Mitral valve prolapse (MVP) is a prevalent valvular abnormality affecting 2-3% of the general population. MVP has two distinct anatomical subtypes: Barlow's disease and fibroelastic deficiency; each reflects different underlying structural and pathological processes. While most individuals generally remain asymptomatic with subclinical regurgitation, some develop significant mitral regurgitation followed by heart failure. A malignant form of MVP, marked by bileaflet prolapse, mitral annular disjunction (MAD), and myocardial fibrosis, is increasingly recognized as a substrate for ventricular arrhythmias and sudden cardiac death. In addition to transthoracic/transesophageal echocardiography, cardiac magnetic resonance is expected to contribute to risk stratification, particularly in identifying high-risk features such as MAD and fibrosis. As diagnostic capabilities continue to advance, integrating phenotypic, imaging, and electrophysiological insights will be key to optimizing outcomes in patients with MVP. This review provides a comprehensive overview of MVP, encompassing its epidemiology, molecular mechanisms, imaging evaluation, and current therapeutic strategies.

Molecular hydrogen (H2) has been shown to exert antioxidant and anti-inflammatory effects across a broad spectrum of disease models and clinical trials; however, its direct reaction rate with hydroxyl radicals (•OH) in aqueous solution is exceedingly slow, and the underlying mechanism of action has remained unresolved for many years as the "hydrogen paradox". The present review delineates a paradigm shift that resolves this enigma from three distinct perspectives. First, oxidized Fe-porphyrin "hematin [Fe(III)-OH]" has been identified as a redox-related biosensor for H2, reducing •OH selectively to water through a catalytic cycle. Ab initio density functional theory calculations support the notion that H2 does not interfere with normal ferrous heme, but intervenes exclusively in pathologically hyperoxidized heme. Second, we propose a novel mechanism whereby H2 performs one-electron reduction of the high-valent ferryl iron intermediate Compound I [Fe(IV) = O·P•[+]] of myeloperoxidase during neutrophil extracellular trap formation, selectively arresting hypochlorous acid production and immunothrombosis without compromising normal bactericidal function. Third, we discuss how the identical concept of "high-valent iron overheat protection" applies to mitochondrial Complex IV, potentially explaining the maintenance of aerobic energy metabolism and the suppression of lactate accumulation. We present a unified paradigm shift in which H2 functions as the ultimate biological fail-safe mechanism, exerting pinpoint control exclusively over the pathological "runaway oxygen engine" driven by oxidative stress, while leaving normal enzymatic activity entirely intact.