AVNRT has ceased to be, probably definitively, the most treated substrate and now occupies third place, despite 371 more procedures than in the previous registry. A total of 3429 AVNRT ablation procedures (22.4% of the total) were performed in 97 hospitals.

The mean number of procedures was 34.9 ± 24.7 (range, 2-122), with a success rate of 98.6%; 77% of centers reported a 100% success rates. Twelve major complications were reported (0.3%): 4 AVBs requiring pacemaker placement (0.12%), 3 vascular complications (0.09%), 2 pulmonary thromboembolisms, 1 stroke, and 1 pericardial effusion. The 4-mm tip radiofrequency ablation catheter was still the most used catheter (95.4% of procedures), followed by the irrigated tip catheter (2.2%). In addition, the cryoablation catheter was used in 1.8% and the 8-mm tip catheter in 0.4%. The use of navigation systems has doubled vs the previous year; they were used in 11.6% of procedures, with 298 of these (8.7% of the total) performed without fluoroscopy.

In all, 3449 CTI ablation procedures (22.6%) were performed in 94.9% of centers, with a mean number of 35.2 ± 29.3 (range, 2-123) procedures per center. Success was reported in 94% of procedures, with a 100% success rate in 60% of centers.

There were 23 major complications (0.7%), including 12 vascular complications (52.2%), 5 pericardial effusions (21.7%), 3 AVBs (13%), 1 stroke (4.3%), 1 myocardial infarction (4.3%), and 1 pericarditis without effusion (4.3%). Three deaths were reported, 1 of them due to embolism. The other 2 deaths were due to complications occurring during surgical treatment of the problem: mesenteric ischemia and death after pericardial window in a patient with tamponade, and twin-to-twin transfusion syndrome and multiorgan failure 3 days after the repair of a vascular tear of the left femoral artery. Left femoral access had been used as the approach to control the bleeding of a lesioned right femoral secondary branch injured during the ablation procedure.

Irrigated tip catheters were the most prevalent catheters, used in 2053 procedures (60.4%; 225 with contact forcesensing technology), followed by 8-mm tip catheters (34.9%) and 4-mm tip catheters (4.3%).

A navigation system was used in 26% of procedures and 14.1% of the total were performed without fluoroscopy.

Accessory pathways were again the fourth most targeted substrate, treated in 91 centers, with a slight increase in absolute number after several years of decline. In total, 1902 procedures were performed (mean, 20.9 ± 17.2; range, 2-88). Success was achieved in 90% of procedures and 33 centers reported a 100% success rate.

Data were available on the conduction direction of 1784 of the accessory pathways, and bidirectional conduction was again the most frequent presentation in electrophysiology laboratories (820, 46%), followed by concealed pathways (632; 35.4%), whereas there were 332 exclusively anterograde conduction pathways (18.6%). Regarding their locations, left-sided accessory pathways continue to predominate (49.5%), followed by inferoseptal (27.8%), right ventricular free wall (12%), and para-Hisian (10.6%) pathways.

Nonfluoroscopic navigation systems were used in 16.2% and 5% of the total were performed without fluoroscopy.

Regarding the approach used in the ablation of left-sided pathways, the preference was for the retrograde aortic approach (68.3%); the remainder were transseptal (31.7%).

The success rate was 97.4% for left ventricular free wall procedures, 93.7% for inferoseptal, 91.8% for para-Hisian/anteroseptal, and 86.9% for right ventricular free wall.

There were 29 major complications (1.5%): 12 pericardial effusions, 10 vascular complications, 1 acute myocardial infarction, 1 systemic embolism, 1 AVB, 1 mitral insufficiency, 1 pulmonary thromboembolism, 1 hematoma, and 1 pericardial puncture during transseptal puncture without effusion.

Most ablations (65.4%) were performed with 4-mm tip ablation catheters, although the use of irrigated tip catheters increased to 27.3%; of these, 39 had contact forcesensing technology. The other catheters used were cryoablation catheters (6.2%) and 8-mm tip catheters (1.3%).

