Mitral valve prolapse: a cardiomyopathic state?

Mechanistic insights of the left ventricle structure and fibrosis in the arrhythmogenic mitral valve prolapse

Mitral valve prolapse (MVP) is a common and benign condition. However, some anatomic forms have been recently associated with life-threatening ventricular arrhythmias and sudden cardiac death. Imaging MVP holds the promise of individualized MVP risk assessment. Noninvasive imaging techniques available today are playing an increasingly important role in the diagnosis, prognosis and monitoring of MVP. In this article, we will review the current evidence on arrhythmogenic MVP, with special focus on the utility of echocardiography and CMR for identifying benign and "malignant" forms of MVP. The clinical relevance of this manuscript lies in the value of imaging technology to improve MVP risk prediction, including those arrhythmic-MVP cases with a higher risk of sudden cardiac death.

Morphofunctional Abnormalities of Mitral Annulus and Arrhythmic Mitral Valve Prolapse

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Background—

Arrhythmic mitral valve prolapse (MVP) is characterized by myxomatous leaflets and left ventricular (LV) fibrosis of papillary muscles and inferobasal wall. We searched for morphofunctional abnormalities of the mitral valve that could explain a regional mechanical myocardial stretch.

Methods and Results—

Thirty-six (27 female patients; median age: 44 years) arrhythmic MVP patients with LV late gadolinium enhancement on cardiac magnetic resonance and no or trivial mitral regurgitation, and 16 (6 female patients; median age: 40 years) MVP patients without LV late gadolinium enhancement were investigated by morphofunctional cardiac magnetic resonance. Mitral annulus disjunction (median: 4.8 versus 1.8 mm; P<0.001), end-systolic mitral annular diameters (median: 41.2 versus 31.5; P=0.004) and end-diastolic mitral annular diameters (median: 35.5 versus 31.5; P=0.042), prevalence of posterior systolic curling (34 [94%] versus 3 [19%]; P<0.001), and basal to mid LV wall thickness ratio >1.5 (22 [61%] versus 4 [25%]; P=0.016) were higher in MVP patients with late gadolinium enhancement than in those without. A linear correlation was found between mitral annulus disjunction and curling (R=0.85). A higher prevalence of auscultatory midsystolic click (26 [72%] versus 6 [38%]; P=0.018) was also noted. Histology of the mitral annulus showed a longer mitral annulus disjunction in 50 sudden death patients with MVP and LV fibrosis than in 20 patients without MVP (median: 3 versus 1.5 mm; P<0.001).

Conclusions—

Mitral annulus disjunction is a constant feature of arrhythmic MVP with LV fibrosis. The excessive mobility of the leaflets caused by posterior systolic curling accounts for a mechanical stretch of the inferobasal wall and papillary muscles, eventually leading to myocardial hypertrophy and scarring. These mitral annulus abnormalities, together with auscultatory midsystolic click, may identify MVP patients who would need arrhythmic risk stratification.

Arrhythmic Mitral Valve Prolapse and Sudden Cardiac Death

BACKGROUND

Mitral valve prolapse (MVP) may present with ventricular arrhythmias and sudden cardiac death (SCD) even in the absence of hemodynamic impairment. The structural basis of ventricular electric instability remains elusive.

METHODS AND RESULTS

The cardiac pathology registry of 650 young adults (≤40 years of age) with SCD was reviewed, and cases with MVP as the only cause of SCD were re-examined. Forty-three patients with MVP (26 females; age range, 19-40 years; median, 32 years) were identified (7% of all SCD, 13% of women). Among 12 cases with available ECG, 10 (83%) had inverted T waves on inferior leads, and all had right bundle-branch block ventricular arrhythmias. A bileaflet involvement was found in 70%. Left ventricular fibrosis was detected at histology at the level of papillary muscles in all patients, and inferobasal wall in 88%. Living patients with MVP with (n=30) and without (control subjects; n=14) complex ventricular arrhythmias underwent a study protocol including contrast-enhanced cardiac magnetic resonance. Patients with either right bundle-branch block type or polymorphic complex ventricular arrhythmias (22 females; age range, 28-43 years; median, 41 years), showed a bileaflet involvement in 70% of cases. Left ventricular late enhancement was identified by contrast-enhanced cardiac magnetic resonance in 93% of patients versus 14% of control subjects (P<0.001), with a regional distribution overlapping the histopathology findings in SCD cases.

