Catheter ablation of atrial fibrillation as first-line therapy--a single-centre experience.

AIMS: The aims of the study were (i) to assess the characteristics of patients selected for atrial fibrillation (AF) ablation as first-line therapy, (ii) to identify current clinical criteria for such a strategy, and (iii) to analyse the outcome compared with patients who had failure of antiarrhythmic drug (AAD) therapy prior to ablation. METHODS AND RESULTS: Consecutive patients undergoing ablation of AF were included in a prospective registry. Serial long-term electrocardiogram monitoring and clinical follow-up were performed after 3, 6, and 12 months. Out of 434 patients, 17% underwent AF catheter ablation as first-line therapy (AAD-), and 83% had undergone at least one AAD trial (AAD+). In AAD- patients, the reasons for this strategy were: (i) patient preference, n= 51 (71%); (ii) contra-indication to AAD, n= 21 (29%). Atrial fibrillation duration prior to ablation was shorter (52 ± 54 vs. 78 ± 81 months, P= 0.005), and the percentage of patients hospitalized for AF (32% vs. 48%, P= 0.01) was lower in AAD- patients. Long-term multiple procedure success rate (78% vs. 64%, P= 0.03) was higher in the AAD- group, and there were less repeat ablations in this group (21% vs. 38%, P= 0.01). CONCLUSION: Catheter ablation was first-line therapy of AF in a significant number of patients, according either to patient preference or to medical factors, and this had important implications. Ablative therapy was performed at an earlier stage of the disease, and was associated with a significantly higher success rate and with a decreased need for repeat procedures.

Brugada syndrome ECG provoked by the selective serotonin reuptake inhibitor fluvoxamine.

A patient with an SCN5A p.W822X nonsense mutation, localized in the transmembrane region DII-S4 of the Na(v)1.5 sodium channel and leading to a non-expression of the mutant allele, was prescribed the selective serotonin reuptake inhibitor (SSRI) fluvoxamine (Floxyfral), 100 mg per day. His normal baseline ECG changed to a characteristic Brugada-Type-1-ECG pattern. To investigate whether fluvoxamine may reduce the cardiac sodium current, the effect of this drug was studied on the wild-type voltage-gated cardiac sodium channel Na(v)1.5 stably expressed in HEK293 cells. Patch-clamp recording showed a 50% inhibition of the current at a concentration of 57.3 microM. In our patient, no arrhythmia occurred but the proarrhythmic potential of SSRI in patients with SCN5A mutations cannot be excluded. Therefore, we advise 12-lead ECG control after administering SSRI in these patients.

Gender differences in patients referred for atrial fibrillation management to a tertiary center.

BACKGROUND: Atrial fibrillation (AF) ablation is less frequently performed in women than in men. Although the prevalence of AF is slightly higher in men, this does not fully account for the lower number of AF ablations performed in women. This study sought to examine the effect of gender on referral for AF and subsequent AF management. METHODS: Consecutive patients referred to our tertiary arrhythmia outpatient clinic for AF management were retrospectively analyzed. RESULTS: Of 264 patients referred, only 27% were women. Women were older than men (63 +/- 9 vs 58 +/- 11 years, P = 0.002), more often had paroxysmal AF (78% vs 63% in men, P = 0.022), and women more frequently complained about palpitations (71% vs 49%, P = 0.002). In addition, they had more often experienced amiodarone side effects than men (56% vs 36%, P = 0.046). In this referred population, there was no difference in the proportion of women and men undergoing AF ablation immediately following the initial evaluation (21% vs 25%, P = ns), at any time during the follow-up (38% vs 44%, P = ns), and there was no difference in the proportion of patients undergoing atrioventricular node ablation in both sexes (6% of women vs 3% of men, P = ns). CONCLUSIONS: There is an important difference in the proportion of men and women referred for management of AF in a specialized outpatient arrhythmia clinic, with women being referred three times less often than men. However, there is no gender-related difference in the subsequent treatment decisions. These findings emphasize the importance of focusing on management of symptomatic AF in women.

A novel SCN5A mutation, F1344S, identified in a patient with Brugada syndrome and fever-induced ventricular fibrillation.