The number remained stable with 700 ablations performed in 81 centers. Success was achieved in 96% of cases. Only 2 complications were reported (0.3%), 1 vascular and the other due to the onset of heart failure. Catheters other than the standard 4-mm tip catheter were used in 233 procedures (33.3%): 144 irrigated tip catheters and 88 8-mm tip catheters, with cryomodulation of the atrioventricular node attempted on 1 occasion.

In all, 429 FAT ablation procedures (3%) were performed in 78 centers, with a success rate of 86%. The available data on location (412 procedures) showed that this substrate was located in the right atrium in 310 cases (with an 87.4% success rate) and in the left atrium in 131 (90.2% success rate). Complications developed in 6 cases (1.4%), 0.7% due to vascular complications, 0.2% due to AVBs, 0.2% due to pericardial effusions, and 0.2% due to pericarditis without effusion.

A total of 142 4-mm tip catheters and 13 8-mm tip catheters were used, but irrigated tip catheters predominated with a continual increase vs previous registries; in 2017, these catheters were used in 61.3% of procedures, with a high number of catheters with contact forcesensing technology (91 catheters).

A navigation system was used in 56.6% of procedures; 7.2% of the total were performed without fluoroscopy.

This ablation target was treated in 58 centers (59.2%), with 538 procedures (3.5% of the total) in 443 patients (mean, 5.4; range, 0-123). The number of procedures performed on this substrate has increased each year: 80 more cases and 4 more centers vs the 2016 registry. The procedure was successful in 76% of cases. The left atrium was the most frequently treated location (234 procedures), with a 76.5% success rate; 134 procedures were performed in the right atrium, successfully in 93.3%. Regarding the information available on the substrate underlying the MAT: 122 cases (40.9%) were secondary to AF ablation, 70 to congenital heart disease (23.5%), 45 to atriotomy (15.1%), and 61 to others (20.5%).

The most used catheters were conventional irrigated tip catheters (38.9%) and irrigated tip catheters with contact forcesensing technology (37.4%); the other types were rarely used. A navigation system was used in 51.5% of procedures; of these, 3.5% of the total were performed without the use of fluoroscopy.

There were 12 nonfatal complications (2.2%): 7 femoral vascular complications, 3 pericardial effusions, and 1 ABV.

For the first year, AF was the most targeted substrate, with 3457 procedures (22.6%) in 3105 patients, spread over 74 centers (75.5%). These data reflect the recent trend for a progressive increase and represent an increase of 504 ablations and 9 centers treating this ablation target vs the previous registry (2016). The mean number of procedures per center was 32.3 (range, 0-199), with a success rate of 93.8%.

More than 50 procedures were performed in 23 centers (31% of the total); of these, 8 centers performed more than 100 procedures (10.8%). According to the type of AF and the available data, paroxysmal AF was the most treated ablation target, with a total of 1912 procedures. The participating centers reported 787 procedures for persistent AF and 120 procedures for long-standing (> 1 year) persistent AF.

Electrical isolation of the pulmonary veins was the most common procedure, performed in 2877 cases (95.6%), with a success rate of 97%, as well as reduction of the antral electrogram in 4%, successful in 100%; placement of left atrial lines in 3.4%, successful in 95.7%; complex fractionated electrogram ablation in 0.5%, successful in 94.4%; superior vena cava isolation in 3.8%, successful in 97.7%; and other objectives in 14 procedures (including 3 magnetic resonance-guided scar ablations and 2 atrial appendage isolations performed with posterior box isolation).

The most widely used technique for AF ablation procedures continues to be point-to-point radiofrequency ablation, with 2171 procedures (62.9%). Cryoablation was in second place with 1235 procedures (35.8%), representing a 5% increase vs the previous registry. Other procedures represented a minority, such as multielectrode radiofrequency catheter ablation (0.9%) and laser ablation (0.4%).

