AVNRT ablation continued to be the third most frequently treated ablation target, after AF and CTI. A total of 3132 procedures were performed, representing an 11.5% increase vs 2020, although the relative percentage vs all other ablation targets was stable at 17.5%.

Together with CTI ablation, AVNRT continued to be the ablation target treated in the highest number of centers (n=93). The reported success rate was 95% and the complications rate was 0.6%, including 9 atrioventricular blocks (2 transient), 4 vascular complications, 1 pneumothorax, and 1 PR interval prolongation. A 4-mm nonirrigated tip catheter was used in most procedures (88%), whereas the use of other types of catheters or energy sources was negligible (cryoablation, 2%; irrigated tip catheter, 1.7%). The use of nonfluoroscopic navigation systems continued to grow and reached 55.7% of procedures for this ablation target (31% in 2020); 44% of procedures using a navigation system were performed without fluoroscopy.

AP ablation was once again the fourth most frequent ablation target, with 9% of all ablations performed and a 6.9% increase in the total number of procedures vs 2020 (1645 vs 1539 in 2020). AP ablation was reported by 90 of the 93 participating centers, with a success rate of 91% and complication rate of 1.6%; these complications included 9 vascular complications, 8 pericardial effusions, 1 bilateral pulmonary thromboembolism 1 week after the procedure, 1 self-limiting Wenckebach atrioventricular block, and 1 catheter entrapment in the mitral subvalvular apparatus requiring surgery.

In addition, 46.5% of the APs showed bidirectional conduction, 17.8% had exclusively anterograde conduction, and 38.2% had exclusively retrograde conduction. Left APs continued to be the most frequent location (44.3% of procedures), with a 93.5% ablation success rate, followed by inferoseptal (24.5%; 99.8% reported success rate), right free wall pathways (9.4%; 89.7% success rate), and Para-Hisian/anteroseptal pathways (8.3%; 86% success rate). Epicardial ablation was necessary in 25 procedures, whereas retroaortic access was used for ablation of the left pathways in 71% of procedures. The use of navigation systems has become predominant, with a highly marked increase vs 2020 (70.8% in 2021 vs 48.7% in 2020), and 29.2% were performed without fluoroscopy.

FAT was the eighth most commonly treated ablation target in 2021, with a total of 504 procedures in 483 patients (3% of all ablations in 2021) and of 5.5 procedures annually per center. In 456 procedures (90%), the ablation was considered a success. In 352 procedures, the origin of the FAT was the right atrium (70%), with effective ablation in 327 (93%). In the remaining 152 procedures, the origin was the left atrium, with procedural success in 123 (81%). The application of a 4-mm nonirrigated catheter continued its downward trend, reaching its current infrequent use (20% of procedures), and there were 10 focal cryoablations and 377 irrigated catheter procedures (75% of the total), 103 without contact forcesensing technology and 274 with the technology. The use of navigation systems continued its upward trend. They were used in 73% of all ablations of this substrate (n=368). In 127 cases, the procedure was performed without fluoroscopy, an increase from 21% in 2020 to 25%. In 2021, a total of 9 complications (1.8%) related to this procedure were reported; 4 were vascular and 4 were atrioventricular blocks and there was 1 pericardial effusion.

In 2021, 3766 CTI ablations were performed in 3646 patients; this ablation target was thus the second most frequent target, after pulmonary vein ablation (21% of all procedures). An average of 41 procedures was performed per center. The acute success rate (CTI block) was 98%. In 2734 of the 3766 procedures (73%), an irrigated tip catheter was used, with contact forcesensing technology in 1283 procedures and without this technology in 1481. In 885 procedures, an 8-mm catheter was used (23.5%, an almost identical percentage to that of 2020). After a marked increase in 2020, mapping system use stabilized and represented slightly less than half of all procedures (46%). Zero-fluoroscopy ablations fell slightly from 25% in 2020 to 20% in 2021 (749 of the 3766 procedures). In line with previous years, a total of 22 complications were recorded (0.6%); once again, those related to the vascular access predominated (n=16), as well as 2 cases of pericardial effusion and 1 myocardial infarction. Notably, there were no cases of atrioventricular block related to CTI ablation and no deaths.

In 2021, the number of ablations of this substrate was considerably higher, with a total of 749 procedures in 633 patients, vs 582 in 2020. In 594 procedures (79%), the ablation was considered successful. This percentage is similar to that of 2020 and significantly lower than that of other ablation targets. A total of 244 procedures (33%) were performed after previous AF ablation, 111 (15%) in patients with congenital heart disease and 62 in patients with previous arteriotomy. Of the 749 ablations of this substrate, 212 (29%) were in the right atrium and 510 (68%) were in the left atrium.

The use of nonirrigated catheters for this substrate was negligible, with absolute predominance of irrigated catheters with contact forcesensing technology (617 of all MAT ablations, 82%). The ablation was performed predominantly with a mapping system (628 procedures, 84%) and without fluoroscopy in 86 (11%). The procedure included administration of ethanol into the vein of Marshall in 16 procedures. A total of 19 complications were recorded (3%), which included 7 vascular complications, 8 pericardial effusions, and 1 embolism.

