Retrospective Window of Interest Annotation Provides New Insights Into Functional Channels in Ventricular Tachycardia Substrate.

BACKGROUND: Accurate annotation of local activation time is crucial in the functional assessment of ventricular tachycardia (VT) substrate. A major limitation of modern mapping systems is the standard prospective window of interest (sWOI) is limited to 490 to 500 milliseconds, preventing annotation of very late potentials (LPs). A novel retrospective window of interest (rWOI), which allows annotation of all diastolic potentials, was used to assess the functional VT substrate. OBJECTIVES: This study sought to investigate the utility of a novel rWOI, which allows accurate visualization and annotation of all LPs during VT substrate mapping. METHODS: Patients with high-density VT substrate maps and a defined isthmus were included. All electrograms were manually annotated to latest activation using a novel rWOI. Reannotated substrate maps were correlated to critical sites, with areas of late activation examined. Propagation patterns were examined to assess the functional aspects of the VT substrate. RESULTS: Forty-eight cases were identified with 1,820 ± 826 points per map. Using the novel rWOI, 31 maps (65%) demonstrated LPs beyond the sWOI limit. Two distinct patterns of channel activation were seen during substrate mapping: 1) functional block with unidirectional conduction into the channel (76%); and 2) wave front collision within the channel (24%). In addition, a novel marker termed the zone of early and late crowding was studied in the rWOI substrate maps and found to have a higher positive predictive value (85%) than traditional deceleration zones (69%) for detecting critical sites of re-entry. CONCLUSIONS: The standard WOI of contemporary mapping systems is arbitrarily limited and results in important very late potentials being excluded from annotation. Future versions of electroanatomical mapping systems should provide longer WOIs for accurate local activation time annotation.

Deglutition-Induced Atrial Tachycardia Localised with Contact Force-Guided Activation Mapping.

Deglutition-induced atrial tachycardia is a rare arrhythmia with a poor response to medical therapy. Electrophysiological study is challenging due to the dependence of induction on swallowing. We present a novel approach to management of deglutition-induced atrial tachycardia arising from right superior pulmonary vein. Use of minimal conscious sedation and repeated swallow challenge inductions, together with contact force-guided mapping were key determinants of success. We review published cases, discussing potential mechanisms including oesophageal distension and neural reflexes.

Efficacy of a non-drinking mental simulation intervention for reducing student alcohol consumption.

OBJECTIVES: To assess the impact of a mental simulation intervention designed to reduce student alcohol consumption by asking participants to imagine potential positive outcomes of and/or strategic processes involved in not drinking during social occasions. DESIGN: English university students aged 18-25 years (n = 211, Mage = 20 years) were randomly allocated to one of four intervention conditions. The dependent variables were weekly alcohol consumption, heavy episodic drinking (HED) frequency and frequency of social occasions at which participants did not drink alcohol when others were drinking alcohol ('episodic non-drinking'). Measures of alcohol-related prototypes (i.e., prototypical non-drinker, prototypical regular drinker) were used to compute sociability prototype difference scores as a potential mediator of any intervention effects. All measures were taken at baseline and at 2- and 4-week follow-up. METHODS: Participants completed one of four exercises involving either imagining positive outcomes of non-drinking during a social occasion (outcome condition); imagining strategies required for non-drinking during a social occasion (process condition); imagining both positive outcomes and required strategies (combined condition); or completing a drinks diary task (control condition). RESULTS: Latent growth curve analyses revealed a more substantial rate of decrease in weekly unit consumption and HED frequency among outcome condition and process condition participants, relative to control condition participants. Non-significant differences were found between the combined condition and the control condition. Across the whole sample, an inverted U-shape trend indicated an initial increase in episodic non-drinking before it returned to baseline levels. CONCLUSION: This study provides preliminary evidence that mental simulation interventions focused on non-drinking can successfully promote behaviour change. Statement of contribution What is already known on this subject? UK drinking recommendations advise two 'dry days' per week (NHS, 2014). Benefits of, and strategies involved in, social non-drinking exist (Conroy & de Visser, 2014). Mental simulation interventions may help reduce student drinking (Hagger, Lonsdale, & Chatzisarantis, 2012; Hagger, Lonsdale, Koka et al., 2012). What does this study add? Demonstrates efficacy of a novel 'non-drinking' mental simulation exercise. Suggests that healthier alcohol prototypes can be encouraged via a health promotion intervention. Shows potential utility of 'episodic non-drinking' as an indicator of health-adherent drinking.

