Targeted Potassium Levels for Prevention of ICD Therapy

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.

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

Ventricular Arrhythmias and Cardiac Arrest, Implantable Defibrillator User, Hypokalemia, Hyperkalemia, Ventricular Tachycardia, Atrial Fibrillation

ICD 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.

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

Time to first major event defined as a combination of: - first occurence of ECG documented ventricular tachycardia > 125 bpm lasting > 30 seconds - first occurence of any appropriate ICD therapy as documented by the ICD - 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.

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

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

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

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.

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

Inclusion Criteria: Implantable cardioverter defibrillator (ICD) or cardiac resynchronization pacemaker with ICD (CRT-D). Age >18 years Exclusion Criteria: Estimated glomerular filtration rate (eGFR) <30 ml/h Pregnancy Lack of ability to understand and sign informed consent