10-year follow-up of interventional electrophysiology: updated German survey during the COVID-19 pandemic

Introduction This study provides an update of survey-based data providing an overview of interventional electrophysiology over the last decade. Overall infrastructure, procedures, and training opportunities in Germany were assessed. Methods By analyzing mandatory quality reports, German cardiology centres performing electrophysiological studies were identified to repeat a questionnaire from 2010 and 2015. Results A complete questionnaire was returned by 192 centers performing about 75% of all ablations in Germany in 2020. In the presence of the COVID-19 pandemic, a total of 76.304 procedures including 68.407 ablations were reported representing a 38% increase compared to 2015. The median number of ablations increased from 180 in 2010 to 377 in 2020. AF was the most common arrhythmia ablated (51 vs. 35% in 2010). PVI with radiofrequency point-by-point ablation (64%) and cryo-balloon ablation (34%) were the preferred strategies. Less than 50 (75) PVI were performed by 31% (36%) of all centres. Only 25 and 24% of participating centres fulfilled EHRA and national requirements for training centre accreditation, respectively. There was a high number of EP centres with no fellows (38%). The proportion of female fellows in EP increased from 26% in 2010 to 33% in 2020. Conclusion Comparing 2020, 2010 and 2015, an increasing number of EP centres and procedures were registered. In 2020, more than every second ablation was for therapy of AF. In the presence of an increasing number of procedures, training opportunities were still limited, and most centres did not fulfill recommended EHRA or national requirements for accreditation. Graphical abstract


Introduction
Over the last decades, cardiac electrophysiology has become a pivotal subspecialty of cardiology with growing numbers of catheter ablations every year [1]. In many patients with supraventricular tachycardias (SVT) or atrial fibrillation (AF), catheter ablation is considered first-line therapy [2,3]. The gradual increase in the number of yearly performed catheter ablations is, e.g. portrayed in mandatory quality reports based on the German operational and procedural key system (OPS) with currently about 90,000 catheter ablations in Germany each year [4,5].
To ensure overall quality, safety, and optimal patient care national and international standards as well as trained specialists in the field of cardiac electrophysiology are encouraged to match this development. In order that aspiring physicians in the field of cardiac electrophysiology receive proper training as heart rhythm specialists, national and international cardiology societies have developed training programs and curricula [6][7][8][9].
To provide an overview and assess the current national status of physician training and patient care in cardiac electrophysiology including infrastructure, training conditions, and ablation procedures, we initiated this survey in 2010 [10] and performed a 5-year follow-up in 2015 [11]. This multi-centre observational study provides a second longer follow-up and overview of a decade of electrophysiological patient care and training comparing data to previous surveys from 2010 and 2015. It is of particular interest as it presents data of a time period in which the worldwide COVID-19 pandemic enforced lock-down measures with cancellation of many elective catheter ablations.
As more than one OPS code can be reported for a single ablation procedure (e.g., radiofrequency ablation plus 3D mapping-based ablation), the number of OPS given is not equal to the number of procedures performed. Centres coding for less than 30 ablation procedures a year were excluded to prevent the accidental inclusion of centres employing external electrophysiologists or coding OPS for externally performed procedures.
Upon identification of the centres, we contacted the cardiology or interventional electrophysiology department by e-mail and/or phone to complete the same questionnaire that was utilized in previous surveys from 2010 [10] and 2015 [11].
Among the included parameters in the questionnaire were: type of hospital; staff numbers and functions in cardiology and electrophysiology, gender aspects, infrastructure, number and types of EP procedures, techniques used, imaging modalities, presence of or distance to cardiac surgery. Furthermore, more detailed information on protection methods of the esophagus during AF ablation was requested. Gathered data were anonymized and consequently analyzed using R-Studio Version 1.4.1106 (R. RStudio, PBC, Boston, MA).

The structure of interventional electrophysiology
The electrophysiological departments were mainly part of a cardiology clinic (90%) with only 19 EP centres (11%) being independent with their own budget. A total of 106 centres (55%) were certified training centres for cardiac electrophysiological procedures by the German cardiac society (DGK). Heads of cardiological departments of 31 centres (16%) counted invasive electrophysiology as their main area of expertise. In 148 centres (77%), at least one catheter laboratory was exclusively used for invasive electrophysiology over 90% of the time. Thirty-five centres (18%) used two laboratories predominantly for EP procedures. 3-D mapping systems (CARTO ® n = 104; NavX ® n = 106; Rhythmia ® n = 29; CARTO ® and NavX ® n = 47) were available in 110 (57%) centres. 101 centres (53%) used the catheter laboratory also for all electrical device implantations, 12 (6%) centres in more than 50% of cases and 45 (23%) centres in less than 50% of cases. In the remaining centres (n = 34; 18%), device implantations were exclusively performed in operating rooms. The primary operator implanting these devices was a cardiologist in 147 (77%) centres and a surgeon in 8 (4%). Both cardiologists and surgeons performed these procedures in the remaining 36 (19%) EP centres.
Cardio-surgical back-up was available in-house in 64 (38%) of the centres performing AF ablations. If not available in-house, the distance to the next hospital having a cardio-surgical unit ranged from 1 to 150 km (mean: 35 ± 31 km). Surgical AF ablations were performed in 44 (26%) centres with 10 (6%) centres performing surgical AF ablations as stand-alone operations.

