Numerical results are expressed as mean (standard deviation) or median [interquartile range], depending on the distribution of the variable. Continuous quantitative variables were compared with analysis of variance or the Kruskal-Wallis test. The relationships between the number of implantations and the number of implantation centers per million population and between the total number of implantations and the number of implantations for primary prevention in each center were evaluated using linear regression models.

A total of 161 centers that perform ICD implantation in Spain participated in the registry (6 fewer than in 2011) (Table 1). This decrease is due to the grouping of several centers into consortiums, which provided pooled data. Of the respondents, 103 were public health care centers (91 more than in 2011). Figure 1 shows the total number of participating centers, the implantation rate per million population, and the total number of implantations by autonomous community according to data collected by the registry. In 2012, only 8 centers implanted more than 100 devices; 83 centers implanted fewer than 10 ICDs and 66 centers fewer than 5 devices.

Figure 1.

Distribution of the 2012 implantation activity by autonomous community: number of implantation centers/implantation rate per million population/total number of implantations.

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In total, 4216 first and replacement implantations were performed in 2012, a substantially lower figure than in 2011 (4481). According to the EUCOMED data,14 this represents 80.8% of the total of 5215 ICD implantations performed in 2011 in Spain. Figure 2 shows the total number of implantations reported to the registry and the number estimated by EUCOMED over the last 10 years.

Figure 2.

Total number of implantations reported to the registry and total number estimated by the European Medical Technology Industry Association (2003-2012). EUCOMED, European Medical Technology Industry Association.

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The implantation rate recorded in the registry was 91.2 per million population, whereas the rate according to the EUCOMED data was 113 per million population. Figure 3 shows the changes occurring in the implantation rate per million population over the last 10 years according to the registry and EUCOMED data. Table 1 shows the number of implantations reported to the registry by participating center. Table 2 shows the number of implantations performed in each province and the rate per million population for the corresponding autonomous community.

Figure 3.

Total number of implantations reported to the registry per million population and as estimated by the European Medical Technology Industry Association (2003-2012). EUCOMED, European Medical Technology Industry Association.

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The name of the participating center was reported in 99.6% of the cases. The majority of the procedures—3820 (90.8%)—were performed in public health centers.

This information was reported in 4092 of the data forms sent to the SEC (97.1%). There were 2842 first implantations, representing 69.4% of the total (70.2% in 2011 and 73.8% in 2010). The rate of first implantations in 2012 was 64 per million population, equaling that in 2011.

The mean age (standard deviation) [range] of patients receiving an ICD or replacement device was 61.8 (13.4) [7-90] years. The majority of patients were men, accounting for 83.4% of all patients and 80.2% of patients receiving a first implantation.

The most common underlying cardiac condition in primary implantation patients was ischemic heart disease (50.7%), followed by dilated cardiomyopathy (27.4%), hypertrophic cardiomyopathy (7.5%), primary conduction abnormalities (Brugada syndrome, idiopathic ventricular fibrillation, and long QT syndrome) (7.7%), and lower percentages of valvular heart disease and arrhythmogenic dysplasia (Fig. 4).

Figure 4.

Type of heart disease prompting device implantation (first implantations).

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Regarding left ventricular function in patients receiving a first implantation, the left ventricular ejection fraction was <30% in 52.3%, 30%-40% in 23.6%, 41%-50% in 6.5%, and >50% in 16.6%. The distribution was similar in patients receiving a replacement ICD (Fig. 5). This information was reported in 79.8% of the data collection forms.

Figure 5.

Left ventricular ejection fraction in registry patients (all implantations and first implantations). LVEF, left ventricular ejection fraction.

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Regarding the New York Heart Association (NYHA) functional class, the majority of the patients were in NYHA II (47.3%), followed by NYHA III (32.6%), NYHA I (17.9%), and NYHA IV (2.1%). In relation to this variable, the distribution between total implantations and first implantations was also very similar (Fig. 6); this information was reported in 65.8% of the data collection forms.

Figure 6.

New York Heart Association functional class in registry patients (all implantations and first implantations). NYHA, New York Heart Association.

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The baseline cardiac rhythm, recorded in 84.9% of patients, was sinus rhythm (78.2%), followed by atrial fibrillation (16.8%) and paced rhythm (4.47%); the remaining patients had other rhythms (atrial flutter and other arrhythmias).

