Left Atrial Scar Research Articles

Abstract 15901: Radiofrequency Ablation for Persistent Atrial Fibrillation: Earlier Catheter-based Interventions are associated With Better Outcomes and in Direct Association With Markers of Pathways of Atrial Remodeling

Introduction: Persistent atrial fibrillation (PerAF) ablation has been associated with significant recurrence rates which could reflect progressive AF-related atrial remodeling. We hypothesized that the first-diagnosis to ablation time for PerAF is a major determinant of success rates and in direct association with pathways of atrial remodeling. Methods: Two-year outcomes were assessed in 1241 patients undergoing first time ablation of PerAF between January 2005 and December 2012 at our institution. The time intervals between the first diagnosis of PerF and the ablation procedures were determined. Patients had echocardiograms and measures of B-type natriuretic peptide (BNP) and C-reactive protein (CRP) before the ablation procedures. During ablations, patients with atrial scarring by voltage were identified. Results: The median time-to-ablation since the first PerAF diagnosis was 3 years (interquartile range 1-6.5). With longer diagnosis-to-ablation time (based on quartiles), there was a significant increase in BNP levels (p=0.01), CRP levels (p<0.0001), left atrial size (p=0.03) and scarring (p=0.04). Atrial arrhythmia recurred after a single ablation in 555 patients (44.7%); and 364 (29.3%) underwent repeat ablations. At last follow-up, 1005 patients (81.0%, 390 on antiarrhythmic medications) were either arrhythmia free or had their arrhythmia controlled. In Cox Proportional Hazard analyzes, BNP levels, CRP levels, left atrial size and scarring were associated with arrhythmia recurrence. The diagnosis-to-ablation time had the strongest association with success rates which persisted in multivariate Cox analyzes (HR for recurrence per +1Log diagnosis-to-ablation time 1.25, 95%CI 1.11-1.42, p<0.0001; 4th vs. 1st quartile 2.27, 95%CI 1.52-3.47, p<0.0001). Conclusions: The success rates with PerAF ablation are highest with early intervention, that is ablation before the progression of atrial remodeling.

Novel association of polymorphic genetic variants with predictors of outcome of catheter ablation in atrial fibrillation: new directions from a prospective study (DECAF)

Non-pulmonary vein (non-PV) triggers and left atrial (LA) scars perpetuate atrial fibrillation (AF) and limit the success rate of catheter ablation. In order to understand the genetic basis of these risk factors, we examined the association of selected single nucleotide polymorphisms (SNPs) with scar and non-PV triggers. Four hundred AF patients (67 %male, 62±12 years, LA size 45.3±7 mm, 64%non-paroxysmal) undergoing catheter ablation were prospectively enrolled. DNA extractions for16 AF-related SNPS from blood samples were performed of which 371 DNA samples were available for genotyping. Multivariate logistic regression analysis was used for assessing predictive role of individual SNP, and logistic kernel-machine approach was applied to test the cumulative effect of multiple SNPs as a group with non-PV triggers and LA scar. False discovery rate (FDR) was computed for all candidate SNPs to address multiple testing. SNPs rs6599230 and rs6843082 were inversely associated (OR 0.68, p=0.04, and 0.62, p=0.01, respectively) whereas rs1448817 (OR 1.74, p=0.04) and rs7193343 (OR 1.66, p=0.02) predicted higher risk of non-PV triggers. Genotypes for rs6599230 and rs6843082 conferred 51 % reduction in the odds for non-PV triggers (combined OR 0.49, p=0.019), while rs1448817 and rs7193343 demonstrated a combined OR of 1.93, p=0.025. FDR was controlled at 16 % to adjust for multiple testing. For LA scar, inverse association was observed with rs1448817 (OR 0.29, p=0.006), rs17042171 (OR 0.27, p=0.032), rs3807989 (OR 0.54, p=0.017), and rs6843082 (OR 0.56, p=0.009). Two SNPs were associated with increased scar risk: rs17375901 (OR 3.68, p=0.03) and rs7193343 (OR 1.74, p=0.037). For global association of SNPs with left atrial scar FDR was controlled at ≤10 % to adjust for multiple testing. This study has a strong clinical significance as it provides important insights into the molecular basis of pertinent therapeutic targets. Our findings demonstrate that the presence of certain genetic polymorphisms increases the risk of scar and non-PV triggers in AF patients. Therefore, PVAI alone will not be enough to eliminate the arrhythmia and the operators may need to identify and isolate the non-PV foci to maximize procedural success in patients carrying these risk variants. Clinical trial registration clinicaltrials.gov (NCT01751607).

Poor scar formation after ablation is associated with atrial fibrillation recurrence.

Patients routinely undergo ablation for atrial fibrillation (AF) but the recurrence rate remains high. We explored in this study whether poor scar formation as seen on late-gadolinium enhancement magnetic resonance imaging (LGE-MRI) correlates with AF recurrence following ablation. We retrospectively identified 94 consecutive patients who underwent their initial ablation for AF at our institution and had pre-procedural magnetic resonance angiography (MRA) merged with left atrial (LA) anatomy in an electroanatomic mapping (EAM) system, ablated areas marked intraprocedurally in EAM, 3-month post-ablation LGE-MRI for assessment of scar, and minimum of 3-months of clinical follow-up. Ablated area was quantified retrospectively in EAM and scarred area was quantified in the 3-month post-ablation LGE-MRI. With the mean follow-up of 336 days, 26 out of 94 patients had AF recurrence. Age, hypertension, and heart failure were not associated with AF recurrence, but LA size and difference between EAM ablated area and LGE-MRI scar area was associated with higher AF recurrence. For each percent higher difference between EAM ablated area and LGE-MRI scar area, there was a 7-9% higher AF recurrence (p values 0.001-0.003) depending on the multivariate analysis. In AF ablation, poor scar formation as seen on LGE-MRI was associated with AF recurrence. Improved mapping and ablation techniques are necessary to achieve the desired LA scar and reduce AF recurrence.

MRI Evaluation of Radiofrequency, Cryothermal, and Laser Left Atrial Lesion Formation in Patients with Atrial Fibrillation.

Catheter ablation utilizing radiofrequency (RF), Cryothermal (Cryo), or Laser energy is effective for treatment of atrial fibrillation (AF). Late gadolinium enhancement magnetic resonance imaging (LGE-MRI) has been used to estimate the burden of left atrial (LA) fibrosis, but no data exist regarding structural changes following each modality. We sought to compare the baseline to postprocedure change in LA scar burden following RF, Cryo, or Laser ablation for treatment of AF. Seventeen patients with AF underwent initial pulmonary vein (PV) isolation (PVI) using RF (n = 7), Cryo (n = 5), and Laser (n = 5). LGE-MRI was performed prior to and at 24 hours and 3 months after PVI. In a linear mixed-effects model, accounting for intrapatient clustering of data and interpatient differences in baseline scar, LGE extent was significantly increased at 24 hours postablation (+14.6 ± 1.9% of LA myocardium, P < 0.001), and remained stable from 24 hours to 3 months (+0.12 ± 1.9%, P = 0.951). There was no statistically significant difference between the postablation scar extent among ablation modalities when compared to RF (Cryo +4.5 ± 3.0%, P = 0.123; Laser -3.2 ± 3.0%, P = 0.291). The PV antral LGE intensity was increased by 25.1 ± 3.8% (P<0.001) 24 hours after ablation and additionally increased by 8.1 ± 3.8 at 3 months (P = 0.033). Radiofrequency, Cryo, and laser ablation result in increased LGE extent and intensity at 24 hours and 3 months postablation. No statistically significant difference was noted in the extent of fibrosis induced by any modality.

DECAAF: Balloon Cryoablation Results in More LA Scarring Than Other Ablation Techniques

Data from a cohort study of the DECAAF trial demonstrate that late gadolinium enhancement magnetic resonance imaging is a useful technique for identifying left atrial scarring following ablation of atrial fibrillation. Of 3 different ablation techniques, cryoablation produces more scarring than does point-by-point and multipolar RF ablation. Neither overall scar nor complete pulmonary vein encirclement was a significant predictor of arrhythmia recurrence.

Impact of Uncontrolled Hypertension on Atrial Fibrillation Ablation Outcome

ObjectivesThe goal of this study was to evaluate the impact of hypertension on the outcome of atrial fibrillation (AF) ablation. BackgroundHypertension is a well-known independent risk factor for incident AF. MethodsA total of 531 consecutive patients undergoing AF ablation were enrolled in this study and divided into 3 groups: patients with uncontrolled hypertension despite medical treatment (group I, n = 160), patients with controlled hypertension (group II, n = 192), and patients without hypertension (group III, n = 179). Pulmonary vein (PV) antrum and posterior wall isolation was always performed, and non-PV triggers were identified during isoproterenol infusion. All patients underwent extensive follow-up. ResultsThree groups differed in terms of left atrial (LA) size, non-PV triggers, and moderate/severe LA scar. Non-PV triggers were present in 94 (58.8%), 64 (33.3%), and 50 (27.9%) patients in groups I, II, and III, respectively (p < 0.001). After 19 ± 7.7 months of follow-up, 65 (40.6%), 54 (28.1%), and 46 (25.7%) patients in groups I, II, and III had recurrences (log-rank test, p = 0.003). Among patients in group I who underwent additional non-PV trigger ablation, freedom from AF/atrial tachycardia was 69.8%, which was similar to groups II and III procedural success (log-rank p = 0.7). After adjusting for confounders, uncontrolled hypertension (group I) (hazard ratio [HR]: 1.52, p = 0.045), non-PV triggers (HR: 1.85, p < 0.001), and nonparoxysmal AF (HR: 1.64, p = 0.002) demonstrated significant association with arrhythmia recurrence. ConclusionsControlled hypertension does not affect the AF ablation outcome when compared with patients without hypertension. By contrast, uncontrolled hypertension confers higher AF recurrence risk and requires more extensive ablation.

Abstract 15318: Association of Single-Nucleotide Polymorphisms with Left Atrial Scar in Patients with Atrial Fibrillation

Introduction: Earlier studies have demonstrated that some AF patients develop spontaneous atrial scarring that leads to genesis and perpetuation of the arrhythmia. However, it is still unclear why it happens in some and not in others. Therefore, we hypothesized that the atrial scar phenotype is associated with certain specific genetic variants and examined the relationship between AF-related single-nucleotide polymorphisms (SNP) and left atrial scar. Methods: Four hundred AF patients (67% male, 62±12 year, left atrial size 45.3±7 mm, 64% non-paroxysmal) undergoing catheter ablation were prospectively enrolled at our center. DNA extraction and genotyping for 16 AF-associated SNPS identified by GWAS study were performed from the collected blood samples using Qiagen QiaAMP 96 well blood kit and TaqMan assay respectively. Three hundred seventy-two DNA samples were available for genotyping. The Hardy-Weinberg equilibrium was assessed using Chi-square analyses. Multivariable logistic model was utilized to identify predictors of LA scar after adjusting for age, gender, LA size, hypertension and diabetes mellitus and odds ratio (OR) and 95% confidence intervals were computed. Results: Of all 16 SNPs, rs3807989 showed a strong inverse association with LA scar at univariate analysis (0.54 [0.348-0.89] p= 0.014) in the overall population. After adjustment for covariates, the association became highly significant indicating a 50% reduction in scar risk (OR 0.50 (0.30-0.83) p=0.007). When stratified by type of AF, rs3807989 genotype predicted a substantially stronger 69% risk-reduction in the non-PAF population (OR 0.31 (0.15-0.62) p=0.0009). Conclusion: The SNP, rs3807989 on chromosome 7p31, was demonstrated to be associated with reduced risk of left atrial scar formation in AF patients. This genetic variant is located in close proximity to the caveolin-1 gene which is known to have an anti-fibrotic role by inhibiting transforming growth factor-β1, a key mediator in the fibrosis process. Therefore, it can be postulated that by some unknown mechanism the candidate chromosomal variant potentially upregulates caveolin-1 function resulting in attenuation of fibrosis and scar formation.

Voltage mapping for delineating inexcitable dense scar in patients undergoing atrial fibrillation ablation: a new end point for enhancing pulmonary vein isolation.

