The presence of extensive atrial scars hinders the differential diagnosis of focal or macroreentrant atrial tachycardias in patients with complex congenital heart disease.

AIMS: Atrial tachycardias (ATs) frequently develop in patients with congenital heart defects (CHDs). This study aimed to evaluate the effects of extensive atrial scar formation on the total atrial activation time (TAAT) and its relation to the tachycardia cycle length (CL) to classify AT. METHODS AND RESULTS: Seventy-one patients were included and divided into two groups: patients without CHD (Group I, 35 patients) and with CHD (Group II, 36 patients). All patients underwent CARTO electroanatomical activation mapping. Two subgroups were created: centrifugal (CAT) or macroreentrant AT (MRAT). Total atrial activation time, CL, and mean bipolar signal amplitude (BiSA) were analysed. In Group I, 18 patients (51.4%) had CAT and 17 (48.6%) MRAT. The mean BiSA for Group I was 1.30 ± 0.32 mV. Total atrial activation time/CL ratios were different between CAT and MRAT (28.4 ± 16.9 vs. 66.6 ± 14.3%, P < 0.001). In Group II, 18 patients (50%) had CAT and 18 patients (50%) MRAT. The mean BiSA was 0.94 ± 0.50 mV and was not different for CAT and MRAT subgroups (1.04 ± 0.64 vs. 0.85 ± 0.29, P = 0.243). Total atrial activation time/CL ratios were comparable between CAT and MRAT patients (69.0 ± 40.4 vs. 83.6 ± 8.3%, P = 0.243). A significant lower BiSA was found for CAT with TAAT/CL ratios above 40% (0.62 ± 0.11 vs. 1.90 ± 0.18 mV, P < 0.001). A strong negative correlation was identified between the BiSA and the TAAT/CL ratio in patients with CAT in Group II (-0.742; P < 0.001). CONCLUSION: Low mean BiSA values in CHD patients are associated with altered impulse propagation, making TAAT- and CL-based diagnostic tools inaccurate. Further diagnostic tests are needed to determine the correct mechanism of ATs.

The prevalence of early repolarization in patients with noncompaction cardiomyopathy presenting with malignant ventricular arrhythmias.

UNLABELLED: Early Repolarization in Noncompaction Cardiomyopathy. BACKGROUND: Early repolarization (ER) is associated with malignant ventricular arrhythmias, including ventricular fibrillation (VF) and sudden cardiac death (SCD). One possible mechanism is increased trabeculation with deep intramyocardial invagination, carrying the Purkinje system deeper into the myocardium resulting in delayed depolarization and inhomogenous repolarization. Noncompaction cardiomyopathy (NCCM) is a recently classified, primary cardiomyopathy with excessive trabeculations. In these patients ventricular arrhythmias, including sustained VT and VF, occur frequently. The aim of this study was to determine the prevalence of ER in NCCM patients, especially in those primarily presenting with malignant ventricular arrhythmias or SCD. METHODS: We analyzed prospective data from our NCCM registry including 84 patients, median age: 40 (3-79) years. RESULTS: Fourteen patients (17%) initially presented with sustained VT (n = 5) or VF (n = 9) and 70 (83%) with heart failure or else. After the exclusion of 20 patients with the left bundle branch block, 25 (39%) NCCM patients had ER; 3 (6%) located in inferior leads, 14 (27%) in lateral leads, and 8 (15%) in both. None had ER in leads V1 to V3. In those presenting with VT/VF, 9/12 (75%) had ER (2 in inferior leads, 3 in lateral leads and 4 in both), versus 16/52 (31%) in the other patients (P = 0.02). If the NCCM population was dichotomized according to the presence or absence of ER, the long-term outcome for VT/VF appeared worse in the ER positive patients (P = 0.05). CONCLUSION: There is a high prevalence of ER in NCCM patients, especially in those who present with malignant ventricular arrhythmias. (J Cardiovasc Electrophysiol, Vol. 23, pp. 938-944, September 2012).

Acute and long-term outcomes of catheter ablation using remote magnetic navigation in patients with congenital heart disease.