The transesophageal echo probe may contribute to esophageal injury after catheter ablation for paroxysmal atrial fibrillation under general anesthesia: a preliminary observation.

INTRODUCTION: The transesophageal echo probe (TEE) is commonly used before and during atrial fibrillation (AF) ablation under general anesthesia (GA). We sought to determine the potential contribution of the TEE probe to esophageal injury after pulmonary vein isolation (PVI) alone for paroxysmal AF. METHODS AND RESULTS: Seventy-six patients undergoing PVI with TEE, PVI/TEE, 16 undergoing PVI without TEE (PVI/No TEE), and 27 undergoing TEE without any left atrial ablation (TEE/No LA ablation) under GA were included. Posterior wall ablation was power (20-25 W) and time limited (electrogram attenuation or ≤30 s). Esophageal capsule endoscopy (n = 206) was performed pre- and post-procedure and at 2 weeks. Esophageal lesions were seen in 30% of PVI/TEE, 0% of patients in the PVI/No TEE (P = 0.009), and 22% of TEE/No LA ablation groups (P = 0.47 vs. PVI/TEE). There were no instances of esophageal bleeding, perforation, or need for gastrointestinal intervention. Self-resolving dysphagia was the only reported symptom (5%). All lesions healed within 2 weeks. There was no significant difference in the location or morphological appearance of esophageal lesions seen in the PVI/TEE versus TEE/No LA ablation groups. CONCLUSIONS: Esophageal lesions were seen in 30% of patients undergoing PVI alone under GA with use of TEE and in a similar proportion (22%) of patients undergoing TEE in the absence of left atrial ablation. This study makes the preliminary observation that one must be cognizant of the TEE probe as a potential contributor to esophageal injury after AF ablation. Larger studies are needed to confirm these findings.

Effects of long-term ω-3 polyunsaturated fatty acid supplementation on paroxysmal atrial tachyarrhythmia burden in patients with implanted pacemakers: results from a prospective randomised study.

BACKGROUND: Sino-atrial node disease and aging increase AF risk. We investigated if long-term fish oil supplementation reduces paroxysmal atrial tachycardia/fibrillation (AT/AF) burden in patients aged ≥60 years with sinoatrial node disease and dual chamber pacemakers. METHODS: Following a run-in period of 6 months (p1) where AT/AF burden was logged,78 patients were randomised to control or fish oil group (total omega-3 6 g/d) and AT/AF burden evaluated after 6 months (p2; 39 controls, 39 fish oil) and 12 months (p3; 39 controls; 18 fish oil). A subset of 21 fish oil patients crossed over to controls in the final 6 months (crossover group). RESULTS: Median AT/AF burden increased significantly in controls (1.5%, 3.2%, 4.3%, P<.001) but not in fish oil patients at 6 months (1.4% to 2%, P=.46) or those continuing for 12 months (1.5%, 0.98%, 1%, P=.16). Time to first episode of AT/AF >1 min was not significantly different between the groups (P=.9). There was a rebound increase in AT/AF burden in p3 in cross over patients (2.2% to 5.8%, P=.01) reaching a level similar to controls (crossover vs. controls, 5.8% vs. 4.3%, P=.63) and higher than those who continued fish oil for 12 months (crossover vs. continued intake 5.8% vs. 1.2%, P=.02). Fish oil patients had shorter duration episodes of AT/AF with no difference in frequency compared to controls. CONCLUSION: Long-term fish oil supplementation did not suppress AT/AF burden but may have attenuated its temporal progression related to aging and sinus node disease.