CONCLUSIONS

MVP is an underestimated cause of arrhythmic SCD, mostly in young adult women. Fibrosis of the papillary muscles and inferobasal left ventricular wall, suggesting a myocardial stretch by the prolapsing leaflet, is the structural hallmark and correlates with ventricular arrhythmias origin. Contrast-enhanced cardiac magnetic resonance may help to identify in vivo this concealed substrate for risk stratification.

Mitral valve prolapse in patients with pure rheumatic mitral stenosis: an angiographic study

Of 122 adult patients suspected of having rheumatic mitral stenosis, 112 fulfilled the hemodynamic and angiographic criteria for pure, isolated mitral stenosis. There were 88 females and 24 males with an age range of 16 to 60 years. The left ventriculograms (30 degrees right anterior oblique) were subjectively assessed for gross bulging of the mitral valve leaflets beyond the mitral fulcrum into the left atrium during a beat with maximal opacification. Seventeen percent of cases had typical evidence of mitral valve prolapse, which is much higher than the 3% to 5% rate reported for the general population. This phenomenon was independent of the patients' age, sex, hemodynamic findings, and/or their underlying cardiac rhythm, thus implying the direct role of rheumatic mitral stenosis in the genesis of secondary mitral valve prolapse.

Histopathologic evidence for cardiomyopathy in a child with mitral valve prolapse

An intriguing relationship between idiopathic mitral valve prolapse (MVP) and cardiomyopathy has been reported in adult cases of MVP. This paper reports a girl with idiopathic MVP, who presented with progressive cardiomegaly and cardiomyopathic findings or, cardiac biopsy; right ventricular endomyocardial biopsy at the age of 15 years showed myocardial hypertrophy, disarray, myocardial degeneration, interstitial fibrosis and endocardial thickening. To our knowledge, this is the first case of idiopathic MVP in childhood that has been shown to have positive biopsy findings for cardiomyopathy.

Coexistence of mitral valve prolapse in a consecutive group of 528 patients with hypertrophic cardiomyopathy assessed with echocardiography

Hypertrophic cardiomyopathy and mitral valve prolapse are both conditions that may be genetically transmitted and incur a risk for sudden cardiac death. Although the small left ventricular cavity and distorted geometry characteristic of hypertrophic cardiomyopathy might suggest a predisposition to mitral valve prolapse, the frequency with which these two entities coexist and the potential clinical significance of such an association are not known. To further define the relation of hypertrophic cardiomyopathy and mitral valve prolapse, 528 consecutive patients with hypertrophic cardiomyopathy were studied by echocardiography. Patients ranged in age from 1 to 86 years (mean 45); 335 (63%) were male. Unequivocal echocardiographic evidence of systolic mitral valve prolapse into the left atrium was identified in only 16 (3%) of the 528 patients. The mitral valve excised at operation from three of the patients had morphologic characteristics of a floppy mitral valve, which was judged to be responsible for the echocardiographic findings. Occurrence of clinically evident atrial fibrillation was common in patients with hypertrophic cardiomyopathy and mitral valve prolapse (9 [56%] of 16). Hence, in a large group of patients with hypertrophic cardiomyopathy, the association of echocardiographically documented mitral valve prolapse was uncommon. The coexistence of mitral valve prolapse in patients with hypertrophic cardiomyopathy appears to predispose such patients to atrial fibrillation.

Papillary muscle traction in mitral valve prolapse: quantitation by two-dimensional echocardiography

Previous angiographic observations in patients with mitral valve prolapse have suggested that superior leaflet displacement results in abnormal superior tension on the papillary muscle tips that causes their superior traction or displacement. It has further been postulated that such tension can potentially affect the mechanical and electrophysiologic function of the left ventricle. The purpose of this study was to confirm and quantitate this phenomenon noninvasively by using two-dimensional echocardiography to determine whether superior displacement of the papillary muscle tips occurs and its relation to the degree of mitral leaflet displacement. Directed echocardiographic examination of the papillary muscles and mitral anulus was carried out in a series of patients with classic mitral valve prolapse and results were compared with those in a group of normal control subjects. Distance from the anulus to the papillary muscle tip was measured both in early and at peak ventricular systole. In normal subjects, this distance did not change significantly through systole, whereas in the patient group it decreased, corresponding to a superior displacement of the papillary muscle tips toward the anulus in systole (8.5 +/- 2.6 vs. 0.8 +/- 0.7 mm; p less than 0.0001). This superior papillary muscle motion paralleled the superior displacement of the leaflets in individual patients (y = 1.0x + 0.8; r = 0.93) and followed a similar time course.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitral valve prolapse, panic disorder, and chest pain