OBJECTIVE: Brugada syndrome (BS) is an inherited electrical cardiac disorder characterized by right bundle branch block pattern and ST segment elevation in leads V1 to V3 on surface electrocardiogram that can potentially lead to malignant ventricular tachycardia and sudden cardiac death. About 20% of patients have mutations in the only so far identified gene, SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent sodium channel (hNa(v)1.5). Fever has been shown to unmask or trigger the BS phenotype, but the associated molecular and the biophysical mechanisms are still poorly understood. We report on the identification and biophysical characterization of a novel heterozygous missense mutation in SCN5A, F1344S, in a 42-year-old male patient showing the BS phenotype leading to ventricular fibrillation during fever. METHODS: The mutation was reproduced in vitro using site-directed mutagenesis and characterized using the patch clamp technique in the whole-cell configuration. RESULTS: The biophysical characterization of the channels carrying the F1344S mutation revealed a 10 mV mid-point shift of the G/V curve toward more positive voltages during activation. Raising the temperature to 40.5 degrees C further shifted the mid-point activation by 18 mV and significantly changed the slope factor in Na(v)1.5/F1344S mutant channels from -6.49 to -10.27 mV. CONCLUSIONS: Our findings indicate for the first time that the shift in activation and change in the slope factor at a higher temperature mimicking fever could reduce sodium currents' amplitude and trigger the manifestation of the BS phenotype.

A novel nonsense mutation in the SCN5A gene leads to Brugada syndrome and a silent gene mutation carrier state.

BACKGROUND: Brugada syndrome (BS) is an electrical cardiac disorder with a right bundle branch block and ST segment elevation in leads V1 to V3 on surface electrocardiograms (ECGs), and is a syndrome that may lead to sudden cardiac death. PURPOSE: The aim of the present study was to screen for mutations in the SCN5A gene in a family with BS, and to characterize the consequences of the mutation on channel function. RESULTS: A heterozygous nonsense SCN5A mutation (W822X) was identified in the index patient. The mutation was confirmed in the patient's asymptomatic 16-year-old brother and 48-year-old father. The mutation was absent in the index patient's sister and mother. The ECG of the index patient showed a BS type 2 ECG phenotype, which converted into a type 1 ECG phenotype in the presence of flecainide. The ECG of the patient's brother was not typical for BS, but ajmaline treatment unmasked a type 1 ECG phenotype. The ECG of the asymptomatic father was normal at baseline and in the presence of ajmaline. No Na+ currents could be measured in tsA201 cells transfected with W822X mutant channels. Heterozygote expression showed a nearly 50% reduction in Na+ current amplitude with no significant alterations of biophysical properties, indicating a loss of functional Na+ channels, obviously without any dominant-negative activity on wild type channels. CONCLUSIONS: The haploinsufficiency of the Nav1.5 protein is the plausible explanation for the clinical BS phenotype in this family. Because the heterozygous W822X mutation theoretically leads to channel expression at one-half of the normal level, the authors suggest that a modifier gene may influence or rescue the phenotype in the asymptomatic family members.

Irrigated-tip catheter ablation of intraatrial reentrant tachycardia in patients late after surgery of congenital heart disease.

OBJECTIVES: The aim of this study was to evaluate irrigated-tip catheter for ablation of intraatrial reentrant tachycardias late after surgical repair of congenital heart disease. BACKGROUND: In congenital heart disease patients, the right atrium can be markedly enlarged with areas of low blood flow. Radiofrequency (RF) lesion creation may be hampered by insufficient electrode cooling at sites with low blood flow. METHODS: Thirty-six consecutive patients with intraatrial reentrant tachycardia refractory to antiarrhythmic therapy from two centers were included in the study. Entrainment pacing and electroanatomic mapping (CARTO) were used to delineate reentrant circuits and critical isthmus sites. RF ablation was performed using an irrigated-tip catheter (Navistar Thermocool). RESULTS: Fifty-two intraatrial reentrant tachycardia circuits were identified, and 48 were targeted with RF ablation. RF ablation was performed using a mean of 13 +/- 11 irrigated RF applications per tachycardia isthmus with a mean power of 36 +/- 8 W. In a historical control group of congenital heart disease patients managed with conventional catheter ablation, the number of lesions per isthmus was higher (23 +/- 11) and mean power was lower (27 +/- 14 W). Acute success was achieved in 45 intraatrial reentrant tachycardias (94% of targeted tachycardias and 87% of all tachycardias). After a mean follow-up of 17 +/- 7 months, 33 (92%) of 36 patients were free of recurrence. Five patients (14%) developed paroxysmal atrial fibrillation. CONCLUSIONS: The combination of modern techniques including electroanatomic mapping and catheter irrigation allows safe and highly effective ablation of intraatrial reentrant tachycardia in patients with surgically repaired congenital heart disease.