The aim of the present study was to assess the feasibility, safety, and long-term results of remote magnetic navigation in arrhythmias associated with complex congenital heart disease (CHD). The improved outcomes for CHD resulted in an increased number of complex arrhythmias requiring distinctive ablation techniques. Thirty-six patients with CHD (age 35 ± 19 years, 21 male) were divided into 3 complexity groups and underwent 43 radiofrequency catheter ablation procedures using the magnetic navigation system (including 7 redo ablations) in combination with the CARTO RMT system. A total of 59 tachyarrhythmias were identified. Most patients had surgical scar-related tachycardia (25 focal, including 4 microreentrant atrial tachycardia, and 27 macroreentrant atrial tachycardia). Four accessory pathways and three ventricular tachycardias were diagnosed and treated. In 31 patients, ablation was successful, with an end point of noninducibility (86%). The success rate for CHD complexity of type I, II, and III was 50%, 88%, and 89%, respectively. The mean procedure and fluoroscopy time was 216 ± 101 minutes and 40 ± 34 minutes, respectively. The number of radiofrequency applications was 42 ± 47. No major complications related to the procedures occurred. Of the patients, 67% remained free of recurrence during a mean follow-up of 26 ± 4 months. Recurrence developed in 0%, 16%, and 45% of patients with CHD type I, II, and III, respectively. In conclusion, the magnetic navigation system is feasible to treat arrhythmias with reasonable success rates and good long-term outcomes in adult patients with CHD. The use of the magnetic navigation system offers advantages in complex anatomic situations.

Catheter ablation of ventricular tachycardias using remote magnetic navigation: a consecutive case-control study.

UNLABELLED: Remote Magnetic Navigation for VT Ablation. BACKGROUND: This study aimed to compare acute and late outcomes of VT ablation using the magnetic navigation system (MNS) to manual techniques (MAN) in patients with (SHD) and without (NSHD) structural heart disease. METHODS: Ablation data of 113 consecutive patients (43 SHD, 70 NSHD) with ventricular tachycardia treated with catheter ablation at our center were analyzed. Success rate, complications, procedure, fluoroscopy, and ablation times, and recurrence rates were systematically recorded for all patients. RESULTS: A total of 72 patients were included in the MNS group and 41 patients were included in the MAN group. Patient age, gender, and right ventricular and left ventricular VT were equally distributed. Acute success was achieved in 59 patients in the MNS group (82%) versus 27 (66%) patients in the MAN group (P = 0.046). Overall procedural time (177 ± 79 vs 232 ± 99 minutes, P < 0.01) and mean patient fluoroscopy time (27 ± 19 vs 56 ± 32 minutes, P < 0.001) were all significantly lower using MNS. In NSHD pts, higher acute success was achieved with MNS (83,7% vs 61.9%, P = 0.049), with shorter procedure times (151 ± 57 vs 210 ± 96, P = 0.011), whereas in SHD-VT these were not significantly different. No major complications occurred in the MNS group (0%) versus 1 cardiac tamponade and 1 significantly damaged ICD lead in the MAN group (4.9%, NS). After follow-up (20 ± 11 vs 20 ± 10 months, NS), VT recurred in 14 pts (23.7%) in the MNS group versus 12 pts (44.4%) in the MAN group (P = 0.047). CONCLUSIONS: The use of MNS offers advantages for ablation of NSHD-VT, while it offers similar efficacy for SHD-VT. (J Cardiovasc Electrophysiol, Vol. 23, pp. 948-954, September 2012).

Flutter ablation with remote magnetic navigation: comparison between the 8-mm tip, the irrigated tip and a manual approach.

INTRODUCTION: Remote magnetic navigated ablation has proven its feasibility in a large group of arrhythmias. Until now only scarce data are available on the use for atrial flutter. In this study we compared remote magnetic navigation (RMN), using non-irrigated and irrigated tip catheters, to manual radiofrequency ablation for ablating typical atrial flutter. METHODS: The 3 study groups consisted of 17 patients treated with RMN 8-mm tip; 14 patients with RMN irrigated tip; and 24 patients with a manual 8-mm tip. The primary outcome was the number of patients in whom bidirectional isthmus block could be obtained with < or = 15 applications. Secondary end points were the median number of applications needed, the need to switch to a manual irrigated tip catheter, the procedural and fluoroscopy times. RESULTS: There was no significant difference in the primary end point (RMN 8 mm-tip group: 59%, RMN irrigated tip group: 64% and manual group: 83%). The median number of applications needed to obtain block was higher in the RMN groups compared to the manual group. In 5 patients from the RMN 8-mm tip group, 1 in the RMN irrigated tip group and 1 in the manual group, a switch to a manually irrigated tip catheter was performed.There was no difference in fluoroscopy time, but procedural time was significantly longer in the RMN groups compared to the manual group (P= 0.03). CONCLUSIONS: The use of magnetic navigation for the ablation of atrial flutter is feasible but not superior to a manual approach. There was no difference concerning the primary end point of acute success within 15 applications. Overall, more applications were needed and procedure times were longer with RMN but RMN with the irrigating tip is promising.

