Cardiac Resynchronisation Therapy (CRT) Survey II: CRT implantation in Europe and in Switzerland

DOI: https://doi.org/10.4414/smw.2018.14643

Introduction

The benefits of cardiac resynchronisation therapy (CRT) on long-term clinical outcomes in symptomatic heart failure patients (New York Heart Association [NYHA] class II–IV) with reduced left ventricular (LV) ejection fraction (EF) and electrical dyssynchrony have been repeatedly proven in randomised controlled trials (RCTs) [1–3]. Surveys and registries supplement RCTs by providing important data on daily clinical practice [1, 3]. These data complement results from RCTs, which tend to exclude high-risk patients [3–5]. The European Cardiac Resynchronisation Therapy (CRT) Survey was conducted in 2008, as a joint project by the Heart Failure Association (HFA) and the European Heart Rhythm Association (EHRA) of the European Society of Cardiology (ESC) [6]. This 6-month snapshot survey included data from 2438 CRT recipients in 13 ESC member countries. At the time, it showed underutilisation of resynchronisation therapy and indicated that large numbers of CRT-pacemaker (CRT-P) or -defibrillator (CRT-D) devices were implanted outside the guideline recommendations [6]. The design of the European CRT Survey II was based on the first CRT Survey [7]. The CRT II survey included 42 ESC member countries and its aim was to gather real-life clinical and demographic data on current patient selection, and implantation and follow-up practice [8]. Ultimately, it provides information relevant for assessing healthcare resource utilisation and the adherence to latest guidelines on CRT implantation [7, 8]. We compared the Swiss CRT utilisation with that in the overall European population.

Materials and methods

The rationale and design of the CRT Survey II have been published earlier [7]. All consecutive patients planned for CRT-P/CRT-D device implantation, de-novo or upgrade, in a 15-month period (October 2015 to December 2016), were included regardless of the success of the procedure. Data were collected prospectively using an online database. A central database was created and maintained at the data management centre at the Institut für Herzinfarktforschung in Ludwigshafen at the Heidelberg University, Germany. The data management centre also performed the analyses.

The European CRT Survey II included two internet-based questionnaires [7]. The first was a one-time questionnaire completed by participating centres and characterised the facility, its catchment area, invasive procedures and device implantations performed, cardiac facilities, types of imaging equipment employed, number and speciality of implanting physicians and the follow-up options provided, as well as the type and source of hospital reimbursement. The second questionnaire was an electronic case report form (eCRF) for each patient, which collected demographic, medical history and clinical data as well as procedural and postprocedural details. Importantly, data from unsuccessful CRT implantations were also included.

Ethics approval from the relevant Ethics Committee in Switzerland was obtained. The study protocol complied with the Declaration of Helsinki and Good Clinical Practice.

Statistical analysis

Continuous variables are presented as median with interquartile range or mean with standard deviation, as appropriate. Categorical variables are presented in absolute values and percentages. Continuous variables were compared with nonparametric Mann-Whitney U-tests and categorical variables were compared with Pearson χ² tests. Descriptive statistics were calculated for the available cases. All p-values are the results of two-tailed tests and a value of <0.05 was considered significant. Statistical analysis was carried out using SAS statistical software, version 9.1 (Cary, North Carolina, USA).

Results

Participating centres

Seven out of 36 CRT-implanting centres in Switzerland participated in the CRT II survey (Universitätsspital Basel, Hôpitaux Universitaires de Genève, Universitätsspital Zurich, Cardiocentro Lugano, Kantonsspital St. Gallen, Stadtspital Triemli Zurich and Clinique Cecil Lausanne) [9]. During the 15-month enrolment period (October 2015 to December 2016), out of 11,088 patients recruited by 288 centres in 42 ESC member countries participating in the CRT II Survey, 320 patients (2.9%) were recruited in Switzerland (table 1). This was 38% of all CRT implantations in Switzerland during this period (n = 838), according to data from the national device registry [9].

Baseline characteristics and procedural

The patient demographics are shown in table 2, procedural data in table 3, and postprocedural data in table 4, together with comparisons between the Swiss and European populations. There were no procedural deaths or bleeding complications. One Swiss patient died during hospitalisation from progressive heart failure.

Differences between Swiss and European CRT recipients

Compared with European CRT recipients, Swiss patients were older (71 vs 68.5 years, p <0.001), with a significantly higher proportion of patients older than 75 years (42 vs 32%, p <0.001). In both groups women were underrepresented (24 vs 24%, p = 0.975). Swiss patients significantly less often had the classical indication of heart failure with a wide QRS complex (40 vs 61%; odds ratio [OR] 0.44, 95% confidence interval [CI] 0.35–0.55; p <0.0001), less often presented with complete left bundle-branch block (68 vs 75%; OR 0.7, 95% CI 0.55–0.89) and consequently displayed a shorter mean duration of the QRS complex (152 ± 29 vs 157 ± 27 ms, p <0.01). Conversely, they significantly more often had underlying second or third degree atrioventricular block (27 vs 19%, OR 1.6, 95% CI 1.24–2.06) with CRT employed for expected dyssynchrony induced by a high amount of right ventricular pacing.