Incidence of arrhythmic events in patients with implantable cardioverter-defibrillator for primary and secondary prevention of sudden cardiac death.

BACKGROUND: Implantable cardioverter-defibrillators (ICD) are increasingly used for prevention of sudden cardiac death (SCD). Although mortality risk reduction is about the same in primary and secondary prevention trials (~30%), we hypothesised that the incidence and the nature of ventricular arrhythmias is different in high risk ICD recipients without prior arrhythmias compared to patients who presented with life threatening arrhythmias. METHODS: A hundred consecutive ICD recipients were allocated to 2 groups: 1) secondary prevention: an ICD was implanted for secondary prevention of episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF). 2) primary prevention: patients at high risk of SCD without prior arrhythmias. They were prospectively followed and the incidence of appropriate ICD therapies was determined by reviewing stored electrograms. RESULTS: During a mean follow-up of 20 (10) months, the overall mortality was 5% and 5% of the patients underwent heart transplantation. Of the 67 secondary prevention patients, 40% (n = 27) had VT/VF triggering ICD therapy, whereas only 15% (n = 5) of the 33 primary prevention patients had VT/VF triggering ICD therapy (p <0.05). The adjusted hazard ratio for arrhythmias triggering ICD interventions in the primary prevention group was 0.345 (95% confidence interval 0.132 to 0.902, p = 0.03). CONCLUSIONS: The risk of developing arrhythmias triggering appropriate ICD intervention was 65% lower among the primary prevention patients than in secondary prevention patients. Importantly, ICD therapies are not correlated with lives saved, and efficacy of ICD therapy in primary and secondary prevention cannot be drawn from these data. However, the low incidence of ICD use in primary prevention patients emphasises that efforts should be made to develop better instruments for stratification.

Prevalence of asymptomatic and electrically undetectable intracardiac inside-out abrasion in silicon-coated Riata® and Riata® ST implantable cardioverter-defibrillator leads.

BACKGROUND: Recently, several cases of symptomatic and/or electrically detectable intracardiac inside-out abrasions in silicon-coated Riata® and Riata® ST leads have been described. However, the prevalence in asymptomatic patients with unremarkable implantable cardioverter defibrillator (ICD) interrogation is unknown. The aim of this study was to determine the prevalence of asymptomatic and electrically undetectable intracardiac inside-out abrasion in silicon-coated Riata® and Riata® ST leads. METHODS: All 52 patients with an active silicone-coated Riata® and Riata® ST lead followed up in our outpatient clinic were scheduled for a premature ICD interrogation and a biplane chest radiograph. When an intracardiac inside-out abrasion was suspected, this finding was confirmed by fluoroscopy. RESULTS: Mean time since implantation was 71 ± 18 months. An intracardiac inside-out abrasion was confirmed by fluoroscopy in 6 patients (11.5%). Mean time from lead implantation to detection of intracardiac inside-out abrasion was 79 ± 14 months. In all patients with an intracardiac inside-out abrasion, ICD interrogation showed normal and stable electrical parameters. Retrospectively, in 4 of these 6 patients, a coronary angiography performed 25 ± 18 months before diagnosis of intracardiac inside-out abrasion already showed the defect. Despite undetected intracardiac inside-out abrasion, 2 of these 4 patients experienced adequate antitachycardia pacing and ICD-shocks. ICD leads were replaced in all 6 patients. CONCLUSIONS: The prevalence of asymptomatic intracardiac inside-out abrasion in silicon-coated Riata® and Riata® ST leads is higher than 10% when assessed by fluoroscopy, and most intracardiac inside-out abrasions are not detectable by ICD interrogation.

Is 7-day event triggered ECG recording equivalent to 7-day Holter ECG recording for atrial fibrillation screening?

