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Ventricular Arrhythmias and Cardiac ArrestPhase 4NCT03833089

Targeted Potassium Levels for Prevention of ICD Therapy

A Phase 4 study testing Targeted serum potassium level in people with Ventricular Arrhythmias and Cardiac Arrest and Implantable Defibrillator User, run by Copenhagen University Hospital, Rigshospitalet at 3 sites in Denmark.

Active, not recruiting

Under way, not looking for participants. Everyone needed has enrolled. The study is still running.

Official record
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Trial summary

This study evaluates whether a rigorously controlled high-normal level of serum-potassium (4.5-5.0 mEq/L) using dietary recommendations, potassium supplements and mineralocorticoid receptor antagonists will results in a lower incidence of cardiac arrhythmias in patients with an ICD. Read more about this study

Who is it for?
Ages 18 years and older
What is being tested?
Targeted serum potassium level
Could I receive a placebo?
No, everyone receives an active treatment
How many people
1,200 participants
Where
3 sitesDenmark
Study dates
1 Mar 2019to 1 Apr 2035
Phase
Phase 4
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 18 years and older
  • All sexes
  • No healthy volunteers
  • Adult, Older adult

Who may be able to join

  • Implantable cardioverter defibrillator (ICD) or cardiac resynchronization pacemaker with ICD (CRT-D).
  • Age >18 years

Who cannot join

  • Estimated glomerular filtration rate (eGFR) <30 ml/h
  • Pregnancy
  • Lack of ability to understand and sign informed consent

Trial locations and contacts

3 sites in 1 country.

Denmark3 sites

  • Rigshospitalet

    Copenhagen, 2100

  • Gentofte University Hospital

    Gentofte Municipality, Hellerup, 2900

  • Roskilde University Hospital

    Roskilde, Region Sjælland, 4000

Other trials in Denmark

About this study

Official title: Arrhythmia Prevention in High Risk Cardiovascular Patients Using Targeted Potassium Levels

This study evaluates whether a rigorously controlled high-normal level of serum-potassium (4.5-5.0 mEq/L) using dietary recommendations, potassium supplements and mineralocorticoid receptor antagonists will results in a lower incidence of cardiac arrhythmias in patients with an ICD. Patients will be randomized to this treatment or a control arm, where patients will receive usual guideline recommended follow-up.

Read the detailed description

There is solid evidence that potassium-sparing drugs increase survival and ameliorates symptoms in heart failure patients and post-hoc studies have suggested that high-normal levels of blood potassium levels (p-K) markedly decreases the risk of malignant arrhythmias in cardiovascular patients.

This trial will randomize patients implanted with implantable cardioverter defibrillators (ICDs), who remain at high risk of life-threatening cardiac arrhythmias, to a standard therapy or standard therapy plus a regimen to keep high-normal p-K levels. The study will enroll 1,000 patients from the outpatient pacemaker clinics at Rigshospitalet and Gentofte hospital. Using a planned regime to increase p-K using inexpensive drugs and potassium supplements, the patients enrolled and followed with regular controls as well as continuous monitoring using existing home monitoring systems over a period of 4 years for the primary endpoint of appropriate ICD therapy and all cause mortality. Including analysis, the trial will be running for 5 years

Being tested
Targeted serum potassium level
Medical subject headings
Heart Arrest, Hypokalemia, Hyperkalemia, Tachycardia, Ventricular, Atrial Fibrillation

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • Targeted serum potassium levelCombination product

    In the following order, following advices end prescriptions will be provided: 1) Potassium rich dietary advice, 2) Mineralocorticoid receptor antagonists, 3) Potassium supplementation,

Study groups in NCT03833089
Study groupRoleWhat they receive
ControlNo interventionICD recipients in optimal Medical treatment as per guidelines according to their comorbidity
Targeted serum potassium levelsExperimentalICD recipients recipients in optimal Medical treatment as per guidelines according to their comorbidity. In addition to guideline recommended treatment, this cohort will be treated to increase serum potassium levels to 4.5-5.0 mEq/L.
Receives: Combination Product: Targeted serum potassium level

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Time to first occurrence of ECG documented ventricular tachycardia, appropriate ICD therapy, hospitalization > 24 hours due to arrhythmias and/or heart failure leading to a change in treatment and all cause mortality

    A combination of:

    • ECG documented ventricular tachycardia > 125 bpm lasting > 30 seconds
    • Any appropriate ICD therapy as documented by the ICD or ECG
    • Any unplanned hospitalizations > 24 hours due to arrhythmias and/or heart failure leading to a change in treatment, e.g., administration of new drugs, or change in doses of already prescribed drugs or invasive or non-invasive treatment.
    • All-cause mortality

    The time period with regards to the Time-to-Event Outcome Measures starts with the randomization of the patient.