Effects of high dose intravenous fish oil on human atrial electrophysiology: implications for possible anti- and pro-arrhythmic mechanisms in atrial fibrillation.

BACKGROUND: Intravenous omega-3 polyunsaturated fatty acids (ω-3 PUFAs) may prevent atrial fibrillation (AF) inducibility and perpetuation in animal models. We examined the effect of high dose IV ω-3 PUFAs on human atrial electrophysiology. METHODS AND RESULTS: We randomised 88 patients with no structural heart disease to receive saline (control group) or high dose IV ω-3 PUFA infusion prior to detailed atrial electrophysiologic evaluation. Biologically active components, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were measured in total lipids, free fatty acid and phospholipid (membrane incorporated) fraction pre and post infusion. Compared to pre-infusion values, EPA and DHA increased significantly in the total lipids and free fatty acid but were unchanged in the phospholipid fraction. IV ω-3 did not alter atrial refractory periods, however it slowed right, left and global atrial conduction (P<.05). Inducible AF was significantly less likely in ω-3 patients compared to controls (AF ≥ 5 min, 20% vs. 58%, P = .02) and was non-sustained (mean AF duration: 14s vs. 39 s, P<.001), however inducible and sustained atrial flutter was more common (≥ 5 min: 28% vs. 0%, P = .01). Organisation of AF into flutter was observed in a greater proportion of inductions in the ω-3 group (8.5% vs. 0.6%, P<.001). CONCLUSIONS: IV ω-3 PUFAs (as free fatty acids) cause acute atrial conduction slowing, suppress AF inducibility, organise AF into atrial flutter and enhance atrial flutter inducibility. These findings provide a novel insight into potential anti and pro-arrhythmic mechanisms of fish oils in human AF.

Impact of collimation on radiation exposure during interventional electrophysiology.

AIMS: Fluoroscopy remains a cornerstone imaging technique in contemporary electrophysiology practice. We evaluated the impact of collimation to the 'minimal required field size' on clinically significant parameters of radiation exposure. METHODS AND RESULTS: Radiation dose measured by dose area product (DAP) and radiation dose rate measured by DAP per minute of fluoroscopy were determined for all 571 electrophysiology procedures performed in a single electrophysiology laboratory from January 2010 to December 2010. Data from 205 procedures performed by one interventional electrophysiologist, who instituted a practice of routinely collimating to the minimum required visual fluoroscopy field on a case-by-case basis, were compared with data from 366 procedures performed by the three other experienced interventional electrophysiologists using the laboratory who continued their existing practice of ad hoc collimation. Significant reductions in radiation exposure were seen with the practice of routine maximal collimation. The largest reductions were seen during 'simple' ablation procedures. CONCLUSION: A practice of routinely collimating to the minimum required visual fluoroscopy field results in significant reductions in radiation exposure when compared with a usual approach to collimation. This may have important implications for risk of malignancy in patients and operators.

Electroanatomic remodeling of the left atrium in paroxysmal and persistent atrial fibrillation patients without structural heart disease.

INTRODUCTION: The nature of the atrial substrate thought to contribute toward maintaining atrial fibrillation (AF) outside the pulmonary veins remains poorly defined. Therefore, our objective was to determine whether patients with paroxysmal and persistent AF have an abnormal electroanatomic substrate within the left atrium (LA). METHODS AND RESULTS: Thirty-one patients with AF (17 paroxysmal AF and 14 persistent AF) were compared with 15 age-matched controls with left-sided supraventricular tachycardia (SVT). High-density 3-dimensional electroanatomic maps were created and the LA was divided into 8 segments for regional analysis. Bipolar voltage, conduction, and effective refractory periods (ERPs) of the posterior LA, left atrial appendage (LAA), and distal coronary sinus (CSd) and percentage complex signals were assessed. In the majority of LA regions, compared with controls, AF patients had: (1) lower mean voltage and a higher percentage low voltage; (2) slower conduction; and (3) more prevalent complex signals. Many of these changes were more marked in the persistent than the paroxysmal AF group. CONCLUSIONS: Patients with AF have lower regional voltage, increased proportion of low voltage, slowed conduction, and increased proportion of complex signals compared to controls. Many of these changes are more pronounced in persistent AF patients, suggesting there may be a progressive nature to the changes. Differences occurred in the absence of structural heart disease. These substrate abnormalities provide further insight into the progressive nature of atrial remodeling and the mechanisms involved in maintenance of AF.

