Continuous variables are expressed as the mean±standard deviation. Differences between continuous variables were evaluated using the Student 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.

The epidemiological characteristics were analyzed using only the prospective data collected in 9 centers, with a total of 1959 ablation procedures.

The overall mean age of the patients was 58±31 years; the youngest were those with an accessory pathway (43±16 years) and the oldest, those who underwent AVN ablation (70±11 years). Regarding the sex distribution, women predominated in AVNRT ablation (72%), whereas men predominated in ablation for ventricular tachycardia (74%), with or without associated structural heart disease, MAT (70%), and AF (66%).

In all, 18.3% of the patients had a history of structural heart disease, and left ventricular dysfunction was generally limited to patients undergoing ablation of AVN, VT-ICM, or VT-NICM.

The technical and human resources available in the participating laboratories and the activity carried out are presented in Table 1 and Table 2.

Fifty-four centers (66%) were equipped with at least 1 dedicated cardiac electrophysiology laboratory, 9 centers (11%) had 2 such laboratories, and 1 center had 3. Similar to previous years, on average, the laboratory was available on 3.5±1.6 (median, 4) days a week. Only 4 of the 21 private centers had a laboratory devoted exclusively to cardiac electrophysiology.

Half of the laboratories (n=41) did not perform external electric cardioversion, and internal cardioversion was done in 11 centers. Implantation of cardiac pacing devices was carried out in 69 centers (84%): implantation of both defibrillators and pacemakers was performed in 74% of the laboratories and defibrillator implantation alone in 9%. None of the centers implanted pacemakers only.

All of the participating centers were equipped with a digital recording system and 77% with digital radiography. A single nonfluoroscopic navigation system was available in 85% of the centers; 29% had 2 such systems and 2.4% had 3, without substantial differences with respect to the 2014 registry. Of note, nonfluoroscopic navigation systems were more widely available in public health care centers than in private centers (93% vs 52%, respectively).

Five centers had a magnetic navigation system and 2 had a robotic navigation system. The number of sites performing intracardiac echocardiography increased (n=28; 34% vs 21% in the 2014 registry). In 2015, ultrasound ablation was available at 2 sites, the number of centers offering cryoablation continued to grow, from 56% in 2014 to 61% in 2015.

Table 2 shows the main findings regarding human resources. Although 80% of the centers had more than 1 full-time physician and 41% more than 2, 15 centers (18%) had no full-time physicians. The staffs of 85% of the laboratories included at least 2 full-time registered nurses. In 2015, 25 centers had resident physicians, usually 1 or 2.

In this registry, the number of participating centers decreased for the first time, from 85 in 2014 to 82 (Figure 1) A total of 12 863 procedures were reported, a number that is also lower than that of the previous registry. This yields a mean of 157±119 procedures and a median of 138 per site, higher than that of the 2014 registry (149.5±103 per center; median, 124). The range of ablations was nearly identical to that of 2014 (Figure 2). Of the publicly-funded health centers, 8 carried out more than 300 ablations and 4 of them, more than 400. Only 9 private centers performed more than 50 ablation procedures in 2015, but 2 of them exceeded 250.

Figure 2.

Number of electrophysiology laboratories participating in the registry by the number of ablation procedures performed in 2015.

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Figure 3 and Figure 4 show the overall results in terms of both successful outcomes and complications, and they are compared with those of previous registries. The overall success rate, excluding the treatment of AF, VT-ICM, and VT-NICM, was 87.5%. The percentages of success in the different ablation targets demonstrate that the rates in the most common arrhythmias and arrhythmogenic substrates and in VT-ICM remained steady and that there was a substantial decrease, between 2014 and 2015, in the success rate for MAT (from 87.7% to 74.4%) and IVT (from 96% to 79%). The number of complications notified in all of the ablation procedures (including AF, VT-ICM, and VT-NICM) was 269 (2%), higher than those reported in 2013 and 2014. The most common complications were vascular (33%), followed by pericardial effusion/cardiac tamponade (30%). There were 13 cases of iatrogenic atrioventricular block (0.1% of all the ablation procedures) requiring permanent pacemaker implantation: 8 during AVNRT ablation, 3 during accessory pathway ablation, 3 during VT-ICM ablation, and another during MAT ablation. Eleven periprocedural deaths were recorded (0.08%), 3 more than the year before. As in the 2014 registry, 3 of the deaths occurred in procedures involving low-risk ablation targets: 1 in AVNRT and 2 in accessory pathways. The other 8 deaths involved high-risk targets: VT-ICM in 6, VT-NICM in 1, and AF in 1.

