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For patients with symptomatic severe mitral stenosis (MS), percutaneous transvenous mitral commissurotomy (PTMC) using an Inoue (or Inoue-like) balloon is the most reasonable initial treatment option.1 For asymptomatic patients, however, there are no reliable data to guide therapy. Guideline recommendations are therefore based largely on consensus, and have varied over time, due perhaps to differing interpretations of the existing data (table 1). The greatest uncertainty pertains to the management of asymptomatic patients with mitral valve area (MVA) between 1 and 1.5 cm2. Kang and colleagues attempt to address this knowledge gap. They randomly allocated 167 asymptomatic patients with rheumatic MS and MVA 1–1.5 cm2, to either undergo PTMC within 3 months of randomisation or to remain on medical treatment.2 Over a median follow-up of just over 6 years, the composite primary outcome, consisting of PTMC-related complications, cardiovascular mortality, ischaemic stroke and systemic embolism, occurred in 7/84 (8.3%) patients in the PTMC arm and 9/83 (10.8%) patients (HR 0.77, 95% CI 0.29 to 2.07; p=0.61). The authors conclude that a strategy of initial PTMC does not reduce the incidence of adverse cardiovascular events and suggest that medical treatment with careful follow-up should continue to remain the standard of care for these patients.
These are important data in a field almost bereft of evidence from randomised trials. However, these results should be interpreted with caution for several reasons. First, the authors powered their study on the assumption of an unrealistically large (about 85%) relative risk reduction with PTMC, based on event rates from their previous observational cohort.3 The effect of PTMC, if any, in this population is likely to be modest …
Contributors GK is the sole contributor.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Commissioned; internally peer reviewed.
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