Long-term omega-3 polyunsaturated fatty acid supplementation reduces the recurrence of persistent atrial fibrillation after electrical cardioversion.

BACKGROUND: Persistent atrial fibrillation (AF) is associated with a high risk of recurrence after electrical cardioversion. OBJECTIVE: We examined if long-term supplementation with omega-3 polyunsaturated fatty acids in fish oils commenced >1 month prior to electrical cardioversion and continued thereafter reduces recurrence of persistent AF. METHODS: This was an open-label, randomized study of 178 patients with persistent AF >1-month duration. Participants were assigned to control group (n = 87) or omega-3 group (6 g/d fish oil; n = 91) and underwent cardioversion 1 month later. Concurrent antiarrhythmic use of sotalol or amiodarone was permitted. Fish oil was continued till return of persistent AF or a maximum of 1 year. Intention-to-treat analysis was performed for the primary end point defined as the recurrence of persistent AF. RESULTS: Mean duration of fish oil intake was 56 days precardioversion and a total of 242 days in follow-up. Eicosapentaenoic acid and docosahexaenoic acid, the active components of fish oils, were 1.8-fold and 2.1-fold higher, respectively, in the omega-3 group compared with controls at the time of cardioversion (P <.001). At 90 days, 38.5% of the patients receiving omega-3 fatty acid supplement had AF recurrence compared with 77.5% of the controls (hazard ratio [omega-3 vs control] 0.38; 95% confidence interval 0.27-0.56; P <.001). Omega-3 intake was associated with a significant reduction in AF recurrence with or without concurrent antiarrhythmic drugs. CONCLUSIONS: Omega-3 polyunsaturated fatty acid supplementation commenced >1 month prior to electrical cardioversion and continued thereafter reduces the recurrence of persistent AF. Randomized controlled trials on long-term fish oil supplementation are needed to confirm these findings.

Effects of chronic omega-3 polyunsaturated fatty acid supplementation on human pulmonary vein and left atrial electrophysiology in paroxysmal atrial fibrillation.

Omega-3 polyunsaturated fatty acids in fish oils may have antifibrillatory effects; however, their electrophysiologic effects in paroxysmal atrial fibrillation (PAF) remain unknown. The aim of this study was to investigate the effects of chronic fish oil supplementation on human pulmonary vein (PV) and left atrial electrophysiology in PAF. Patients with PAF undergoing PV isolation were randomized ≥1 month before their procedure into a control group (n = 18) or a fish oil group (n = 18) in an unblinded fashion. The latter were supplemented with fish oil 6 g/day for a mean of 40 ± 12 days. Pulmonary venous and left atrial effective refractory periods (ERPs), PV conduction, and susceptibility to AF initiated within PVs were assessed. Compared to the control group, the fish oil group had (1) longer left-sided (p = 0.002) and right-sided (p = 0.001) pulmonary venous ERPs; (2) less dispersion of pulmonary venous ERPs (left PVs p = 0.001, right PVs p = 0.07); (3) longer left atrial ERPs (p = 0.02); (4) no difference in pulmonary venous conduction; (5) lower incidence of AF initiated from PVs during ERP testing (77% vs 31%, p = 0.02); and (6) prolongation of mean AF cycle length (p = 0.009) and shortest AF cycle length in PVs (p = 0.04). In conclusion, patients with PAF chronically supplemented with fish oils exhibit distinctive electrophysiologic properties including prolonged pulmonary venous and left atrial ERPs and decreased susceptibility to initiation AF from within PVs. These changes may in part explain the antifibrillatory effect of chronic omega-3 polyunsaturated fatty acid supplementation in patients with PAF.

