Tubog et al [7] concluded that the incidence of bradycardia was significantly lower in those that received prophylactic ondansetron.  This systematic review with meta-analysis [7] contained a total of 13 RCTs and 1,224 participants; similarly, in a meta-analysis evaluating 10 RCTs with 863 patients. Gao et al [25] concluded the prophylactic administration of ondansetron effectively mitigated the incidence of bradycardia. However, a large number of RCTs [3, 8, 10, 12–16, 23, 26–29] within the literature suggest there are no statistically significant differences in heart rate or bradycardia when ondansetron intervention groups are compared with placebo. In the randomized double-blinded controlled trial performed by Marashi et al [9], which contained 210 patients ages 20-50, there was no significant evidence that prophylactic administration of ondansetron had any effect on heart rate. In an RCT containing 91 patients, Terkawi et al [26] found the incidence of bradycardia was approximately 15% in the placebo group as well as the ondansetron intervention group. In an RCT containing a group of 70 patients, Mohamed et al [27] found there was no significant difference in incidences of bradycardia between the experimental and control groups. In a similar RCT, Tatikonda et al [23] observed no bradycardia in either the control or experimental group.