In total, 905 AVN ablations were performed in 854 patients, with an average of 10 ablations of this substrate per center. AVN was once again the fifth most commonly treated target, with 5% of all ablations in 2021. In addition, 96% of procedures were successful, a similar percentage to previous years. A 4-mm catheter continued to be the most frequently used catheter type (499 procedures, 55%), with irrigated catheters used in 304 procedures (without contact forcesensing technology in 250 of them). An 8-mm catheter was applied in 109 procedures (12%), with no decrease from previous years. A total of 7 complications were recorded (0.8%), including 3 vascular complications, 1 pericardial effusion, and 1 embolic event related to the procedure. A mapping system was used in 45 procedures (5%) and 65 (7%) were performed without fluoroscopy.

AF ablation continued its growing predominance and was the most frequently treated ablation target in 2021. It represented 32.6% of all reported ablation procedures (5848 procedures in 5601 patients). According to the available data, 3516 of the 5848 procedures were performed in patients with paroxysmal AF, 1888 in patients with persistent AF, and 213 in patients with long-standing persistent AF. Once again, a not insignificant number of centers (n=13) performed no AF ablations, 31 centers performed fewer than 50, and 51 (54% of the total) performed most of the ablations of this substrate (more than 50 per center). In contrast, 8 centers performed more than 150 ablations. Figure 6 shows the number of centers by annual ablation volume (in blocks of 50 procedures).

Figure 6.

Distribution of centers by annual volume of AF ablation procedures (in blocks of 50 procedures) in 2020 and 2021.

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An irrigated catheter was used in 3286 procedures (56%), with contact forcesensing technology in 95% while cryoablation was used in 2399 (41%). Figure 7 shows the changes over time in point-by-point ablation and cryoablation of AF from 2013 to 2021. An additional 83 procedures were performed with laser. Steerable sheaths and intracardiac echocardiography continue to show continuous year-on-year growth and were used in 32% and 11% of procedures in 2021, respectively. In 2021, a seventh center performing fluoroscopy-free AF ablation was added, giving a total of 242 procedures (much higher than the 75 such procedures in 2020). The objective of the procedure was pulmonary vein isolation alone in 92% of cases. The ablation was considered a success in 97% of cases, with pulmonary vein isolation successful in 99% of such procedures. In addition to performing or confirming pulmonary vein isolation, additional ablation lines were placed in the left atrium in 355 procedures (6% of the total, with a successful result in 354, practically 100%), superior vena cava isolation in 116 procedures (97% success rate), ablation of complex/fragmented electrograms in 50 (80% success rate), and ethanol ablation of the vein of Marshall in 28. A mapping system was used in 3576 procedures (61%).

Figure 7.

Changes over time in ablation techniques for atrial fibrillation via the point-by-point and cryoablation techniques from 2013 to 2021.

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The percentage of complications related to the AF procedure was maintained at 3.4% (202 of 5848 procedures). The data revealed 55 pericardial effusions (0.9%), 47 vascular complications (0.8%), and 14 embolisms (0.2%), as well as 45 phrenic nerve palsies (0.8%). In addition, there was 1 death associated with an atrioesophageal fistula.

IVT ablation represented 4% of all procedures, the same number as in 2020. In absolute numbers, with a total of 709 procedures, there was an 8.5% increase vs 2020; however, this is still far from the 807 procedures recorded in 2019. The number of centers performing this ablation dropped considerably, from 88 in 2020 to 75 in 2021, with an average of 9.5 ± 8.3 (range, 1-55) procedures per center. The reported success rate was 81.8%.

Regarding the locations of the tachycardias, 333 involved VT of the right ventricular outflow tract, 123 involved VT of the left ventricular outflow tract, 63 involved VT of the aortic root, 41 were fascicular tachycardias, 30 were epicardial tachycardias, 9 had an origin in the pulmonary artery, and 48 were in other locations, such as the papillary muscles, moderator band, right ventricular free wall, and mitral annulus.

A navigation system was used in 82.5% of procedures and 16.6% were fluoroscopy-free. The use of ablation catheters with an irrigated tip and contact forcesensing technology predominated for this target (78%), whereas the use of irrigated catheters without this technology markedly dropped to 7.8%, vs 24.3% in 2020. Six alcohol ablation procedures were reported, of which 5 were performed in the same center. There were 18 complications (2.5%): 1 atrioventricular block, 4 vascular complications, 12 pericardial effusions, and 1 embolism. There was 1 death after the cardiac surgery due to tamponade and aortic dissection.

