Complications of idiopathic mitral valve prolapse. Prevention and treatment

Mitral valve prolapse is the most common form of heart disease, as it occurs in 4 to 6 per cent of the population. It has a benign course in the majority of cases, but 5 types of severe complication can occur in 15 per cent of cases. Mitral incompetence occurs in 14.8 per cent of cases. It may develop gradually or suddenly, following rupture of the chordae, which requires rapid surgical repair. Mitral valve prolapse is complicated by infectious endocarditis in 2.9 per cent of cases, hence the need for antibiotic prophylaxis prior to dental treatment or surgery in patients with a pan-systolic or end-systolic murmur. The only arrhythmias which should be considered as complications and treated as such are frequent ventricular extrasystoles of more than 30 per hour, usually associated with bigeminy, runs or polymorphism, ventricular tachycardia and ventricular fibrillation. Treatment consists, primarily, of beta-blockers. Sudden death is of course the major complication, occurring in 1.4 to 2.4 per cent of cases. The patients at risk of this complication are middle-aged women (40 years) with a past history of syncope or faintness due, in most cases, to episodes of ventricular tachycardia or ventricular fibrillation. Apart from arrhythmia, coronary artery spasm has also been found to be a cause of sudden death in these patients. Transient or definitive ocular and cerebral ischaemic episodes can also complicate mitral valve prolapse. Mitral valve prolapse is found in 20 to 30 per cent of patients with neurological accidents before the age of 45. Preventative treatment consists of anti-platelet aggregation agents and anticoagulants in recurrent cases.     

Familial occurrence of mitral valve prolapse in X-linked muscular dystrophy.

A high incidence of mitral valve prolapse (MVP) has been reported in patients with X-linked Duchenne muscular dystrophy. In our study MVP was present in six of 22 Duchenne dystrophy cases (27%) followed in the Maryland General Hospital Muscular Dystrophy Clinic. In addition, seven carriers of Duchenne and X-linked benign (Becker) dystrophy had evidence of MVP. Autosomal dominant transmission of MVP was present in four families. The unusually high prevalence of MVP in families with X-linked muscular dystrophy may have potential value in the recognition of the carrier trait.     

Prevalence of mitral valve prolapse in presumably healthy young men.

We determined the prevalence of mitral valve prolapse (MVP) in presumably healthy young men by studying 107 male house officers and medical students with cardiac auscultation in the supine, sitting and standing positions. Echocardiograms were performed at rest in the supine position before and after amyl nitrite inhalation and were obtainable in 101 subjects. Eleven of the 101 subjects had abnormal findings on auscultation: four had an isolated click and seven had a click and late systolic murmur. Correlation of the independent auscultatory and echocardiographic data in the 101 subjects showed that all seven of the subjects with a click and a murmur had echocardiographic evidence of prolapse. None of the 90 subjects with normal auscultation or the four with an isolated click had an abnormal echocardiogram. All seven subjects with MVP had thoracic skeletal abnormalities, but only one was symptomatic. These data suggest that the prevalence of MVP in healthy young males is similar to the reported 6-10% prevalence in healthy young females.     

The significance of mitral valve prolapse in middle-aged and elderly men.

The clinical, roentgenographic, phonocardiographic, ECG, and echocardiographic data were evaluated in 40 consecutive middle-aged and elderly male patients with echocardiographically detectable systolic prolapse of mitral valve leaflets. Prolapse was present during more than half of systole in 31 patients and was holosystolic in six patients. In most instances, both leaflets prolapsed during systole. The closing velocity and excursion of the anterior leaflet were frequently increased particularly in association with evidence of mitral insufficiency. A majority of the patients had cardiac symptomatology. Moreover, roentgenographic and/or ECG evidence of cardiac enlargement or hypertrophy was evident in 45 percent of patients with mitral valve prolapse.     

Mitral valve echoes in patients with mitral valve prolapse syndrome.

