Editorial Note
The Syndrome of Mitral Valve Prolapse: Problems and Perspectives THE CLINICAL MANIFESTATIONS of the mitral valve prolapse syndrome, which was long thought to be an obscure, infrequently encountered disorder, have become recognized with increasing frequency. Auscultatory abnormalities of mitral valve prolapse have been recognized, for example, in as many as 17% of asymptomatic female patients during screening examinations ( 1 ) . Indeed, so frequently has auscultatory, echocardiographic, or cineangiographic evidence of the syndrome been found in asymptomatic persons without other evidence of heart disease, that clinical significance of the abnormalities thus detected has come into question. Nevertheless severe complications, presumably related to mitral valve prolapse, have been seen to occur in patients with clinical evidence of the syndrome. In this issue (pp. 453-457), Leichtman and associates report another complication with major therapeutic and prognostic significance: symptomatic and potentially fatal bradycardia. So benign were the findings on examination and the subsequent course of the initial patients with the syndrome of mitral valve prolapse that the characteristic auscultatory findings of midsystolic click and late systolic murmur were originally thought to be extracardiac in origin ( 2 ) . Only in 1965 were the midsystolic click and late systolic murmur identified as representing mitral regurgitation secondary to prolapse or herniation of the mitral valve leaflets into the left atrium during systole ( 3 ) . Subsequently, patients with these auscultatory findings were frequently recognized also to manifest a variety of cardiac symptoms, electrocardiographic abnormalities including cardiac arrhythmias, and disturbances of left ventricular contractile pattern, and to be susceptible to catastrophic events such as sudden death and bacterial endocarditis. Thus, only recently has mitral
prolapse been seen to be not as benign a condition as originally believed. Echocardiography has provided an atraumatic method to establish the diagnosis. With the greater use of cineangiography in management of patients having cardiac symptoms, the syndrome could be recognized in patients with the atypical pansystolic murmur or even total absence of auscultatory abnormalities (so-called "silent mitral prolapse") ( 4 ) . The use of echocardiography and cineangiography, however, also brought questions as to the sensitivity and specificity of the various manifestations observed during these examinations. This problem was soon compounded by the frequent finding of asymptomatic persons with evidence of mitral valve prolapse only by auscultation, or ultrasound, or cineangiography, but not by all three methods. Further, agreement has not been reached as to precisely which findings with any of these methods unequivocally identify the presence of mitral prolapse. Thus, with the lack of unequivocal diagnostic standards, the clinical significance of the syndrome remains unclear. That at least some patients are at increased risk to develop serious manifestations of cardiac disease is indisputable. Previous studies have documented the occurrence of subacute bacterial endocarditis and torn chordae tendineae. Mitral valve replacement has been needed because of severe mitral regurgitation, even without the aforementioned abnormalities. The complication of greatest concern is, however, sudden death presumably related to the presence of arrhythmias. In this regard a 13% occurrence of sudden death was reported in one 10-year longitudinal study of 40 symptomatic patients with mitral prolapse with obvious auscultatory findings and a high prevalence of electrocardiographic abnormalities ( 5 ) . Cardiac arrhythmias have long been recognized as commonly occurring in the syndrome, and supraventricular and ventricular tachyarrhythmias were among the earliest Editorials
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features of this disorder to be described. A recent study has shown that arrhythmias occur more commonly in patients with mitral prolapse than in normal persons and that such arrhythmias may occur in a variable spectrum including bradyarrhythmias as well as tachyarrhythmias (6). The study reported in this issue confirms bradyarrhythmias in the syndrome and provides evidence that such rhythm disturbances may significantly impair hemodynamic function so as to result in syncope and, possibly, sudden death. In addition, the findings suggest that the bradycardia is consequent to an increase in vagal tone rather than to an intrinsic cardiac abnormality. Thus the severity of the arrhythmia may not be related to the severity of mitral prolapse. As with the complications previously described, the exact frequency with which severe symptomatic bradyarrhythmias occur remains uncertain. Nevertheless the physician must look for such potentially lethal rhythm disturbances in all patients with clinical evidence of the syndrome. Clearly the prevalence, clinical significance, and prognosis of the mitral valve prolapse syndrome are still not known with certainty. The major unanswered question is the frequency with which the various auscultatory, echographic, and cineangiographic abnormalities are associated with the known complications. This question remains an important one for study. Similarly, whereas the indications for mitral valve replacement in the presence of severe regurgitations and for pacemaker implants for symptomatic bradyarrhythmias are obvious, the roles for antiarrhythmic
526
therapy and antibiotic prophylaxis for bacterial endocarditis need to be clarified further. Significant complications associated with mitral prolapse will probably be found to occur mainly in those patients with definite abnormalities observable by all diagnostic methods including auscultation, echocardiography, and cineangiography. For the present, the progressively increasing list of major forms of cardiac dysfunction associated with the syndrome of mitral valve prolapse warrants the close evaluation of all patients with its clinical manifestations. (ANTHONY N. DEMARIA,
M.D.; Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis; Davis, California) References 1. MARKIEWICZ W, STONER J, LONDON E, et al: Mitral valve pro-
lapse in one hundred presumably healthy young females. Circulation 53:464-473, 1976 2. GALLAVARDIN L: Pseudo-dedoublement du deuxieme bruit du coeur simulant le dedoublement mitral. Par bruit extracardiaque telesystolique surajoute. Lyon Med 121:409-422, 1913 3. CRILEY JM, LEWIS KB, HUMPHRIES JO, et al: Prolapse of the
mitral valve: clinical and cine-angiographic findings. Br Heart J 28:488-496, 1966 4. DEMARIA AN, KING JF, BOGREN HG, et al: The variable spec-
trum of echocardiographic manifestations of the mitral valve prolapse syndrome. Circulation 50:33-41, 1974 5. KOCH FH, HANCOCK EW: Ten year follow-up of forty patients with the mid-systolic click/late systolic murmur syndrome. Am J Cardiol 37:149, 1976 6. DEMARIA AN, AMSTERDAM EA, VISMARA LA, et al: Arrhyth-
October 2976 • Annals of Internal Medicine • Volume 85 • Number 4
Downloaded from https://annals.org by Tulane University user on 01/17/2019
mias in the mitral valve prolapse syndrome. Prevalence, and frequency. Ann Intern Med 84:656-660, 1976
nature
The Syndrome of Mitral Valve Prolapse: Problems and Perspectives THE CLINICAL MANIFESTATIONS of the mitral valve prolapse syndrome, which was long thought to be an obscure, infrequently encountered disorder, have become recognized with increasing frequency. Auscultatory abnormalities of mitral valve prolapse have been recognized, for example, in as many as 17% of asymptomatic female patients during screening examinations ( 1 ) . Indeed, so frequently has auscultatory, echocardiographic, or cineangiographic evidence of the syndrome been found in asymptomatic persons without other evidence of heart disease, that clinical significance of the abnormalities thus detected has come into question. Nevertheless severe complications, presumably related to mitral valve prolapse, have been seen to occur in patients with clinical evidence of the syndrome. In this issue (pp. 453-457), Leichtman and associates report another complication with major therapeutic and prognostic significance: symptomatic and potentially fatal bradycardia. So benign were the findings on examination and the subsequent course of the initial patients with the syndrome of mitral valve prolapse that the characteristic auscultatory findings of midsystolic click and late systolic murmur were originally thought to be extracardiac in origin ( 2 ) . