Results are expressed as mean ± standard deviation or median [interquartile range], depending on the distribution of the variable. Continuous quantitative variables were analyzed using analysis of variance or the Kruskal-Wallis test, whereas qualitative variables were analyzed using the chi-square test. Linear models were used to analyze the number of implants and devices implanted per million population, the total number of implants, and the number of implants for primary prevention in each center.

In total, 173 hospitals participated in the registry. This number is similar to those of 2019 (n = 172) and 2018 (n = 173) but slightly lower than that of 2017 (n = 181, the highest number recorded since registry formation). Figure 1 shows the total number of implantation centers, the rate per million population, and the total number of implants per autonomous community according to the data submitted to the registry. In 2020, 22 centers implanted ≥ 100 devices, 75 between 11 and 99 devices, 49 ≤ 10, and 27 only 1.

Figure 1.

Distribution of activity by autonomous community in 2020: number of implantation centers/rate per million population/total number of implants. Mean rate = 149 implants/million population.

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The name of the hospital performing the procedure was recorded in 99.8% of forms (table 1). Most procedures (6405, 91%) were performed in publicly-funded health centers.

The total number of implants reported to the registry and those estimated by Eucomed in the last 10 years are shown in Figure 2. In 2020, the total number of implants (first and replacements) recorded was 7056, which suggests an increase vs 2019 (7003) and 2018 (6421). However, according to the data provided by Eucomed, the total for 2020 (7106) represents a fall in the number of ICD implants in Spain (7389 in 2019 and 7077 in 2018).

Figure 2.

Total number of implants recorded and those estimated by the European Medical Technology Industry Association from 2011 to 2020. Eucomed, European Confederation of Medical Suppliers Associations; ICD, implantable cardioverter-defibrillator.

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Changes in the implantation rate per million population in the last 10 years according to registry and Eucomed data are shown in Figure 3. According to Eucomed, the total implantation rate recorded was 150 implants/million population in 2020, 157 in 2019 and 152 in 2018. This figure represents a reduction vs the last 2 years and continues to be much lower than the average ICD implantation rate in Europe, which was 285/million population in 2020 (303/million in 2019).

Figure 3.

Total number of implants recorded per million population and those estimated by the European Medical Technology Industry Association from 2011 to 2020. Eucomed, European Confederation of Medical Suppliers Associations; ICD, implantable cardioverter-defibrillator.

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Figure 4, which shows the number of ICD implants by month between 2017 and 2020, reveals a fall in implantation in March (−17%) and particularly in April (−50%) and May (−39%) of 2020 vs the same months in the previous year. A recovery in ICD implantation activity can also be seen in the second half of 2020, although the total number of implants remained lower than that of 2019.

Figure 4.

Numbers of implants per month from 2017 to 2020.

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This information was available in 4405 forms (62.4% of those included in the registry). First implants comprised 3127, representing 71.0% of the total (74.3% in 2019, 71.5% in 2018, 71.4% in 2017, 66.8% in 2016, 71.8% in 2015, and 72.6% in 2014).

The mean age of all the patients included in the registry was 62.2 ± 13.4 (range, 5-95) years in 2020. This figure is similar to the average ages in 2019 and 2020 (62.1 ± 13.8 [4-97] years and 62.4 ± 13.5 [7-97] years, respectively). The age at first implantation was 61 ± 13.1 years (60.8 ± 13.8 in 2019). As in previous years, patients were overwhelming male: they represented 82.6% of all patients and 83.6% of first implants.

The most frequent underlying cardiac condition in first implant patients was ischemic (50.9%), followed by dilated cardiomyopathy (27.1%), hypertrophic cardiomyopathy (8.4%), primary conduction abnormalities (Brugada syndrome and long QT syndrome; 2.8%), valve diseases (1.9%), and arrhythmogenic right ventricular cardiomyopathy (1.3%) (Figure 5).

Figure 5.