Echocardiology is an important tool in diagnosing patients with the mitral valve prolapse (MVP) syndrome. An unusual echocardiographic finding reported in this study was observed in 12 of 83 patients (14.5 per cent) with MVP syndrome. The finding consisted of a pattern of multiple, high-intensity parallel echoes behind the anterior mitral leaflet noted throughout diastole which in character were closely akin to those previously observed in left atrial myxoma or hemodynamically significant flail mitral valve leaflet. These latter diagnoses were excluded by other criteria. The prevalence of this finding in patients with MVP was significantly increased (P < .01 by Chi-square contingency testing) when contrasted with 44 patients without MVP. There was no identifying feature in the clinical history or physical examination which could be used to predict those in whom the diastolic echoes were observed. However, a significant increase in dysrhythmias as recorded by routine electrocardiogram or 24-hour Holter monitoring was noted. Angiographic information obtained in selected patients suggested that the posterior leaflet per se caused these diastolic echoes. Because of patulous transformation of the valve, elongation of the chordae, or loss of support of the papillary muscle from the posterior free wall, the posterior leaflet appeared drawn forward toward the anterior leaflet, perhaps from a venturi-like effect caused by the rapid ingress of blood during diastolic filling. This malpositioning of the posterior leaflet was not associated with significant mitral regurgitation and appears to represent but another facet in the spectrum of mitral valve prolapse.     

Insensitivity of echocardiography in detecting mitral valve prolapse in older patients with chest pain

Although echocardiography has proved useful in detecting mitral valve prolapse, its limitations have not yet been adequately defined. This study was designed to evaluate the prevalence of false negative echocardiograms in patients with angiographically proved mitral valve prolapse. Twelve patients, eight men and four women with a mean age of 47 years, were selected on the basis of the results of cardiac catheterization for chest pain. Each patient had moderate to severe mitral valve prolapse, confirmed angiographically by two observers, with no coronary artery disease or other detectable cardiac abnormalities. Clinically, a systolic click was detected in three patients, a mid-systolic murmur in five, an abnormal electrocardiogram in four and a positive maximal treadmill stress test in two of eight tested. Left ventricular angiograms exhibited anterior and posterior leaflet prolapse in five, and posterior leaflet prolapse alone in seven. High quality echocardiograms were obtained in 11 patients; one record of inadequate quality was excluded. The echocardiograms revealed mitral valve prolapse in only one case, and were “probably” negative in two, and clearly negative in eight. Although these results may reflect the well recognized variable clinical expression of this syndrome, they indicate that false negative echocardiograms are common in this selected older population of patients with angiographic mitral valve prolapse who present with chest pain and few other clinical features. Thus, caution must be exercised in the clinical interpretation of a single echocardiogram negative for mitral valve prolapse.     

Dysautonomia in mitral valve prolapse.

Many of the clinical features of patients with mitral valve prolapse can logically be attributed to abnormal autonomic neural function. Accordingly, we have studied heart rate and blood pressure response to a standardized Valsalva maneuver and postural test in 44 untreated patients with demonstrated mitral valve prolapse. Fifteen healthy subjects of similar age served as controls. The directional changes of blood pressure and heart rate were similar in control subjects and patients in both tests, but patients differed from control subjects by their widely oscillating heart rate during the upright posture, and their exaggerated and prolonged bradycardia during the recovery phase of the Valsalva maneuver and following their return to recumbency in the postural test. This bradycardia persisted for 30 to 90 seconds after blood pressure returned to control values. Patients also showed a greater respiratory variation of R-R interval, which became especially marked during the adjustment to changes of posture. We postulate an abnormal central modulation of baroreflexes as the best explanation for the dysautonomic responses of symptomatic patients with prolapsed mitral valves.     