Characterization of left atrial scar using bipolar voltage (BiV) mapping is not well defined. We have previously shown that the BiV range of 0.2-0.45 mV can identify chronic scar from prior pulmonary vein isolation (PVI). This study sought to determine a BiV range that can identify atrial inexcitable dense scar (IDS) in patients acutely and chronically after PVI. Thirty consecutive patients undergoing first time (n = 15) or redo (n = 15) PVI were included. A left atrial shell was created using electroanatomic mapping, and IDS was defined by inability to capture at an output of 10 mA and a pulse width of 2 ms in sinus rhythm, circumferentially at the edge of PVI-related scar (≤5 mm). At each pacing site, BiV amplitude and atrial capture were recorded. Overall, 837 pacing sites were assessed. BiV predicted IDS (receiver operating characteristic curve area 0.93 for first time PVI and 0.90 for redo PVI). In first time PVI, the best BiV value to predict IDS was 0.45 mV for the left pulmonary vein-left atrial appendage (LAA-LPV) ridge (sensitivity 0.98; specificity 1.0) and 0.2 mV for other localizations (sensitivity 0.91; specificity 0.86). In redo PVI, the best BiV value to predict IDS was 0.2 mV for the LAA-LPV ridge (sensitivity 0.77; specificity 1.0) and 0.15 mV for other localizations (sensitivity 0.81; specificity 0.82). BiV reproducibly identifies acute and chronic IDS using a cutoff value of 0.2 mV (0.45 mV for the LAA-LPV ridge) in patients undergoing first time PVI and 0.15 mV (0.2 mV for the LAA-LPV ridge) in patients undergoing redo PVI. IDS thus identified may be a rigorous tool for validating PVI.

The impact of hypertension on the electromechanical properties and outcome of catheter ablation in atrial fibrillation patients.

Although hypertension is associated with atrial fibrillation (AF), the impact of hypertension on the electromechanical properties and outcome of catheter ablation in AF patients is unclear. AF patients [n=213, 136 paroxysmal AF (PAF) patients and 77 persistent AF patients] undergoing circumferential pulmonary vein (PV) isolation guided by CARTO mapping were enrolled, and then were divided into normotension group and hypertension group. Several left atrial (LA) electroanatomical parameters determined by the CARTO system were compared between groups. The LA bipolar voltage was lower in PAF patients with than without hypertension (1.44±1.09 vs. 1.92±0.76 mV, P=0.048); a significant difference was also observed in persistent AF patients. Hypertension significantly increased the size of the LA scar and low-voltage zones (LVZs) in both PAF and persistent AF patients. However, hypertension did not significantly affect recurrence in either PAF or persistent AF patients. The LA bipolar voltage was higher in PAF patients without recurrence than in those with recurrence (1.77±1.01 vs. 1.29±0.93 mV, P=0.048); a significant difference was also observed in persistent AF patients. PAF and persistent AF patients with AF recurrence had significantly larger LA scar and LVZs than patients without recurrence. Hypertension has a significant impact on the LA electromechanical properties in AF patients, and the LA substrate has an important influence on the outcome of catheter ablation.

Cardiac magnetic resonance imaging to detect non-contiguous scar following atrial fibrillation ablation: identifying our knowledge gaps

This editorial refers to ‘Cardiac magnetic resonance and electroanatomical mapping of acute and chronic atrial ablation injury: a histological validation study’, by J.L. Harrison et al. doi:10.1093/eurheartj/eht560. The advent of catheter ablation for atrial fibrillation (AF) has revolutionized our approach to this most common of arrhythmias, and in selected instances the procedure is now considered first-line therapy. Indeed, over the past decade, tools and techniques have evolved to the stage where this procedure is routinely offered to many patients with refractory paroxysmal and early persistent AF. However, the recurrence rate following ablation continues to present an ongoing challenge with need for repeat ablation procedures in anywhere between 20% and 50% of patients. While there may be many reasons for recurrence, key amongst these is the development of recurrent pulmonary vein (PV) to left atrial (LA) connection. Over recent years, the success in cardiac magnetic resonance (CMR) imaging of ventricular scar has led to attempts to reproduce these results in the atrium. In particular, a number of studies have used CMR late gadolinium enhancement (LGE) in order to characterize non-invasively the extent and distribution of scarring present following AF ablation.1–3 However, translation of the excellent results obtained from CMR imaging of ventricular scar to the atrium has faced the considerable hurdles associated with image resolution in a thin-walled structure and the absence of a widely available and standardized protocol for analysis of atrial scar. Several studies demonstrated that CMR could identify the extent of LA scarring present at 3 months post-ablation and observed that patients with more extensive scar (or greater percentage scar around the PV circumference) had a lower AF recurrence rate.2,4 In addition, there appears to be a correlation between measured contact force at the time of ablation and the extent of CMR-determined …

