Radiofrequency catheter ablation can be performed with high success rates and very low complication rates in children and adolescents.

AIM: Radiofrequency catheter ablation is a standard treatment for tachyarrhythmia in children. Recently, several centres using cryoenergy for ablation have reported high success and low complication rates, but an increased risk of recurrence of arrhythmia. The aim of this study was to report success, complications and recurrence rates for radiofrequency catheter ablation in children under current conditions. METHODS: A retrospective cohort study of 333 consecutive children undergoing radiofrequency catheter ablation over the last two decades. RESULTS: Radiofrequency catheter ablation was performed successfully in 96.7% of patients, but was significantly less successful in patients with a right anterior or right anterolateral accessory pathway (81.8%). Overall mortality was 0%; there was only one (0.3%) major complication, a pericardial haemorrhage, and only 2.8% of the patients developed minor vascular complications at the puncture site. None of the patients developed a persistent atrioventricular block. Over a median observation time of 4.3 years (0.1; 17.8), recurrence of arrhythmia occurred in 9.3% of all patients, but 50% of children with right lateral accessory pathways. CONCLUSION: Radiofrequency catheter ablation can be performed with high success and very low complication rates in children. Recurrence rates are substantially lower than those reported for cryoablation in the literature.

Combined circular multielectrode catheter and point-by-point ablation is superior to point-by-point ablation alone in eliminating atrial fibrillation.

BACKGROUND: Besides conventional point-by-point ablation, novel multielectrode catheters emerge for ablation of atrial fibrillation (AF). We sought to evaluate the clinical utility of a pulmonary vein (PV) isolation approach combining the advantages of both technologies. METHODS: The study included 240 consecutive AF patients (60±11 years, 68% males, 62% paroxysmal). In the combined ablation group (n=120), PV isolation was performed with a circular multielectrode catheter (PVAC, Medtronic Ablation Frontiers) and completed by conventional point-by-point ablation (NaviStar ThermoCool Catheter, Lasso/CARTO technology, Biosense Webster). In the point-by-point ablation group (n=120), PV isolation was performed with point-by-point ablation alone. RESULTS: Complete 1-year ablation success (freedom from any atrial arrhythmia off antiarrhythmic drugs) was more frequently observed in the combined ablation group (58.0% versus 43.3%, hazard ratio 1.72, 95% confidence interval 1.19-2.48, p=0.004). Also clinical success (≥90% reduction of arrhythmia burden on/off antiarrhythmic drugs) was significantly associated with the combined ablation approach (p=0.001). These associations remained significant after multivariable adjustment (both p≤0.005) and were not dependent on the type of AF. The rate of major adverse events (3.3% versus 2.5%) and the procedure time did not differ between groups. The fluoroscopy time, however, was significantly shorter in the combined ablation group (p<0.001) reflecting the reduced need for radiation during multielectrode catheter ablation. CONCLUSIONS: A combined PV isolation approach based on multielectrode catheter ablation and complementary point-by-point ablation is superior to point-by-point ablation alone and reveals to be safe. A potential explanation for these findings is the improved durability of ablation lesion after the combined ablation approach.

Prognostic value of induction of atrial fibrillation before and after pulmonary vein isolation.

BACKGROUND: Apart from pulmonary vein isolation, catheter ablation of atrial fibrillation (AF) lacks reliable electrophysiological endpoints. The present study investigated the prognostic value of changes in AF inducibility due to ablation. METHODS: Between 10/2006 and 10/2009 121 patients referred for catheter ablation of symptomatic, drug refractory paroxysmal AF were included. Sinus rhythm immediately before ablation was a prerequisite for study entry. Two respective attempts to induce AF (>1min) by decremental coronary sinus stimulation before and after ablation were performed. RESULTS: A total of 121 patients aged 59.5±10.4years undergoing pulmonary vein isolation due to paroxysmal AF were included. The median follow-up duration was 12.1months [quartiles: 6.5-20.3months]. In 36 (30%) patients AF was inducible before, but not after ablation. Forty-nine (41%) patients were neither inducible before nor after the procedure, whereas 25 patients (21%) displayed unchanged inducibility. In 11 patients (9%) AF was inducible only after ablation. Patients with inducibility solely after the ablation had the highest risk of AF recurrence (HR 6.71 [95%-CI 2.76-16.30], p=0.0005) compared to patients without inducibility before and after the procedure. CONCLUSION: The results of attempted AF induction before and after ablation have significance with respect to ablation outcome. Both patient groups with either unchanged inducibility or facilitated induction after ablation had the highest recurrence rates of AF.