Figure 3.

Changes in catheter ablation success rates since 2009 by the 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 2006 by the 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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Regarding the frequency of treatment in each arrhythmia or arrhythmogenic substrate, CTI was the most prevalent (23.2%), followed by AVNRT (23%). Ablation of AF was the third most frequently performed intervention (20.5%). Ablation for VT-NICM continued to be the least common procedure (2%). Compared with the 2014 registry, there were increases in the number of ablations of AF, CTI, VT-ICM, and AVN and decreases in those involving accessory pathways and MAT (Figure 5). The changes in the relative frequency of the different ablation targets since 2006 are shown in Figure 6. Since the registry was first published, there have been increases in the ablation of AF and ventricular tachycardia and a gradual, progressive decrease in accessory pathway ablation.

Figure 5.

Relative frequency of arrhythmias and arrhythmogenic substrates treated by catheter ablation in Spain in 2015 (n=12 863). The change in the number of cases compared with the 2014 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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Figure 6.

Changes in the relative frequency of different ablation targets treated since 2006. AF, atrial fibrillation; AP, accessory pathway; AVN, atrioventricular node; AVNRT, atrioventricular nodal reentrant tachycardia; AT, atrial tachycardia; CTI, cavotricuspid isthmus; VT, ventricular tachycardia.

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In 2015, AVNRT, CTI, and accessory pathway ablation were performed in 81 of the 82 centers (Figure 7). The number of sites carrying out AF ablation increased from 50 in 2012 to 60 in 2015, representing 73% of all the centers. The ablation target treated in the fewest centers continued to be VT-NICM (42 of the 82).

Figure 7.

Number of electrophysiology laboratories participating in the 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.

In 2015, AVNRT was the second most frequently targeted condition, and its ablation was performed in 98.8% of the centers. A total of 2966 ablations of AVNRT were carried out (23% of all the ablation procedures), with a mean number per site of 35.6±25.6 (range, 2-115). The success rate was 97.4%, and 53 centers (65%) reported a rate of 100%. Fifteen major complications were notified (0.5%): 8 cases of atrioventricular block requiring a permanent pacemaker, 5 vascular access complications, 1 stroke, and 1 case of pericardial effusion or tamponade. One death was reported in a 15-year-old patient; the cause remains unclear. The most commonly used ablation catheter was a standard 4-mm tip radiofrequency catheter. In addition, an irrigated tip catheter was used in 52 cases (1.7%), and a cryoablation catheter in 91 (3%).

In 2015, ablation of the CTI was the procedure most frequently performed in our laboratories and was carried out in 98.8% of the centers. In all, there were 2992 CTI ablation procedures (23.2%), with a mean of 36.9±28 (range, 1-106) procedures per center. Success was reported in 93.6% of the cases, with a 100% success rate in 47 centers (57%). There were 39 major complications (1.3%), including 15 vascular complications, 2 episodes of stroke, 2 cases of heart failure, and 1 case of pericardial effusion/tamponade. The data available in the registry specify that 1666 irrigated tip catheters (55.7%), 1062 8-mm tip catheters (35.5%), 63 10-mm tip catheters (2.1%), and 23 cryoablation catheters (0.8%) were employed.