OBJECTIVE: Prolonged ECG monitoring is standard for atrial fibrillation (AF) screening. This study investigated whether 7-day event triggered (tECG) ECG recording is equivalent to 7-day continuous Holter (cECG) ECG recording for AF screening. DESIGN: Both a cECG (Lifecard CF) and a tECG (R.Test Evolution 3) were simultaneously worn for 7 days by patients with known or suspected paroxysmal AF. RESULTS: In 100 corresponding recordings, median effective duration of monitoring was 165 h (range 10-170 h) for cECG and 137 h (0-169 h) for tECG (p<0.001). Median number and total duration of arrhythmias (AF, atrial flutter or atrial tachycardia) of ≥30 s duration recorded by cECG were 10 (1-428) and 1030 min (≤1-10,020), respectively. An arrhythmia was recorded in 42 cECGs (42%) versus 37 tECGs (37%, p=0.56). Triggered ECG failed to record an arrhythmia in cECG positive cases because of interrupted monitoring in four cases and because of recording failure in one case. Sensitivity, specificity, and positive and negative predictive values of tECG therefore were 88%, 100%, 100%, and 92%, respectively. Quantitative cECG analysis required a median of 20 min (3-205 min) and qualitative tECG analysis 4 min (1-20 min; p<0.001). Skin irritation was a frequent side effect (42%) resulting in premature removal of devices in 16% of patients. CONCLUSION: Sensitivity of tECG for AF screening as compared to cECG is lower, mainly because of shorter effective monitoring duration. Qualitative tECG analysis is less time consuming than quantitative cECG analysis. Skin irritation is a frequent side effect and reason for premature device removal.

Dual-loop circuits in postoperative atrial macro re-entrant tachycardias.

BACKGROUND: Patients may develop dual-loop re-entrant atrial arrhythmias late after open-heart surgery, and mapping and catheter ablation remain challenging despite computer-assisted mapping techniques. OBJECTIVES: The purpose of the study was to demonstrate the prevalence and characteristics of dual-loop re-entrant arrhythmias, and to define the optimal mapping and ablation strategy. METHODS: 40 consecutive patients (mean (SD) age 52 (12) years) with intra-atrial re-entrant tachycardia (IART) after open-heart surgery (with an incision of the right atrial free wall) were studied. Dual-loop IART was defined as the presence of two simultaneous atrial circuits. After an abrupt tachycardia change during radiofrequency ablation, electrical disconnection of the targeted re-entry isthmus from the remaining circuit was demonstrated by entrainment mapping. Furthermore, the second circuit loop was localised using electroanatomical mapping and/or entrainment mapping. RESULTS: Dual-loop IART was demonstrated in eight (20%, 5 patients with congenital heart disease, 3 with acquired heart disease) patients. Dual-loop IART included an isthmus-dependant atrial flutter combined with a re-entry related to the atriotomy scar. The diagnosis of dual-loop IART required the comparison of entrainment mapping before and after tachycardia modification. Overall, 35 patients had successful radiofrequency ablation (88%). Success rates were lower in patients with dual-loop IART than in patients without dual-loop IART. Ablation failures in three patients with dual-loop IART were related to the inability to properly transect the second tachycardia isthmus in the right atrial free wall. CONCLUSIONS: Dual-loop IART is relatively common after heart surgery involving a right atriotomy. Abrupt tachycardia change and specific entrainment mapping manoeuvres demonstrate these circuits. Electroanatomical mapping appears to be important to assist catheter ablation of periatriotomy circuits.

Electrocardiographic pattern as a guide for management and radiofrequency ablation of idiopathic ventricular tachycardia.

BACKGROUND: Idiopathic ventricular tachycardia (VT) often originates from the right ventricular outflow tract (RVOT), but foci deep to the endocardium, in the epicardium, or in the left ventricle are not uncommon. Although these extra-RVOT foci can be targeted with ablation, risks involved are higher and success rates lower. Simple electrocardiographic (ECG) criteria allowing (1) discrimination of RVOT foci from extra-RVOT foci and (2) assessment of the chance of success of a right heart ablation procedure are desirable. METHODS: Twenty-five consecutive patients referred for radiofrequency (RF) ablation of idiopathic VT or severely symptomatic idiopathic ventricular premature contractions were included. Localization of VT origin and success rates of VT ablation in the RVOT were analyzed according to the ECG pattern. RESULTS: The analysis of the R wave in V2 was the strongest single predictor of whether the VT had an RVOT or an extra-RVOT origin. An R wave amplitude < or =30% of the QRS amplitude designated the VT focus in the RVOT with positive and negative predictive values of 95 and 100%, respectively. Analysis of R wave duration in V2 had similar predictive values, whereas the R/S transition zone in precordial leads had slightly lower predictive values. Seventeen of 20 arrhythmias (85%) with an R wave amplitude < or =30% of the QRS amplitude in V2 could be successfully abolished by an exclusively right heart procedure. CONCLUSIONS: The analysis of ECG pattern makes it possible to guide the management of patients with idiopathic VT in predicting the arrhythmias that can be safely targeted with RF ablation from the RVOT with high success rates.