Markers of oxidative stress after ablation of atrial fibrillation are associated with inflammation, delivered radiofrequency energy and early recurrence of atrial fibrillation.

BACKGROUND: The role of oxidative stress after radiofrequency ablation of atrial fibrillation (AF) has not yet been well characterized. We sought to evaluate the time course of biomarkers of oxidative stress and inflammation after AF ablation and their association with clinical variables. METHODS: Thirty consecutive patients (57.9 ± 1.7 years, 63% males) with paroxysmal AF underwent pulmonary vein isolation and ablation of complex fractionated atrial electrograms. Biomarkers were determined in blood samples before ablation and 6 h, 1, 2, 7, 30, 90 and 180 days post-ablation. RESULTS: The pro-oxidant enzyme myeloperoxidase and oxidized low-density lipoprotein reflecting oxidant damage of lipoproteins increased 2.9 ± 0.2-fold and 1.2 ± 0.1-fold, respectively, and were significantly up-regulated until day 2 post-ablation. The anti-oxidant enzyme copper/zinc superoxide dismutase did not change significantly. Inflammatory markers significantly increased (high-sensitivity C-reactive protein (hs-CRP): 41 ± 8-fold; interleukin-6: 4.4 ± 0.7-fold) for 7 and 2 days, respectively. The increase of myeloperoxidase and hs-CRP was interrelated and both predicted early recurrence of AF within the first post-ablation week (both p < 0.05). The increase of both markers was associated with the amount of delivered radiofrequency energy (p < 0.05). The up-regulation of hs-CRP correlated with troponin T (p = 0.008), while myeloperoxidase and troponin T were borderline associated (p = 0.054). However, the oxidative and inflammatory responses did not predict long-term ablation outcome (p > 0.05). CONCLUSIONS: Markers of oxidative stress showed a significant up-regulation during the first 2 days after AF ablation. Their up-regulation was linked to inflammation, delivered radiofrequency energy, and early recurrence of AF, but did not predict long-term ablation outcome.

Time course of markers of tissue repair after ablation of atrial fibrillation and their relation to left atrial structural changes and clinical ablation outcome.

BACKGROUND: Radiofrequency ablation of atrial fibrillation (AF) creates left atrial (LA) tissue damage with a subsequent healing process. We sought to prospectively assess the time course of biomarkers of tissue repair after ablation and to evaluate their association with clinical variables. METHODS: 30 consecutive patients (57.9 ± 1.7 yrs, 63% males) with paroxysmal AF underwent a CARTO-guided LA circumferential ablation, Lasso-guided segmental pulmonary vein isolation and ablation of complex fractionated atrial electrograms. Matrix metalloproteinase-9 (MMP-9) and transforming growth factor-ß1 (TGF-ß1), both key regulators of tissue repair, and the aminoterminal propeptide of type III procollagen (PIIINP), reflecting collagen synthesis, were determined in blood samples before and 6h, 1, 2, 7, 30, 90 and 180 days post-ablation. RESULTS: All markers showed a significant ablation-induced up-regulation (MMP-9: 1.8 ± 0.1-fold, TGF-ß1: 2.4 ± 0.4-fold, PIIINP: 1.3 ± 0.1-fold). MMP-9 was significantly up-regulated until day 90, TGF-ß1 only on day 2. PIIINP increased from day 2 to 7. The area under the curve (AUC) of MMP-9 and TGF-ß1 correlated with the ablation-induced reduction of LA volume (both p<0.05). The AUC of MMP-9 was additionally associated with the amount of radiofrequency energy delivered during ablation (p < 0.05). At 12 months of follow-up 57% of patients were free of AF off antiarrhythmic drugs. The AUC of PIIINP independently predicted recurrent AF (p < 0.05). CONCLUSIONS: Markers of healing showed a significant up-regulation after AF ablation detectable for up to 90 days. A more pronounced up-regulation of MMP-9 or TGF-ß1 is associated with a greater reduction of LA size. High PIIINP levels after ablation predict a poor ablation outcome.