Insulation defects of thin high-voltage ICD leads: an underestimated problem?

BACKGROUND: Long-term lead failure is a known complication of ICD therapy. The precise incidence and sequelae of insulation defects at the tricuspid level, however, are not well characterized. OBJECTIVE: This study determined the risk of lead failure, with particular emphasis on insulation defects at the level of the tricuspid valve, in a large series of consecutive ICD recipients. METHODS: Data from 357 consecutive patients, who had received transvenous 7 and 8 French ICD-leads (St. Jude Medical, Riata family) and were followed at our center, formed the basis of this study. RESULTS: During a mean follow-up of 42 ± 24 months, 30 of 357 (8%) patients required surgical intervention due to lead failure. For overall lead defects, lead access via the subclavian vein and subpectoral device placement were independent predictors of overall lead failure (OR 3.47, 95% CI 1.38-8.72, P = 0.013 and OR 3.83, 95% CI 1.77-8.27, P = 0.001, respectively). Lead insulation defects at the level of the tricuspid valve accounted for 20% of all lead failures. Diagnosis of this specific insulation defect could only be established by fluoroscopy, while electrical parameters were within normal limits in all of these patients. On univariate but not on multivariate analysis the presence of nonischemic cardiomyopathy was a predictor of this lead complication (OR 8.2, CI 1.5-46.1, P = 0.02). CONCLUSION: Insulation defects of 7 and 8 French ICD leads at the tricuspid level represent an important complication of device therapy. Even moderate changes in lead impedance within the normal limits at follow-up should prompt careful fluoroscopic evaluation to avoid spurious shocks.

The magnetic navigation system allows safety and high efficacy for ablation of arrhythmias.

AIMS: We aimed to evaluate the safety and long-term efficacy of the magnetic navigation system (MNS) in a large number of patients. The MNS has the potential for improving safety and efficacy based on atraumatic catheter design and superior navigation capabilities. METHODS AND RESULTS: In this study, 610 consecutive patients underwent ablation. Patients were divided into two age- and sex-matched groups. Ablations were performed either using MNS (group MNS, 292) or conventional manual ablation [group manual navigation (MAN), 318]. The following parameters were analysed: acute success rate, fluoroscopy time, procedure time, complications [major: pericardial tamponade, permanent atrioventricular (AV) block, major bleeding, and death; minor: minor bleeding and temporary AV block]. Recurrence rate was assessed during follow-up (15±9.5 months). Subgroup analysis was performed for the following groups: atrial fibrillation, isthmus dependent and atypical atrial flutter, atrial tachycardia, AV nodal re-entrant tachycardia, circus movement tachycardia, and ventricular tachycardia (VT). Magnetic navigation system was associated with less major complications (0.34 vs. 3.2%, P=0.01). The total numbers of complications were lower in group MNS (4.5 vs. 10%, P=0.005). Magnetic navigation system was equally effective as MAN in acute success rate for overall groups (92 vs. 94%, P=ns). Magnetic navigation system was more successful for VTs (93 vs. 72%, P<0.05). Less fluoroscopy was used in group MNS (30±20 vs. 35±25 min, P<0.01). There were no differences in procedure times and recurrence rates for the overall groups (168±67 vs. 159±75 min, P=ns; 14 vs. 11%, P=ns; respectively). CONCLUSIONS: Our data suggest that the use of MNS improves safety without compromising efficiency of ablations. Magnetic navigation system is more effective than manual ablation for VTs.

Diagnostic value of the left atrial electrical potentials detected by body surface potential mapping in the prediction of coronary artery disease.