Information on this item was reported in 80.2% of the data collection forms. The largest group of first-implantation patients was comprised of those with no documented clinical arrhythmia (54.5%), followed by those with sustained monomorphic ventricular tachycardia, nonsustained ventricular tachycardia, and ventricular fibrillation (18.8%, 13.8%, and 11.4%, respectively). Of the total implantation procedures performed, 50.2% of devices were placed in patients without documented clinical arrhythmia (Fig. 7). Differences in the type of arrhythmias between patients receiving first implantations and the total group of patients were statistically significant for patients without arrhythmia (P=.0008) and those with sustained monomorphic ventricular tachycardia (P=.001), but not for patients with nonsustained ventricular tachycardia or ventricular fibrillation.

Figure 7.

Arrhythmia prompting device implantation (first implantations and all implantations). NSMVT, nonsustained monomorphic ventricular tachycardia; PVT, polymorphic ventricular tachycardia; SMVT, sustained monomorphic ventricular tachycardia; VF, ventricular fibrillatio. *P<.001.

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The most common clinical presentation in the overall group and the first implantation group (72.5% and 69.7% completed responses) was an absence of symptoms, followed by “other symptoms” and syncope (Fig. 8). There were no statistically significant differences between the first implantation group and the overall group in the form of presentation.

Figure 8.

Clinical presentation of arrhythmia in registry patients (first implantations and all implantations). SCD, sudden cardiac death.

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Information on electrophysiological studies was available on 2326 patients receiving a first implantation (78.6%). Electrophysiological studies were conducted in only 297 patients (14.6%). The most frequently induced arrhythmia was sustained monomorphic ventricular tachycardia (44.6%), followed by ventricular fibrillation (19.2%), and less frequently, nonsustained ventricular tachycardia (8.7%) and others (2.9%). Arrhythmia was not induced in 24.6% of the patients who underwent electrophysiological studies, which were mainly conducted in patients with ischemic heart disease and dilated cardiomyopathy.

Since 2011, several new fields related to the patient's clinical history have been incorporated in the data collection form.

For patients with first implantations, 66.9% to 78.8% of these fields were completed, with the following results: hypertension, 55.7%; hypercholesterolemia, 45.6%; smoking, 38.1%; diabetes mellitus, 31.3%; a history of atrial fibrillation, 26.3%; kidney failure, 15.8%; history of sudden cardiac death, 8.5%; and stroke, 7.3%. The QRS interval was documented in 53% of the records (mean value 126.2 [59] ms). The QRS interval was >140ms in 69.5% of the patients. Of these, 85.3% of the patients in the first implantation group (78.6% of the total group) received a combined resynchronization/ICD (ICD-CRT [cardiac resynchronization therapy]) device.

Table 3 shows changes in first implantations by type of heart disease and presentation from 2009 to 2012. This information was reported in 91% of the data collection forms. Ischemic heart disease was the condition most often associated with ICD implantation, and the indication was mainly for primary prevention (59.5%), a percentage that has not increased in recent years (59.6% in 2011 and 58.5% in 2010). The trend in primary prevention for dilated cardiomyopathy was also similar (74.1% vs 74.7% in 2011 and 72.8% in 2010). Regarding the less common types of heart disease, the predominant indication was primary prevention in valvular heart disease, hypertrophic cardiomyopathy, and Brugada syndrome and other channelopathies. In congenital heart disease, the main indication was secondary prevention.

Information on indications for implantation was reported in 90.1% of the data collection forms. The majority of implantations were indicated for primary prevention (58.1%), although this was the first year that the number of implantations decreased for this indication. This variation has been increasing and was statistically significant (P<.01) until 2008 and again between 2009 and 2010 (Table 4).

Information on these items was reported in 90.5% of the data collection forms. The main setting in which implantations were performed was the electrophysiology laboratory in 81.4% of cases (76.4% in 2011, 70.3% in 2010, and 67% in 2009), followed by the operating room (17.31%).

The procedure was performed by electrophysiologists in 81% of cases (78.4% in 2011 and 76.1% in 2010), surgeons in 14% (15.5% in 2011), both specialists in 1.9%, and other specialists and intensivists in 1.6% and 1.4%, respectively.

Information on the generator implantation site in first implantations was reported in 3735 (83%) of the data collection forms. The generator was placed subcutaneously in a pectoral position in 95% of cases and in a subpectoral position in the remaining 5%. Regarding the total number of devices implanted, the values were 93.4% and 6.6%, respectively.

This information was reported in 94% of the data collection forms and is summarized in Table 5. Single-chamber ICDs were implanted in 49.4% (46.7% in 2011), dual-chamber ICDs in 18% (18.4% in 2011), and ICD-CRTs in 32.5% (34.9% in 2011).