Idiopathic Right Atrial Scar

Right atrial scars participating in macro reentrant tachycardia circuits are generally seen in patients following cardiac surgery for congenital heart disease. Right and left atrial scars without any prior cardiac surgery have been reported but are rare [1,2]. A 65 year old farmer had recurrent drug refractory atrial tachycardia for which he underwent an EP study with three dimensional mapping and radiofrequency ablation. He was not a diabetic or hypertensive, had a structurally normal heart with preserved biventricular function, and normal coronaries. He had not undergone any cardiac surgery prior. Three dimensional mapping was done using CARTO 3 (Biosence, Webster). Sinus rhythm mapping of the right atrium (RA) showed a large atrial scar, defined as electrically silent areas with no recordable activity or bipolar voltage amplitude < 0.25 V. The scar was distributed over posterior, anterior and anterolateral areas near the tricuspid annulus (TA). Mapping during tachycardia showed macro reentrant tachycardia (cycle length =370 msec) propagating around RA scar. Figure 1 shows the sinus rhythm bipolar voltage map of the right atrium (RA) shows the large extent of the RA scar. Figure 2 shows the split atrial potentials mapped at the scar borders. Figure 3 shows activation map of atrial tachycardia, demonstrating Early meets late at the upper scar border.

Detection of left atrial scar and changes of cardiac function in relation to AF ablation, by 3D late gadolinium enhancement

Background Atrial Fibrillation (AF) is the most common arrhythmia in clinical practice; cathete ra blation (AFCA) is aw idespread treatment. Determinants of AFCA success and post-AFCA left atrial remodeling are poorly understood. Delayed Enhancement Cardiac Magnetic Resonance (DE-CMR) has been used to image LA scar post-AFCA and its relation to ablation outcome. Here we explored the role of postablation LA scar in subsequent cardiac remodeling. Methods We correlated post AFCA scar with cardiac volumes and function including LA volume, LV ejection fraction (LVEF), and LV cardiac output (LVCO). In a retrospective analysis, we identified 46 patients who underwent AFCA -pulmonary vein antral isolation in whom DE-CMR was obtained before and after AFCA (174 ± 160 days postablation). In 20 patients, a repeat AFCA procedure was performed due to recurrent AF. DE-CMR procedure was performed utilizing a navigated 3D inversion recovery gradient echo sequence (Siemens 1.5T Avanto or 3.0T Verio) approximately 15 minutes after administration of 0.2 mmol/kg Gadolinium (Magnevist). Scans were ECG-gated and acquired during a 150 ms window in mid-diastole with navigator-gating and fat suppression. We have developed an image analysis method and graphical user interface (GUI) to semi-automatically quantify hyperenhanced regions (scar) in the entire LA wall. Scar was quantified semi-automatically as fraction of LA contour in every slice from base to roof. STATA/IC 13.0 was used for statistical analysis. Two-way Interclass Correlation (ICC) for rater agreement was tested for LA perimeter and LA scar detection between two independent readers for 40 MRI slices. Variable normality was assessed with the Shapiro-Wilk test. The Wilcoxon signed-rank test was used to determine statistical significance between non-parametric variables in pre and post AFCA. Results ICC indicates similarity between observers in both LA Perimeter (ICC: 0.785, CI: 0.59-0.886, p < 0.05) and LA Scar (ICC: 0.609, CI: -0.14-0.844, p < 0.05). The extent of LA Scar was higher in postablation (Median: 8.62, IQR: 5.43-16.4) DE-CMR compared to baseline

A Method to Standardize Quantification of Left Atrial Scar From Delayed-Enhancement MR Images.

Delayed-enhancement magnetic resonance imaging (DE-MRI) is an effective technique for detecting left atrial (LA) fibrosis both pre and postradiofrequency ablation for the treatment of atrial fibrillation. Fixed thresholding models are frequently utilized clinically to segment and quantify scar in DE-MRI due to their simplicity. These methods fail to provide a standardized quantification due to interobserver variability. Quantification of scar can be used as an endpoint in clinical studies and therefore standardization is important. In this paper, we propose a segmentation algorithm for LA fibrosis quantification and investigate its performance. The algorithm was validated using numerical phantoms and 15 clinical data sets from patients undergoing LA ablation. We demonstrate that the approach produces good concordance with expert manual delineations. The method offers a standardized quantification technique for evaluation and interpretation of DE-MRI scans.