Type of heart disease prompting implantation (first implants). ARVC, arrhythmogenic right ventricular cardiomyopathy; Others, patients with more than 1 diagnosis.

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Left ventricular systolic function data were provided in 51.8% of forms. Left ventricular ejection fraction was > 50% in 16% of patients, from 41% to 50% in 9.4%, from 36% to 40% in 9.8%, from 31% to 35% in 21%, and ≤ 30% in 43.9% (Figure 6). The distribution was similar when it was grouped by first implants and replacements.

Figure 6.

Clinical characteristics of the registry patients (total and first implants). A: left ventricular ejection fraction (LVEF). B: NYHA functional class. C: distribution of arrhythmias prompting implantation (first implants and total). D: clinical presentation of the arrhythmia in the registry patients (first implants and total). NSVT, nonsustained ventricular tachycardia; NYHA, New York Heart Association; PVT, polymorphic ventricular tachycardia; SCD, sudden cardiac death; SMVT, sustained monomorphic ventricular tachycardia; VF, ventricular fibrillation.

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New York Heart Association (NYHA) functional class was recorded in 31.2% of forms. Most patients were in NYHA class II (59.8%), followed by NYHA III (24.8%), NYHA I (14.1%), and NYHA IV (1.2%). The distribution for this variable was also similar in the overall and first implantation groups (Figure 6).

With data from 52.9% of forms, the baseline cardiac rhythm was primarily sinus (78.9%), followed by atrial fibrillation (18.1%) and pacemaker rhythm (3.3%). The remaining patients had other rhythms (eg, atrial flutter and other arrhythmias).

The clinical arrhythm ia prompting device implantation was reported in 52.2% of forms. In the total group, patients with no documented clinical arrhythmia comprised 71.2%. For first implants, most patients had no documented clinical arrhythmias (72.6%), whereas 10.2% had sustained monomorphic ventricular tachycardia, 7.8% had nonsustained ventricular tachycardia, and 8.9% had ventricular fibrillation (Figure 6).

The most frequent presentation in both the total implantation group and in first implantation patients (39.3% of completed responses) was asymptomatic (in more than half of patients), followed by syncope, sudden cardiac death, and other symptoms (Figure 6).

Information on the electrophysiological studies performed before ICD implantation was provided in 40.7% of forms. These studies were performed in 379 patients (5.5%), mainly in those with ischemic heart disease or dilated cardiomyopathy and in 40.9% of patients with Brugada syndrome. Sustained monomorphic ventricular tachycardia was the most common induced arrhythmia (27.9%), followed by ventricular fibrillation (15.2%), nonsustained ventricular tachycardia (6.4%) and, to a lesser extent, other arrhythmias (4.2%). No arrhythmia was induced in 46.3% of the electrophysiological studies.

In all forms submitted to the registry, 52.7% provided some data on the clinical history of the patient undergoing ICD implantation. Hypertension was present in 52.9% of patients, as well as hypercholesterolemia in 44.6%, smoking in 30.5%, diabetes mellitus in 28.1%, history of atrial fibrillation in 25.9%, renal failure in 11.3%, family history of sudden cardiac death in 8.9%, and history of stroke in 4.7%.

The QRS duration interval was reported in 40.6% of first implants (mean, 127.2ms). In 33.4% of the patients, the duration was > 140ms, and 83.0% of these patients had a resynchronization-defibrillator device (ICD-cardiac resynchronization therapy [CRT]).

Device indications over time are shown in table 2. These data were provided in 43.8% of forms in 2020. Ischemic heart disease was the most frequent reason for ICD implantation (50.9% of first implants in 2020). Among ischemic heart disease patients, the most common indication was primary prevention (56.1%). However, a considerable number of forms returned failed to note the reason or it was unclassifiable. The second most common reason for ICD implantation was dilated cardiomyopathy (27.1% of all first implants), and the absolute number of first implants increased in 2020 vs previous years, due to the increase in primary prevention indications. In the less common heart diseases, the most frequent indication was primary prevention.

