Midodrine hydrochloride as a treatment for postural orthostatic tachycardia syndrome: A systematic review and meta-analysis

The aim of this review is to evaluate the evidence for midodrine as a treatment for patients with postural orthostatic tachycardia syndrome (POTS). We conducted a systematic review of the literature to identify studies which evaluate midodrine treatment in patients with POTS. Random-effects meta-analysis was used to determine the impact of midodrine on symptoms compared to placebo and beta-blockers. A total of 14 studies with 968 patients were included which took place between 2000 and 2017. The proportion of patients who clinically benefited from postural orthostatic tachycardia syndrome from 10 studies ranged from 46.2% to 91.3%. Meta-analysis of midodrine versus control for studies of children showed that midodrine had significantly increased odds of symptom response (RR 1.52 95%CI 1.09-2.13, p=0.01, I2=78%, 4 studies). The pooled result comparing midodrine to beta-blockers in pediatric populations showed that there was a 1.16-fold increase in odds for symptom response compared to beta-blockers (RR 1.16 95%CI 1.02-1.32, p=0.02, I2=0%, 4 studies). Hypertension was reported in 3 studies to occur in 8.2% of patients (7/85). Gastrointestinal disturbance was reported in 4 studies, and it occurred in 3.4% of patients (6/ 175). The evidence for midodrine efficacy in patients with POTS is limited, particularly in adults. Additional studies are needed to better understand which patients may benefit the most. Midodrine may be considered as a second- or third-line therapy in patients who remain symptomatic particularly if an enhancement of vascular tone or preload is desired. The use of midodrine in older patients with hypertension should be discouraged.