Continuous variables are expressed as the mean±standard deviation. Differences between continuous variables were evaluated using Student's t test for dependent or independent samples, as appropriate. Differences between categorical variables were assessed using the chi-square or Fisher exact test. Statistical significance was set at a P value of <.05. The statistical analysis was carried out using an SPSS (20.0) database.

As in previous registries, the epidemiological characteristics were analyzed using patient data only from centers providing prospective data. In 2014, there were 9 such centers (1 more than in 2011, 2012, and 2013, years in which 8 of the participating centers used this format); these 9 centers reported a total of 1857 ablation procedures.

The overall mean age of the patients was 44 ± 15 years. The mean ages corresponding to the 10 different ablation targets ranged between 36±9.8 years for AP ablation and 73±7 years for atrioventricular node ablation. Regarding the distribution by sexes, most of the AVNRT ablation procedures were carried out in women (79%), whereas ablation of AF or of ventricular tachycardia, with or without associated structural heart disease, was mostly performed in men (75% and 71%, respectively). These data are virtually identical to those reported in previous registries.

Again, consistent with the findings in previous years, 41% of the patients had a history of structural heart disease, and left ventricular dysfunction was generally limited to patients undergoing atrioventricular node ablation or ablation of ventricular tachycardia associated with heart disease (VT-NICM). The same distribution was observed in the group of patients with implantable cardioverter defibrillators.

The technical and human resources available in the arrhythmia units participating in the 2014 registry and the activity carried out are presented in Tables 1 and 2.

Fifty-three centers (61.6%) were equipped with at least 1 dedicated cardiac electrophysiology laboratory, and 7 centers (8.2%) had 2 such laboratories. As in previous years, the laboratory was available 3.7±1.4 (median, 4) days a week. Only 3 of the 17 private centers had an area devoted exclusively to cardiac electrophysiology.

External electric cardioversion was performed in 52 laboratories and internal cardioversion in only 22 of these centers. Most units, although in a slightly lower percentage than in 2013 (78.8%), were also equipped to perform implantation of cardiac pacing devices, mainly defibrillators: implantation of both defibrillators and pacemakers was performed in 74.4% of the laboratories, defibrillator implantation alone in 3.5%, and pacemaker implantation alone in 2.3%.

All the participating centers were equipped with a digital recording system, 52% with digital radiography, and 41% with portable fluoroscopy. A single nonfluoroscopic navigation system was available in 79% of the centers; 27% had 2 such systems, and 1.2% had 3. Although the differences were less marked than in the 2013 registry, nonfluoroscopic navigation systems were more widely available in publicly-funded centers than in private ones (75% vs 59%).

The number of remote navigation systems was slightly lower than in previous years. Two centers had a magnetic navigation system and 2 a robotic navigation system. The number of sites performing intracardiac echocardiography also decreased (to 18, representing a reduction from 25% in 2013 to 21% in 2014). Ultrasound ablation was available at a single site, as reported in previous registries. However, the number of centers offering cryoablation continued to grow (48, representing an increase from 52.5% in 2013 to 56% this past year).

After the slight decrease in the number of health care professionals working in electrophysiology laboratories reported in recent years, this decline appears to have leveled off in 2014, with data similar to those of the 2013 registry.13 In all, 76.4% of the centers had more than 1 full-time physician, and 47% had more than 2, figures considerably higher than those of the registry of the preceding year.13 One noteworthy finding was that 23 health care centers had 4 staff physicians working full-time in electrophysiology laboratories, in contrast to the 10 centers reported in 2013. The staff of 74.1% of the laboratories included at least 2 full-time nursing graduates. In 2014, 28 centers had resident physicians, in most cases 1 or 2 (1 hospital had 8 residents).

In 2014, a total of 85 centers submitted their data to the registry, the highest level of participation since its inception (Figures 1 and 2). In all, 12 871 procedures were reported, yielding a mean of 149.5±103 (median, 124; range, 7-486) procedures per site. Only 8 private centers performed more than 50 ablation procedures per year, and 3 of them exceeded 200 per year. Seven public health centers carried out more than 300 ablations (2 of them, more than 400).

Figure 2.

Number of electrophysiology laboratories participating in the registry by number of ablation procedures performed in 2014.

