A beta-blocker, not magnesium, is effective prophylaxis for atrial tachyarrhythmias after coronary artery bypass graft surgery.
OBJECTIVE
To evaluate magnesium as a sole or adjuvant agent with currently used prophylactic drugs in suppressing postoperative atrial tachyarrhythmias (POAT) after coronary artery bypass graft (CABG) surgery.


METHODS
Single-center prospective, randomized clinical trial.


METHODS
University hospital.


METHODS
Patients (n = 400) undergoing CABG surgery.


METHODS
Patients were randomized among 6 prophylaxis regimens: (1) control (no antiarrhythmics), (2) magnesium only, (3) digoxin only, (4) magnesium and digoxin, (5) propranolol only, and (6) magnesium and propranolol. Patients randomized to a regimen including magnesium received 12 g given during 96 hours postoperatively. Patients in a digoxin regimen received 1 mg after cardiopulmonary bypass and 0.25 mg daily. Patients in a propranolol regimen received 1 mg intravenously every 6 hours until able to take 10 mg orally 4 times a day. Prophylaxis regimens were discontinued after 4 days postoperatively.


RESULTS
The primary outcome was a sustained POAT or discharge from the hospital. Control patients had an incidence of POAT (38%) not significantly different from patients in magnesium-only (38%), digoxin-only (31%), and magnesium with digoxin (37%) regimens. Patients treated with propranolol had a significant reduction in POAT. Nearly identical POAT rates in the propranolol-only (18%) and propranolol with magnesium (19%) groups support the lack of efficacy of magnesium in this trial. Study design allowed analysis of and showed a beta-blocker withdrawal effect in addition to suppressive benefit of postoperative beta-blockers.


CONCLUSIONS
beta-Blocker prophylaxis is indicated to reduce the incidence of POAT in CABG surgery patients and to prevent a beta-blocker withdrawal effect in patients receiving these medications preoperatively. Digoxin and magnesium as sole or adjuvant agents do not offer suppressive or ventricular rate reduction benefits in POAT.
Bert
A A
AA
Department of Anesthesiology, Rhode Island Hospital and Brown Medical School, Providence, RI 02903, USA.
Reinert
S E
SE
Singh
A K
AK
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D002316:Cardiotonic Agents / Q000627:therapeutic use; D001026:Coronary Artery Bypass / Q000009:adverse effects*; D004077:Digoxin / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008274:Magnesium / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000517:prevention & control*; D011433:Propranolol / Q000627:therapeutic use*; D011446:Prospective Studies; D013617:Tachycardia, Supraventricular / Q000209:etiology / Q000517:prevention & control*
D000319:Adrenergic beta-Antagonists; D002316:Cardiotonic Agents; D004077:Digoxin; D011433:Propranolol; D008274:Magnesium