Progression of mitral regurgitation in patients with mitral valve prolapse

Mitral valve prolapse (MVP) is a very common clinical entity which is frequently associated with mild mitral regurgitation (MR) and which most commonly becomes clinically manifest in the third and fourth decades of life. Severe MR associated with MVP, occurs much less frequently and is most commonly seen in patients above the age of 50 years. Relatively little information is available regarding the progression of mild to severe MR in patients with MVP. This report reviews a recent study which investigated the progression from mild to severe MR in patients with MVP. The study included 86 patients, average age 60 years, who presented with cardiac symptoms and severe MR. A high incidence of MVP was seen on echocardiograms (57 of 75 [75%]) and on left ventriculography (61 of 84 [73%]). Mitral valve replacement was performed in 75 patients. Pathologically all valves appeared grossly enlarged, severely floppy and had extensive myxomatous changes with collagen dissolution. 80 patients had a pre-existing heart murmur first detected at average age 34. Patients remained asymptomatic for an average of 25 years at which time clinical symptoms first appeared. After symptoms developed mitral valve surgery was necessary in most patients within one year. This rapid deterioration could partially be attributed to ruptured chordae in 39 of 76 patients (51%) or atrial fibrillation in 48 of 86 patients (56%). 28 patients had one or more serial clinical evaluations including auscultation, chest x-ray, echocardiography, and cardiac catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mitral valve dimensions and motion in Marfan patients with and without mitral valve prolapse. Comparison to primary mitral valve prolapse and normal subjects

To determine mitral valve and extravalvular findings associated with mitral valve prolapse (MVP) in patients with the Marfan syndrome, we compared mitral leaflet and anular dimensions and motion by computerized two-dimensional echocardiography in 53 Marfan patients (28 with M-mode echocardiographic MVP) to those in 48 adults with primary MVP and in 35 normal subjects. Mitral leaflet billowing occurred in 28 of 28 Marfan patients with M-mode MVP versus 24 of 48 with primary MVP (p less than 0.00005), 0 of 25 Marfan patients without M-mode MVP, and 0 of 35 normal subjects (both, p less than 0.0001). Billowing occurred on the first systolic frame in 8 of 28 Marfan-MVP patients, in whom posterior leaflet chordae arose abnormally from the posterior ventricular wall, and in no other subjects. These patients had large mitral valves and normal anular dynamics, whereas the remaining 20 Marfan-MVP patients had increased systolic anular expansion. Marfan-MVP patients were younger than those without MVP (29 +/- 12 vs. 38 +/- 15 years, p less than 0.02) and had lower body mass index (19.8 +/- 2.7 vs. 23.9 +/- 2.9 kg/m2, p less than 0.00005) and systolic blood pressure (120 +/- 20 vs. 133 +/- 20 mm Hg, p less than 0.05), similar to differences between primary MVP and normal subjects in body mass index (21.5 +/- 3.0 vs. 23.9 +/- 4.8 kg/m2, p less than 0.01) and systolic pressure (118 +/- 14 vs. 125 +/- 18 mm Hg, p less than 0.05). Marfan patients with and without MVP had similar arm span, arm span to height ratio, upper to lower segment ratio, and prevalence of ectopia lentis and thoracic bony abnormalities, but arachnodactyly was more frequent in those with MVP (82% and 48%, respectively; p less than 0.02). We conclude that 1) leaflet billowing occurs more uniformly in Marfan patients with MVP than in primary MVP, 2) MVP in Marfan patients may be due to either valve enlargement with distinctively abnormal chordal architecture or abnormal mitral anular distensibility, 3) Marfan patients with MVP have low body weight and systolic blood pressure, similar to primary MVP, and 4) Marfan patients with MVP more commonly have arachnodactyly but otherwise have similar skeletal and anthropometric characteristics to other Marfan patients.     

Isolated mitral valve prolapse: chordal architecture as an anatomic basis in older patients

Ten patients with an average age of 58 years underwent valve replacement because of isolated mitral valve prolapse with severe regurgitation. None had clinical evidence of Marfan's syndrome or another systemic disease that would indicate that a primary connective tissue disorder was the cause of the prolapse. All 10 patients had a dome configuration of the posterior leaflet and one or more ruptured chordae related to it. The gross morphology of the resected specimens revealed marked deviations in chordal branching and the pattern of anchoring in each of the 10 cases, rendering the most severely affected parts of the leaflets less well supported. Similar changes occurred at sites remote from the principal abnormality. Microscopically, the dominant tissue change was myxomatous transformation within the affected leaflets and chordae with secondary changes at both atrial and ventricular surfaces. These findings could indicate that insufficient chordal support may have promoted the development of the floppy valve through a process of chronic undue and unbalanced stress on the valve tension and closure apparatus. The resultant degeneration of the connective tissues, histologically expressed as myxomatous transformation, may underlie stretching and thus redundance of the leaflets and eventually rupture of chordae. It is suggested that this sequence of events be considered as a possible pathogenetic mechanism of isolated mitral valve prolapse, particularly in the subset of aged patients.     

