Data are expressed as mean±SD or median [interquartile range] depending on the normality of distribution. Continuous quantitative variables were analyzed using analysis of variance or the Kruskal-Wallis test, while qualitative variables were analyzed using the chi-square test. Linear regression models were used to analyze the number of implants and implanting centers per million population, the total number of implants, and the number of primary prevention implants per hospital.

A total of 170 hospitals participated in the Spanish ICD registry in 2022. This figure is down from previous years (198 in 2021, 173 in 2020, 172 in 2019, 173 in 2018) due to a reduction in the number of hospitals with low procedure volumes. The data for the 170 hospitals are shown in table 1. Numbers of implanting centers, implants per million population, and implants per autonomous community according to the data submitted are shown in figure 1. Twenty-five hospitals (23 in 2021) implanted ≥100 ICDs, and 5 of these implanted >200. Sixty-seven hospitals (74 in 2021) implanted 11-99 devices and 78 (101 in 2021) implanted ≤10. In this last group, 13 (28 in 2021) implanted just 1 device.

Figure 1.

Distribution of implantation activity by autonomous community in 2022: number of implanting centers/rate per million population/total number of implants. Mean rate, 162 implants per million population.

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The implanting center was specified in 99.9% of cases (table 1). Most procedures (7235, 94%) were performed in a public hospital.

The total number of ICD implants reported to the registry over the past 10 years and the corresponding Eucomed estimates are shown in figure 2. In 2002, information was submitted for 7693 procedures, including de novo implants and replacements. This is a historic high for the registry and represents an increase of 2.6% compared with 2021 (7499 implants). The 2022 Eucomed estimate for 2022 (7970 implants) is also the highest to be reported since the creation of the Spanish ICD registry and represents a 2.9% increase with respect to 2021 (7743 implants).

Figure 2.

Total number of implants and Eucomed estimates for 2013 to 2023. Eucomed, European Confederation of Medical Suppliers Associations; ICD, implantable cardioverter-defibrillator.

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Changes in the number of implants per million population reported by the ICD registry and Eucomed are shown in figure 3. The Eucomed estimate for 2022-168 implants per million population-is higher than in recent years (163 in 2021, 150 in 2020, and 157 in 2019), but still well below the mean for Europe, which was 296 units per million population in 2021, when normal hospital activity had resumed in the wake of the COVID-19 pandemic.10

Figure 3.

Number of implants per million population and Eucomed estimates for 2013 to 2023. Eucomed, European Confederation of Medical Suppliers Associations; ICD, implantable cardioverter-defibrillator.

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Monthly implantation figures for 2018 to 2022 are shown in figure 4, which reflects variations throughout the year, with a notable drop in April and May 2020 (COVID-19 pandemic) followed by a return to normal levels. ICD implantation activity throughout 2022 can be considered normal. The findings are similar to those observed in 2021 and were minimally impacted by the COVID-19 waves that occurred during the year.

Figure 4.

Number of implants per month from 2018 to 2022.

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The mean age of patients included in the Spanish ICD registry in 2022 was 62.4±13.9 years (range, 2-92 years). Similar to previous years, de novo ICD recipients were slightly younger (61.6±13.5 years). Also in line with previous findings, the patients were overwhelmingly male (82.4% of patients overall and 83.7% of de novo implant recipients).

Ischemic heart disease was the most common heart disease in de novo ICD recipients (51.8%), followed by dilated cardiomyopathy (24.9%), hypertrophic cardiomyopathy (8.4%), primary electrical diseases–Brugada syndrome and long QT syndrome– (2.1%), valve disease (2.1%), and arrhythmogenic right ventricular cardiomyopathy (1.5%) (figure 5).

Figure 5.

Underlying heart disease in de novo ICD recipients. ARVC, arrhythmogenic right ventricular cardiomyopathy; ICD, implantable cardioverter-defibrillator; Other, patients with more than 1 diagnosis.

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Left ventricular systolic function was reported in 41% of cases. Left ventricular ejection fraction (LVEF) was >50% in 16.7% of patients, 50% to 41% in 8.5%, 40% to 36% in 9.8%, 35% to 31% in 19.9%, and ≤30% in 45.1% (figure 6). The values were similar among patients receiving their first implant and those undergoing replacement.

Figure 6.

LVEF values among patients in the registry (total and de novo ICD recipients). ICD, implantable cardioverter-defibrillator; LVEF, left ventricular ejection fraction.

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New York Heart Association (NYHA) functional class was specified in 22.6% of registry forms. Most patients were in class II (64.9%); 21.9% were in class II, 11.9% in class I, and 1.2% in class IV. Again, the distribution was similar on analyzing de novo recipients and those undergoing replacement.