Abstract 18282: Association Between Cardiac Computed Tomography Perfusion Imaging and Electronatomic Mapping to Evaluate Left Atrial Fibrosis in Patients With Atrial Fibrillation

Background: Prior studies have shown that contrast enhanced multislice computed tomography (ceMSCT) can visualize ventricular scar. The purpose of this manuscript is to assess the ability of ceMDCT to detect left atrial (LA) fibrosis in patients undergoing repeat ablation for atrial fibrillation (AF). Methods and Results: We enrolled 10 patients prior to repeat ablation. All patients underwent pre-procedural ceMSCT of the LA followed by voltage mapping of the LA during the ablation procedure. The ceMSCT images were processed off-line using Seg3D software (University of Utah, Salt Lake City, USA). Epicardial and endocardial contours were manually drawn around LA myocardium on multi-planar axial images. Electroanatomic mapping points were retrospectively registered to the corresponding ceMSCT images. LA Scar identified by an image intensity range between 0-30 Hounsfeld units (HU) on ceMSCT correlated qualitatively with scar identified by low-voltage (bipolar voltage &lt;0.1 mV). Qualitative agreement in the posterior wall and the left pulmonary vein antrum was excellent. In a linear regression model of a subset of 4 patients, the local CT image intensity was associated with local bipolar voltage (+0.1 mV +/- 0.06 / 100 HU,P=0.019) Conclutions: We demonstrate that ceMSCT can provide valuable information about LA myocardial fibrosis with excellent electro-anatomic concordance. Electroanatomic voltage map of a redo PVI patient showing LA fibrosis in red corresponding to Low voltage (&lt;0.1 mV). Figure 1-B. Contrast enhanced multislice computed tomography imaging derived scar map of the same patient showing the same projection of the left atrium. Image intensity of LA between 0 to 30 is shown in red and blood pool of left atrium is shown in light blue.

Quantitative Magnetic Resonance Imaging Analysis of the Relationship Between Contact Force and Left Atrial Scar Formation After Catheter Ablation of Atrial Fibrillation

Catheter contact force (CF) is an important determinant of radiofrequency (RF) lesion quality during pulmonary vein isolation (PVI). Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) allows good visualization of ablation lesions. This study describes a new technique to examine the relationship between CF during RF delivery and LGE signal intensity (SI) following PVI. Six patients underwent PVI for paroxysmal AF using a CF-sensing catheter and following preprocedural MRI. During ablation, CF-time integral (FTI) and position was documented for each RF application. All patients underwent repeat LGE MRI 3 months later. The LGE SIs were projected onto a MRI-derived 3-dimensional left atrial (LA) shell and a CF map was generated on the same shell. The entire LA surface was divided into 5 mm(2) segments. Force and LGE maps were fused and compared for each 5 mm(2) zone. An effective lesion was defined when MRI-defined scar occupied >90% of a 5 mm(2) analysis zone. Acute PVI was achieved in 100%. Two hundred sixty-eight RF lesions were tagged on the LA shells and given a lesion-specific FTI. Increasing FTI correlated with increased LGE SI, which was greater when the FTI was > 1,200 gs. Below an FTI of 1,200 gs, an increment in the FTI resulted in only a small increment in scar, whereas above 1,200 gs an increment in the FTI resulted in a large change of scar. There is a correlation between FTI and LGE SI in MRI following AF ablation. Real-time FTI maps are feasible and may prevent inadequate lesion formation.

Magnetic resonance image intensity ratio, a normalized measure to enable interpatient comparability of left atrial fibrosis

