A Phase 4 interventional study of Experimental intervention and Control Intervention in Atrial Fibrillation (AF), sponsored by University Hospital, Basel, Switzerland. Not yet recruiting at 1 site in Switzerland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by University Hospital, Basel, Switzerland · Phase 4, Interventional, and Treatment
Beta-blockers are generally prescribed for the treatment of atrial fibrillation. Their purpose is to slow the heart rate and thereby reduce the workload on the heart. However, beta-blockers can affect patients' quality of life, for example by reducing physical performance or causing fatigue in daily life.
In this study, we aim to determine whether calcium channel blockers can improve the treatment of atrial fibrillation and have a positive impact on the quality of life of patients with atrial fibrillation compared with beta-blockers. We will also investigate how calcium channel blockers affect the physical exercise capacity. In addition, we will monitor potential side effects of both medications and explore whether there are any differences between women and men over the course of the study.
Both study medications, the calcium channel blocker diltiazem and the beta-blocker bisoprolol, are approved by authorities and are recommended by the European Society of Cardiology for rate control in atrial fibrillation.
Atrial fibrillation (AF) is the most prevalent cardiac arrhythmia. Many AF patients present with a rapid ventricular response resulting in a high heart rate (HR). In these patients, it is important to lower the HR. To achieve rate control, several pharmacological agents are available, but beta-blockers (BB) are predominantly used. There is little evidence supporting the preference for BB. Side effects of BB such as fatigue, dizziness, and effort intolerance are widely known. Non-dihydropyridine calcium channel blockers (NDCC) represent an alternative for rate control and might be associated with better quality of life (QoL) than BB in AF patients. This study aims to investigate the impact on the QoL of AF patients who are currently on BB therapy and are switching to NDCC. Both men and women affected by AF and its complications will be enrolled in the study.
If this study can show an advantage of NDCC over BB in AF patients, a paradigm shift in the treatment of AF could take place. This could mean an easily implementable potential therapeutic advantage at no supplementary cost for patients and the health care system. Given the very common use of BB in AF patients, the negative impact of this drug on QoL could affect thousands of patients.
The investigational medicinal product (IMP) is diltiazem, a NDCC. Diltiazem belongs to the benzothiazepine class and exerts its pharmacological effect through inhibition of L-type calcium channels in atrioventricular nodal tissue, resulting in negative dromotropic effects and effective ventricular rate control in AF. Diltiazem is approved by the authorities and recommended by current guidelines as an alternative to BB for rate control in AF.
In the present study, diltiazem is administered orally in a prolonged-release formulation at daily doses of 90 mg, 180 mg, or 360 mg, corresponding to low, normal, or high dose categories. The comparator is bisoprolol, a β1-selective beta-adrenergic receptor blocker. BB are the most frequently prescribed agents for rate control in AF and represent the current standard of care. Bisoprolol is administered orally at daily doses of 2.5 mg, 5 mg, or 10 mg, reflecting standard clinical practice.
Patient representatives have been involved in developing our research from the beginning. Their insights have guided our approach to ensure the study addresses real concerns faced by patients affected by AF.
4,009 studies on the registry are indexed under Atrial Fibrillation; 961 are open to participants now.
This study's planned enrollment of 266 is above the median of 150 across 2,476 interventional studies indexed under Atrial Fibrillation.
Browse Atrial Fibrillation studies →University Hospital, Basel, Switzerland is the lead sponsor of 990 studies on the registry; 189 are open to participants now.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Both women and men will be enrolled, and sex-specific differences in treatment effects will be examined in a subgroup analysis. No vulnerable populations will be included. All participants are capable of judgment.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
LVEF (left ventricular ejection fraction)
The share of blood the heart’s main pumping chamber (the left ventricle) pushes out with each beat, measured by an echocardiogram (heart ultrasound) or a MUGA scan. About 50–70% is normal.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ECG (electrocardiogram)
A recording of the heart’s electrical activity, taken with stickers on the chest, arms and legs. It takes a few minutes and does not hurt.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
133 patients are randomized to the experimental intervention and treated with the non-dihydropyridine calcium channel blocker (NDCC) Diltiazem.
Drug: Experimental intervention
133 patients are randomized to the control arm and treated with the beta-blocker Bisoprolol.