Baseline rhythm was reported for 41.3% of cases. At the time of implantation, 78.4% of patients were in sinus rhythm, 17.3% had atrial fibrillation, and 3.5% had a pacemaker rhythm. The remaining patients had atrial flutter or other arrhythmias.

Clinical arrhythmias leading to ICD implantation were specified in 44.3% of forms and are shown in figure 7. Most de novo implant recipients (69.9%) did not have documented clinical arrhythmias, 12.8% had sustained monomorphic ventricular tachycardia, 9% had ventricular fibrillation, and 6.9% had nonsustained ventricular tachycardia.

Figure 7.

Arrhythmias leading to ICD implantation among patients in the registry (total and de novo recipients). NSVT, nonsustained ventricular tachycardia; PVT, polymorphic ventricular tachycardia; SMVT, sustained monomorphic ventricular tachycardia; VF, ventricular fibrillation.

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Almost 44% of patients were asymptomatic. Less common clinical presentations were syncope, aborted SCD), and other symptoms (figure 8).

Figure 8.

Clinical presentation of arrythmias among patients in the registry (total and de novo ICD recipients). ICD, implantable cardioverter-defibrillator; SCD, sudden cardiac death.

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The electrophysiology study section of the form was completed in 40.6% of cases. This study was performed before ICD placement in 196 patients (6.2% of patients for whom information was provided). It was performed more often in those with ischemic heart disease, dilated cardiomyopathy, and Brugada syndrome (41.8% of patients for whom these diagnoses were specified). The most common arrhythmia induced electrophysiologically was sustained monomorphic ventricular tachycardia (67.3%), followed by ventricular fibrillation (24.3%), nonsustained ventricular tachycardia (6.5%) and other arrhythmias (1.9%). No arrhythmias were induced in 20.2% of cases.

The main indications for ICD implantation between 2018 and 2022 are shown in table 2. This information was submitted for 54.5% of cases in 2022. Ischemic heart disease is the most common indication in Spain, and in 2022, it accounted for 51.8% of all de novo indications. Primary prevention was the most common indication for ICD therapy in patients with ischemic heart disease (64.7%). The second most common indication overall was dilated cardiomyopathy (24.9% of all de novo implant recipients had this diagnosis). In total, 696 patients with dilated cardiomyopathy underwent ICD implantation in 2022, confirming the downward trend observed in 2021 with respect to previous years (619 in 2021, 1214 in 2020, 925 in 2019, and 803 in 2018). Most ICDs implanted in patients with less common heart diseases were for primary prevention.

ICD indications were specified in 54.4% of forms. The most common indication reported for de novo implant recipients was primary prevention of SCD (75.6% of cases). Although this rate is lower than in 2021 (86.4%), it supports the upward trend observed in recent years, with values of close of 80% (table 3).

Data on implantation settings and treating specialists were provided in 51.5% and 49.9% of forms, respectively. Overall, 86.5% of procedures were performed in the electrophysiology laboratory and 12.8% in the operating room. The devices were implanted by an electrophysiologist in 90.2% of cases, a surgeon in 1.9%, an intensive care specialist in 1.7%, a cardiologist in 1.3%, and a combination of specialists in 0.6%.

Generator placement site was specified in 51.4% of forms submitted to the registry. Placement was subcutaneous in 97.2% of cases and subpectoral in 2.9%.

The ICD devices used by Spanish hospitals in 2022 are shown in table 4. This information was reported for 98.8% of cases and shows an even larger decrease in the use of subcutaneous devices for first-time implants than in previous years. The year 2022 also saw a reduction in CRT-ICD implantations, with the lowest rate observed since 2013. The use of single-chamber ICDs remained stable, at around 51%.

The main reason for ICD generator replacement was battery depletion (73.2%), followed by upgrading (17.7%), device dysfunction (5%), device infections (1.4%), and other reasons (2.7%).

Lead condition was described in 58.5% of forms, and was defective in 27 cases.

Device programing details were provided in 47.4% of forms. The most widely used pacing mode was VVI (50.4%), followed by DDD (21.6%), VVIR (5.9%), DDDR (5.21%), and resynchronization (9.2%). Other modes, which mostly included algorithms or modes to prevent ventricular stimulation, accounted for 9.2% of cases.

Postimplantation induction of ventricular fibrillation was performed at least once in 311 patients (8.6% of those for whom this information was reported). The defibrillation test was mainly performed in patients with a subcutaneous ICD. Just 36 patients with a transvenous ICD underwent ventricular fibrillation induction. The mean number of shocks delivered was 1.06. Accordingly, correct device functioning rather than thresholds was checked in most cases.

Information on complications was reported in 46.8% of forms. There were 50 complications: 13 coronary sinus dissections, 9 suboptimal left ventricular electrode positions, 4 cases of pneumothorax, 1 tamponade, and 23 unspecified complications. No procedure-related deaths were reported in 2022.