The relationship between complex fractionated electrograms and atrial low-voltage zones during atrial fibrillation and paced rhythm.

AIMS: Mapping of atrial fibrillation (AF) involves identification of low-voltage regions associated with complex fractionated electrograms (CFE) which theoretically represent abnormal substrate and targets for ablation. Whether low-voltage CFE areas also identify abnormal substrate during paced rhythm is unknown. METHODS AND RESULTS: Twelve patients with persistent AF undergoing ablation of AF had high-density three-dimensional electroanatomic maps created during AF and paced rhythm (24 maps) and the mean voltage during AF and paced rhythm was compared for eight segments of the left atrium (LA). The following were correlated during AF and paced rhythm: regional mean voltage; %low voltage (defined as <0.5 mV); and extent of CFE. In addition, the relationship between the extent of CFE in AF: (i) %low voltage and (ii) conduction during paced rhythm were determined. Mean voltage was lower during AF than paced rhythm for all regions and globally (0.7 ± 0.2 mV vs. 2.1 ± 0.6 mV, P < 0.001). The regional and overall %low voltage of the LA was greater during AF than paced rhythm (53 ± 19% vs. 9 ± 2%, P < 0.001). There was no correlation between mean voltage or %low voltage during AF and paced rhythm. Complex fractionated electrograms were prevalent throughout all regions during AF, but did not correlate with %low voltage, fractionation, or slowed conduction during paced rhythm. CONCLUSION: Areas of CFE and low voltage recorded during AF frequently demonstrate normal atrial myocardial characteristics (normal conduction, electrograms, and voltage) during sinus rhythm. Therefore, AF CFE sites do not necessarily identify regions of an abnormal atrial substrate. However, this does not exclude the possibility that CFE might identify a focal driver or source occurring in a region of normal atrial myocardium.

Effects of chronic omega-3 polyunsaturated fatty acid supplementation on human atrial mechanical function after reversion of atrial arrhythmias to sinus rhythm: reversal of tachycardia-mediated atrial cardiomyopathy with fish oils.

BACKGROUND: Atrial mechanical stunning is a form of tachycardia-mediated atrial cardiomyopathy that manifests after reversion of persistent atrial arrhythmias to sinus rhythm. OBJECTIVES: This study sought to examine whether chronic omega-3 polyunsaturated fatty acid supplementation with fish oils can reverse atrial mechanical stunning. METHODS: Patients undergoing reversion of persistent atrial fibrillation (AF) or atrial flutter (AFL) to sinus rhythm were randomized to a control group (n = 26) or an omega-3 group (n = 23). The latter were prescribed 6 g/day of fish oil for ≥1 month prior to the procedure. Parameters of left atrial appendage function were compared immediately before and immediately after reversion. RESULTS: After fish oil intake for a mean of 70 days, the following were noted favoring the omega-3 group among both AF and AFL patients: (1) 2-fold higher serum omega-3 levels (P < .001), (2) less mean decrease in emptying velocity (e.g., AF: 8% vs. 32%, P = .02), (3) less mean decrease in appendage emptying fraction (e.g., AFL: 7% vs. 60%, P = .002), (4) lower incidence of new or increased spontaneous echocardiographic contrast (e.g., AF: 11% vs. 62.5%, P = .003), and (5) lower incidence of atrial mechanical stunning (e.g., AFL: 20% vs. 100%, P = .001). Omega-3 intake conferred protection against stunning in a multivariable analysis (odds ratio 0.18, P = .02). CONCLUSION: Chronic fish oil ingestion in humans attenuates atrial mechanical stunning after reversion of atrial arrhythmias to sinus rhythm. This suggests that fish oils may target or even reverse underlying cellular and/or structural remodeling that occurs in response to persistent atrial arrhythmias.

Effects of chronic omega-3 polyunsaturated fatty acid supplementation on human atrial electrophysiology.