The most commonly used catheter in point-to-point ablation was the irrigated tip ablation catheter and contact force sensor (72.3% in this type of procedure). The remainder comprised conventional irrigated tip catheters, 1.2% of them with microelectrodes.

There was another increase in the use of steerable sheaths, with 26.9% of all procedures in 31 centers vs 23.3% in the previous registry. The use of intracardiac echocardiography continues to be negligible: 304 procedures (8.8%).

Three-dimensional navigation was used for this ablation target in 61.8% of the procedures. Several centers reported the use of “minimal fluoroscopy” and have even described procedures performed completely without fluoroscopy.

A total of 124 complications were recorded (3.6%, slightly lower than the 3.9% of the previous year) subdivided as follows: vascular complications (39; 1.1%), pericardial effusion/cardiac tamponade (37; 1.1%), stroke (11; 0.3%), phrenic nerve palsy (19; 0.5%), and infarction/angina (3; 0.1%). Additionally reported were 2 air embolisms (with ST-segment elevation), 2 cases of pulmonary vein stenosis requiring stent dilatation or placement, 2 atrioesophageal fistulas 1 left atrial appendage perforation (requiring surgery), 1 atrial free wall perforation during transseptal puncture (which also required surgery), 1 hemoptysis, 1 fistula between the coronary cusp and right atrium, 1 coronary spasm with secondary ventricular fibrillation, 1 esophageal perforation during transesophageal echocardiography, 1 angioplasty guidewire fracture in the left atrium during transseptal puncture, recovered with a loop, and 1 esophageal hematoma with internal hemorrhage resulting in death. Of the 2 cases of fistula, 1 died due to massive digestive bleeding during transesophageal echocardiography a few days after the procedure; the other patient underwent surgical repair, but experienced severe neurological sequelae.

In total, 600 IVT ablation procedures (3.9%) were performed in 548 patients and 72 centers (mean, 6.1; range, 0-24). A successful outcome was achieved in 81.5% (81.1% in 2016). The type of ventricular tachycardia (VT) targeted was known for 95%: 292 of the right ventricular outflow tract, 107 of the left ventricular outflow tract, 52 originating from the aortic root/aortic cusps, 41 fascicular tachycardias, and 24 originating from the coronary/pericardial sinus. Other origins described in lesser proportion were the papillary muscles, lateral mitral ring, and ventricular free wall. The most successful ablation tachycardias were those originating from the right ventricular outflow tract and fascicular tachycardias (92.5% and 90.2%, respectively), with a lower success rate in those originating from the aortic root/coronary cusps, left ventricular outflow tract, and epicardial/coronary sinus (78.8%, 76.6%, and 50%).

Irrigated tip catheters were used in 88.6% of the cases reported: conventional in 46% and contact forcesensing in 42.6%. The 4-mm tip catheter was used in 8.3% and the use of other types of catheter was negligible. Fluoroscopy was not used in 3.5% of the procedures.

There were 18 complications (3%): 9 effusions/tamponades, 5 vascular complications, 2 acute coronary syndromes, 1 AVB, and 1 coronary spasm.

The total number of VT-AMI ablation procedures slightly increased, reaching 531 procedures (3.5%) in 438 patients (mean, 5.4; range, 0-33).

The type of ablation performed was reported for 89.8% of the cases: 101 with a “standard” approach and 376 with a substrate approach (a slight increase vs the previous year). The overall success rate was 78.7% (slightly lower than that reported in 2016 and 2015: 83.1% and 80.0%, respectively).

A high number of cases are still performed with an exclusively endocardial approach (89.9%). Consequently, the number of procedures with an epicardial or combined (endocardial and epicardial) approach continues to fall, with 43 procedures with a combined approach (8.9%) and 6 with a combined epicardial approach (1.2%). The rate of procedures with an exclusively epicardial approach continues to decline (8.7% in 2015, 4.9% in 2016, and 1.2% in the current registry) and there was a slight uptick in procedures with a combined approach (from 7.6% in 2016 to 8.9% in 2017).