In patients with ischemic heart disease, 72.3% of the devices were single-chamber or dual-chamber and 27.7% were ICD-CRTs. In patients with dilated cardiomyopathy, 56.5% (59.7% in 2011) of the devices were ICD-CRTs.

Information on the 1133 replacement procedures was reported in 977 (86.2%) of the data collection forms. The most common reason was battery depletion (85.3%), followed by complications (7.8%), and change of indication (6.8%). Of the 54 cases of early replacement procedures reported, 14.8% were performed within 6 months of the implantation procedure.

In 77% of the replacement reports, information was provided on the status of the leads: 8.9% (78 records) were malfunctioning and lead extraction was performed in 23% (18) of the cases in which this information was recorded.

Information on this item was reported in 56.2% of the data collection forms. The antibradycardia pacing most commonly used was VVI mode (57.4%), followed by DDD mode (30.1%), VVIR mode (5.5%), DDDR (4.7%), and other pacing modes, mainly preventive algorithms for ventricular pacing (2.3%).

Information on the induction of ventricular fibrillation was reported in 3591 of the data collection forms. In total, 250 patients (6.7%) underwent this procedure; the mean threshold was 20.5 (7.1) and a mean of 1.1 shocks were delivered.

Information on this item was reported in 87.1% of the data collection forms. In total, 28 complications were reported: 8 dissections of the coronary sinus, 3 deaths, 2 cases of pneumothorax, 1 case of tamponade, and 13 cases of various or unspecified complications. The death rate was 0.08%, similar to that reported for the previous year (0.1%).

In 2005, the first Spanish Implantable Cardioverter-Defibrillator Registry was published, in which the results for the period 2002-2004 were presented.4 There was an increase in the number of ICDs implanted each year until 20115–11 and 2012 was the second consecutive year in which a decrease was observed in the number of devices implanted in Spain. These data are consistent with the results reported by EUCOMED. In Europe, there was a slight increase in the number of ICD implantations and ICD-CRTs.14

There was a decrease in the indication for ICD implantation for primary prevention compared to 201111 (58.1% vs 59.4%), which broke the trend established since 2003. There was also a slight decrease in ICD-CRT implantations (32.5% vs 34.9%); however, the number of single-chamber ICD implantations increased (49.4% vs 46.7% in 2011). There was practically no change in the use of dual-chamber ICDs (18% vs 18.4%). In 2011, there was a decrease in the use of single- and dual-chamber ICDs compared to ICD-CRTs, whereas in 2012 this trend reversed; there is no obvious reason for this change, but it is probably explained by the decrease in indications for primary prevention in that year.

The most common indication for ICD implantation continued to be ischemic heart disease (50.7%), followed by dilated cardiomyopathy (27.4%). As in previous years,11 more than half of the implantations in patients with dilated cardiomyopathy were ICD-CRTs (56.5%), whereas the percentage was lower in patients with ischemic heart disease (27.7%).

The trend of gradual increase in the number of ICD implantations changed in 2011 and 2012, becoming stable or decreasing.14 No study has reported a change in indications for ICD implantation in recent years. The Multicenter Automatic Defibrillator Implantation Trial II,15 published in 2002, and the Comparison of Medical Therapy, Pacing and Defibrillation in Heart Failure16 and Sudden Cardiac Death in Heart Failure Trial,17 published in 2005 and 2006, respectively, established the current indications for primary prevention and CRT, leading to a gradual increase in the number of implantations over the next 10 years. Although the indications for ICD and CRT implantation are well supported in the clinical practice guidelines,18–21 the implantation rate per million population does not match the rate that would be expected according to the clinical evidence, either for Spain or for other European countries.22

As in previous registries, differences remain between the number of implantations in the present registry and the EUCOMED data, at proportions similar to those of other years.

The number of participating centers has decreased since 2011, mainly due to the grouping of several hospitals into consortiums that provided pooled data. Only 8 hospitals (11 in 2011) implanted more than 100 devices and 83 centers implanted fewer than 10 devices. An association has been shown between procedure volume and the number of complications,23 which decrease with increasing procedure volume per center.

Compared to previous registries, there were no changes in the epidemiologic characteristics of the patients. Patients with severe left ventricular dysfunction and those in NYHA functional class II and III continue to predominate. There was a slight gradual increase in the number of ICD implantations performed in the electrophysiology laboratory (81.4% vs 76.4% in 2011) and in those performed by electrophysiologists (81% vs 78.4% in 2011).

