October 15, 2020
MITHRAS Evaluates Interventional Closure of Residual Atrial Septal Defect After TMVR
October 15, 2020—The MITHRAS randomized clinical trial found that interventional closure of an iatrogenic atrial septal defect (iASD) driven by transcatheter mitral valve repair (TMVR) was not superior to conservative medical treatment with regard to the primary endpoint of change in 6-minute walking distance.
The findings from the MITHRAS trial were presented by principal investigator Philipp Lurz, MD, at TCT Connect, the 32nd annual Transcatheter Cardiovascular Therapeutics scientific symposium of the Cardiovascular Research Foundation held online October 14–18, 2020.
As summarized by TCT Connect, this prospective, randomized, single-center trial was composed of 80 patients enrolled between January 2016 and October 2019 who had a persistent iASD at 1 month after TMVR and relevant left-to-right shunting (Qp:Qs ≥ 1.3). The patients were randomly assigned in a 1:1 ratio to standard medical therapy alone or closure of the iASD using the Occlutech ASD occlude (Occlutech AG). The primary endpoint was change in 6-minute walk distance at 5 months after iASD occlusion. Secondary endpoints included all-cause mortality and rate of heart failure hospitalization at 1 year.
All patients underwent TMVR with 95% using the MitraClip device (Abbott) 1 month before enrollment and were diagnosed with an iASD with relevant left-to-right shunting on transesophageal echocardiography. Overall, 40 patients were randomized into the iASD closure group and 40 patients into the medical therapy-only group. There were no differences observed in change in the primary endpoint of 6-minute walking distance or any of the prespecified secondary endpoints at 5 months between groups.
“Interventional closure of iASD 1-month post transcatheter mitral valve repair was not superior to conservative treatment with regard to the primary endpoint 6-minute walking distance,” commented Dr. Lurz in the TCT Connect announcement. “The results are corroborated by no difference in secondary endpoints such as heart failure symptoms or hospitalization and survival. The presence of an iASD is associated with a higher rate of heart failure hospitalization irrespective of its management when compared to patients without relevant iASD following TMVR. The presence of an iASD following transcatheter mitral valve interventions might be a prognostically relevant surrogate, but not necessarily causative for inferior outcomes.”