Observer variation in the angiocardiographic diagnosis of mitral valve prolapse

Mitral valve prolapse:--the facts

Mitral Valve Prolapse does not cause chest pain or other symptoms and is extremely unlikely to give rise to complications. In practice it is difficult to differentiate a 'prolapsing' valve from one that is 'normal' no matter what methods are used. Since diagnosing 'heart disease' is itself a well known cause of ill health, the most stringent criteria must be adopted before the mitral valve is labelled as being abnormal. The need for the diagnosis at all is, in most cases, doubtful.

The relationship of mitral annular shape to the diagnosis of mitral valve prolapse

The geometric or anatomic diagnosis of mitral valve prolapse, as opposed to the pathologic diagnosis of myxomatous valve disease, is based on the relationship of the mitral leaflets to the surrounding anulus. Current echocardiographic criteria for this diagnosis include leaflet displacement above the annular hinge points in any two-dimensional view; implicit in this equivalent use of intersecting views is the assumption that the mitral anulus is a euclidean plane. Prolapse by these criteria is found in a surprisingly large proportion of the general population. In most of these individuals, however, prolapse is present in the apical four-chamber view and absent in roughly orthogonal long-axis views of the left ventricle. This frequently observed discrepancy between leaflet-annular relationships in intersecting views suggests an underlying geometric property of the mitral apparatus that would produce the appearance of prolapse in one view without actual leaflet distortion. To address this possibility, a model of the mitral valve and anulus was constructed. When the model anulus was given a nonplanar, saddle-shaped configuration, the clinical observations were reproduced: the leaflets appeared to lie above the low points of the anulus in one plane, and below its high points in a perpendicular plane. Therefore, the appearance of mitral valve prolapse can occur without actual leaflet displacement above the most superior points of the mitral anulus if the anulus is nonplanar. To determine whether this pattern is reflected in the human mitral anulus, two-dimensional echocardiographic views of the mitral apparatus were obtained by rotation about the cardiac apex in 20 patients without evident annular or rheumatic valvular disease. In all cases the mitral anulus, as reconstructed from these views, had a nonplanar systolic configuration, with high points located anteriorly and posteriorly. This is consistent with the findings of other groups in animals, and would favor the appearance of prolapse in the four-chamber view and its absence in long-axis views that are oriented anteroposteriorly. This model can therefore explain the frequently observed discrepancy between leaflet-annular relationships in roughly orthogonal views. It challenges the assumption that the mitral anulus is planar as well as the diagnosis of prolapse in many otherwise normal individuals based on that assumption.

Observer variation in the echocardiographic diagnosis of mitral valve prolapse

To assess inter- and intraobserver variation in the echocardiographic diagnosis of mitral valve prolapse, three independent observers analyzed M-mode echocardiograms (n = 80) and two-dimensional echocardiograms (n = 65) of patients with a mobile midsystolic click with or without a late or holosystolic murmur. In addition, a control group of 100 normal echocardiograms were interspersed among the echocardiograms of patients with mitral valve prolapse and were then interpreted. Each of the three observers analyzed all M-mode and two-dimensional echocardiograms initially and then 2 weeks later for the presence or absence of mitral valve prolapse. M-mode echocardiographic criteria for mitral valve prolapse consisted of late systolic posterior motion (greater than or equal to 3 mm) of one or both mitral leaflets or holosystolic hammocking (greater than or equal to 3 mm) of one or both mitral leaflets. Two-dimensional echocardiographic criteria for mitral valve prolapse consisted of: posterior systolic arching of one or both mitral leaflets in the parasternal long-axis view, and/or posterior systolic bowing of one or both mitral leaflets in the apical four-chamber view posterior to the plane of the mitral anulus, and/or excessive posterior coaptation of the mitral leaflets in either view flush with or posterior to the plane of the mitral anulus. There was insignificant observer variation both in the M-mode and two-dimensional echo groups, as determined using Cochran's Q test.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrocardiography and echocardiography in patients with chest pain and mitral leaflet prolapse

34 patients with catheter verified, haemodynamically trivial mitral leaflet prolapse with chest pain and normal coronary arteries were studied. Nineteen had no auscultatory signs of MLP despite clear catheter or echocardiographic evidence of prolapse. Infero-lateral repolarisation changes on the resting electrocardiogram were present in 29%. 50% had false positive exercise tests. M-mode echocardiography proved diagnostically disappointing but sector scans revealed mitral leaflet prolapse in 62%. The apical 4 chamber acoustic window was markedly superior to the parasternal long axis acoustic window.