The differences in the ICD implantation rate between the various autonomous communities remained steady. The implantation rate in Spain was 91.2 per million population and 113 per million population according to EUCOMED, both of which were less than in 2011 (97 and 116.2, respectively). Several autonomous communities were above this average: Principality of Asturias (153), Castile and León (114), La Rioja (118), Extremadura (108), the Chartered Community of Navarre (104), Galicia (101), the Community of Madrid (99), Cantabria (95), and Castile-La Mancha (93). Autonomous communities below this average included Andalusia (62), the Region of Murcia (63), the Basque Country (64), the Balearic Islands (68), Catalonia (79), the Valencian Community (83), the Canary Islands (84), and Aragon (87). The autonomous community with the highest rate of ICD implantations reported more than twice that of the autonomous community with the lowest rate. There was an increase in ICD implantations in Extremadura, the Chartered Community of Navarre, the Canary Islands, and Galicia. There was a striking decrease in ICD implantations in Cantabria (143 vs 95) and the Community of Madrid (121 vs 99.1), whereas the decrease was less marked in the other autonomous communities.

There was no association between the gross domestic product of each autonomous community and the number of implantations. Interestingly, most of the autonomous communities with highest per capita income were those in which the number of ICD implantations performed was below the average. Neither was there an association between the number of ICD implantations and the incidence of ischemic heart disease and heart failure among the various autonomous communities. These differences may be explained by the health organization in each autonomous community, the number of arrhythmia units, or distribution of the referrals.

The implantation rate including ICDs and ICD-CRTs in the countries participating in EUCOMED was 273 per million population (269 in 2011). Germany, with 496 implantations, remained the country with the highest rate. Greece, with 111 implantations per million population, had the lowest rate. The following countries were above the average: the Netherlands (364), Italy (363), Norway (285), Denmark (280), and the Czech Republic (277). Countries below the average included Austria (259), Poland (252), Belgium (216), Switzerland (198), Sweden (191), France (191), Ireland (175), Finland (158), the United Kingdom (156), Portugal (125), Spain (113), and Greece (111).

The ICD implantation rate was 167 per million population in 2012 (162 in 2011). Germany (324) had the highest rate of ICD implantations, whereas Spain (74) had the lowest rate.

The ICD-CRT implantation rate was 106 per million population (107 in 2011). Germany (192 implantations) had the highest rate, whereas Greece (34) had the lowest rate. In Spain, the ICD-CRT implantation rate was 39 implantations per million population.

There was little change in the data for Europe between 2012 and 2011. There was a slowdown in the growth of the number of ICD implantations in 2012 compared to growth in previous years. The difference between Spain and the European average was maintained.

Differences between regions of European countries were similar to those reported in Spain,24,25 a situation for which there is no clear explanation. Although the cause has been attributed to the number of arrhythmia units available, this is an unlikely explanation, at least in Spain, where the autonomous communities with the highest number of arrhythmia units available have the lowest ICD implantation rates. Neither does per capita income appear to be related, since countries such as Ireland, the Czech Republic, and Poland have ICD implantation rates well above those in Spain. The ICD implantation rates and regional variations in Spain may be related to the incidence of cardiovascular diseases, access to and organization of the health care system, and the degree to which the clinical practice guidelines are accepted and implemented.

According to EUCOMED data, 80.8% of implantations performed in Spain were reported to the registry. This value is lower than the 83.6% reported in 2011 and the 90% reported in 2007, the year in which the percentage began its decrease to the current value. However, this value is still representative of the current situation in Spain and the number of centers participating in the registry has steadily increased.

In some hospitals, the true number of implantations performed differed from the number reported to the registry because the registry only included information provided in the data collection forms. Some of the forms may not have been received, since there are several ways to send and receive information, or the data may have been entered incorrectly. Next year there will likely be an online data reporting option, which could both improve the outcome and reduce the difference between the data collected in this registry and the data provided by EUCOMED.

There were great variations in the response rates for the various fields on the data collection form, ranging from 99.6% for the name of the participating hospital to 53% for QRS width. Finally, the percentage of complications reported in the registry does not accurately reflect the true situation because the data form was completed during or immediately after the procedure and therefore the majority of the subacute complications would not be recorded.

The current registry is the 9th official report of this activity in Spain. The fact that the registry has been maintained over so many years should be a cause of genuine satisfaction for all participating members of the Electrophysiology and Arrhythmias Section of the SEC. The steady modernization of the registry will make it possible to obtain more and better information with less effort by the personnel involved in its maintenance. Future improvements in online data collection may make it possible to achieve more ambitious clinical goals and could include parameters such as mortality, shocks delivered, complications, etc., thus improving both, the clinical data and the overall value of the registry.