present analysis was to investigate the association between LA volume and total atrial emptying fraction with AF progression phenotypes: persistent AF and LVA.

METHODS

Patients undergoing first AF ablation were included in the analysis. LVA were determined using high-density maps and defined as <0.5 mV. All patients underwent cardiovascular magnetic resonance imaging before the intervention. Cardiovascular magnetic resonance data (LA volume, LA emptying fraction [LA-EF], and right atrial emptying fraction [RA-EF]) were measured in all patients.

RESULTS

The study population included 211 patients (65 ± 11 years; 124 (59%) men; 122 (58%) persistent AF; 54 (26%) LVA). There were 4 disease progression groups: paroxysmal AF without LVA, paroxysmal AF with LVA, persistent AF without LVA, and persistent AF with LVA. While LA volume increased according to the AF progression phenotype (98 ± 27, 145 ± 34, 134 ± 41, 141 ± 39 mL, respectively; P < .001), total LA-EF (51% ± 17%, 32% ± 17%, 33% ± 17%, 22% ± 11%; P < .001) and RA-EF (47% ± 13%, 36% ± 17%, 30% ± 16%, 23% ± 12%; P < .001) decreased. In multivariable analysis, age (odds ratio [OR] 1.084; 95% confidence interval [CI] 1.028-1.142; P = .003), persistent AF (OR 3.478; 95% CI 1.117-10.830; P = .031), and total LA-EF (OR 0.933; 95% CI 0.899-0.968; P < .001) showed a significant association for LVA. Using receiver operating characteristic curve analysis, LA-EF (area under the curve 0.778; 95% CI 0.711-0.846; P < .001) and RA-EF (area under the curve 0.726; 95% CI 0.650-0.802; P < .001) were significantly associated with the absence of LVA.

CONCLUSION

LVA and persistent AF are associated with worse total atrial emptying fraction.

Agreement between gadolinium-enhanced cardiac magnetic resonance and electro-anatomical maps in patients with non-ischaemic dilated cardiomyopathy and ventricular arrhythmias

AIMS

We sought to investigate the overlap between late gadolinium enhancement (LGE) in cardiac magnetic resonance (CMR) and electro-anatomical maps (EAM) of patients with non-ischaemic dilated cardiomyopathy (NIDCM) and how it relates with the outcomes after catheter ablation of ventricular arrhythmias (VA).

METHODS AND RESULTS

We identified 50 patients with NIDCM who received CMR and ablation for VA. Late gadolinium enhancement was detected in 16 (32%) patients, mostly in those presenting with sustained ventricular tachycardia (VT): 15 patients. Low-voltage areas (<1.5 mV) were observed in 23 (46%) cases; in 7 (14%) cases without evidence of LGE. Using a threshold of 1.5 mV, a good and partially good agreement between the bipolar EAM and LGE-CMR was observed in only 4 (8%) and 9 (18%) patients, respectively. With further adjustments of EAM to match the LGE, we defined new cut-off limits of median 1.5 and 5 mV for bipolar and unipolar maps, respectively. Most VT exits (12 out of 16 patients) were found in areas with LGE. VT exits were found in segments without LGE in two patients with VT recurrence as well as in two patients without recurrence, P = 0.77. In patients with VT recurrence, the LGE volume was significantly larger than in those without recurrence: 12% ± 5.8% vs. 6.9% ± 3.4%; P = 0.049.

CONCLUSIONS

In NIDCM, the agreement between LGE and bipolar EAM was fairly poor but can be improved with adjustment of the thresholds for EAM according to the amount of LGE. The outcomes were related to the volume of LGE.

Role of NT-proANP and NT-proBNP in patients with atrial fibrillation: Association with atrial fibrillation progression phenotypes

BACKGROUND

Electroanatomic remodeling in atrial fibrillation (AF) leads to disease initiation and perpetuation. Although atrial natriuretic peptide (ANP) is specifically expressed in the atria and is involved in atrial remodeling, B-type natriuretic peptide (BNP) is associated with mortality and cardiovascular events in AF.

OBJECTIVE

The purpose of this study was to investigate the association between N-terminal (NT)-proBNP and NT-proANP levels with 3 AF progression phenotypes: persistent AF, left atrial diameter (LAD) dilation, and left atrial low-voltage areas (LVAs).

METHODS

We studied NT-proBNP and NT-proANP in a discovery cohort (n = 51) and replicated the findings in a validation cohort (n = 241) undergoing first AF catheter ablation. Blood plasma samples from femoral vein were collected before catheter ablation. LVAs were determined using high-density maps and defined as <0.5 mV.

RESULTS

In our pilot cohort (age 62 ± 10 years; 63% male; 59% persistent AF; 22% LVA), NT-proANP-but not NT-proBNP-levels were significantly higher in LVA patients (14.1 vs 8.6 ng/mL; P = .009) and correlated with LAD (r² = 0.362; P = .011). These results were replicated in the validation cohort (age 64 ± 11 years; 59% male; 59% persistent AF; 27% LVA) (12.7 vs 8.8 ng/mL; P = .016) and correlated with LAD (r² = 0.180; P = .019). NT-proANP levels increased according to 4 disease progression groups: paroxysmal AF without LVA, persistent AF without LVA, paroxysmal AF with LVA, and persistent AF with LVA (mean 15, 20, 19, and 27 ng/mL, respectively; P = .004).

CONCLUSION

Natriuretic peptides show different sensitivity for phenotypes of AF progression. The clinical impact of NT-proANP in refining individualized therapy and disease prevention should be addressed in larger studies.