Training centre requirements
The requirements to be accredited as an EP training centre according to the European Heart Rhythm Association (EHRA) and the German Cardiac Society (DGK) are illustrated in Table 4. Only a quarter (n = 48) of the responding centres fulfilled the requirements provided by the EHRA or DGK (n = 47; 24%; for the requirement of 75 AF ablations/ per year n = 36 (19%)).

Discussion
Reporting data from German centres performing electrophysiological studies, this multi-centre observational study is able to describe clear trends in electrophysiology over the recent decade comparing data from 2010 [10], 2015 [11], and 2020. Most contacted clinics responded with a complete questionnaire. Collectively, there were 68.407 catheter ablations reported by the responding centres in 2020 illustrating a 39 and 105% increase in yearly performed ablations compared to survey data from 2015 [11] and 2010 [10], respectively. This is in line with an increase in the number of hospitals performing EP studies in Germany and was observed despite the presence of the COVID-19 pandemic with many weeks of lock-down and cancellation of elective EP procedures in most centres. As training requirements differ not only in Europe but also in the U.S. it is difficult to determine an exact number of necessary ablation procedures needed to be an experienced EP centre [17]. Reference publications are the curricula published by the German cardiac society (DGK) [7,8] and the European Heart Rhythm Association (EHRA) [6] as well as the 2017 HRS/EHRA/ECAS/ APHRS/SOLAECE expert consensus statement on catheter and surgical ablation of atrial fibrillation [17]. These recommendations are very similar, except the required ablation numbers in Europe being slightly higher. The EHRA (DGK) recommend that an EP centre ought to have a (moderate) quantity of at least 200 (250) EP studies and at least 150 (200) catheter ablations a year which was, however, fulfilled by only 58% (55%) of the responding centres. Besides, the EHRA requires a centre to have a cardio-surgical unit which was present in only 38% of the participating German centres. Altogether, only a quarter of responding centres fulfilled all EHRA or DGK criteria. Of note, only 16% of the centres fulfilled the requirement of the DGK of always having two physicians present during catheter ablation procedures. Analyzing these results and comparing them with data from 2010 and 2015, there is still a relevant need to enhance the quality of EP physician training and for collaboration between centres to provide high-quality electrophysiological patient care. Because many centres do not fulfill requirements set by the EHRA and/or DGK, one can assume there is a scarcity of training opportunities for physicians aspiring a career in EP. However, a centre accreditation by neither institution reflects the capacity of a single operator and is only supposed to show which centre would have met certain requirements agreed upon by a committee of experienced electrophysiologists. Very recently, a survey of members of the "Young DGK" (median age 33 ± 3.3 years) regarding training opportunities for cardiology was published [18]. The majority wished more electrophysiological training opportunities with 50% of cardiological fellows reporting not to receive any EP training [18]. These results directly reflect to our survey with still more than a third (38%) of the responding centers reporting to have no EP fellows at all. This has remained almost unchanged throughout the last decade (2010: 34%; 2015: 33%). Thus, the present situation of German cardiac electrophysiology clearly illustrates (1) an increasing number of catheter ablations in the presence of (2) the necessity of more and better training opportunities.
In the presence of increasing ablation numbers with growing complexity and novel ablation technologies, a high degree of sub-specialization is needed to perform these ablations. It is therefore surprising that (1) only 11% of the centres have an independent EP department (with/without its own budget) and (2) the majority of EP consultants  Table 4 Curriculum heart rhythm specialists: Training centre requirements and reality (Germany 2020) Values are n or (n%). Requirements are defined according to guidelines and curricula as published (6-9) 3D 3-dimensional, DGK German Society of Cardiology, EHRA European Heart Rhythm Association a Under the requirement that always 2 physicians are present during an ablation only 31 centres (16%) would have fulfilled DGK requirements *According to a position paper by the DGK (8) 1 3 also performs PCI on a routine basis. This proportion even increased in comparison with data from 2015 (63 vs. 72%). One may speculate that these aspects as well as the abovementioned limited training opportunities require more dedicated independent EP centres in the future.
Despite an overall increase of female physicians in most cardiological specialties, only less than 10% choose a career in EP [19]. Addressing this disparity, a survey by Abdulsalam et al. determined factors influencing physicians in training and career planning. Of the responding participants having an interest in EP, the vast majority that ultimately chose to train as a heart rhythm specialist were men (84 vs. 16%). As potential reasons women reported, e.g. radiation concerns and a perceived "old boys' club" culture with discrimination/harassment concerns [20]. This issue is also addressed by a survey of Estner et al. [21] showing a large gap between male and female physicians in training (63 vs. 37%) as well as consultants (86 vs. 14%). This corresponds to results from our national survey showing that the proportion of female fellows as well as female EP consultants remain distinctly low with even a decrease in female EP fellows as compared to 2015 (38%; 2020: 33%) and an almost unchanged number of employed female EP consultants (2015: 17%; 2020: 19%). Addressing this issue and improving the training and work environment (e.g., working parttime for both genders, childcare support) will be pivotal to change this disparity in the future. Besides, implementing certain mentorship programs would be of great interest.
As it was seen in 2010 and 2015, PVI remains the most performed catheter ablation procedure even showing an increase in number compared to prior results (2010: 35%; 2015: 47%, 2020: 51%). Considering that during the COVID-19 pandemic more elective PVI were cancelled than urgent ablations such as VT ablations, the true number of scheduled PVI may have been even higher. Nevertheless, the trend of an un-proportional increase in PVI as compared to all other ablation procedures over the last decade is demonstrated by survey comparisons from 2010, over 2015 to 2020 (Fig. 5). In contrast to AF, the number of supraventricular tachycardia (SVT) and atrial flutter ablations remained relatively constant over the years with 22% (32%) and 20% (25%) in 2015 (2010) and 21 and 17% in 2020, respectively. Following the trend in AF ablations and the demography of western countries, one would not be surprised if the next decade will result in PVI accounting for 2/3 of all catheter ablations. Of note, no relevant change is seen regarding the proportion of RF versus cryo-ablations. Most ablations were performed with point-by-point RF ablation (2015: 63%; 2020: 64%) as compared to the cryo-balloon technology (2015: 33%; 2020: 34%). Besides, we could clearly show the less experienced a centre is the more the cryo-balloon is used (Fig. 3). This is in line with the observations of a relevant and increasing portion of centres not ablating consecutive left atrial arrhythmias after PVI compared to 2015 (19 vs. 23% in 2020) [11]. This also most probably reflects the lack of experienced electrophysiologists able to treat consecutive left-sided atrial arrhythmias and the increased use of the technically less demanding cryo-balloon-based ablation by less experienced centres [22]. The STAR AF II Trial [23] and a recent sub-study by Sanchez-Somonte et al. [24] showed that even patients with complete linear block and/or ablation of fractionated electrograms after PVI did not have a better outcome regarding recurring AF. This correlates to our analysis seeing most centres performing PVI only as their first treatment approach for patients with persistent AF as recommended by current guidelines.
As the number of EP procedures increases each year, our observational study is supposed to offer interesting insights into current electrophysiological training and treatment concepts and may help recognizing certain issues that need to be addressed in the future. Besides, further studies setting safety, efficacy, and overall treatment quality in relation to the amount of EP procedures performed per year per centre would give interesting insights and may offer perspectives regarding patient care and physician training.