Mitral valve prolapse is a common cardiac disorder that can readily be diagnosed by characteristic auscultatory and echocardiographic criteria. Although many diseases have been associated with mitral valve prolapse, most affected individuals have the primary form of the disorder. Mitral valve prolapse is an inherited condition commonly associated with myxomatous degeneration of the mitral valve and its support structures. Complications of mitral valve prolapse, including cardiac arrhythmias, sudden death, infective endocarditis, severe mitral regurgitation (with or without chordae tendineae rupture), and cerebral ischemic events, occur infrequently considering the wide prevalence of the disorder. Panic disorder is a specific type of anxiety disorder characterized by at least three panic attacks within a 3-week period or one panic attack followed by fear of subsequent panic attacks for at least 1 month. It too is a common condition with a prevalence and age and gender distribution similar to that of mitral valve prolapse. Panic disorder and mitral valve prolapse share many nonspecific symptoms, including chest pain or discomfort, palpitations, dyspnea, effort intolerance, and pre-syncope. Chest pain is the symptom in both conditions that most commonly brings the patient to medical attention. The clinical description of chest pain in patients with mitral valve prolapse is highly variable, possibly reflecting multiple etiologies. Chest pain in panic disorder is usually characterized as atypical angina pectoris and as such bears resemblance to the chest pain commonly described by patients with mitral valve prolapse. Multiple investigative attempts to elucidate the mechanism of chest pain in both conditions have failed to identify a unifying cause. Review of the literature leaves little doubt that mitral valve prolapse and panic disorder frequently co-occur. Given the similarities in their symptomatology, a high rate of co-occurrence is, in fact, entirely predictable. There is, however, no convincing evidence of a cause-effect relationship between the two disorders, nor has a single pathophysiologic or biochemical mechanism been identified that unites these two common conditions. Until specific biologic markers for these disorders are identified, it may be impossible to do so. The lack of a proven cause-and-effect relationship between mitral valve prolapse and panic disorder and the absence of a unifying mechanism do not diminish the clinical significance of the high rate of co-occurrence between the two conditions. Primary care physicians and cardiologists frequently encounter patients with mitral valve prolapse and nonspecific symptoms with no discernible objective cause who fail to respond to beta-blockade. Panic disorder should be considered as a possible explanation for symptoms in such patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Simultaneous occurrence of mitral valve prolapse and systolic anterior motion in hypertrophic cardiomyopathy

This report describes the simultaneous occurrence of mitral valve prolapse (MVP) and systolic anterior motion (SAM) in hypertrophic cardiomyopathy (HC). In 25 patients (aged 7 to 62 years, mean 29), 15 (60%) of whom were male, distal portions of the anterior or posterior mitral leaflets approached or made midsystolic contact with the ventricular septum, whereas the proximal portion of the mitral leaflets showed marked cephalad excursion into the left atrium, 5 to 15 mm beyond the mitral annular plane. Three mitral valves that were available for gross visual inspection were not morphologically typical of patients with primary MVP. Clinical features and natural history (1 to 14 years [mean 6] of follow-up), cardiac dimensions, and distribution of left ventricular hypertrophy defined in the study patients did not appear to differ distinctly from those in the overall referral population of patients with HC evaluated at our institution. Hence, patients with HC may show a striking pattern of mitral valvular motion involving SAM into the left ventricular outflow tract, as well as MVP; this prolapse motion is probably due to anatomic disproportion between the mitral valve and the small left ventricular cavity rather than to the coexistence of 2 separate disease entities. Such patients further define the great diversity evident within the broad clinical spectrum of HC.

Acute mitral regurgitation due to short periods of ischemia during percutaneous transluminal coronary angioplasty: an angiographic study

The frequency and severity of mitral regurgitation were investigated during a short period of ischemia (60 seconds) in patients undergoing elective percutaneous transluminal coronary angioplasty of single vessel disease. Thirty patients showed stenoses in the left anterior descending artery, 3 patients in the circumflex artery and 1 patient in the right coronary artery. Only patients with global and regional normal left ventricular function, and without collaterals reaching or filling the target vessel, were enrolled in the study. All patients suffered pain during occlusion of the vessel. Signs of mitral regurgitation of grade 1 could be documented angiographically in 9 patients and of grade 2 in 4 patients. In no patient mitral regurgitation of grades 3 or 4 was seen. A highly significant (P less than 0.001) decrease of global, as well as regional, left ventricular function could be documented during ischemia in all patients. The breakdown of wall motion was more pronounced in patients with mitral regurgitation, and reached statistical significance (P less than 0.05) in the apical and anterolateral segments. All patients with mitral regurgitation showed extended severely hypokinetic or akinetic wall segments adjacent to the anterior papillary muscle. There were no angiographic signs of mitral valvar prolapse or dilation of the mitral annulus. We concluded that transient mitral regurgitation is common during short periods of ischemia in humans, but of only minimal degree in the setting of single vessel disease. The mechanism is different from mechanisms in chronic ischemic incompetence of the mitral valve.

