Left atrial wall stress distribution and its relationship to electrophysiologic remodeling in persistent atrial fibrillation.
ABSTRACT Atrial stretch causes remodeling that predisposes to atrial fibrillation. We tested the hypothesis that peaks in left atrial (LA) wall stress are associated with focal remodeling.
Nineteen patients underwent LA mapping before catheter ablation for persistent atrial fibrillation. Finite Element Analysis was used to predict wall stress distribution based on LA geometry from CT. The relationship was assessed between wall stress and (1) electrogram voltage and (2) complex fractionated atrial electrograms (CFAE), using CFAE mean (the mean interval between deflections). Wall stress varied widely within atria and between subjects (median, 36 kPa; interquartile range, 26-51 kP). Peaks in wall stress (≥90th percentile) were common at the pulmonary vein (PV) ostia (93%), the appendage ridge (100%), the high posterior wall (84%), and the anterior wall and septal regions (42-84%). Electrogram voltage showed an inverse relationship across quartiles for wall stress (19% difference across quartiles, P=0.016). There was no effect on CFAE mean across quartiles of wall stress. Receiver operating characteristic analysis showed high wall stress was associated with low voltage (ie, <0.5 mV) and electrical scar (ie, <0.05 mV; both P<0.0001) and with absence of CFAE (ie, CFAE mean <120 ms; P<0.0001). However, peaks in wall stress and CFAE were found at 88% of PV ostia.
Peaks in wall stress were associated with areas of low voltage, suggestive of focal remodeling. Although peaks in wall stress were not associated with LA CFAE, the PV ostia may respond differently.
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ABSTRACT: Restoration of sinus rhythm may result in an improvement of left heart function in patients with atrial fibrillation (AF). Cardiovascular magnetic resonance (CMR) feature tracking (FT) technique may help detect subtle wall-motion abnormalities. Consequently this study aimed to analyse existence and reversibility of subclinical cardiac dysfunction following atrial fibrillation ablation. 28 consecutive patients (mean age 61 years) with paroxysmal AF underwent pulmonary vein isolation. CMR imaging was done 3 (±3) days before and 3.4 (±1.1) months after ablation. Left heart function was determined by performing FT analysis. Statistical analysis included paired student's t test, random effects metaanalysis to assess the cohort's health status and Bland-Altman analysis. 17 patients (61 %) were free from AF at follow-up. Bland-Altman analysis showed good coefficients of variation. Of all 195 parameters, 27 changed (14 %):9 improved significantly (5 %), 12 worsened significantly (6 %), whereas 6 parameters worsened not significantly (3 %). 18 of 120 systolic parameters changed (15 %), 14 worsened (12 %), 4 improved (3 %). In 9 of 75 diastolic parameters, values changed (12 %): 5 improved (7 %) and 4 worsened (5 %). Meta-analysis revealed that our collective's FT values at baseline didn't differ significantly from healthy volunteers' values [Q values of 0.01 (p value 0.921) and 1.499 (p value 0.221)]. AF patients undergoing ablation appear to have near normal cardiac wall motion, which does not improve following successful ablation. Feature tracking analysis is a reliable tool to determine treatment effects but is more likely to show positive findings if the population is unhealthy.The international journal of cardiovascular imaging 09/2013; · 2.15 Impact Factor
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ABSTRACT: The aim of this study was to analyze the therapeutic effects of various methods for the treatment of chronic atrial fibrillation (AF). Randomized controlled trials (RCT) concerning drug therapy and catheter ablation for the treatment of chronic AF were retrieved. The RevMan 5.1 software package was used for the meta-analysis. A total of 20 papers were assessed in this study. The results of the analysis indicated that the success rate was lower [odds ratio (OR), 8.94; 95% confidence interval (CI), 4.70-17.02; P<0.0001] and the relapse rate was higher (OR, 0.07, 95% CI, 0.05-0.10; P<0.0001) for drug therapy compared with that for catheter ablation. With regard to different catheter ablation procedures, the success rate for pulmonary vein antrum isolation (PVAI) was lower compared with that for PVAI plus complex fractionated atrial electrogram (CFAE; OR, 0.53; 95% CI, 0.37-0.78; P=0.0001). Pulmonary vein isolation (PVI) plus left atrial ablation (LAA) had a higher success rate compared with PVI alone (OR, 2.79; 95% CI, 1.59-4.88, P=0.0003). There was not identified to be a significant difference in the success rates between PVAI and CFAE (OR, 2.05; 95% CI, 0.06-205.74; P=0.76) or between PVI and circumferential pulmonary vein isolation (CPVI; OR, 0.94; 95% CI, 0.29-3.00; P=0.91). All the funnel plots of publication bias were essentially symmetrical. In conclusion, the success rate was higher and the relapse rate was lower for catheter ablation compared with drug therapy. Among the different procedures of catheter ablation, there were no significant differences in success rate between two single procedures; however, the success rates were higher for the combined methods compared with those for the single methods.Experimental and therapeutic medicine 08/2013; 6(2):489-496. · 0.34 Impact Factor
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ABSTRACT: In humans, the existence of rotors or reentrant sources maintaining AF and the underlying electroanatomic substrate has not been well defined. Our objective was to determine the prevalence of localized rotational activation (RotA) in the left atrium (LA) during human AF and whether CFAEs or low voltage areas co-localize with RotA sites. We prospectively studied 32 patients (57±8yrs, 88% persistent AF) undergoing AF catheter ablation. Bipolar EGMs were recorded for 2.5sec during AF using a roving 20-pole circular catheter in the LA. RotA was defined as sequential temporal activation of bipoles around the circular catheter. Bipolar EGM fractionation index and bipolar voltage were used to define CFAEs and low voltage areas, respectively. In 21 (66%) patients, 47 RotA sites were identified. Few (9%) lasted 2.5sec (CL 183±6ms), while the majority (91%) were nonsustained (duration 610±288ms, CL 149±11ms). RotA was most common in the PV antrum (71%) and posterior LA (25%). CFAEs were recorded from 18±12% of LA area and most (92±7%) were not associated with RotA sites. However, 85% of RotA sites contained CFAEs. Very low voltage (<0.1mV) areas comprised 12±10% of LA area and were present in 23% of RotA sites. In patients with predominantly persistent AF, localized RotA is commonly present, but tends to be transient (<1 second). Although most CFAEs do not co-localize with RotA sites, the high prevalence of CFAEs and very low voltages within RotA sites may indicate slow conduction in diseased myocardium necessary for their maintenance.Heart rhythm: the official journal of the Heart Rhythm Society 09/2013; · 4.56 Impact Factor