Although more ICD devices than ever were implanted in Spain in 2022, the number of implanting centers decreased with respect to previous years, essentially because of a reduction in the number of hospitals with low volumes of procedures (<100 and in particular<10).

With some exceptions (2011-2012, 2017, and 2020), implantation activity in Spain has increased progressively over the years since the launch of the national ICD registry. There was a 4% reduction in the number of procedures performed in 2020 relative to 2018 and 2019 (the years with the most activity up to 2021), but this was attributable to a general reduction in hospital activity due to the COVID-19 pandemic. Implantation rates returned to normal in 2021, when hospitals resumed normal operation. Although the effects of the pandemic were still somewhat evident in January and February, 2021, they were offset by the increase in procedures over the rest of the year, which ended with a record high. This increase continued into 2022, which set a new record in the number of procedures performed. Nonetheless, and in line with findings from previous years, Spain, with 168 implants per million population, has the lowest implantation rate in all the European Union and is still well behind the European mean of 296 implants per million population reported for 2021.

As evidenced by the above figures, Spain still has a long way to go before it attains a level of activity that would be expected in light of the scientific evidence underlying current clinical practice guidelines.1–3 This situation, however, is not specific to Spain, and its ramifications can be observed in a Swedish study that found that just 10% of patients with an ICD indication for the primary prevention of SCD (according to the European Society of Cardiology [ESC] guidelines) between 2000 and 2016 received a device.15 The same study found that ICD use was associated with a 27% 1-year and a 12% 5-year reduction in mortality. Data from the European EU-CERT-ICD registry have also shown a survival benefit among patients with and without ischemic heart disease who received an ICD for the primary prevention of SCD, with an overall 27% reduction in mortality over a mean follow-up of 2.5 years.16 The Spanish ICD Registry shows that ICD therapy is clearly underused in Spain. The reasons are difficult to pinpoint, but the figures highlight the need to implement measures ensuring that all patients who could benefit from ICD therapy receive a device.

Most (75.6%) of the ICDs implanted in Spain in 2022 were for primary prevention, confirming the upward trend observed in recent years (table 3). Prophylactic ICD therapy has increased by more than 50% in the past 10 years, positioning Spain at a similar level to other European countries, where approximately 80% of implants are for primary prevention.17,18

The percentage of de novo CRT-ICD implants had remained stable, at around 30% in recent years, but in 2022, it was well below this level. There was also an increase in the use of dual chamber ICDs and a stabilization in the use of single-chamber devices. Finally, the data confirmed a downward trend in the use of subcutaneous ICDs among de novo recipients. The rate in 2022 was 6.5%, down from the peaks of 8.3% in 2019 and 8.1% in 2020. Although the favorable results reported for subcutaneous ICDs in 2020 by the PRAETORIAN (Prospective, Randomized Comparison of Subcutaneous and Transvenous Implantable Cardioverter Defibrillator Therapy)19 and UNTOUCHED (Understanding Outcomes With the S-ICD in Primary Prevention Patients With Low Ejection Fraction)20 clinical trials indicated that subcutaneous ICD use would gain traction, this has not been the case in Spain. Possible reasons include higher costs per unit and recent safety alerts. Nonetheless, 2 recent subanalyses of data from the PRAETORIAN trial showed that subcutaneous ICDs were effective in the treatment of ventricular arrhythmias21 and associated with fewer device-related complications than transvenous ICDs.22 A new extravascular ICD recently authorized for use in the European Union has a ventricular stimulation feature that provides pause-prevention and antitachycardia pacing.23 The impact of this novel device and emerging evidence on the use of subcutaneous ICDs will become clearer in the years to come.