Once again, accessory pathway ablation was the fourth most frequently performed procedure; it was carried out in 98.8% of the centers and, again, there was a decrease in the number of interventions compared respect to 2014. There were 1842 procedures, yielding a mean of 22.7±16 per site (range, 2-77). A successful outcome was reported in 1649 (89.5%) procedures, and a success rate of 100% was achieved in 21 centers. However, if we analyze only the 58 performing more than 10 accessory pathway ablation procedures annually, this figure is reduced to 13 sites. Although many centers still do not provide information on the direction of accessory pathway conduction, the available data indicate that 47.2% of the pathways exhibited bidirectional conduction; conduction was exclusively anterograde in 8.8% and retrograde in 44%. With respect to their locations, there were no marked changes in the distribution. Left-sided accessory pathways continued to be those most frequently found (56.7%), followed by inferoseptal (26.1%), and right-sided (13.5%). Parahisian pathways were the least common (10.3%). Procedural success by location was as follows: left ventricular free wall, 95.4%; right ventricular free wall, 92.1%; inferoparaseptal, 90.2%; and parahisian/anteroseptal, 81.2%. There were 22 major complications (1.2%), including 11 vascular complications, 5 cases of pericardial effusion, 2 acute coronary events (in 1 of them, the records specify that it was secondary to coronary spasm 3hours after ablation and was resolved with intravenous nitroglycerin), and 4 cases of atrioventricular block, 3 of which required a permanent pacemaker. Two deaths were reported as complications of accessory pathway ablation. No information was provided on 1 of these deaths; the other was secondary to cardiac tamponade, and the autopsy revealed a multivalvular malformation with leaflet dysplasia. The use of unconventional ablation catheters increased compared with 2014: irrigated tip catheters were used in 333 cases (18%), cryoablation catheters in 112 (6%), and 8-mm tip catheters in 2 (0.1%).

In all, 578 atrioventricular node ablation procedures were reported by 69 centers. Success was achieved in 92.7% of the cases. There were 7 complications (1.2%): 6 vascular complications and 1 case of heart failure. Ablation catheters other than the standard 4-mm tip catheters were used in 186 cases (32.2%): 79 irrigated tip catheters (13.7%) and 111 8-mm tip catheters (19.2).

In all, 376 FAT ablation procedures were performed in 69 centers, with an overall success rate of 85.9%. The available data show that the intervention was performed for FAT localized in right atrium in 274 cases (88.7% of which were successful) and in left atrium in 73 (83.5% successful). One vascular complication (0.3%) was reported. In all, 191 (50.8%) catheters other than the 4-mm tip catheter were used, mainly irrigated tip catheters (n=179; 47.6%), the remainder being cryoablation (n=8; 2.1%) and 8-mm tip (n=4; 1.06%) catheters.

This ablation target was treated in 54 centers (65.9%) in a total of 313 procedures (mean, 5.61 procedures per center; range, 1-18), 151 fewer than in 2014. The procedure was successful in 74.4% of the cases (n=233). Six complications were reported (1.9%): 3 femoral vascular complications, 1 case of pericardial effusion, 1 atrioventricular block, and 1 stroke.

The origin of the tachycardia was notified in 293 procedures: right atrium was identified in 127 cases and left atrium in 166, with success rates of 84.3% and 74.7%, respectively. In 85% of the cases, devices other than the 4-mm tip catheter were used. Irrigated tip catheters were used in 251 cases (80.2%) and 8-mm tip catheters in 15 (5.8%).

A total of 2640 AF ablation procedures were carried out in 2378 patients in 60 (73%) of the participating centers (range, 1-170 per site). This activity represented an increase of 142 ablations (5.7%) compared with the 2014 registry (which, in turn, had shown a 13.5% increase with respect to 2013), with a mean of 44 procedures per center. Nine laboratories performed less than 10 procedures, and 23 less than 25. Twenty-two centers carried out more than 50 procedures and, in this group, only 6 performed more than 100 procedures. A total of 65.3% were for paroxysmal AF and 34.7% were for persistent AF. Of the ablation procedures for persistent AF, 116 were for long-standing AF.

The treatment approach used was reported in 2498 (94.6%) of the procedures: electrical disconnection at the pulmonary vein ostium in 11.4% of the cases, circumferential isolation with the aim of disconnection in 86.7%, and circumferential isolation to reduce electrical connections in the remaining 1.9%. The right atrium was treated in 58 (2.3%) of the procedures.

Most of the teams (69.8%) used irrigated-tip catheters. The proportion of procedures performed with cryoballoon (n=674; 25.9%) remained steady with respect to the 2014 registry (27%). Ablation of AF using other single-shot systems continued to be negligible: laser (1.3%), PVAC (pulmonary vein ablation catheter, 1.6%), and nMARQ (0.6%). Again, there was a slight decrease in the use of steerable sheaths, used in a total of 306 cases (11.6% of all the procedures vs 14.3% in the 2014 registry). These sheaths were used in 15 centers (25%).

