Comparison of the Effect of Spinal Anesthesia Applied in Elective Cesarean Cases on Frontal QRS Angle in Anemic and Non-Anemic Patients

<b>Background/Objectives</b>: Pregnancy is associated with profound physiological alterations that, together with anemia and spinal anesthesia, may influence myocardial repolarization. The frontal QRS-T [f(QRS-T)] angle has emerged as a reliable electrocardiographic parameter for evaluating repolarization heterogeneity. <b>Materials and Methods</b>: This observational prospective study included 100 term pregnant women [18-45 years, American Society of Anaesthesiologists (ASA) II] undergoing elective cesarean delivery under spinal anesthesia at Sanliurfa Training and Research Hospital between May and August 2025. Participants were divided into two groups: anemic (Hb < 10.5 g/dL, <i>n</i> = 50) and non-anemic (Hb ≥ 10.5 g/dL, <i>n</i> = 50). Standard monitoring and 12-lead ECGs were performed preoperatively and postoperatively. The f(QRS-T) angle was calculated as the absolute difference between QRS and T axes; values > 180° were adjusted by subtracting from 360°. <b>Results</b>: Demographic variables were comparable between groups. No significant differences were observed in mean arterial pressure or heart rate. Preoperative QTc and f(QRS-T) angle values did not differ significantly. However, postoperative QTc was prolonged in the anemic group compared with non-anemic women (426.3 ± 19.2 ms vs. 417.2 ± 20.7 ms, <i>p</i> = 0.026). Likewise, the postoperative f(QRS-T) angle was significantly higher in anemic patients (29.5 [16.0-45.3] vs. 20.5 [9.8-34.5], <i>p</i> = 0.017). Within-group analysis revealed significant postoperative increases in both QTc (<i>p</i> < 0.001) and f(QRS-T) angle (<i>p</i> < 0.001) in the anemic group, but not in controls. Hemoglobin levels correlated negatively with postoperative QTc (r = -0.267, <i>p</i> = 0.008) and f(QRS-T) angle (r = -0.264, <i>p</i> = 0.008). <b>Conclusions</b>: In anemic patients undergoing cesarean delivery under spinal anesthesia, the postoperative QTc interval and f(QRS-T) angle increased significantly compared with both baseline values and non-anemic counterparts. Assessment of the f(QRS-T) angle, a simple and inexpensive ECG-derived parameter, may aid in perioperative risk stratification and enhance patient safety.