BACKGROUND: Omega-3 polyunsaturated fatty acids in fish oils may have antifibrillatory effects. Their mechanism of action in humans is poorly understood. OBJECTIVE: The purpose of this study was to investigate the effects of chronic fish oil supplementation on human atrial electrophysiology (EP). METHODS: Two groups of patients without clinical AF or structural heart disease and fish intake ≤1/week were prospectively recruited into a control group (n = 30) and a fish oil group (n = 31). The latter were prescribed 6 g/day of fish oil for ≥1 month before an EP study. The following were compared at time of EP study: serum omega-3 levels; right atrial and coronary sinus effective refractory periods (ERPs); interatrial, intra-atrial, left atrial, and coronary sinus conduction at baseline and the maximal conduction delay with the shortest propagated extrastimulus; and inducibility of AF (10 inductions/patient). RESULTS: The following significant differences were noted favoring the fish oil group at time of EP: (1) twofold higher total omega-3 levels (P < .001); (2) lengthening of ERPs by 8%-14% at all measured sites and pacing cycle lengths (P < .05); (3) no effect on baseline interatrial, intra-atrial, left atrial, and coronary sinus conduction but a significant attenuation of maximal conduction delay (P < .05); (4) less inducible AF (AF ≥30 seconds: 24.2% vs. 7.9%; P < .001); (5) shorter mean duration of induced AF (P = .003); and (6) prolongation of induced AF cycle length (P < .001). CONCLUSIONS: Chronic fish oil supplementation in humans prolongs atrial refractoriness and reduces vulnerability to inducible AF. These EP changes may explain the antifibrillatory effect of chronic fish oil ingestion.

Prevalence of fractionated electrograms in the coronary sinus: comparison between patients with persistent or paroxysmal atrial fibrillation and a control population.

BACKGROUND: Complex fractionated atrial electrograms (CFAEs) are often identified as targets for radiofrequency ablation in the coronary sinus (CS) of patients with atrial fibrillation (AF). OBJECTIVE: The purpose of this study was to determine whether similar features are present in a normal control population. METHODS: Twenty-four patients with AF (12 paroxysmal, 12 persistent) were compared with 12 controls (undergoing radiofrequency ablation for supraventricular tachycardia) in whom at least 1 minute of AF was induced by rapid atrial pacing. Electrogram comparisons during sinus rhythm and AF were made offline. A random 10-second window of AF was used for analysis of fractionation and dominant frequency. RESULTS: The three groups were age matched. CFAEs during AF were less prevalent in the control versus the AF groups (control = 30% +/- 28%, paroxysmal AF = 63% +/- 34%, persistent AF = 62% +/- 29%, P = .01). This difference was significant for the proximal to mid-CS only. Conduction velocity within the CS was slower in AF versus control patients (paroxysmal AF = 51 +/- 6 cm/s, persistent AF = 52 +/- 6 cm/s, control = 73 +/- 11 cm/s, P <.001). Minimum AF cycle length was shorter in the AF groups versus the control group (paroxysmal AF = 132 +/- 34 ms, persistent AF = 127 +/- 34 ms, control = 168 +/- 30 ms, P = .01). No differences in dominant frequency or prevalence of sinus rhythm CFAE was seen among the three groups. CONCLUSION: AF patients have a higher prevalence of CFAE and short cycle length activation within the proximal CS than control patients with nonclinical AF. CFAE are associated with slowed CS conduction in AF patients. No difference in the dominant frequency during AF was seen. CS CFAEs are common in a control population with induced AF and are unlikely to signify clinically important AF drivers in this setting.

Long-term outcome following successful catheter ablation of atrial tachycardia originating from the pulmonary veins: absence of late atrial fibrillation.