Treatment of a recurrent atrial tachycardia by isolation of the right inferior pulmonary vein using a multi-electrode duty cycled ablation catheter.

We report on a 29-year-old man who underwent an ablation procedure for a focal atrial tachycardia. Three-dimensional mapping located the site of origin to the ostium of the right inferior pulmonary vein. By using a novel multi-electrode duty cycled ablation catheter, pulmonary vein isolation and elimination of tachycardia was achieved.

Evaluation of left atrial function by multidetector computed tomography before left atrial radiofrequency-catheter ablation: comparison of a manual and automated 3D volume segmentation method.

INTRODUCTION: The purpose of this study was to compare a manual and automated 3D volume segmentation tool for evaluation of left atrial (LA) function by 64-slice multidetector-CT (MDCT). METHODS AND MATERIALS: In 33 patients with paroxysmal atrial fibrillation a MDCT scan was performed before radiofrequency-catheter ablation. Atrial function (minimal volume (LAmin), maximal volume (LAmax), stroke volume (SV), ejection fraction (EF)) was evaluated by two readers using a manual and an automatic tool and measurement time was evaluated. RESULTS: Automated LA volume segmentation failed in one patient due to low LA enhancement (103HU). Mean LAmax, LAmin, SV and EF were 127.7 ml, 93 ml, 34.7 ml, 27.1% by the automated, and 122.7 ml, 89.9 ml, 32.8 ml, 26.3% by the manual method with no significant difference (p>0.05) and high Pearsons correlation coefficients (r=0.94, r=0.94, r=0.82 and r=0.85, p<0.0001), respectively. The automated method was significantly faster (p<0.001). Interobserver variability was low for both methods with Pearson's correlation coefficients between 0.98 and 0.99 (p<0.0001). CONCLUSIONS: Evaluation of LA volume and function with 64-slice MDCT is feasible with a very low interobserver variability. The automatic method is as accurate as the manual method but significantly less time consuming permitting a routine use in clinical practice before RF-catheter ablation.

Intramural left atrial haematoma mimicking cardiac tamponade after catheter ablation of atrial fibrillation.

Catheter ablation is an established treatment modality for patients with drug refractory atrial fibrillation (AF). This procedure carries a 6% major complication rate including cardiac tamponade due to cardiac perforation. We report on a patient with clinical signs of cardiac tamponade due to a diffuse intramural left atrial haematoma obstructing left ventricular filling after catheter ablation of AF.

Frequency of recurrence of atrial fibrillation within 48 hours after ablation and its impact on long-term outcome.

Because of delayed structural and electrophysiologic effects of radiofrequency ablation of atrial fibrillation (AF), early recurrence of AF after ablation does not necessarily indicate long-term ablation failure. This study was intended to assess the prognostic value of early recurrence of AF within 48 hours after ablation. The study included 234 patients (aged 23 to 80 years; 72% men) with symptomatic drug-resistant paroxysmal (n = 165) or persistent AF (n = 69) who underwent either Lasso-guided segmental pulmonary vein isolation (n = 83) or CARTO-guided left atrial circumferential ablation (n = 151). After a median follow-up of 12.7 months, 64% of patients with paroxysmal and 45% of patients with persistent AF were AF free. Early recurrence of AF occurred in 43% of patients and was more frequently observed in the persistent-AF group (paroxysmal vs persistent 39% vs 54%; p = 0.037). Early recurrence of AF was a significant predictor of long-term ablation failure in univariate (hazard ratio [HR] 2.29, p <0.001) and multivariate (HR 2.17. p <0.001) Cox regression analysis. Nevertheless, 46% of patients with early recurrence of AF were AF free during long-term follow-up compared with 68% of patients without early recurrence of AF. The prognostic value of early recurrence of AF was found in patients with paroxysmal (HR 2.05, p = 0.005) and persistent AF (HR 2.35, p = 0.013). In conclusion, early recurrence of AF within 48 hours after ablation was a significant predictor of a poor long-term ablation outcome. However, because nearly half the patients with early recurrence of AF remained AF free during long-term follow-up, early recurrence of AF should not automatically result in an early repeated procedure.