The measurement of late gadolinium-enhanced magnetic resonance imaging (LGE-MRI) intensity in arbitrary units limits the objectivity of thresholds for focal scar detection and interpatient comparisons of scar burden. To develop and validate a normalized measure, the image intensity ratio (IIR), for the assessment of left atrial (LA) scar on LGE-MRI. Electrocardiogram- and respiratory-gated 1.5 Tesla LGE-MRI was performed in 75 patients (75% men; 62 ± 8 years) before atrial fibrillation ablation. The local IIR was defined as LA myocardial signal intensity for each of the 20 sectors on contiguous axial image planes divided by the mean LA blood pool image intensity. Intracardiac point-by-point sampled electroanatomic map points were coregistered with the corresponding image sectors. The average bipolar voltage for all 8153 electroanatomic map points was 0.9 ± 1.1 mV. In a mixed effects model accounting for within patient clustering, and adjusting for age, LA volume, mass, body mass index, sex, CHA2DS2-VASc score, atrial fibrillation type, history of previous ablations, and contrast delay time, each unit increase in local IIR was associated with 91.3% decrease in bipolar LA voltage (P < .001). Local IIR thresholds of >0.97 and >1.61 corresponded to bipolar voltage <0.5 and <0.1 mV, respectively. Normalization of LGE-MRI intensity by the mean blood pool intensity results in a metric that is closely associated with intracardiac voltage as a surrogate of atrial fibrosis.

Atrial fibrillation ablation in patients with gastroesophageal reflux disease or irritable bowel syndrome—the heart to gut connection!

An association between atrial fibrillation (AF) and gastroesophageal reflux disease (GERD) and/or irritable bowel syndrome (IBS) is increasingly being identified; yet the role of radiofrequency catheter ablation (RFA) of AF has not been systematically evaluated in these patient populations. We performed a prospective matched case-control study of AF patients with GERD and/or IBS who underwent RFA for AF in two centers in North America. AF patients with GERD and/or IBS (gastrointestinal [GI] group) were matched by age, gender, and type of AF at each of the centers with an equal number of AF patients without GERD or IBS (non-GI group). Sixty patients were included in the study with 30 in each group. Mean age of the population was 45years with 14 (47%) males and 21 (87%) patients with paroxysmal AF in each group. More patients in the GI group had identifiable GI triggers for AF episodes. During RFA, more patients in the GI group had a "vagal response" compared to non-GI group (60 vs 13%; p < 0.001). Left atrial scar as identified by electroanatomical mapping was more common in patients in the non-GI group compared to the GI group (57 vs 27%; p = 0.018). At 1-year follow-up, 56 (93%) of the patients were free from AF with no difference between both groups. Majority of AF patients with GERD and/or IBS have triggered AF and a positive vagal response during RFA. RFA is equally effective in this patient population when compared to those without GERD or IBS.

Automated analysis of atrial late gadolinium enhancement imaging that correlates with endocardial voltage and clinical outcomes: A 2-center study

BackgroundFor late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) assessment of atrial scar to guide management and targeting of ablation in atrial fibrillation (AF), an objective, reproducible method of identifying atrial scar is required.ObjectiveTo describe an automated method for operator-independent quantification of LGE that correlates with colocated endocardial voltage and clinical outcomes.MethodsLGE CMR imaging was performed at 2 centers, before and 3 months after pulmonary vein isolation for paroxysmal AF (n = 50). A left atrial (LA) surface scar map was constructed by using automated software, expressing intensity as multiples of standard deviation (SD) above blood pool mean. Twenty-one patients underwent endocardial voltage mapping at the time of pulmonary vein isolation (11 were redo procedures). Scar maps and voltage maps were spatially registered to the same magnetic resonance angiography (MRA) segmentation.ResultsThe LGE levels of 3, 4, and 5SDs above blood pool mean were associated with progressively lower bipolar voltages compared to the preceding enhancement level (0.85 ± 0.33, 0.50 ± 0.22, and 0.38 ± 0.28 mV; P = .002, P < .001, and P = .048, respectively). The proportion of atrial surface area classified as scar (ie, >3 SD above blood pool mean) on preablation scans was greater in patients with postablation AF recurrence than those without recurrence (6.6% ± 6.7% vs 3.5% ± 3.0%, P = .032). The LA volume >102 mL was associated with a significantly greater proportion of LA scar (6.4% ± 5.9% vs 3.4% ± 2.2%; P = .007).ConclusionsLA scar quantified automatically by a simple objective method correlates with colocated endocardial voltage. Greater preablation scar is associated with LA dilatation and AF recurrence.