BACKGROUND: The electrocardiographic diagnosis of significant coronary artery stenosis (CAD) is often based on the investigation of the left ventricular repolarization changes during exercise ECG stress test (EST). Our aim was to prove that the electric activity of the left atrium can indicate the ischemic damage of the left ventricle, and furthermore, it is able to indicate CAD without exercise. METHODS AND RESULTS: Patients with chest complaints but without evidence of acute coronary syndrome were investigated by EST and body surface potential mapping (BSPM, 63 leads). CAD was proven in 45 cases (32 men, years 40-76) and excluded in 50 cases (35 men, years 38-72) with coronary angiography. Left atrial electric potentials (EP-LA) before and after 0.08 mg sublingual nitroglycerine administration differed significantly (p<0.001) in the two groups. According to Fischer linear discriminant analysis, this difference in % (EP-LA(d%)) was the best separating parameter: below limit of -14.17% (CAD prevalence was considered) this parameter predicted CAD with 93% sensitivity, 100% specificity, >10 positive and 0.05 negative likelihood ratio (weighted for prevalence). The EST predicted CAD with 71% sensitivity, 78% specificity, 2.43 positive and 0.28 negative likelihood ratios. CONCLUSION: The electrical activity changes of the left atrium seemed to be suitable to predict CAD as an EST-alternative resting method.

Diagnostic value of body surface potential mapping in assessment of the coronary artery lesion after angina pectoris and without repolarization changes on the electrocardiogram.

BACKGROUND: The body surface potential mapping (BSPM) method is sensitive in detecting minor electrical potential abnormalities, but its diagnostic value is unclear in detection and localization of significant coronary artery lesion (CAL) in patients after angina pectoris and without ischemic electrocardiogram abnormalities at the time of the BSPM record. METHODS AND RESULTS: Characteristic features and quantitative parameters of the isopotential maps during the depolarization were evaluated and compared with the result of coronary angiography in 228 patients (164 males; age, 61.6 +/- 9.5 years). Twenty-three of them had their first angina, but the others had a history of earlier angina, unstable angina, non-ST-elevation infarction. Fifty-nine healthy subjects (32 males; age, 53.3 +/- 12.2 years) served as control. The diagnostic power was high in detection of CAL among patients with previous ischemic events, but it was low in first angina. The accuracy of the CAL localization by multiple regression was different: at 90% specificity level, the sensitivity was near 80% for right/posterior descending CAL and slightly more than 60% for left anterior descending CAL but only 19% for first marginal/first diagonal CAL. CONCLUSIONS: The BSPM changes during the depolarization could well indicate CAL only after previous ischemic events. Sensitivity and specificity of the CAL localization depended on the extension and location of the underlying myocardium damage.

Double intra-atrial connections in a patient late after orthotopic heart transplantation.

Atrial tachycardias occurring late after orthotopic heart transplantation are frequently caused by an ongoing atrial tachycardia in the recipient remnant atrium that is associated with intra-atrial muscle band connections between the 2 atrial compartments. The standard approach for most centers that treat these patients is to identify and disconnect these intra-atrial connections. We present a patient where double intra-atrial connections were capable of different degrees of stimulus propagation from the recipient remnant atrium to the donor atrial compartment. After the ablation of both intra-atrial connections, we also ablated the index arrhythmia in the recipient remnant atrium. This case presentation draws attention to the possibility of the presence of multiple intra-atrial connections.

Diagnosis and discrimination of remote antero- and inferoseptal non-Q wave myocardial infarctions with body surface potential mapping.

BACKGROUND: Previous studies have shown that the diagnosis and localization of previous non-Q wave myocardial infarction (NQMI) is possible by body surface potential mapping (BSPM), but the criteria for the discrimination between anteroseptal and inferoseptal middle regions remain to be determined. METHODS: BSPM using 63 unipolar leads was recorded in 119 patients with previous NQMI (36 to 76 years of age, average 61 years; 85 men). Localization of anteroseptal or inferior middle NQMI occurred in 70 cases (44 to 76 years of age, average 61 years, 53 men) by determining early anterior minimum potential with only slight negativity. In these cases, isopotential maps obtained at additional time points were investigated to discriminate between anteroseptal and inferoseptal NQMI. The clinical localization was based on the concordance of two of the following tests: wall motion disturbances on echocardiography, coronary angiogram and repolarization changes in the acute-phase electrocardiogram. RESULTS: Two milliseconds before the appearance of the first anterior minimum, a more accentuated superior negativity indicated anteroseptal NQMI (32 of 70 cases), while a more pronounced inferior negativity indicated inferoseptal NQMI (38 of 70 cases). Fisher's exact test showed statistically significant associations between the above BSPM localizations and the clinical localizations (P<0.001). Occlusion or stenosis of the expected infarct-related coronary artery was detected in all patients either as a single lesion or together with other coronary artery lesions. CONCLUSIONS: The BSPM criteria proposed here are suitable to detect the most frequent NQMI localizations. The narrowing of the infarct-related coronary arteries, the left anterior descending or the posterior descending coronary artery, can be thus differentiated.