Diagnostic precision of echocardiography in mitral valve prolapse

In order to determine the precision with which currently used echocardiographic criteria can be applied for the diagnosis of mitral valve prolapse, three independent observers (A, B, and C) blindly analyzed the separate M-mode and two-dimensional echocardiograms of 50 patients, 27 of whom had previously been identified clinically as having echocardiographic evidence of prolapse. Observer A's intraobserver repeatability for M-mode echocardiography was 92%, Observer B's was 84%, and Observer C's was 90%. For two-dimensional echocardiography, Observer A's intraobserver repeatability was 98%, Observer B's was 80%, and Observer C's was 82%. We believe that the variability in intraobserver repeatability is related to the frequency with which individual observers diagnosed prolapse. The interobserver repeatability for M-mode echocardiography for Observer A versus B was 64%, for Observer A versus C it was 80%, and for Observer B versus C it was 66%. The interobserver repeatability for two-dimensional echocardiography for Observer A versus B was 54%, for Observer A versus C it was 70%, and for Observer B versus C it was 52%. There was no significant difference between the inter- and intraobserver variability of M-mode versus two-dimensional echocardiography. Review of cases in which readings were discrepant revealed that these cases usually had relatively mild changes. Clinicians should be aware of the inherent variability of echocardiographic interpretation when they make a diagnosis of mitral valve prolapse.

Angiographic diagnosis of posterior mitral valve leaflet prolapse

The left ventricular cineangiograms of 22 asymptomatic, apparently healthy male aviators without noninvasive (echocardiographic or auscultatory) evidence of mitral valve prolapse were reviewed and compared with those of 12 men with noninvasive evidence of mild mitral valve prolapse. The maximal protrusion of the posterior mitral valve leaflet superior and posterior to a line perpendicular to the long axis of the left ventricle at end-systole was measured from the right anterior oblique left ventricular cineangiogram by repeated observation of left ventricular inflow. The values were 7.5 +/- 1.6 mm in patients without mitral valve prolapse and 11.2 +/- 3.4 mm in patients with mitral valve prolapse (mean +/- 1 standard deviation). This measurement did not exceed 11 mm in any patient without prolapse. It is concluded that: 1) with meticulous attention to angiographic landmarks of the left ventricular inflow area, the limits of normal systolic posterior mitral leaflet motion can be defined; and 2) systolic motion outside these limits constitutes a quantitative criterion for the angiographic diagnosis of mitral valve prolapse.

Mitral valve prolapse. Cross sectional and provocative M-mode echocardiography

False-negative supine M-mode echocardiograms occur in some patients with proved mitral valve prolapse. To investigate further, we performed M-mode echocardiography (MME) during standing and after the inhalation of amyl nitrite in 17 patients (group 1) selected for auscultatory evidence of mitral valve prolapse (MVP) but negative supine MME. To validate the standing MME technique, eight patients with classic auscultatory MVP with positive supine MME for MVP (group 2) and 15 control subjects (group 3) were studied. Supine cross-sectional echocardiography (CSE) was compared to MME in all three groups. Standing MME elicited echocardiographic evidence of MVP in 14/17 (82 percent) of group 1--auscultatory evidence of MVP but negative supine MME; CSE demonstrated MVP in 8/13 (62 per cent) of the same patients. There was no clear advantage of the CSE long axis view over the CSE apical four chamber view in the diagnosis of MVP in these selected subjects; however, the two views were complementary. Amyl nitrite was ineffective in eliciting echocardiographic evidence of MVP.