Is there a relationship between spinal anesthesia-related cardiovascular events and the preoperative Tp-e/QT ratio?

Aim: A high Tp-e/QT ratio on electrocardiography is associated with adverse cardiovascular events. A prolonged QT interval is associated with mortality, while a prolonged Tp-e interval is associated with serious arrhythmias. The most significant undesirable events related to spinal anesthesia are bradycardia and hypotension. In this study, we investigated whether there is a relationship between a high preoperative Tp-e/QT ratio and cardiovascular adverse events related to spinal anesthesia.Methods: This prospective observational cohort study enrolled 249 adult patients who underwent spinal anesthesia. Preoperative Tp-e and QT intervals were measured manually, and the Tp-e/QT ratio was calculated. After spinal anesthesia, noninvasive mean arterial pressure (MAP) and heart rate (HR) were monitored at predetermined intervals.Results: Median Tp-e/QT ratios did not differ by sex (p = 0.336). An increase in the Tp-e/QT ratio was statistically significantly associated with decreases in MAP at the 1st, 5th, and 10th minutes (p = 0.007, p < 0.001, and p = 0.015, respectively). A statistically significant association was also found between the increase in the Tp-e/QT ratio and the decrease in HR at the 1st and 5th minutes (p = 0.011 and p < 0.001, respectively). Additionally, a statistically significant positive association was observed between increased Tp-e/QT ratios and ephedrine and atropine consumption (p = 0.018 and p < 0.001, respectively).Conclusion: This study demonstrated that patients with a high preoperative Tp-e/QT ratio may have a higher risk of developing hypotension and bradycardia following spinal anesthesia. Patients with high Tp-e/QT ratios should be closely monitored after spinal anesthesia.