Mitral Valve Prolapse and Sudden Cardiac Death in the Young
S Rizzo, A Peralta, A Abudurheman, M Valente, G Thiene, C Basso. University of Padua Medical School, Padua, Italy
Background: Mitral valve prolapse (MVP) occurs in up to 5% of the general population. Since the disorder may be associated with sudden death (SD), the aim of our study was to evaluate the prevalence of MVP in young SD victims and the pathological substrate of electrical instability.
Design: The study has been carried by selecting young SD victims with MVP as the sole cardiac abnormality found at autopsy and 15 age-matched controls who died due to extracardiac causes (mean age 28 years, range 15-43). Gross and histology were carried out according to the SD protocol with sampling from the mitral valve leaflets and ventricular myocardium. In selected cases, primary antibodies against the phosphorilated form of Smad 2 were used.
Results: MVP was the cause of SD in 27 (10 M, 17 F, mean age 29,7 years, range 14-40) out of 481 cases of cardiovascular SD (6%). The mean weight of the heart was 415,43±153,5g (p<0,0001). MVP leaflets had a four-fold increase in thickness compared to the normal valves (2,09±0,23, p<0,0001) with fragmented, irregular elastin and collagen and accumulation of proteoglycans. Significant endoperimysial and replacement type fibrosis was observed in patients with MVP, particularly at the level of papillary muscle implantation (100%). By histomorphometry, fibrosis was 26,9±10,9% vs 7,2±4,7% in controls (p<0,0001) and cardiomyocyte diameter was 17,6±4,9 vs 13,2±0,8 in controls (p=0,0006). Immunohistochemistry showed increased nuclear staining for of p-Smad-2 in both mitral valve and cardiac interstitium of MVP cases (p=0.02).
Conclusions: MVP represent a no-so rare cause (6%) of SD in the young due to fatal arrhythmias. The electrical instability seems associated to endoperimysial fibrosis and replacement-type fibrosis, even in the setting of still competent mitral valves, due to a concomitant myocardial involvement (“valvular cardiomyopathy”). These findings suggest a potential role for risk stratification of tissue characterization by late-enhancement cardiac magnetic resonance in MVP patients.
Wednesday, March 24, 2010 1:00 PM
Poster Session VI # 26, Wednesday Afternoon