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The overall success rate was 95%, excluding the treatment of AF, VT-ICM, and VT-NICM. Among the total number of ablation procedures performed (including AF, VT-ICM, and VT-NICM), 237 complications were notified (1.8%). A total of 8 deaths were reported (0.06%), twice the number in 2013: 1 patient died during AVNRT ablation, another 6 during ablation for VT-ICM, and the eighth during ablation for macroreentrant atrial tachycardia. No deaths were reported in AF ablation procedures. There were 14 cases of iatrogenic atrioventricular block (0.1%) requiring permanent pacemaker implantation: 10 during AVNRT ablation (exactly twice the number recorded in 2013), 1 during AP ablation, 2 during cavotricuspid isthmus ablation, and 1 during VT-ICM ablation. The overall success and complications rates in 2014, compared with the rates in previous years, are shown in Figures 3 and 4. The success rates for the different procedures have remained steady, with a certain degree of recovery of the results for ablation to treat ventricular tachycardia in heart disease in general (VT-NICM), which, after a decrease from 77% to 69% reported in the previous registry, rose to 77.7% in 2014. These variations could be related to the criteria used to determine success in these arrhythmias, which differ between laboratories. The incidence of complications has leveled off in recent years, with outcomes similar to those recorded in the 2013 registry.13 Once again, of the ablation targets reported, AVNRT was that most frequently treated, followed by cavotricuspid isthmus. For the second year in a row, after being observed for the first time in the 2013 registry, AF ablation was the third most frequently performed intervention (Figure 5). The number of procedures rose for all the ablation targets, including VT-ICM, which had shown a 3% drop in recent years. There was a decrease of 3% (54 fewer procedures) in AP ablation. The most significant increases occurred in the treatment of AF, macroreentrant atrial tachycardia and, in general, in ablation of ischemic and nonischemic heart disease-related ventricular tachycardia (VT-ICM and VT-NICM). The number of AF ablation procedures continued to increase, accounting for 19% of all the procedures carried out, and was, as mentioned above, the third most frequently performed intervention, ahead of AP ablation, which, in this registry, represented only 15% of the ablation procedures performed. Ablation for VT-NICM continued to be the least common procedure (2%).

Figure 3.

Changes in catheter ablation success rates since 2008 by arrhythmia or arrhythmogenic substrate treated. AP, accessory pathway; AVN, atrioventricular node; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IVT, idiopathic ventricular tachycardia.

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Figure 4.

Percentage of major complications related to catheter ablation since 2005 by arrhythmia or arrhythmogenic substrate treated. AF, atrial fibrillation; AP, accessory pathway; AVN, atrioventricular node; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; VT, ventricular tachycardia.

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Figure 5.

Relative frequency of arrhythmias and arrhythmogenic substrates treated by catheter ablation recorded in the 2014 registry (n = 12871). The change in the number of cases with respect to the 2013 registry is shown for each ablation target. AF, atrial fibrillation; AP, accessory pathway; AVN, atrioventricular node; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IVT, idiopathic ventricular tachycardia; MAT, macroreentrant atrial tachycardia/atypical atrial flutter; VT-ICM, ventricular tachycardia in ischemic cardiomyopathy; VT-NICM, ventricular tachycardia in nonischemic cardiomyopathy.

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The changes in the relative frequency of procedures for the treatment of the various arrhythmias and arrhythmogenic substrates are shown in Figure 6.

Figure 6.

Changes in the relative frequency of different ablation targets treated since 2005. AF, atrial fibrillation; AP, accessory pathway; AVN, atrioventricular node; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; AT, atrial tachycardia; VT, ventricular tachycardia.

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In 2014, AVNRT and AP were the only ablation targets treated in all 85 centers. Cavotricuspid isthmus was treated in 97.6% and atrioventricular node in 88.2% (Figure 7). The condition treated at the fewest centers continued to be VT-NICM (although it increased from 48.7% of the participating centers in 2013 to 55.3% in 2014). The number of centers performing AF ablation rose from 50 in 2012 and 52 in 2013 to 59 centers in 2014, representing 69.5% of all the centers and 70.5% of those in the public health system.

Figure 7.

Number of electrophysiology laboratories participating in the 2014 registry that treat each of the different ablation targets. AF, atrial fibrillation; AP, accessory pathway; AVN, atrioventricular node; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IVT, idiopathic ventricular tachycardia; MAT, macroreentrant atrial tachycardia/atypical atrial flutter; VT-ICM, ventricular tachycardia in ischemic cardiomyopathy; VT-NICM, ventricular tachycardia in nonischemic cardiomyopathy.

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The following sections summarize the results of the data analysis for each specific arrhythmia or arrhythmogenic substrate.

Atrioventricular nodal reentrant tachycardia was, once again, the most frequently targeted condition, and catheter ablation of this arrhythmia was carried out in all centers. A total of 3026 AVNRT ablation procedures were performed (23.5% of all the ablations), with a mean of 35.6±23.5 interventions per site (range, 2-105). The overall success rate was 98.7%, and 58 centers (69%) had a rate of 100%. There were 20 complications (0.6%), including 10 cases of atrioventricular block requiring a permanent pacemaker, 7 vascular access complications, and 1 death of unknown cause. Another patient with severe heart disease experienced resuscitated cardiac arrest. The most commonly used ablation catheter was a conventional 4-mm tip radiofrequency catheter. In addition, an irrigated tip catheter was used in 137 cases, a cryoablation catheter in 78, and an 8-mm tip catheter in 18.