Regarding the endocardial approach, retroaortic access continues to predominate and was used in 261 procedures (59.9%).

An irrigated tip ablation catheter was the most popular choice for VT-AMI ablations (93.7%), of which 66.5% were contact forcesensing catheters. Steerable sheaths were used in 24.3%.

The following complications (44; 7.3%) were reported: 14 pericardial effusions (2.3%), 11 vascular complications (1.8%), 10 heart failure events (1.7%), 3 AVBs (0.4%), 2 embolic episodes (0.4%), and 1 pleural cavity puncture during an attempted epicardial approach (0.2%). Three deaths (0.5%) were reported: in 1 case, tamponade occurred due to coronary sinus perforation, prolonged cardiopulmonary resuscitation, and surgery with sternotomy; the patient died at 48hours due to cardiogenic shock. The second patient experienced electromechanical dissociation secondary to rapid VT induction after ablation completion. Finally, the third patient had refractory heart failure after 2 failed attempted incessant VT ablation procedures.

A total of 249 VT-NAMI ablation procedures were performed (1.6%) in 48 laboratories (52.2%) (mean, 2.5; range, 0-37). The type of VT substrate was specified in 212 cases: 105 in nonischemic dilated cardiomyopathy (68.6% success rate), 34 in arrhythmogenic cardiomyopathy (82.4% success rate), 37 in congenital heart diseases (86.5% success rate), 10 bundle branch reentrant VTs (100% success rate), and 15 reported as being of “another type” (80% success rate), which included 6 cases of valvular heart disease, 2 after myocarditis, 1 in Chagas disease, and 1 in Brugada syndrome.

Regarding the approach used for these ablation targets, there was greater use of the epicardial or combined (endocardial and epicardial) approach vs VT-AMI procedures, similar to the previous registry. In total, 21 procedures were exclusively performed with an epicardial approach (8.4%) and 42 with a combined endocardial and epicardial approach (16.9%).

The most used catheter type was the irrigated tip (93.4%), with contact forcesensing technology used in most (53.7%).

There were 15 complications (6%), divided into 3 effusions/tamponades (1.2%), 3 heart failure events (1.2%), 2 AVBs (0.8%), 1 peripheral embolism (0.4%), 1 myocardial infarction (0.4%), and 3 “others” (1.2%): 1 pulmonary thromboembolism, 1 arrhythmic storm during ablation, and 1 pneumothorax. Two deaths were reported: an intraprocedural arrhythmic storm and an electromechanical dissociation in a patient with dilated cardiomyopathy.

The use of nonfluoroscopic navigation systems was reported in 5388 procedures (35%). Such navigation systems were most commonly used for point-by-point pulmonary vein isolation (61.8% of the procedures).

Although its use has been mostly complementary to fluoroscopy, the percentage of zero-fluoroscopy procedures has continued to increase, reaching 6% (3.5% in 2016).18,19

As in the previous registry, the ablation target most commonly treated without fluoroscopy has been the CTI (14.1% of all CTI ablations). At the other extreme, TV-AMI was not ablated at any time without fluoroscopy.

The registry recorded 347 ablation procedures (2.3% of the total number) in 34 centers; the most frequent ablation target was the accessory pathways (69.7%), representing 12.7% of the total number of ablations performed of this target. The data on the other procedures are shown in Figure 8.

Figure 8.

Pediatric ablation procedures. The bar chart shows the proportion of pediatric procedures for each ablation target and the total number of procedures in the registry while the pie chart shows the proportion of each substrate ablated with respect to the total number of pediatric procedures. AP, pathways pathway; AVNRT, atrioventricular nodal reentrant tachycardia; CTI, cavotricuspid isthmus; FAT, focal atrial tachycardia; IVT, idiopathic ventricular tachycardia; MAT, macroreentrant atrial tachycardia; VT-NAMI, ventricular tachycardia not associated with acute myocardial infarction.

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