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Sodium nitroprusside reduces AF after myocardial revascularization
30 July 2008
MedWire News: The incidence and duration of postoperative atrial fibrillation (AF) after myocardial revascularization was reduced significantly by perioperative sodium nitroprusside (SNP) infusion in a small, pilot study.
"Even though postoperative AF is often a short-lived, self-limiting complication, it is associated with significant morbidity," note Raif Cavolli (Umut Heart Hospital, Ankara, Turkey) and team.
The researchers conducted a prospective, randomized, placebo-controlled study in 100 consecutive patients undergoing elective coronary artery bypass graft (CABG) surgery.
Half the patients received the nitric oxide donor SNP as a continuous infusion at 0.5-1.0 µg/kg/min during the rewarming period, the dose being titrated to maintain mean arterial pressure around 65 mmHg. The other half of patients received a placebo infusion of 5% dextrose in water during rewarming.
The authors report in the journal Circulation that patient characteristics at baseline were similar between treatment groups.
During 5 days of follow-up, 6 (12%) of patients who received SNP developed AF compared with 18 (36%) of those who received the placebo treatment (p=0.005).
Among those who developed AF, the duration of AF was significantly shorter among those in the SNP than placebo group, at an average of 5.33 versus 7.55 hours (p=0.023).
In an accompanying editorial, Gregory Marcus and Jeffrey Olgin (both from the University of California, San Francisco, USA) highlighted several drawbacks to the study, including its small size and that history of AF in particular was not considered among the baseline clinical characteristics.
Also, the mean blood pressure during rewarming did not differ between treatment groups, suggesting that other cardiovascular drugs were administered differentially between them, and significantly fewer patients in the SNP group required intraoperative defibrillations, which could mean that, purely by chance, this group had "healthier hearts" less prone to arrhythmias.
Nevertheless the editorialists pointed out that SNP is relatively inexpensive and easy to administer and that the approach also may offer new clues as to the mechanisms underlying AF after cardiac surgery.
They concluded: "This initial investigation should motivate larger studies that can validate the primary findings while providing comprehensive data collection to answer several lingering questions."
