Lisa A. Freed

Prevalence and clinical outcome of mitral-valve prolapse

BACKGROUND Mitral-valve prolapse has been described as a common disease with frequent complications. To determine the prevalence of mitral-valve prolapse in the general population, as diagnosed with the use of current two-dimensional echocardiographic criteria, we examined the echocardiograms of 1845 women and 1646 men (mean [+/-SD] age, 54.7+/-10.0 years) who participated in the fifth examination of the offspring cohort of the Framingham Heart Study. METHODS Classic mitral-valve prolapse was defined as superior displacement of the mitral leaflets of more than 2 mm during systole and as a maximal leaflet thickness of at least 5 mm during diastasis, and nonclassic prolapse was defined as displacement of more than 2 mm, with a maximal thickness of less than 5 mm. RESULTS A total of 84 subjects (2.4 percent) had mitral-valve prolapse: 47 (1.3 percent) had classic prolapse, and 37 (1.1 percent) had nonclassic prolapse. Their age and sex distributions were similar to those of the subjects without prolapse. None of the subjects with prolapse had a history of heart failure, one (1.2 percent) had atrial fibrillation, one (1.2 percent) had cerebrovascular disease, and three (3.6 percent) had syncope, as compared with unadjusted prevalences of these findings in the subjects without prolapse of 0.7, 1.7, 1.5, and 3.0 percent, respectively. The frequencies of chest pain, dyspnea, and electrocardiographic abnormalities were similar among subjects with prolapse and those without prolapse. The subjects with prolapse were leaner (P<0.001) and had a greater degree of mitral regurgitation than those without prolapse, but on average the regurgitation was classified as trace or mild. CONCLUSIONS In a community based sample of the population, the prevalence of mitral-valve prolapse was lower than previously reported. The prevalence of adverse sequelae commonly associated with mitral-valve prolapse in studies of patients referred for that diagnosis was also low.

Mitral valve prolapse in the general population: the benign nature of echocardiographic features in the Framingham Heart Study.

OBJECTIVE The aim of this study was to examine the echocardiographic features and associations of mitral valve prolapse (MVP) diagnosed by current two-dimensional echocardiographic criteria in an unselected outpatient sample. BACKGROUND Previous studies of patients with MVP have emphasized the frequent occurrence of echocardiographic abnormalities such as significant mitral regurgitation (MR) and left atrial (LA) enlargement that are associated with clinical complications. These studies, however, have been limited by the use of hospital-based or referral series. METHODS We quantitatively studied all 150 subjects with possible MVP by echocardiography and 150 age- and gender-matched subjects without MVP from the 3,491 subjects in the Framingham Heart Study. Based on leaflet morphology, subjects were classified as having classic (n = 46), nonclassic (n = 37), or no MVP. RESULTS Leaflet length, MR degree, and LA and left ventricular size were significantly but mildly increased in MVP (p < 0.0001 to 0.004), with mean values typically within normal range. Average MR jet area was 15.1 +/- 1.4% (mild) in classic MVP and 8.9 +/- 1.5% (trace) in nonclassic MVP; MR was severe in only 3 of 46 (6.5%) subjects with classic MVP, and LA volume was increased in only 8.7% of those with classic MVP and 2.7% of those with nonclassic MVP. CONCLUSIONS Although the echocardiographic characteristics of subjects with MVP in the Framingham Heart Study differ from those without MVP, they display a far more benign profile of associated valvular, atrial, and ventricular abnormalities than previously reported in hospital- or referral-based series. Therefore, these findings may influence the perception of and approach to the outpatient with MVP.

A Locus for Autosomal Dominant Mitral Valve Prolapse on Chromosome 11p15.4

Mitral valve prolapse (MVP) is a common cardiovascular abnormality in the United States, occurring in approximately 2.4% of the general population. Clinically, patients with MVP exhibit fibromyxomatous changes in one or both of the mitral leaflets that result in superior displacement of the leaflets into the left atrium. Although often clinically benign, MVP can be associated with important accompanying sequelae, including mitral regurgitation, bacterial endocarditis, congestive heart failure, atrial fibrillation, and even sudden death. MVP is genetically heterogeneous and is inherited as an autosomal dominant trait that exhibits both sex- and age-dependent penetrance. In this report, we describe the results of a genome scan and show that a locus for MVP maps to chromosome 11p15.4. Multipoint parametric analysis performed by use of GENEHUNTER gave a maximum LOD score of 3.12 for the chromosomal region immediately surrounding the four-marker haplotype D11S4124-D11S2349-D11S1338-D11S1323, and multipoint nonparametric analysis (NPL) confirms this finding (NPL=38.59; P=.000397). Haplotype analysis across this region defines a 4.3-cM region between the markers D11S1923 and D11S1331 as the location of a new MVP locus, MMVP2, and confirms the genetic heterogeneity of this disorder. The discovery of genes involved in the pathogenesis of this common disease is crucial to understanding the marked variability in disease expression and mortality seen in MVP.

Mitral valve prolapse and atrial septal aneurysm: an evaluation in the Framingham Heart Study.

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Gender differences in presentation, management, and cardiac event-free survival in patients with syncope

In a MEDLINE search of published English studies (1966 to 1996), no prior study was identified that examined gender-based differences in the management and prognosis of patients admitted with syncope. We studied 109 consecutive patients (48 women) admitted with syncope at the Massachusetts General Hospital (1989 to 1990). All patients underwent Holter monitoring, signal-averaged electrocardiography, and echocardiography according to study protocol. Follow-up was 100% complete (10 +/- 4 months). Women were older (74 +/- 2 vs 66 +/- 2 years, p <0.01) and less likely to have premonitory symptoms when compared with men (46% vs 66%, p <0.05). A greater proportion of men had left ventricular ejection fractions of <0.40 (18% vs 0%, p <0.01), abnormal signal-averaged electrocardiograms (28% vs 8%, p <0.01), and a cardiac cause for syncope (49% vs 25%, p <0.01). Although referral for diagnostic electrophysiologic testing was >3 times as frequent for men compared with women (20% of men vs 6% of women, p <0.05), this difference was not significant after adjustment for age, ventricular arrhythmia, and referral for coronary angiography. During follow-up, 21% of men versus 6% of women (p <0.05) had cardiac events (recurrent syncope, myocardial infarction, or sudden death). Cardiac event-free survival rates were worse for men (p = 0.045). Thus, we have identified gender-based differences in the clinical presentation of syncope for hospital admission. Left ventricular dysfunction and an abnormal signal-averaged electrocardiogram occur more frequently in men. Men are more likely to have cardiac syncope and worse cardiac event-free survival when compared with women.