Midodrine is modestly effective for prevention of vasovagal syncope: Meta-analysis
Canada: Midodrine is effective for the significant prevention of vasovagal syncope (VVS) in controlled settings but in clinical settings, its efficacy is much more modest, says a recent study published in the journal EP Europace. The study further states that midodrine is the only medical treatment for recurrent VVS that is successful with this evidence level.
Vasovagal syncope is a common clinical condition that is associated with significant morbidity. Despite this, the condition lacks effective medical therapies. Midodrine is a prodrug for an α1-adrenergic receptor agonist. Current guidelines indicate that midodrine might suppress syncope but supporting studies have utilized heterogeneous methods and given inconsistent results.
Against the above background, Robert S Sheldon, University of Calgary, Calgary, Canada, and colleagues aimed to investigate the efficacy of midodrine for syncope prevention in patients with recurrent vasovagal syncope by conducting a systematic review and meta-analysis of published studies.
For this purpose, the researchers identified relevant randomized controlled trials from online databases without language restriction from inception to June 2021. All studies were performed in clinical syncope populations and compared the benefit of midodrine vs. placebo or non-pharmacological standard care. A total of seven studies comprising 315 patients met the inclusion criteria. Patients were 33 ± 17 years of age and 31%, were male.
Based on the study, the researchers found the following:
- Midodrine was found to substantially reduce the likelihood of positive head-up-tilt (HUT) test outcomes [RR = 0.37].
- The pooled results of single- and double-blind clinical trials (I2 = 54%) suggested a more modest benefit from midodrine for the prevention of clinical syncope [RR = 0.51].
- The two rigorous double-blind, randomized, placebo-controlled clinical trials included 179 VVS patients with minimal between-study heterogeneity and reported a risk reduction with midodrine [RR = 0.71].
"Midodrine is effective for the prevention of syncope induced by HUT testing and less, but still significant, RR reduction in randomized, double-blinded clinical trials," the researchers wrote.
"The large difference in estimates of effectiveness is mirrored by the degree of blinding and limitation of HUT testing in predicting the true patient response to pharmacological therapies," they conclude.
Reference:
Lucy Y Lei, Satish R Raj, Robert S Sheldon, Midodrine for the prevention of vasovagal syncope: a systematic review and meta-analysis, EP Europace, Volume 24, Issue 7, July 2022, Pages 1171–1178, https://doi.org/10.1093/europace/euab323