OBJECTIVES: This study aimed to characterize the long-term outcome and incidence of atrial fibrillation (AF) in patients following catheter ablation of focal atrial tachycardia (AT) from the pulmonary veins (PV). BACKGROUND: Although both AT and AF may originate from ectopic foci within PVs, it is unknown whether PV AT patients subsequently develop AF. METHODS: Twenty-eight patients with 29 PV ATs (14%) from a consecutive series of 194 patients who underwent RFA for focal AT were included. Patients with concomitant AF prior to the index procedure were excluded. RESULTS: The minimum follow-up duration was 4 years; mean age 38 +/- 18 years with symptoms for 6.5 +/- 10 years, having tried 1.5 +/- 0.9 antiarrhythmic drugs. The distribution of foci was: left superior 12 (41%), right superior 10 (34%), left inferior 5 (17%), and right inferior 2 (7%). The focus was ostial in 93% and 2-4 cm distally within the vein in 7%. Mean tachycardia cycle length was 364 +/- 90 ms. Focal ablation was performed in 25 of 28 patients. There were 6 recurrences with 5 from the original site. Twenty-six patients were available for long-term clinical follow-up. At a mean of 7.2 +/- 2.1 years, 25 of 26 (96%) were free from recurrence off antiarrhythmic drugs. No patients developed AF. CONCLUSIONS: Focal ablation for tachycardia originating from the PVs is associated with long-term freedom from both AT and AF. Therefore, although PV AT and PV AF share a common anatomic distribution, PV AT is a distinct clinical entity successfully treated with focal RFA and not associated with AF in the long term.

Fundamental differences in electrophysiologic and electroanatomic substrate between ischemic cardiomyopathy patients with and without clinical ventricular tachycardia.

OBJECTIVES: The aim of this study was to compare the electrophysiologic substrate in ischemic cardiomyopathy (ICM) patients with and without sustained monomorphic ventricular tachycardia (SMVT). BACKGROUND: Despite the universal presence of potentially arrhythmogenic left ventricular (LV) scarring, it is not clear why the majority of ICM patients never develop SMVT. METHODS: Detailed electroanatomic mapping of the LV endocardium was performed in 17 stable control ICM patients (16 males) without clinical SMVT. They were compared with 17 ICM patients (15 males) with spontaneous SMVT. Standard definitions of low-voltage zones and fractionated, isolated, and very late potentials were used. RESULTS: There were no significant baseline differences between the groups in terms of LV diameter, ejection fraction (27% vs. 28%), infarct territory, or time from infarction. However, control patients had smaller total low-voltage area < or =1.5 mv (30% of surface area vs. 55%, p < 0.001); smaller very low-voltage area <0.5 mv (7.3% vs. 29%, p < 0.001); higher mean voltage of low-voltage zones; fewer fractionated, isolated, and very late potentials with lower density of these scar-related electrograms per unit low-voltage area; and less SMVT inducibility. Potential conducting channels within dense scar and adjacent to the mitral annulus were more frequent in SMVT patients. CONCLUSIONS: Compared with ICM patients with SMVT, an otherwise similar control group demonstrated markedly smaller endocardial low-voltage zones, lower scar-related electrogram density, and fewer conducting channels with faster conduction velocity. These findings may explain why some ICM patients develop SMVT and others do not.

Fractionated atrial electrograms during sinus rhythm: relationship to age, voltage, and conduction velocity.

BACKGROUND: Fractionated atrial electrograms (CFAEs) have been implicated in the mechanism of atrial fibrillation (AF). The prevalence and distribution of CFAEs in normal populations have not been clearly defined. OBJECTIVE: This study sought to determine the influence of age on CFAEs and investigate the relationship between CFAEs and the underlying atrial substrate. METHODS: Twenty-one patients without structural heart disease underwent electroanatomic mapping of their right atrium (RA). Patients were categorized into 3 groups according to age: group A, patients <30 years (25.1 +/- 3.1 years, n = 7); group B, patients between 31 and 59 years (51.7 +/- 10.3 years, n = 6); group C, patients >60 years (66.9 +/- 7.7 years, n = 8). The proportion of points with CFAEs was analyzed for the high and low septal RA, high and low lateral RA, and high and low posterior RA. The mean atrial voltage and conduction velocity were assessed in each of these regions. RESULTS: The percentage of CFAEs was greater in group C (14.6% +/- 7.7%) than in group A (2.7% +/- 2.1%; P = 0.001). The percentage of CFAEs in group B (8.5% +/- 3.5%) was not significantly different from that in group A (P = 0.21) and group C (P = 0.14). The CFAEs were predominantly located in the posterior RA and high septal RA. There were significant correlations between the proportion of CFAEs and age (R = 0.72; P < 0.01), atrial voltage (R = -0.57; P < 0.01), and conduction velocity (R = -0.73; P < 0.001). CONCLUSION: CFAEs increase with age and occur in regions of low atrial voltage and slowed conduction. The distribution of CFAE is predominantly along the posterior and high septal RA, regions where there are marked changes in myocardial fiber orientation. This suggests that the underlying myocardial architecture is the main influence on electrogram morphology.