Although there was no overall difference in the NYHA status, more Swiss patients were in NYHA functional class I (6 vs 3%; OR 1.73, 95% CI 1.07–2.82) and they were significantly less often hospitalised for heart failure the year before implantation (32 vs 47%; OR 0.54, 95% CI 0.42–0.68), although they had significantly higher levels of preprocedural brain natriuretic peptide (BNP) (1422 vs 1104 pg/ml, p = 0.012). Swiss patients had a higher prevalence of chronic kidney disease (OR 1.58, 95% CI 1.26–1.98; p <0.001) and previously implanted devices (OR 1.28, 95% CI 1.01–1.62; p = 0.043).

In Switzerland, CRT-D systems were more often implanted than CRT-P systems (63 vs 37%). Compared with the European population, however, Swiss patients received fewer CRT-D devices (63 vs 70%, p = 0.007). This may be explained by the older age of the patients and the fact that the procedure was done significantly more often by an electrophysiologist (OR 2.84, 95% CI 1.95–4.12; p <0.001). In Switzerland, the quadripolar left ventricular lead was used more often (OR 1.67, 95% CI 1.32–2.13; p <0.001), reflecting unhindered access to modern technology.

The overall complication rate was 4% and not different from the European average. Postprocedural QRS duration was not different nor was the incidence of major adverse events. Total length of hospital stay was lower in Swiss hospitals (5.5 vs 6.3 days, p <0.001). There was a statistically significant difference between the groups regarding the discharge medication therapy, programming of the device and follow-up planning.

Discussion

The most important findings in this registry study comparing Swiss CRT recipients with their European counterparts is that Swiss patients were older, had fewer heart failure hospitalisations in the year before implantation and significantly less often had the “classical” CRT indication of symptomatic heart failure in the presence of a wide left bundle-branch block. Although the reimbursement system in Switzerland allows for easy access to all available technologies, significantly fewer Swiss patients received the more expensive CRT defibrillator (CRT-D) system than in the rest of Europe. Nonetheless, CRT-D systems still account for two thirds of all CRT implants in Switzerland.

The higher prevalence of CRT pacemaker (CRT-P) systems may in part be explained by the fact that Swiss patients were older and that more procedures were done by electrophysiologists with potentially more detailed knowledge of current risk stratification for sudden cardiac death [10–13]. On the other hand, it may also reflect a different attitude of the patient population to the mode of death. Swiss patients were less often hospitalised for heart failure before CRT implantation, although they had higher levels of preprocedural BNP. Better access to ambulatory healthcare services than in other countries may be the reason for that.

After the type of CRT system was chosen, Swiss patients received the latest technology with a higher proportion of quadripolar left ventricular leads than the European population. Furthermore, although our population had the same overall incidence of comorbidities, they had a higher prevalence of chronic kidney disease, a risk factor repeatedly identified as hampering the effectiveness of implantable cardioverter-defibrillator (ICD) therapy and which is not improved by CRT [14, 15]. As in other CRT and ICD trials and registries, only 25% of the recipients were women, reflecting the fact that women are undertreated in the field of cardiovascular diseases [1, 8, 16–18].

The “classical” class I indication of symptomatic heart failure and a wide left bundle-branch block was less often the indication for implantation in Switzerland. Relatively more patients received an upgrade or a de-novo CRT system because they had the indication for pacing with or without defibrillation therapy, with an expected or actual high percentage of ventricular pacing (e.g., in the presence of atrioventricular block II or III). Consequently, the Swiss group had a greater share of patients with preprocedural QRS duration <120 ms and NYHA class I. However, most patients had symptomatic heart failure as an indication for CRT implantation, displayed a left bundle-branch block morphology on the 12-lead ECG, had a LVEF <35% and very high mean NT-pro BNP, which also means high adherence to guideline recommendations by physicians [19].

Electrocardiographically, the average QRS duration decreased significantly with biventricular pacing, which is expected and a predictor of good clinical response [1–3]. The reported perioperative complication rates were low, which is in line with the fact that most of the participating Swiss centres are high-volume centres [9, 16, 17]. The Swiss group had no relevant bleeding complications, despite the fact that almost 80% of patients took either oral anticoagulation, antiplatelet therapy, or even both. This could be explained by high adherence to new recommendations on antithrombotic dual and triple therapy, as well as by the experience of the recruiting centres [19–22].

In conclusion, when compared with other European countries, Swiss CRT recipients were older, less symptomatic, received more device upgrades, had a higher incidence of chronic kidney disease and more frequently received quadripolar left ventricular leads. At the same time, the percentage of CRT-D implantations was lower than in the overall European population. Our data indicate that, despite almost free access to modern technology, Swiss patients and physicians more often use the less expensive CRT-pacemaker system with the primary goal of symptomatic relieve from heart failure when compared with their European counterparts. The data from Swiss patients participating in the European CRT Survey II provide important information for physicians, patients and health economists and demonstrate significant differences between Swiss and European patients in some aspects of the application of CRT.

Acknowledgments

The authors wish to thank Beat Schaer, MD, Carine Stettler, RN, Rainer Zbinden, MD, for their continued support in enrolling patients.

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