Genes, gender and geometry and the prolapsing mitral valve

Prevalence and characteristics of mitral valve prolapse in military young adults in Taiwan of the CHIEF Heart Study

The prevalence of mitral valve prolapse (MVP) among middle- and older-aged individuals is estimated to be 2–4% in Western countries. However, few studies have been conducted among Asian individuals and young adults. This study included a sample of 2442 consecutive military adults aged 18–39 years in Hualien, Taiwan. MVP was defined as displacement of the anterior or posterior leaflet of the mitral valve to the mid portion of the annular hinge point > 2 mm in the parasternal long-axis view of echocardiography. Cardiac chamber size and wall thickness were measured based on the latest criteria of the American Society of Echocardiography. The clinical features of participants with MVP and those without MVP were compared using a two-sample t test, and the cardiac structures were compared using analysis of covariance with adjustment for body surface area (BSA). Eighty-two participants were diagnosed with MVP, and the prevalence was 3.36% in the overall population. Compared with those without MVP, participants with MVP had a lower body mass index (kg/m²) (24.89 ± 3.70 vs. 23.91 ± 3.45, p = 0.02) and higher prevalence of somatic symptoms related to exercise (11.0% vs. 4.9%, p = 0.02) and systolic click in auscultation (18.3% vs. 0.6%, p < 0.01). In addition, participants with MVP had greater left ventricular mass (gm) and smaller right ventricular wall thickness (mm) and dimensions (mm) indexed by BSA than those without MVP (149.12 ± 35.76 vs. 155.38 ± 36.26; 4.66 ± 0.63 vs. 4.40 ± 0.68; 26.57 ± 3.99 vs. 25.41 ± 4.35, respectively, all p-values < 0.01). In conclusion, the prevalence and clinical features of MVP in military young adults in Taiwan were in line with those in Western countries. Whether the novel MVP phenotype found in this study has any pathological meaning needs further investigation.

Pathology, protein expression and signaling in myxomatous mitral valve degeneration: comparison of dogs and humans

Myxomatous degenerative mitral valve disease (MMVD) is a common heart disease in dogs. Although several morphological similarities occur between human and canine MMVD differences exist. However, in advanced stages the accumulation of proteoglycans is the main finding in both species. The extracellular matrix (ECM) in normal canine and human mitral valves is similar. In MMVD of both species proteoglycans is the major alteration, although specific changes in collagen distribution exists. The valvular expression pattern of matrix metalloproteinases (MMPs) and of their inhibitors (TIMPs) differs, in part, between dogs and humans. The MMPs and TIMPs expression patterns are similar in normal canine and human mitral valves, but they are quite different during degenerative progression. Valve endothelial cells (VEC) and interstitial cells (VIC) are phenotypically transformed in canine and human MMVD. Inflammation is an unlikely cause of valve degeneration in humans and dogs. There are several lines of evidence suggesting that transforming growth factor β1 (TGF β1) and serotonin signaling may mediate valve degeneration in humans and dogs. Although human and canine MMVD share structural similarities, there are some differences in ECM changes, enzyme expression and cell transformation, which may reflect a varied pathogenesis of these diseases.

Angiotensinogen M235T associated with mitral valve prolapse in young Han Chinese male

BACKGROUND

A potential role for the renin-angiotensin system (RAS) in mitral valve prolapse (MVP) has been reported. The RAS genes are good candidates for evaluating the association with MVP. The angiotensinogen (AGT) gene has an important role in RAS and was shown to be related to MVP. However, no study on the association of AGT M235T in men with MVP has been reported. In this article, we investigated the potential role of AGT M235T polymorphism in men with MVP.

METHODS

Seventy-one unrelated study subjects with MVP, 236 control subjects (matched with respect to age and sex), and 178 community subjects from southern Taiwan were included in this study. All participants were male Han Chinese population. All cases fulfilled the criteria of MVP and the new echocardiographic criteria for MVP. The AGT M235T polymorphism was detected by polymerase chain reaction-restricted fragment length polymorphism.

RESULTS

There was a statistically significant difference in the M235 allelic frequency between MVP study subjects and control subjects (chi = 4.390; P = 0.036). The chi test for trend also showed that the MM genotype frequency had a statistically significant increase with MVP study subjects (chi = 4.339; P = 0.037).

CONCLUSIONS

The results suggest a significant association between MM genotype of AGT M235T polymorphism and MVP in men. Therefore, this study indirectly supports the idea that the polymorphism of AGT M235T should be considered when interpreting and designing genetic studies which underlie differences in blood pressure.

Long-term outcome after mitral valve repair: a risk factor analysis

OBJECTIVE

Mitral valve repair is the gold standard to restore mitral valve function and is now known to have good long-term outcome. In order to help perioperative decision making, we analyzed our collective to find independent risk factors affecting their outcome.

METHODS

We retrospectively studied our first 175 consecutive adult patients (mean age: 64+/-10.4 years; 113 males) who underwent primary mitral valve repair associated with any other cardiac procedures between January 1986 and December 1998. Risk factors influencing reoperations and late survival were plotted in a uni- and multivariate analyses.

RESULTS

Operative mortality was 3.4% (6 deaths, 0-22nd postoperative day (POD)). Late mortality was 9.1% (16 deaths, 3rd-125th POM). Reoperation was required in five patients. Kaplan-Meier actuarial analysis demonstrated a 96+/-1% 1-year survival, 88+/-3% 5-year survival and a 69+/-8% 10-year survival. Freedom from reoperations was 99% at 1 year after repair, 97+/-2% after 5 years and 88+/-6% after 10 years. Multivariate analysis demonstrated that residual NYHA class III and IV (p=0.001, RR 4.55, 95% CI: 1.85-14.29), poor preoperative ejection fraction (p=0.013, RR 1.09, 95% CI: 1.02-1.18), functional MR (p=0.018, RR 4.17, 95% CI: 1.32-16.67), and ischemic MR (p=0.049, RR 3.13, 95% CI: 1.01-10.0) were all independent predictors of late death. Persistent mitral regurgitation at seventh POD (p=0.005, RR 4.55, 95% CI: 1.56-20.0), age below 60 (p=0.012, RR 8.7, 95% CI: 2.44-37.8), and absence of prosthetic ring (p=0.034, RR 4.76, 95% CI: 1.79-33.3) were all independent risk factors for reoperation.

CONCLUSIONS

Mitral valve repair provides excellent survival. However, long-term outcome can be negatively influenced by perioperative risk factors. Risk of reoperation is higher in younger patients with a residual mitral regurgitation and without ring annuloplasty.