Acute rupture of chordae tendineae of the mitral valve in infants: a nationwide survey in Japan exploring a new syndrome.

BACKGROUND: Recently, infant cases of acute heart failure attributable to rupture of the mitral chordae tendineae have been reported. However, little is known about the pathogenesis and clinical course of this condition. METHODS AND RESULTS: Ninety-five children with rupture of mitral chordae tendineae were identified in nationwide surveys of Japan diagnosed from 1995 to 2013. The clinical manifestations, management strategies, and prognosis were investigated. Eighty-one (85%) patients were between 4 and 6 months (median, 5 months) of age. In 63 (66%) patients, rupture occurred during the spring or summer. The underlying conditions before rupture included Kawasaki disease (10 cases), maternally derived anti-SSA antibodies (2 cases), and infective endocarditis (1 case). Surgery was performed in 80 patients (94 operations), and the final operations included plasty of mitral chordae in 52 cases and mechanical valve replacement in 26 cases. The histopathologic examinations of the mitral valves and chordae (n=28) revealed inflammatory reactions with predominant mononuclear cell infiltration in 18 cases (64%) and increased fibrous and myxoid tissue in 11 cases (39%), suggesting that nonbacterial infectious or autoimmune endocarditis and myxoid changes are involved in the pathogenesis. Eight patients (8.4%) died before (n=6) and shortly after (n=2) the operation, and significant neurological complications persisted in 10 cases (11%). CONCLUSIONS: Acute heart failure attributable to rupture of the mitral chordae tendineae in infants is a unique disease resulting from diverse causes. This condition should be recognized as a significant cardiovascular disorder that may cause sudden onset of cardiogenic shock and death in infants.