Drug: Control Intervention
Study participants randomized in the experimental intervention group will receive Non-dihydropyridine calcium channel blockers (NDCC) Diltiazem retard for 90 days. Depending on the dosage of the beta-blocker treatment of these patients at baseline, three different dosage options will be used (low, normal, high). Diltiazem capsules of 90mg will be provided, meaning that patients with the low dosage will take one capsule a day (morning), patients with the normal dosage two capsules a day (morning and evening) and patients with the high dosage four capsules a day (2x morning and 2x evening). Based on previous data, we assume that most patients will use the low or normal dosage. The medication Diltiazem 90mg will be over-encapsulated, packed and labelled by a pharmacy specialist.
Study patients will receive the beta-blocker (BB) Bisoprolol for 90 days. Depending on the dosage of the BB treatment of these patients at baseline, three different dosage options will be used (low, normal high). Low dosage of Bisoprolol is corresponding to 2.5mg, normal dosage to 5mg and high dosage to 10mg/day. Bisoprolol capsules of 2.5mg will be provided, meaning that patients with the low dosage will take one capsule a day (morning), patients with the normal dosage two capsules a day (morning and evening) and patients with the high dosage four capsules (2x morning and 2x evening). The medication Bisoprolol will be over-encapsulated, packed and labelled by a pharmacy specialist.
Atrial-Fibrillation-related Quality of Life
Change in Atrial-Fibrillation-related Quality of Life between Non-dihydropyridine calcium channel blockers (NDCC) versus continuation of beta-blockers (BB) from baseline to 3 months in patients with Atrial-Fibrillation. The primary outcome uses the AFEQT questionnaire: The AFEQT 20-item questionnaire is a validated, AF-specific QoL tool. It assesses 4 domains: symptoms, daily activities, treatment concerns, and treatment satisfaction. The overall AFEQT score is calculated using the first 3 domains and ranges from 0 = worst to 100 = best QoL. Additionally, for each domain of interest, there is a corresponding subscale score: symptoms, daily activities, treatment concerns, and treatment satisfaction subscale scores. Each subscale ranges from 0 = worst to 100 = best QoL and is scored separately. The AFEQT questionnaire will be done at baseline before the intake of the first study drug and after three months of intervention.
Time frame: From baseline to 3 months
NT-proBNP
Change in NT-proBNP levels measured at baseline and after 3 months. NT-proBNP is released into the circulation in response to myocardial cell stretch. This biomarker is commonly used to evaluate the degree of heart failure in cardiac patients. Non-fasting blood samples will be taken at baseline before randomization and at the final study visit (4.7ml each). NT-proBNP levels will be measured in the laboratory of the respective study site by using an electrochemiluminescence immunoassay (Elecsys, Roche Diagnostics, Switzerland). Furthermore, if patients provide consent, additional blood samples (serum, plasma and whole blood) will be taken, processed, frozen and stored at -80°C, according to the ethical guidelines concerning biobanking, at the Cardiovascular Research Institute Basel. These samples will be used for future genetic analyses and for the assessment of emerging biomarkers of interest in this context.
Time frame: At Baseline and after 3 Months
6-minute walking test (6MWT) distance
Change in 6MWT distance assessed at baseline and after 3 months The 6MWT is a simple test which does not require expensive equipment or advanced training for technicians. The test involves asking the patient to walk the longest distance possible in a set interval of 6 minutes, through a walking course (corridor) preferably 30 meters long. The result of the 6MWT will be entered in the CRF as the distance in meters. In this context, other variables will be assessed, including the Borg Scale after the test and information on whether the test was done with a walking aid or must be terminated earlier. The 6MWT will be done at baseline before randomization and after 3 months of intervention.
Time frame: At baseline and after 3 months
Peak flow measurement
Change in peak flow measured at baseline and at the study end visit after 90 days of study intervention. The patient will perform the test in a standing position. Study personnel will instruct the patient to inhale as deeply as possible and then exhale as forcefully and rapidly as they can. The measurement will be repeated three times, and the results of all three attempts will be recorded in the study database.
Time frame: At baseline and after 3 months
Hierarchical composite endpoint comprising
A hierarchical win ratio will be calculated comparing participants between treatment groups using the following pre-specified hierarchy (in order of priority), all assessed as change from baseline to 3 months: * AF-related QoL * 6MWT distance * NT-proBNP
Time frame: Baseline to 3 months
Start is estimated for Nov 2026; primary completion for Oct 2029, 35 months later.
Of 129 non-industry phase 4 interventional studies under Atrial Fibrillation, half reached primary completion within 53 months of starting (the median), counting those still running; a quarter within 28 and three quarters within 81. This study's planned 35 months is below that.
Counting every sponsor, half of 141 studies reached it within 48 months; a quarter within 27 and three quarters within 81.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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University Hospital, Basel, Switzerland →