Moderate to severe aortic stenosis (AS) is one of the most prevalent valvular heart diseases in the elderly, reaching a prevalence of 2.8% in patients aged ≥75 years (1). AS is associated with high morbidity and mortality; the mean survival of patients with untreated severe AS is 2 years (2). According to current guidelines, therapy of AS comprises surgical or transcatheter aortic valve implantation (TAVI) (3). In recent years, a growing number of TAVI procedures have been performed globally and, according to current recommendations, the indication for TAVI has been extended to younger and low-risk patients (3, 4). This was associated with an increase in waiting times for elective AS outpatients (5). In many centers, the waiting time between the heart team's decision and intervention exceeds 1 month. In addition, the COVID-19 pandemic resulted in limited resources also affecting TAVI procedures (6). During this period, many patients with AS stayed untreated at home and were kept on a waiting list. TAVIs were performed according to symptoms and severity of AS versus available hospital resources (7). Albassam et al. observed a mortality of approximately 5% during a median waiting period of 84 days (8). In addition to reported mortality, untreated severe AS may exacerbate and lead to decompensated heart failure (9).

Telemedical interventional management (TIM) may reduce morbidity and mortality among patients with AS. TIM, including a wide range of devices, is well studied as an outpatient management of patients with heart failure (10–14). In the TIM-HF2 trial, the remote patient management (RPM) comprised non-invasive TIM, treatment of heart failure and comorbidities, close cooperation with primary care physicians, and patient education, and was used for a maximum follow-up period of 393 days (15). In this specific patient cohort, the RPM reduced days lost to unplanned cardiovascular hospitalizations and all-cause deaths compared to standard care (15).

Despite a lack of evidence, national cardiac societies recommended the establishment of TIM in valvular heart disease during the COVID-19 pandemic (7, 16). Comprehensive TIM may address the healthcare gap during the waiting period between the day of the heart team's decision to inpatient admission for TAVI in patients with AS in times of limited healthcare resources but also under normal conditions when waiting times are long due to increased demand. Therefore, we implemented telemedical approaches to identify AS patients at risk for clinical deterioration during the waiting time. The purpose of the ResKriVer-TAVI study is to investigate whether a digital concept of telemedical interventional management (TIM) in AS patients waiting for a TAVI improves the clinical outcome of these patients. Here, we report the study protocol of the ResKriVer-TAVI trial.

The ResKriVer-TAVI study (DRKS00027842) is a single-center, prospective, parallel-group randomized, controlled, superior, open-label trial started in 2022 at the Charité—Universitätsmedizin Berlin, Germany, and complies with the Declaration of Helsinki. The study is approved by the institutional ethics committee (EA1/017/22) and financially supported by the German Federal Ministry for Economic Affairs and Climate Action, Berlin, Germany.

We will enroll patients with AS recommended to undergo TAVI by our local heart team. AS will be defined and assessed according to the guidelines of the European Society of Cardiology (ESC) and the European Association for Cardio-Thoracic Surgery (EACTS) (3). Patients with an inability or unwillingness to measure daily vital signs (e.g., dementia, blindness, deafness, or wheelchair use) and patients enrolled in other interventional trials will be excluded from the study. Patients with AS will be screened for eligibility during their outpatient visit or hospital stay for AS assessment followed by a baseline visit after the patients have provided signed informed consent. Diagnostic work-up to grade AS and evaluate patients for TAVI or surgical approach will include medical history, laboratory measurements, echocardiography, electrocardiogram, coronary angiography, and computed tomography as a part of clinical routine. On the day of the heart team’s decision, patients will be randomized to TIM and standard care or standard care alone. Standard care will not include any additional support for patients with AS who are on the waiting list. Stratified randomization will be performed using an automatic randomization tool considering three covariates: male vs. female, age ≤80 years vs. age >80 years, and NYHA class ≤ II vs. NYHA class ≥ III. Data management will be completed in electronic case report forms.

The ResKriVer-TAVI study will be the first prospective, randomized, controlled trial to evaluate the impact of TIM on the outcome of AS patients undergoing TAVI in comparison to standard care. The main objective is to shorten the length of hospital stay to perform TAVI and to avoid hospitalization as well as mortality during the waiting period and after TAVI. A comprehensive TIM, including patient education, daily assessment of vital signs, and telemedical interventions, e.g., adjustment of medication or admission for early TAVI, will enable intensive outpatient care from the day of the heart team's decision until admission for TAVI. Patient education with a focus on AS and the involvement of family and caregivers allows self-reliant management. A strict modification of drug therapy is possible due to daily measurement of vital signs and, if necessary, telephone calls. The telehealth approach may reduce morbidity and mortality in case of limited healthcare resources but may also create optimal patient conditions prior to TAVI under normal circumstances. We assume that the effect of TIM in cardiovascular patients, which is established before TAVI, persists up to 6 months after the heart team's decisions. Thus, we hypothesize that days lost to cardiovascular hospitalization and all-cause mortality will be sustainably reduced by TIM compared to standard care up to 6 months after the heart team's decision (primary endpoint). In addition to hospitalization and mortality, we will also assess the quality of life, and expect patients in the TIM group to report fewer symptoms and greater well-being due to intensive outpatient care and trained self-reliant management. TIM interventions, including adjustment or prescription of medication, recommendation of hospital admissions, and patients’ adherence to TIM, will be reported as secondary endpoints. However, the telemedicine center comprises a team of four physicians and heart failure nurses with 8 working hours per day. Therefore, a requirement for the successful integration of TIM into daily clinical practice is the reimbursement by the healthcare system.

Few studies investigated TIM in AS patients undergoing TAVI. The studies focused mainly on the detection of conduction disturbances after TAVI and the need for pacemaker implantation (19, 20). In the prospective cohort study Redirect TAVI, continuous pocket electrocardiograms were used to detect conduction disturbances in 192 AS patients without pacemakers 14 days before and after TAVI (19). Another study used a wearable smartwatch-facilitated remote health management including assessment of heart rate, rhythm, oxygen saturation, and activity in 100 patients with AS 1 day before to 30 days after TAVI discharge (20). Both cohort studies detected relevant arrhythmias leading to pacemaker implantation in 4%–5% of patients post-TAVI; wearable smartwatch-facilitated management enabled additional telemedicine interventions such as a change in medical treatment in 5% of patients (19, 20). In contrast, we plan to use TIM in the waiting period before admission for TAVI compared with standard care. We expect to reduce days lost due to cardiovascular hospitalization and all-cause mortality before TAVI and according to the sustained effect of TIM until 180 days after the heart team's decision.

A potential limitation of the ResKriVer-TAVI study may be the variable and sometimes short period of TIM in patients with AS who are planned for TAVI.

In conclusion, the ResKriVer-TAVI study will be the first randomized trial to evaluate the efficiency of TIM in AS patients who are planned for TAVI. Results are awaited in 2025.