Ischemic heart disease (51.8%) and dilated cardiomyopathy (24.9%) continue to be the main heart conditions in ICD carriers. Together, they account for more than 75% of all indications for ICD therapy in Spain. The data from 2022, however, show a reduction in the percentage of patients with dilated cardiomyopathy in the registry, which was manifested in a corresponding reduction in the number of prophylactic indications for this disease and probably also explains the reduction in the percentage of CRT-ICD implantations observed. These reductions can be explained by the findings of several recent publications, including the DANISH (Defibrillator Implantation in Patients with Nonischemic Systolic Heart Failure) trial24 and the latest ESC guidelines for the diagnosis and treatment of heart failure3 and the management of patients with ventricular arrhythmias and the prevention of SCD.2 Both guidelines, published in 2021 and 2022, respectively, downgraded the recommendation for using ICDs in the primary prevention of SCD in patients with nonischemic dilated cardiomyopathy to a level IIa A recommendation. The use of ICDs in patients with dilated cardiomyopathy, however, remains controversial. The 2021 heart failure guidelines recognize a potential survival benefit in patients younger than 70 years and cite the 30% reduction in mortality (hazard ratio [HR], 0.70; 95% CI, 0.51-0.96; P=.03) reported by the DANISH trial.3 The guidelines also refer to the findings of a meta-analysis (including the DANISH trial) that showed an association between ICD therapy and a reduction in all-cause mortality in patients with nonischemic cardiomyopathy.25 The ESC guidelines for the management of patients with ventricular arrhythmias recommend genetic testing (eg, to detect LMNA mutations, which are associated with a high risk of SCD) and assessment of late gadolinium enhancement on cardiac magnetic resonance imaging to improve SCD risk stratification in patients with dilated cardiomyopathy.2 This latter recommendation is based on the findings of several studies and meta-analyses showing that late gadolinium enhancement is superior to LVEF as a risk marker for SCD. Finally, a cost-effectiveness analysis of ICD therapy for the primary prevention of SCD in Spain showed this treatment to be associated with a reduction in all-cause mortality in both ischemic (HR, 0.70; 95% CI, 0.58-0.85) and nonischemic heart disease (HR, 0.79; 95% CI, 0.66-0.96).26 Using probabilistic modeling, the study showed cost-effectiveness ratios of €19171 per quality-adjusted life year (QALY) for patients with ischemic heart disease, €31084/QALY for patients with nonischemic dilated cardiomyopathy, and €23230/QALY for patients younger than 68 years.26 These results confirm that ICD therapy in Spain is a cost-effective strategy for the primary prevention of SCD in patients with left ventricular dysfunction of ischemic or nonischemic origin, especially in younger populations (<68 years).

Similar to previous years, the 2022 registry showed significant differences in implant numbers per million population among autonomous communities. The rates were higher than average in several regions, namely Principality of Asturias (n=331), Cantabria (n=242), Extremadura (n=219), Aragon (n=214), La Rioja (n=193), Galicia (n=190), Castile-La Mancha (n=188), the Valencian Community (n=180), and the Basque Country (n=163). Below-average rates were observed in Community of Madrid (n=161), Balearic Islands (n=160), Catalonia (n=151), Castile-León (n=150), Chartered Community of Navarre (n=147), Andalusia (n=139), the Canary Islands (n=130), and Region of Murcia (n=108). The difference between communities with the highest and lowest rates again exceeded 200 implants per million population (265 in 2021, 180 in 2020, and 139 in 2019). The level of disparities across regions in a supposedly uniform health care system such as that of Spain remains a puzzle and indicates that, despite the available evidence and the work of the SEC, hospitals are not applying the same criteria in this area. The differences cannot be explained by differences in income or population density, or by varying rates of ischemic heart disease and heart failure. They do, however, raise questions on the equity of the Spanish health care system in an area as important as SCD prevention.

On average, 296 devices (ICDs and CRT-ICDs) per million population were implanted in countries covered by Eucomed in 2021. This is higher than the rate of 285 per million population reported for 2020 (the year most affected by the COVID-19 pandemic) and similar to rates from previous years (303 in 2019, 302 in 2018, 307 in 2017, and 316 in 2016). The countries with the highest activity were the Czech Republic, Italy, and Germany, which respectively performed 470, 440, and 436 implantations per million population. Spain again ranked bottom in 2022, with a total of 168 implants per million population, and continues to trail behind other countries with low activity, such as the United Kingdom and Portugal, which respectively performed 197 and 229 implants per million population in 2021.

The Spanish ICD registry collected data on 96.5% of all implants performed in Spain in 2022 according to Eucomed data. As in previous years, and despite the creation of the online CardioDispositivos platform in 2019 to facilitate reporting,27 the completeness of the information submitted was inconsistent across hospitals and less than ideal. Just 23.6% of hospitals used the online platform in 2022, down from 30% in 2021. In addition, the registry does not collect important ICD programming data that would help analyze morbidity and mortality. Combined analyses of parameters such as detection times, heart rate thresholds, and intervals at which supraventricular rhythm discriminators operate are helpful for reducing appropriate and inappropriate therapies. The registry also does not collect follow-up data, limiting thus the conduct of more relevant clinical studies. Finally, inconsistent reporting and a lack of follow-up data probably contributed to an underestimation of procedure- and device-related complications.

This is the 19th official report of the Spanish ICD Registry. The continued publication of these annual reports is a credit to all participating members of the SEC Heart Rhythm Association. The online platform, a joint initiative of the SEC and the Agencia Española de Medicamento y Productos Sanitarios (AEMPS), has yet to find traction, and its use by hospitals across the country remains inconsistent. To ensure the success of the registry, hospitals need to recognize the importance of the online platform, which facilitates real-time reporting and can serve as a breeding ground for more complex studies.