Nonischemic ventricular tachycardia. Clinical course and long-term follow-up in patients without clinically overt heart disease

This report describes the clinical, laboratory, and electrophysiologic features of 52 patients with ventricular tachycardia (VT) who had no clinical evidence of heart disease. The mean age of patients was 36 years, cardiovascular collapse occurred in 18 patients (35%), and exercise-related symptoms were present in 24 of 49 patients (49%). There were 20 patients with sustained monomorphic VT, 11 with incessant VT, and 21 with nonsustained VT. Abnormalities were present in 14 of 38 patients (37%) during echocardiography and in 21 of 47 patients (45%) who underwent cardiac catheterization. During baseline evaluation while patients were not receiving antiarrhythmic drugs, ambulatory monitoring and exercise testing showed an 88% and 57% incidence, respectively, of nonsustained or sustained monomorphic VT, whereas 31 of 50 patients (62%) had inducible VT (requiring an infusion of isoproterenol in 11 patients) during programmed electrical stimulation. The clinical VT (when a 12-lead electrocardiogram was available for analysis) had a left bundle branch block (LBBB) configuration in 20 of 33 patients (61%) and a right axis deviation in 17 of 33 patients (51%). The VT occurring during exercise testing and programmed electrical stimulation had the same configuration as the clinical VT in 22 of 22 patients. Three patients have received an antitachycardia pacemaker, and one patient underwent endocardial resection. Forty-eight patients (92%) were treated medically. One patient died of cancer; the remaining 47 patients were alive at a mean follow-up of 96 months after initial symptoms and 46 months after programmed electrical stimulation. We conclude that in patients without clinical evidence of heart disease, VT may be incessant, sustained, or nonsustained and that VT originates from the right ventricular outflow tract in more than 50% of patients. Although cardiac abnormalities may be found in more than 30% of patients, the exact significance of these abnormalities is unclear because of the absence of progressive changes and the excellent prognosis of this group of patients.

Mitral valve prolapse

Mitral valve prolapse is a common mitral valve disorder manifested clinically as a midsystolic click and/or a late systolic murmur (the click-murmur syndrome) and pathologically as billowing or prolapsing mitral leaflets (the floppy valve syndrome). Not only is it one of the two most common congenital heart diseases and the most common valve disorder diagnosed in the United States, but it is also prevalent throughout the world. Mitral valve prolapse may be associated with a variety of other conditions or diseases. Diagnosis of mitral valve prolapse should be made on clinical grounds and, if necessary, supported by echocardiography. The majority of patients with mitral valve prolapse suffer no serious sequelae. However, major complications such as disabling angina-like chest pains, progressive mitral regurgitation, infective endocarditis, thromboembolism, serious arrhythmias, and sudden death may occur. Unless these serious complications occur, most of the patients with mitral valve prolapse need no treatment other than reassurance, including those with atypical chest pain or palpitation unconfirmed by objective data. Therapy with a beta-blocker for disabling chest pain and/or arrhythmias and antiplatelet therapy for cerebral embolic events may be indicated. In occasional patients with significant mitral regurgitation surgery may be necessary.

Surgical pathology of the mitral valve: a study of 712 cases spanning 21 years

The gross surgical pathologic features of the mitral valve were reviewed in 712 patients who had undergone mitral valve replacement at our institution during 1965, 1970, 1975, 1980, and 1985. Among the 452 cases of mitral stenosis, either with or without mitral insufficiency, 99% were attributable to postinflammatory disease and 1% were related to congenital mitral stenosis. Among the 260 cases of pure mitral regurgitation, the two most common causes were a floppy valve (38%) and postinflammatory disease (31%). Moreover, a floppy valve was observed in 73% of the 59 examples of chordal rupture and in 38% of the 16 cases of infective endocarditis. Women accounted for 73% of the 452 cases of mitral stenosis and for 72% of the 530 cases of postinflammatory disease. In contrast, men accounted for 58% of the 260 cases of pure mitral regurgitation, including 76% of the floppy valves and 69% of the infected valves. During the 21 years spanned by the study, the relative frequency of postinflammatory mitral insufficiency progressively decreased, whereas that of floppy mitral valves increased. It is unclear whether aging, heredity, environmental factors, changes in the frequency of acute rheumatic fever, or changes in patient referral practices may account for this observation.