Follow-up observations in patients with mitral valve prolapse

The discrepancies reported in various studies with respect to long-term prognosis in mitral valve prolapse can be attributed to the criteria employed for diagnosis and to the differing patient populations studied. Furthermore, mitral valve prolapse is not a single, well-defined disease but reflects rather a broad spectrum of a disease process. Echocardiographically, patients can be identified with redundant, thickened leaflets with excessive mitral valve motion and prolapse as well as those with normal appearing leaflets but systolic prolapse representative of differing disease processes with differing prognosis. The incidence of sudden cardiac death is estimated at a low value of 1.9/10,000 patients per year. In the presence of a normal resting ECG, with no hemodynamically-meaningful mitral regurgitation and no evidence of redundant mitral leaflets the risk is even less. Cerebral embolic events occur with an estimated incidence of 1/6000 patients per year, similarly low; it can be assumed that patients with very myxomatous, redundant mitral leaflets have the highest risk. The incidence of infective endocarditis is also low, estimated at 1/5725 patients per year (0.175%). Risk factors for complications include: a systolic murmur, advanced age, male sex and leaflet redundancy. The most important complication is mitral regurgitation for which the incidence is highest in older men and in the presence of left ventricular, dilatation.     

Arrhythmia in young patients with mitral valve prolapse

Twenty four-hour ambulatory ECG monitoring were examined in 68 patients (33 patients in a young group and 35 patients in an adult group) with mitral valve prolapse (MVP) in order to characterize the features of arrhythmias in young patients with MVP in comparison with those in adult patients. Diagnosis of MVP was made by two-dimensional echocardiography. On 24-hour ambulatory ECG monitoring 29 patients (88%) in a young group had arrhythmias which was as frequent as those in adult group, but serious ventricular arrhythmias were more often detected in the young group (7 patients) than in the adult group (2 patients). It was considered that arrhythmias in young patients with MVP were frequently serious but accompanied without any symptoms and cardiac dysfunction.     

Joint hypermobility in primary mitral valve prolapse patients

Summary Twenty-seven patients with echocardiographic evidence of primary mitral valve prolapse (MVP) were tested for the presence of joint hypermobility using the criteria of Beighton and Horan. In the examined group, joint hypermobility was found in 14 patients (52%). This occurrence was statistically significant. In patients with simultaneous occurrence of MVP and articular hypermobility we have found a number of pathologic arthrologic manifestations, such as arthralgias, synovitic reactions, distortions, low back pain, and others. In patients with articular hypermobility, there were increased functions of antigen B 35.     

Platelet activation in patients with mitral valve prolapse

An increased frequency of thromboembolic events in patients with mitral valve prolapse has been demonstrated. It has been suggested that this association may be related to increased systemic platelet activity. Beta-thromboglobulin (BTG) is a platelet specific protein secreted during the platelet release reaction, with BTG levels reflecting ongoing platelet activation. Plasma BTG levels were measured in 14 normal volunteers, 23 patients with mitral valve prolapse and nonthickened mitral leaflets (group 1) and 13 patients with mitral valve prolapse and thickened mitral leaflets (group 2). The BTG level was 8.1 +/- 4.6 ng/mL (mean +/- SD) in normal subjects, 9.6 +/- 5.5 ng/mL in the nonthickened mitral valve prolapse group and 10.0 +/- 5.7 ng/mL in thickened mitral valve prolapse group. There was no significant difference in the BTG levels between groups. Five patients with multiple valvular prolapse did not show elevation of BTG levels. The present study did not demonstrate increased BTG levels in neurologically asymptomatic mitral valve prolapse patients.