VT-AMI ablation comprised 3% of all ablations performed, with 453 procedures in 403 patients. This represented a very slight increase vs 2020 (31 procedures more); the procedure was performed in 65 centers (mean, 7.1 ± 5.4 procedures per center; range, 1-26). The use of navigation systems fell to 85% vs 91.7% reported in 2020, and just 9 procedures (2%) were fluoroscopy-free. The success rate was 82.6% and the use of ablation catheters with an irrigated tip and contact forcesensing technology was standard, at 90.3% of procedures. Three cases of radioablation were reported, as well as 4 of cryoablation and 1 of alcohol ablation. The data showed an increase in the use of the transseptal approach, reaching 55.8% of procedures; it now exceeds the retroaortic approach, which was used in 41.3%. The combined endocardial/epicardial approach was adopted in 9.5% of procedures while exclusively epicardial access was used in 3.3%. The predominant strategy was ablation of the substrate (66.9% of procedures) while conventional activation mapping was applied in 24.3%. The complication rate was as high as 7.5%, similar to previous years, and comprised 11 vascular complications, 2 atrioventricular blocks, 5 pericardial effusions, 1 embolism, 1 myocardial infarction, and 8 heart failure decompensations. A total of 7 deaths associated with this procedure were reported (1.5% mortality).

VT-NAMI underwent a slight reduction vs the numbers reported in recent years. A total of 199 procedures were conducted in 184 patients (48 procedures fewer than in 2020) and the number of centers performing this type of ablation also decreased, from 51 in 2020 to 45. The mean number of procedures per center was 4.6 ± 4.4 (range, 1-22) and the success rate was 74.9%. A nonfluoroscopic navigation system was used in most procedures (96%). The substrates treated included nonischemic dilated cardiomyopathy, 112 (77.7% success rate); arrhythmogenic cardiomyopathy, 29 (86.2% success rate); hypertrophic cardiomyopathy, 9 (100% success rate); congenital heart diseases, 17 (88.2% success rate); bundle-branch tachycardia, 9 (88.9% success rate); and 26 miscellaneous conditions, which included Chagas disease, sarcoidosis, myocarditis, and valvular heart disease.

The use of ablation catheters with an irrigated tip and contact forcesensing technology was standard (91%), whereas the other ablation sources were rare, including 3 radioablations, 1 cryoablation, and 1 alcohol ablation. A transseptal approach was used in 35% of procedures and retroaortic in 31.7%. The combined endocardial-epicardial approach was used in 21.6% of procedures while exclusively epicardial was used in 9.5%.

The rate of reported complications was 5%, including 2 atrioventricular blocks, 2 vascular complications, 4 pericardial effusions, 1 thoracic artery bleeding, and 1 lead displacement of an implantable cardioverter-defibrillator. Two deaths occurred, 1 after cardiac tamponade and the other a result of thoracic bleeding in relation to epicardial access.

The percentage of ablation procedures conducted with nonfluoroscopic navigation systems grew vs previous years, from 49% in 2020 to 52% in 2021 (9394 procedures). As a percentage, the ablation target with the greatest use of navigation systems was once again VT (85% of procedures), whereas the use of a navigation system was less common for less complex substrates (AVNRT, AP, CTI, and, in particular, AVN): from 5% for AVN ablation to 46% for AP ablation.

The number of fluoroscopy-free procedures grew to 2929, 16% of the total, slightly higher than the 14% recorded in 2020. The ablation targets most commonly treated without fluoroscopy were once again AVNRT (29%), CTI (28%), and FAT (25%).

A total of 401 ablations were reported in pediatric patients, representing a 39% increase vs 2020 (158 more ablations performed in 2021). The relative weight of ablations in pediatric patients significantly increased from 1.6% in 2020 to 3.8% in 2021. However, the number of centers reporting ablations in pediatric patients fell from 37 in 2020 to 24. The most frequently treated ablation target in pediatric patients continued to be the APs (66.6% of procedures; 267 procedures), followed by AVNRT (19.9%, 80 procedures), FAT (5.5%, 22 procedures), and IVT (5%, 20 procedures). CTI (2%, 8 procedures) and MAT (1%, 2 procedures) were the least frequently treated ablation targets in this population group. Figure 8 shows the distribution of pediatric procedures by ablation target and their proportion in relation to the total number of procedures.

Figure 8.

Distribution of pediatric procedures by ablation target and as a proportion of the total number of procedures. AP, accessory pathway; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IVT, idiopathic ventricular tachycardia; MAT, macroreentrant atrial tachycardia.

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The SARS-CoV-2 pandemic was much less impactful in 2021, and just 29 laboratories (31.2%) provided specific data on the effect of the pandemic on their clinical practice. In 2021, the electrophysiology laboratories were closed due to the pandemic for an average of 9.33 ± 22 days. A total of 70 electrophysiologists (21.17%) were infected with SARS-CoV-2 or were isolated and procedures were performed on 182 patients who tested positive for SARS-CoV-2.

For the first time, cardioneuroablation procedures have been described. A total of 10 centers conducted 31 procedures in 30 patients (1 center, 10 procedures), both as indicated for cardioinhibitory syncope and for sinus node dysfunction. An irrigated catheter with contact forcesensing technology was used in all procedures. Both atria were treated in 24 procedures (77.5%), only the left atrium in 6 (19.3%), and just the right in 1 (3.2%).