Pulmonary Hypertension Following Maze Surgery for Atrial Fibrillation

Purpose The Maze procedure is considered the definitive surgical approach to atrial fibrillation. Pulmonary hypertension (PH) has not been reported following Maze, but has been associated with radiofrequency ablation due to left atrial scarring and diastolic dysfunction (stiff left atrial syndrome). We sought to investigate the development of PH following Maze using echocardiographic indices. Methods and Materials Data from all patients undergoing Maze surgery between 1/1/1999 and 12/31/2004 at Mayo Clinic Rochester was retrospectively reviewed. Patients with adequate pre- and post-operative transthoracic echocardiograms (TTE) (>90 days after surgery) were included. Patients with congenital heart disease, isolated right-sided Maze, mitral stenosis, and pre-existing elevated right ventricular systolic pressure (RVSP ≥40 mm Hg) were excluded. Diastolic parameters including left atrial volume index, E/e’, and E:A were reported when available. Results Forty-one patients (26 males) met inclusion criteria. Mean age at surgery was 63 ± 10 years, with normal ejection fraction pre- and post-operatively (60 vs 58%). Two patients underwent Maze surgery only, 5 had coronary bypass grafting, 36 had concomitant valvular operations (29 mitral, 4 aortic, 3 tricuspid), and 2 underwent septal myectomy for hypertrophic obstructive cardiomyopathy. Median RVSP increased from 32 mm Hg (interquartile range [IQ] 27;37) pre-operatively to 41 mm Hg (IQ 33;58) post-operatively. RVSP ≥40 mm Hg was observed in 26/41 patients on 150 total post-operative TTEs at a median follow-up of 1545 days (IQ 610;2339). Measures of left ventricular diastolic function worsened, with median pre-operative E/e’ of 14 (IQ 10;18) increasing to 22 (IQ 15;28), and median E:A ratio increasing from 1.8 (IQ 1.1;2.4) to 2.33 (IQ 2.0;3.3). Conclusions Maze surgery may be complicated by the development of increased right heart pressures and worsening diastolic function, raising the possibility that stiff left atrial syndrome may be a significant sequela of Maze surgery warranting further study.

Accelerated Late Gadolinium Enhancement Cardiac MR Imaging with Isotropic Spatial Resolution Using Compressed Sensing: Initial Experience

To evaluate the use of low-dimensional-structure self-learning and thresholding (LOST) compressed sensing acquisition and reconstruction in the assessment of left atrial (LA) and left ventricular (LV) scar by using late gadolinium enhancement (LGE) magnetic resonance (MR) imaging with isotropic spatial resolution. The study was approved by the local institutional review board and was compliant with HIPAA. All subjects provided written informed consent. Twenty-eight patients (eight women; mean age, 58.0 years ± 10.1) with a history of atrial fibrillation were recruited for the LA LGE study, and 14 patients (five women; mean age, 54.2 years ± 18.6) were recruited for assessment of LV myocardial infarction. With use of a pseudorandom k-space undersampling pattern, threefold accelerated three-dimensional (3D) LGE data were acquired with isotropic spatial resolution and reconstructed off-line by using LOST. For comparison, subjects were also imaged by using standard 3D LGE protocols with nonisotropic spatial resolution. Images were compared qualitatively by three cardiologists with regard to diagnostic value, presence of enhancement, and image quality. The signed rank test and Wilcoxon unpaired two-sample test were used to test the hypothesis that there would be no significant difference in image quality ratings with different resolutions. Interpretable images were obtained in 26 of the 28 patients (93%) in the LA LGE study. LGE was seen in 17 of 30 cases (57%) with nonisotropic resolution and in 18 cases (60%) with isotropic resolution. Diagnostic quality scores of isotropic images were significantly higher than those of nonisotropic images with coronal views (median, 3 vs 2, respectively [25th and 75th percentiles: 3, 3 vs 2, 3]; P < .001) and sagittal views (median, 3 vs 2 [25th and 75th percentiles: 3, 4 vs 2, 3]; P < .001) but lower with axial views (median, 4 vs 3 [25th and 75th percentiles: 3, 4 vs 3, 3]; P < .001). For the LV LGE study, all patients had interpretable images. LGE was seen in six of 14 patients (43%), with 100% agreement between both data sets. Diagnostic quality scores of high-isotropic-resolution LV images were higher than those of nonisotropic images with short-axis views (median, 4 vs 3 [25th and 75th percentiles: 3, 4 vs 2, 3]; P = .014) and two-chamber views (median, 4 vs 3 [25th and 75th percentiles: 3, 4 vs 2, 3]; P = .001). An accelerated LGE acquisition with LOST enables imaging with high isotropic spatial resolution for improved assessment of LV, LA, and pulmonary vein scar.