Routine Magnesium Testing and Supplementation in Acute Heart Failure (MAG-HF)

Acute heart failure (AHF) is a common cause of hospitalization and is associated with high rates of morbidity and rehospitalization. Magnesium abnormalities are frequently observed in hospitalized patients, and intravenous magnesium supplementation is commonly used in clinical practice despite limited evidence supporting routine testing and replacement strategies in this population. Variation in practice patterns exists, and the clinical impact of routine magnesium testing and supplementation in AHF remains uncertain.

The MAG-HF trial is an investigator-initiated, pragmatic, randomized controlled feasibility trial designed to evaluate the feasibility of conducting a definitive multi-centre trial comparing two strategies for magnesium management in adults hospitalized with AHF. Participants will be randomized to either a strategy of no routine magnesium testing or intravenous (IV) supplementation, or to a strategy of routine magnesium testing with IV supplementation according to standard of care. The study is conducted within the HEART platform, which provides a shared infrastructure to evaluate multiple interventions in heart failure.

The primary objective is to assess feasibility, including recruitment rates, consent rates, intervention adherence, and completeness of follow-up over 30 days. The study will enroll 260 participants across two centres over approximately 24 months.

In addition to feasibility outcomes, the trial will evaluate clinical event rates to inform the design of a future definitive study. Clinical outcomes assessed within 30 days of randomization will include all-cause death, all-cause hospital readmission, and heart failure readmission, capturing events both during the index hospitalization and after discharge. In-hospital outcomes during the index admission will include clinically significant arrhythmias, symptomatic hypotension, serious adverse events, intensive care unit admission, and length of hospital stay. Health-related quality of life will be assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ) at protocol-defined timepoints.

This feasibility trial is not powered to assess treatment effectiveness. Instead, the results will be used to inform the design, sample size, and operational considerations of a future definitive randomized controlled trial evaluating magnesium management strategies in AHF.

Participants assigned to a strategy of no routine magnesium testing and no routine intravenous magnesium supplementation during the index hospitalization

Other: No Routine Magnesium Testing or Supplementation

Participants assigned to a strategy of routine magnesium testing with intravenous magnesium supplementation administered according to standard of care.

Other: Routine Magnesium Testing and Supplementation

A strategy in which no routine serum magnesium testing is performed and no routine intravenous magnesium supplementation is administered during the index hospitalization.

A strategy in which serum magnesium is measured and intravenous magnesium supplementation is administered according to standard of care during the index hospitalization.

Plazo: Up to 30 days

Feasibility will be assessed by recruitment rate, consent rate, intervention fidelity, and completeness of follow-up and outcome ascertainment at 30 days.

Plazo: Up to 24 months (recruitment period)

Number of participants enrolled per site per month.

Plazo: Up to 30 days

Proportion of eligible patients who provide consent.

Plazo: During index hospitalization

Adherence to assigned strategy and separation between randomized groups.

Plazo: Up to 30 days

Proportion of participants with complete follow-up and outcome ascertainment.

Plazo: Up to 30 days

All-cause death following randomization.

Plazo: Up to 30 days

Hospital readmission for any cause following discharge from the index hospitalization.

Plazo: Up to 30 days

Hospital readmission due to heart failure following discharge from the index hospitalization.

Plazo: Up to 30 days

Incident new or worsened clinically significant supraventricular or ventricular arrhythmia during the index hospitalization.

Plazo: During index hospitalization

Occurrence of symptomatic hypotension during the index hospitalization.

Plazo: Up to 30 days

Serious adverse events occurring during the index hospitalization.

Plazo: Up to 30 days

Admission to the intensive care unit during the index hospitalization.

Plazo: Up to 30 days

Duration of the index hospitalization in days.

Plazo: Up to 30 days

Change in Kansas City Cardiomyopathy Questionnaire (KCCQ) Total Symptom Score from baseline to Day 5 comparing treatment groups. The Kansas City Cardiomyopathy Questionnaire Total Symptom Score (KCCQ-TSS) ranges from 0 to 100, where higher scores indicate fewer heart failure symptoms and better health status, and lower scores indicate more severe symptoms and worse health status.

Routine Magnesium Testing and Supplementation in Acute Heart Failure (MAG-HF): a Pragmatic Randomized Controlled Trial