Comment on “The Effect of Continuous Magnesium Infusion to Prevent Postoperative Atrial Fibrillation in Patients Undergoing OffPump Coronary Artery Bypass Grafting”

Dear Editor, We read with great interest the recent article by George et al. titled “The Effect of Continuous Magnesium Infusion to Prevent Postoperative Atrial Fibrillation in Patients Undergoing OffPump Coronary Artery Bypass Grafting”, recently published in the Annals of Cardiac Anaesthesia.1 We appreciate the authors for their praiseworthy attempt to explore the efficacy and effectiveness of magnesium infusion to prevent the incidence of postoperative atrial fibrillation (POAF) in patients undergoing off-pump coronary artery bypass grafting (OP-CABG). Nevertheless, we would like to highlight a few limitations that, if addressed, can increase the robustness of the study and guide future research. A notable limitation of this study lies in the ambiguous use of the term “continuous infusion” with regard to magnesium infusion. While the authors report magnesium administration as continuous, their protocol required discontinuing the magnesium infusion anytime serum levels surpass 2 mmol/L and resuming it once levels fell below this target. This technique represents an intermittent titration infusion rather than a true continuous infusion. Clarification of the pause criteria, infusion rate, and the duration of interruption can provide a clear interpretation. By labeling it continuous, the study creates obscurity regarding the dosing regimen, which may misdirect clinicians from replicating the protocol and could obscure differences in pharmacodynamic strength between continuous and periodic administration.2 Another substantial weakness is the absence of standardization in analgesia and block methods. The anesthetic plan allowed the use of some different facial plane blocks (parasternal, serratus anterior, erector spinae) based on the anesthesiologist’s discretion for ethical reasons to ensure adequate pain control. However, there is no description of any standardized method to assess pain or an analgesic protocol. It is difficult to establish whether variations in analgesia have affected POAF incidence without describing how pain relief was managed or evaluated, as these procedures differ in their potency for pain control and modulation of sympathetic activity, both of which directly affect arrhythmia risk.3 Moreover, the results showed that the patients who received the magnesium batch had a higher VIS max, meaning they needed more medications to support blood pressure and heart function. The authors soft-pedaled this finding, stating that the median amount of those medicines was similar in both groups. However, although the difference is statistically insignificant, it can still be clinically important. In a high-risk post-CABG population, even small increases in vasoactive necessities can be clinically significant. A better interpretation of this finding can help describe whether the effect was compensatory, incidental, or pharmacologically linked to magnesium administration.4 Finally, the primary issue in the study is its unblinded design, as acknowledged by the authors themselves. This introduces observer and performance bias. Future studies can be improved by using a blinded study design to minimize bias and strengthen the validity of the findings. Authors contribution MBK: Conceptualization and manuscript writing and editing. DR: Conceptualization and manuscript writing. Financial support and sponsorship Nil. Conflict of interest No conflict of interest.