Ablation of the cavotricuspid isthmus continued to be the second most frequent procedure, performed in 83 centers (97.6%). In all, it was carried out in 2833 cases (22%), with a mean of 34.1±27 (range, 1-120) procedures per center. Success was reported in 97% of the cases, with a 100% success rate in 43 centers. There were 36 major complications (1.2%), including 12 vascular complications, 2 cases of atrioventricular block requiring a permanent pacemaker, 2 episodes of stroke, 1 case of heart failure, and 1 case of pericardial effusion/tamponade. The devices employed included 1690 irrigated tip, 951 8-mm tip, 16 10-mm tip, and 3 cryoablation catheters.

Once again, AP ablation was the fourth most frequently performed procedure, and was carried out in all the centers, although with a slight decrease in the number of interventions. There were 1946 AP procedures, yielding a mean of 22.8±16.8 per site (range, 1–75), and 1749 (89.9%) had a successful outcome. Twenty-eight centers achieved a success rate of 100%. Nonetheless, on separate analysis of the 60 centers reporting more than 10 AP ablation procedures a year, only 10 reached 100%. Many centers still do not provide information on the direction of AP conduction. The available data indicate that 52% of the AP exhibited bidirectional conduction, whereas conduction was exclusively anterograde in 9.8% and retrograde in 38.1%. With respect to the locations of the abnormal pathways, the percentages were similar to those of previous years. Left-sided AP continued to be the most common finding (51%), followed by inferoseptal (25.5%), and right-sided (14%) AP. Parahisian pathways were the least common (9.5%). Procedural success according to AP location was as follows: left ventricular free wall, 94.6%; right ventricular free wall, 81.5%; inferoparaseptal, 89%; and parahisian/anteroseptal, 78.1%. There were 25 (1.3%) major complications, including 13 vascular complications, 8 cases of pericardial effusion, 2 strokes, and 1 case of atrioventricular block requiring a permanent pacemaker. Nonconventional ablation catheters were employed in fewer procedures: irrigated tip catheters were used in 293 cases, cryoablation catheters in 78, and 8-mm tip catheters in 22.

In all, 540 atrioventricular node ablation procedures were reported by 75 centers. Success was achieved in 98.8% of the cases. There were 4 complications (0.7%), 3 of them vascular. Ablation catheters other than the conventional 4-mm tip catheters were used in 158 cases: 75 irrigated tip, 73 8-mm tip, and 10 cryoablation catheters.

In all, 396 focal atrial tachycardia ablation procedures were performed in 74 centers, with an overall success rate of 84.6%. The data provided show that the intervention was performed for focal atrial tachycardia localized in right atrium in 266 cases (88% of which were successful) and in the left atrium in 92 (85.8% successful), with an increase in the number of centers that treated left-sided focal atrial tachycardia (n=46) compared with 2013. Seven complications (1.8%) were reported, including 2 vascular complications, 1 case of pericardial effusion, 1 periprocedural myocardial infarction, and 1 case of heart failure. Again, there was an increase in the use of special catheters for the ablation of this arrhythmia. In 2014, 193 were used, mostly irrigated tip catheters (n=168), the remainder being cryoablation (n=16) and 8-mm tip (n=9) catheters.

This ablation target was treated in 49 centers (58%) in a total of 464 procedures (mean, 5.45 procedures per center; range, 1-103), 159 more than in 2013. Success was documented in 407 procedures (88%). There were 5 complications (1.1%): 2 femoral vascular complications, 2 cases of cardiac tamponade, and 1 death (no cause was reported).

The origin of tachycardia was notified in 285 procedures: the right atrium was identified in 145 cases and the left atrium in 140, with success rates of 84.8% and 76.4%, respectively. In 87.7% of the cases, devices other than conventional 4-mm tip catheters were used, mainly irrigated tip catheters in 241 cases (51.9%) and 8-mm tip catheters in 148 (31.9%).

A total of 2498 AF ablation procedures were carried out in 59 (69%) of the participating centers (range, 1-159). This activity represents an increase of 297 ablations (13.5%) compared with the 2013 registry (which had shown an 18.8% increase compared with 2012), with a mean of 29.4 procedures per center. Seven catheterization laboratories performed less than 10 procedures, and 24 less than 25. Sixteen centers carried out more than 50 and, in this group, only 5 performed more than 100 procedures. Among the total, 65.7% (1641 procedures) were for paroxysmal AF and 43.2% (1079 procedures) were for persistent AF. Of the ablation procedures for persistent AF, 149 were for long-standing and 17 for very long-standing AF. The entry referring to ablation for permanent AF was deleted from this registry as it represents a conceptual error.