A total of 114 complications (4.3%), similar to the percentage in 2014, were recorded as follows: pericardial effusion/cardiac tamponade (n=44; 1.7%), vascular access (n=43; 1.7%), stroke (n=3; 0.1%), phrenic nerve palsy (n=7; 0.3%), myocardial infarction/angina (n=5; 0.2%), pulmonary vein stenosis (n=1; 0.04%), and heart failure (n=1; 0.04%). There were 6 cases of air embolism (all resolved during the procedure, with coronary angiography in 1 case), 1 case of coronary spasm (cryoablation in left superior pulmonary vein), 2 cases of catheter entrapment in the mitral valve apparatus, which did not require surgery but resulted in mild and moderate mitral regurgitation, respectively, and hemoperitoneum in 1 of the cases. There was 1 death (0.03%), in a patient with pericardial effusion/tamponade (although the cause of death was not specified).

Ablation of IVT was carried out in 429 procedures in 65 centers (79%) (mean, 6.6 procedures per center; range, 1-19). In all, 338 procedures were successful (78.8%), a much lower proportion than that reported in the 2014 registry (95.8%). There were 14 complications (3.3%): 4 vascular complications (0.9%), 7 cases of pericardial effusion/cardiac tamponade (1.6%), 2 strokes (0.5%), and 1 case of non—ST-segment elevation acute coronary syndrome (0.2%).

The type of ventricular tachycardia treated was specified in 410 procedures (95%): right ventricular outflow tract in 228; left ventricular outflow tract in 95; fascicular tachycardia in 43, and ventricular tachycardia other than the above (reported as “other locations”) in 44 procedures. Ablation was successful in 82.9%, 67.4%, 86%, and 72.7% of these procedures, respectively. The site of origin of the ventricular tachycardia was aortic root in 25 cases, pulmonary artery in 23, and the interior of a coronary vein in 8.

Catheters other than the 4-mm tip device were used in 74.1% of the cases. An irrigated tip catheter was used in 316 cases (73.7%), an 8-mm tip catheter in 2 (0.5%), and a cryoablation catheter in 1 (0.2%).

In all, VT-ICM was treated in 56 centers (68.3%) performing 474 ablation procedures (8.6 per center; range, 1-40).

The type of ablation performed was specified in 95.6% of the cases: a “standard” approach was used in 103 cases and a substrate approach in 350. The overall success rate was 80% (similar to the rate of 81.2% reported in 2014). The success rate was 74.8% with the standard approach and 90.3% with the substrate approach. The access route was reported in 89.2% of the cases: 335 endocardial, 37 epicardial, and 51 endocardial and epicardial, indicating a further increase in the percentage involving epicardial access over that recorded in previous years (26.3% vs 15.7% in 2014 and 11.8% in 2013). The complications (n=36; 7.6%) involved vascular access (n=10; 2.1%), pericardial effusion/cardiac tamponade (n=18; 3.8%), ischemia/myocardial infarction (n=1; 0.2%), heart failure (n=6; 1.3%), and atrioventricular block (n=1; 0.2%). Six patients (1.3%) died after the procedure and the cause was specified in 3: electromechanical dissociation that did not respond to resuscitation maneuvers, cardiogenic shock, and perforation of an aortic cusp requiring emergency sternotomy.

An irrigated-tip ablation catheter was used in most of the cases of VT-ICM ablation (95.6%). Steerable sheaths were used in 175 cases (36.7%).

A total of 253 VT-NICM ablation procedures were performed in 42 laboratories (51.2%) (6.2 procedures per center; range 1-25). The type of ventricular tachycardia was specified in 231 cases. There were 34 interventions for arrhythmogenic cardiomyopathy (success rate, 73.5%), 12 for bundle branch reentrant ventricular tachycardia (success rate, 91.7%), 108 for nonischemic dilated cardiomyopathy (success rate, 69.4%), 50 for nonsustained ventricular tachycardia (success rate, 78%), and 31 for conditions reported as being of “another type” (success rate, 61.3%).

There were 12 complications (4.7%): 2 episodes of heart failure (0.8%), 2 vascular complications (0.8%), 7 cases of pericardial effusion/cardiac tamponade (2.8%), and 1 case of arrhythmic storm (0.4%), leading to death due to electromechanical dissociation in a patient with dilated cardiomyopathy.

A catheter other than the 4-mm tip model was used in 89.3% of the cases. An irrigated-tip catheter was used in 220 (87%), an 8-mm tip catheter in 5 (2%), and a cryoablation catheter in 1 (0.4%).