The implantation indication was identified in 62.2% of forms, and primary prevention was the main indication in first implants (72.7%). This figure is the highest in registry history (table 3).

The implantation setting and specialist performing the procedure were recorded in 60.5% of forms; 85.6% of procedures were performed in electrophysiology laboratories and 13.3% in operating rooms. Cardiac electrophysiologists performed 82.4% of implants, surgeons performed 7.9%, and both together performed 5.5%. Other specialists and intensivists were involved in 1.5% and 2.7%, respectively.

Transvenous ICD generator placement represented 65.5% of first implants, with a subcutaneous location in 95.6% of cases and subpectoral in the remaining 4.4%. These figures were 95.5% and 4.5%, respectively, for all devices implanted.

The types of devices implanted are shown in table 4. This information was provided in 78.3% of forms submitted to the registry. In 2020, first implants of subcutaneous defibrillators became established, with a market penetration of 8.1%.

The most frequent reason for ICD generator replacement was battery depletion (84.3%); complications prompted 8.7% of replacements and a change in indication prompted 7.0%.

Of the 627 replacements providing this information, 1.7% were performed before 6 months. In addition, 30.2% of forms provided information on the status of leads, which were malfunctioning in 33 patients.

Complication data were recorded in 44.7% of forms. In total, 30 patients with complications were reported: 4 pneumothoraces, 3 coronary sinus dissections, 2 tamponades, 2 deaths, and 24 unspecified. The mortality rate was 0.06%, which fortunately was very low, as in previous years.

The 2020 registry confirms the major differences in implantation rates per million population among Spanish autonomous communities. Several communities showed higher than average rates: Cantabria, Aragon, the Principality of Asturias, Galicia, Valencian Community, Castile-La Mancha, Castile and León, and the Community of Madrid. Below the average were Region of Murcia, the Chartered Community of Navarre, Extremadura, Catalonia, Andalusia, La Rioja, the Basque Country, the Balearic Islands, and the Canary Islands. The data from 2020 indicate an increase in the difference between the communities with the highest (Cantabria) and lowest (the Canary Islands) rates of implantation per million population. The gap has widened to 180 units/million population from 139/million in 2019. The disparity in the ICD implantation rate among the various autonomous communities, present in previous registries and magnified in the current registry, is hard to explain. It cannot be explained by the gross domestic product per capita in each autonomous community, by health expenditure or population density, or by a different incidence in the type of heart disease most prevalent in each community. The COVID-19 pandemic may have unequally affected the autonomous communities and could explain the aggravation in the pre-existing differences in Spain. This situation might call into question the equity of our health care system in an area as important as the prevention of sudden cardiac death.

In 2020, the implantation rate in the countries participating in the Eucomed was 285/million population, dropping below 300/million population for the first time in more than 5 years. The countries with the highest implant numbers were the Czech Republic and Germany (474 and 445/million population, respectively). One consistent result is that Spain (150 implants/million population in 2020 and 157/million in 2019) is the country with the lowest number of implants.

Other European countries also exhibit regional differences22 that cannot be easily explained. A possible reason is the number of arrhythmia units available, but countries with many units have low implantation rates. Regarding income, countries with lower incomes than Spain, such as Ireland, the Czech Republic, and Poland, have higher implantation rates. The prevalence of cardiovascular disease also fails to explain these differences. The low implantation rate reflects a low level of adherence to clinical practice guidelines, which has been linked to increased mortality. We need to be aware of this problem and do everything in our power to alleviate it.

As in previous years, completion of the different fields in the implantation form varied and was lower than desired. In addition, no follow-up data were collected from patients, which would permit more relevant clinical studies. Finally, the unequal completion of the data on ICD-associated complications and the absence of follow-up data probably underestimate the actual complication rate.