The treatment approach used was reported in 2047 (81.9%) of the procedures: electrical disconnection at the pulmonary vein ostium in 6.6% of the cases, circumferential isolation with the aim of disconnection in 74.4%, and circumferential isolation to reduce electrical connections in the remaining 1.3%. The right atrium was treated in 69 (2.8%) of the procedures.

Nearly all the teams (74.4%) used irrigated-tip catheters. In 2014, number of procedures performed with cryoballoon increased (n=674 [27%]), up from 20.8% in 2013. The present registry includes reports of AF ablation procedures using new single-shot systems: nMARQ® (69 procedures [2.8%] and laser ablation (30 procedures [1.2%]). The use of steerable sheaths decreased, employed in a total of 357 cases (14.3% of all the procedures vs 20.7% in the 2013 registry), despite being used in a larger number of centers: they were utilized in 19 centers in 2014 and in 9 in 2013.

There were 113 complications (4.5%, very similar to the percentage in 2013) reported as follows: significant pericardial effusion/cardiac tamponade (n=52 [2%]), vascular access (n=35 [1.4%]), pericarditis (n=11 [0.4%]), stroke (n=3 [0.1%]), phrenic nerve palsy (n=7 [0.3%]), infarction/angina (n=2 [0.1%]), pulmonary vein stenosis (n=1 [0.04%]), congestive heart failure (1 [0.04%]), and gastroesophageal ulcer (1 [0.04%]). There was 1 case of postprocedural esophageal ulceration with no evidence of atrioesophageal fistula. There were no deaths.

Idiopathic ventricular tachycardia ablation was carried out in 457 procedures in 69 centers (81%) (mean, 5.4 procedures per center; range, 1-23). In all, 438 procedures were successful (95.8%), and there were 14 complications (3.1%): 9 vascular complications (2.0%), 4 cases of cardiac tamponade (2.0%), and 1 atrioventricular block (0.2%).

The type of ventricular tachycardia treated was specified in 424 procedures (92.7%): right ventricular outflow tract in 264; left ventricular outflow tract in 74; fascicular tachycardia in 47, and ventricular tachycardias other than the above (reported as other locations) in 39 procedures. Ablation was successful in 83.7%, 79.7%, 91.5%, and 80.0% of these procedures, respectively. The focal site of origin of the condition was the aortic root in 22 cases, the pulmonary artery in 24, and the interior of a coronary vein in 3.

Catheters other than the 4-mm tip device were used in 71.5% of the cases. An irrigated tip catheter was used in 305 cases (66.7%), an 8-mm tip catheter in 9 (2.0%), and a cryoablation catheter in 20 (4.4%).

In all, VT-ICM was treated in 53 centers (62%) performing 455 ablation procedures (5.4 per center; range, 1-28).

The type of ablation performed was specified in 90.3% of the cases: a “conventional” approach was used in 99 cases and a substrate approach in 312 (a proportion similar to that reported in 2013). The overall success rate was 81.2% (lower than the rate of 90.8% reported in 2013). The success rate was 83.8% with the conventional approach and 85.6% with the substrate approach. The access route was reported in 75% of the cases: 290 endocardial, 18 epicardial, and 36 endocardial and epicardial, indicating an increase in the percentage involving epicardial access over that recorded in 2013 (15.7% vs 11.8%). The complications (n=38 [8.4%]) involved: vascular access (n=7 [1.5%]), cardiac tamponade (n=10 [2.2%]), stroke (n=4 [0.9%]), heart failure (n=10 [2.2%], and atrioventricular block (n=1 [0.2%]). Two patients (0.4%) died after the procedure due to heart failure.

An irrigated-tip ablation catheter was used in most cases of VT-ICM (96.2%). Steerable sheaths were employed in 122 cases (26.8%).

A total of 254 VT-NICM ablation procedures were performed in 47 laboratories (55%) (3 procedures per center; range 1-32). These included 39 interventions for arrhythmogenic cardiomyopathy (success rate, 76.9%), 15 for bundle branch reentrant ventricular tachycardia (success rate, 100%), 98 for nonischemic dilated cardiomyopathy (success rate, 71.4%), 78 for nonsustained ventricular tachycardia (success rate, 87.2%), and 24 for conditions reported as being of another type (success rate, 75%).

There were 10 complications (3.9%): 2 episodes of heart failure (0.8%), 2 atrioventricular blocks (0.8%), 1 vascular complication (0.4%), and 5 cases of cardiac tamponade (2.0%), with 1 death from this cause in the context of an epicardial approach.

A catheter other than the 4-mm tip model was employed in 90.6% of the cases. An irrigated-tip catheter was used in 220 (85.9%) of the procedures, an 8-mm tip catheter in 4 (1.6%), and a cryoablation catheter in 20 (3.1%).