Limitations
Certainly, as in the previous studies from 2010 and 2015, not all centres performing EP studies responded and as coding data are not continuously reliable probably not all centres were identified. Nevertheless, our study does include most centres as well as ablations (75%) performed in Germany in 2020 and gives the chance to observe trends over a decade of electrophysiological advances. As the responding centres account for most ablations performed in 2020, smaller clinics might not be well represented in this survey, leading to the possibility of a slight over-estimation of median number of ablations per centre. To prevent the over-estimation of small centres where fewer catheter ablations are performed, we excluded centres coding for less than 30 ablations per year. This again might over-estimate the percentage of possible training centres fulfilling all requirements by the DGK and EHRA. Data about complications and specific outcome would have been of interest (e.g., safety of certain procedures corresponding to the amount of performed procedures a year). But as this survey was devised to assess structural conditions in electrophysiological patient care and physician training, these data are not available.

Summary
The present multi-centre observational study demonstrates a distinct rise in the need for electrophysiological treatment with increasing numbers of EP centres and performed ablation procedures as compared to 2010 and 2015. Only about a quarter of the centres fulfilled requirements of the EHRA and DGK for EP training centres, respectively. Training positions for physicians in electrophysiology have not adapted to this rising demand and have remained constant over the years. Women are still only scarcely represented in the field of interventional electrophysiology. PVI with point-by-point radiofrequency current (RF) as the mainly used ablation strategy remains the most performed ablation.