Tako-tsubo cardiomyopathy complicating left atrial radiofrequency ablation.

Two female patients undergoing left atrial radiofrequency catheter ablation developed Tako-tsubo cardiomyopathy. This reversible form of left ventricular dysfunction is known to occur under conditions associated with marked sympathetic nervous activation. Radiofrequency catheter ablation in the left atrium can damage autonomic ganglionated plexi, leading to vagal withdrawal, thus resulting in enhanced sympathetic tone. Tako-tsubo cardiomyopathy has not been previously described following radiofrequency catheter ablation.

Therapy with angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, and statins: no effect on ablation outcome after ablation of atrial fibrillation.

BACKGROUND: The renin-angiotensin-aldosterone system and inflammation are supposed to play a key role in the pathogenesis of atrial fibrillation (AF). This retrospective clinical study was intended to assess the influence of drugs with antiinflammatory and/or renin-angiotensin-aldosterone system-modulating properties, namely angiotensin-converting enzyme inhibitors (ACE-Is), angiotensin II receptor blockers (ARBs), and statins, on AF-free survival after AF ablation. METHODS: The study included 234 patients (23-80 years; 71.8% men) with drug-resistant paroxysmal (n = 165) or persistent AF (n = 69) who either underwent a Lasso-guided segmental pulmonary vein isolation (n = 83) or a CARTO-guided left atrial circumferential ablation (n = 151). Treatment with statins (n = 113), ACE-Is, or ARBs (n = 124), or a combination of a statin and an ACE-I or ARB (n = 75) was started >3 months before ablation and was continued during follow-up. RESULTS: After a median follow-up of 12.7 months, 64% of patients with paroxysmal and 45% of patients with persistent AF were free of AF. Statin use (hazard ratio [HR], 1.06; P = .79), ACE-I or ARB use (HR, 1.12; P = .59), and their combined use (statin + ACE-I/ARB; HR, 1.17; P = .54) did not significantly influence ablation outcome as assessed by Cox regression analysis. In addition, after multivariate adjustment for potential confounders, the examined drugs did not significantly affect ablation outcome. Ablation induced an acute up-regulation of C-reactive protein levels (preablation vs 48 hours postablation, 5.9 +/- 8.1 vs 33.7 +/- 30 mg/L; P < .001) and other inflammatory markers. The examined drugs did not significantly alter baseline levels or ablation-induced up-regulation of inflammatory markers. CONCLUSIONS: The routine use of statins, ACE-Is, or ARBs did not result in an improved outcome of AF ablation.

Is inducibility of atrial fibrillation after radio frequency ablation really a relevant prognostic factor?

AIMS: The study was intended to assess the prognostic value of inducibility of atrial fibrillation (AF) after radio frequency ablation. METHODS AND RESULTS: Two hundred and thirty four patients with drug-resistant paroxysmal (n=165) or persistent AF (n=69) underwent either Lasso-guided segmental pulmonary vein isolation (n=83) or CARTO-guided left atrial circumferential ablation (n=151). After ablation, two attempts to induce AF (>1 min) by decremental coronary sinus stimulation were performed. Patients were followed for at least 6 months (median: 12.7 months). At 6 months of follow-up, 67% of patients with paroxysmal and 48% of patients with persistent AF were AF-free. Inducibility of AF was a significant predictor of AF recurrence in univariate [hazard ratio (HR)=2.32, P<0.001] and multivariable (HR=2.19, P<0.001) Cox regression analyses. The prognostic value of inducibility was present in both patients with paroxysmal (HR=2.38, P=0.001) and persistent AF (HR=1.91, P=0.034) and did not significantly differ between both ablation techniques. The sensitivity, specificity, positive, and negative predictive values of the AF induction test to predict the 6-month ablation outcome were 46.7, 75, 53.8, and 69.2%, respectively. CONCLUSION: Inducibility of AF after ablation is a significant predictor of recurrent AF. However, owing to the low diagnostic accuracy of the AF induction test, non-inducibility does not qualify as reliable procedural endpoint.