    ECG documented tachycardia from ECGs or ICD interrogations will be obtained from hospitalizations or outpatients clinic visits via electronic records after patient consent. Information of ventricular tachyarrhythmia therapy will be obtained from home monitoring systems or interrogation of the ICD devices during in-clinic visits.

    Mortality will be obtained from danish electronic hospital files or the danish death registry.

    Measured: Total 291 events, expected 6 years

Secondary outcomes (7)

  1. Time to first incidence of supraventricular arrhythmias as documented by ECG or the ICD

    Any supraventricular tahcycardia documented on ECG, telemetry or as monitored/treated event on the ICD

    Measured: 6 years

  2. Proportion of patients experiencing <92 % CRT-pacing for > 2 weeks (only CRT-D patients)

    CRT-D home monitoring systems allow temporal evaluation of percentage of CRT pacing.

    Measured: 6 years

  3. Time to first hospitalization for heart failure

    Hospitalization with symptoms of heart failure and with a diagnosis of heart failure where treatment with i.v. diuretics was initiated.

    Measured: 6 years

  4. Time to first hospitalization for cardiac arrhythmias

    Hospitalization were records indicate that supraventricular or ventricular arrhythmias were implicated in the cause of the hospitalization

    Measured: 6 years

  5. Time to hospitalization for electrolyte disturbances or kidney failure

    Hospitalization were records indicate that kidney failure or disturbances in the potassium or sodium plasma leves were implicated in the cause of the hospitalization

    Measured: 6 years

  6. First occurrence of appropriate ICD therapy for ventricular tachycardia or ventricular fibrillation irrespective of outcome.

    Ventricular tachy-arrhythmia therapy, which will be obtained from home monitoring systems or interrogation of the ICD devices during in-clinic visits. All ICD therapy is routinely adjudicated as appropriate or in-appropriate by electrophysiologists at the study sites.

    Measured: 6 years

  7. Time to first occurence of inappropriate ICD therapy

    Any cause of inappropriate shock including atrial fibrillation, other supraventricular arrhythmias, ICD lead problems etc.

    Measured: 6 years

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted6 Feb 2019
  2. Study start1 Mar 2019
  3. Primary completion9 May 2025 (estimated)
  4. Study completion1 Apr 2035 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 4
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
None (open label)
Enrolment
1,200 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT03833089
Sponsor's protocol ID
3589
Status last verified
May 2025
First submitted
1 Feb 2019
Last updated
9 May 2025
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
No
FDA-regulated device
No

Publications

  • Sakthivel T, Winslow UC, Zheng C, Danielsen EM, Bosselmann HS, Vinther M, Bruun NE, Bundgaard H, Jons C, Risum N. Effects of plasma potassium on myocardial function: a POTCAST substudy. J Cardiovasc Imaging. 2026 Apr 2;34(1):7. doi: 10.1186/s44348-026-00068-7.

    PubMed 41923135

  • Jons C, Zheng C, Winslow UCG, Danielsen EM, Sakthivel T, Frandsen EA, Saffi H, Vakilzadeh-Hashemi SS, Haugan KJ, Bruun NE, Iversen KK, Bosselmann HS, Risum N, Bundgaard H; POTCAST Study Group. Increasing the Potassium Level in Patients at High Risk for Ventricular Arrhythmias. N Engl J Med. 2025 Nov 20;393(20):1979-1989. doi: 10.1056/NEJMoa2509542. Epub 2025 Aug 29.

    PubMed 40879429

  • Winslow U, Sakthivel T, Zheng C, Bosselmann H, Haugan K, Bruun N, Larroude C, Iversen K, Saffi H, Frandsen E, Oturai P, Jensen HJ, Vinther M, Risum N, Bundgaard H, Jons C. Treatment-induced increase in total body potassium in patients at high risk of ventricular arrhythmias; a randomized POTCAST substudy. PLoS One. 2023 Jul 19;18(7):e0288756. doi: 10.1371/journal.pone.0288756. eCollection 2023.

    PubMed 37467227

Questions about this trial

What is this clinical trial studying?

A Phase 4 study testing Targeted serum potassium level in people with Ventricular Arrhythmias and Cardiac Arrest and Implantable Defibrillator User, run by Copenhagen University Hospital, Rigshospitalet at 3 sites in Denmark.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 2 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: under way, not looking for participants, as of the sponsor's last update on 9 May 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 3 sites in Denmark. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Time to first occurrence of ECG documented ventricular tachycardia, appropriate ICD therapy, hospitalization > 24 hours due to arrhythmias and/or heart failure leading to a change in treatment and all cause mortality (time frame: Total 291 events, expected 6 years). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT03833089, which also lists 3 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 9 May 2025.

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