Multiple focal atrial tachycardias in a healthy adult population: characterization and description of successful radiofrequency ablation.

BACKGROUND: The electrophysiologic (EP) characteristics and ablation outcomes of focal atrial tachycardia (AT) have been extensively characterized over recent years. However, there are limited published data describing patients who at EP study have more than one sustained focal tachycardia. OBJECTIVE: To characterize the demographics, tachycardia data, and outcome of patients with successful ablation of more than one focal AT. METHODS: A retrospective review of our supraventricular tachycardia database from 2000 to 2006 identified 258 patients who had undergone radiofrequency ablation of focal AT. Ten patients were identified who had more than one sustained focal tachycardia at EP study, including seven patients with two ATs and three patients with three ATs. The patients were all women with a mean age of 54.2 +/- 10.3 years. AT locations included the crista terminalis, coronary sinus ostium, tricuspid and mitral annuli, and pulmonary vein ostium. Successful ablation was performed for 22 (95.7%) of 23 tachycardias. RESULTS: During long-term follow-up of 32.7 +/- 22.2 months, there were no recurrences of AT in those patients with successful ablation. No patients developed new AT foci, and only one developed late AF. CONCLUSIONS: We have described a series of patients with multiple focal ATs with typical anatomic distribution. These patients do not have significant cardiac or respiratory disease, and in this series, all were women. This report demonstrates that up to three focal ATs can be successfully ablated at a single procedure without recurrence or development of other atrial arrhythmias in long-term follow-up.

Focal atrial tachycardias arising from the right atrial appendage: electrocardiographic and electrophysiologic characteristics and radiofrequency ablation.

OBJECTIVE: To characterize the electrocardiographic and electrophysiological features and frequency of focal atrial tachycardia (AT) originating from the right atrial appendage (RAA). BACKGROUND: The RAA has been described as a site of origin of AT, but detailed characterization of these tachycardias is limited. METHODS: Ten patients (3.8%) of 261 undergoing radiofrequency ablation (RFA) for focal AT are reported. Endocardial activation maps (EAM) were recorded from catheters at the CS (10 pole), tricuspid annulus (20 pole Halo catheter), and His positions. P waves were classified as negative, positive, isoelectric, or biphasic. RESULTS: The mean age was 39 +/- 20 years, nine males, with symptoms for 4.1 +/- 5.1 years. Tachycardia was incessant in seven patients, spontaneous in one patient, and induced by programmed extrastimuli in two patients. These foci had a characteristic P wave morphology. The P wave was negative in lead V(1) in all patients, becoming progressively positive across the precordial leads. The P waves in the inferior leads were low amplitude positive in the majority of patients. Earliest EAM activity occurred on the Halo catheter in all patients. Mean activation time at the successful RFA site =-38 +/- 15 msec. Irrigated catheters were used in six patients, due to difficulty achieving adequate power. RFA was acutely successful in all patients. Long-term success was achieved in all patients over a mean follow up of 8 +/- 7 months. CONCLUSIONS: The RAA is an uncommon site of origin for focal AT (3.8%). It can be suspected as a potential anatomic site of AT origin from the characteristic P wave and activation timing. Irrigated ablation catheters are often required for successful ablation. Long-term success was achieved with focal ablation in all patients.