MPAACS: Magnesium for the Prevention of Atrial Arrhythmias After Cardiac Surgery

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

TERMINATED

Clinical Phase

PHASE3

Total Enrollment

927 participants

Study Classification

INTERVENTIONAL

Study Start Date

2004-07-31

Study Completion Date

2009-02-28

Brief Summary

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The objective of our research is to determine whether treatment with magnesium will reduce the incidence of atrial fibrillation in patients undergoing cardiac surgery. Several small studies of magnesium have already been conducted, but these studies were small and the results conflicting. A large, well-conducted study of magnesium treatment is required to definitively determine whether magnesium is effective in preventing this common complication after surgery. In addition, our study will include patients undergoing valvular surgery, a group previously excluded from research despite the fact that they are at increased risk of atrial fibrillation.

Detailed Description

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All patients referred for non-emergent cardiac surgery for isolated CABG, isolated valvular heart surgery, or combined valvular and CABG surgery are eligible for the study. Subjects will be randomized prior to surgery (1:1) to receive 5 g magnesium or placebo (saline) bolus by the anaesthesiologist upon removal of the crossclamp. On postoperative days 1 through 4, subjects will receive either IV MgSO4 (5g in 250 ml normal saline) or IV placebo (250 ml normal saline) infusion over 4 hours daily. Atrial fibrillation (and other arrhythmias) will be detected by placing all subjects on continuous 24-hour ECG telemetry monitoring for postoperative days 0 through 4.

The study is powered to detect at least a 30% relative reduction in postoperative atrial fibrillation in the CABG group; n=756. Because of the higher incidence of atrial fibrillation in the Valve +/- CABG group a total of 500 patients will be required to detect at least a 30% difference between treatment groups. These sample sizes are based on an alpha of 0.05 and 80% power.

Conditions

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Coronary Artery Disease Valvular Heart Disease

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

TREATMENT

Blinding Strategy

TRIPLE

Participants Investigators Outcome Assessors

Interventions

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intravenous magnesium

Subjects will be randomized prior to surgery (1:1) to receive 5 g magnesium or placebo (saline) bolus by the anaesthesiologist upon removal of the crossclamp. On postoperative days 1 through 4, subjects will receive either IV MgSO4 (5g in 250 ml normal saline) or IV placebo (250 ml normal saline) infusion over 4 hours daily.

Intervention Type DRUG

Eligibility Criteria

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Inclusion Criteria

* patient undergoing coronary artery bypass surgery with or without valve procedure
* scheduled for on-pump or cardiopulmonary bypass protocol

Exclusion Criteria

* existing atrial fibrillation/flutter in the past year or on antiarrhythmic medications
* ventricular fibrillation
* sustained ventricular tachycardia
* 2nd or 3rd degree heart block
* paroxysmal supraventricular tachycardia
* major aortic repair planned during open-heart procedure
* permanent atrial/ventricular pacemaker implanted
* dialysis dependent or creatinine clearance \< 35 umoles/min or oliguric/anuric renal failure
* patient intolerant of beta blockers
* patient has reactive airways disease dependent on regular beta-adrenergic agents
* patient is scheduled to undergo off-pump surgical protocol

Minimum Eligible Age

20 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Responsible Party

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University of British Columbia

Principal Investigators

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Karin H Humphries, DSc

Role: PRINCIPAL_INVESTIGATOR

University of British Columbia/St. Paul's Hospital

Hubert Wong, PhD

Role: STUDY_CHAIR

University of British Columbia, Department of Health Care & Epidemiology

Locations

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Vancouver General Hospital

Vancouver, British Columbia, Canada

Site Status

St. Paul's Hospital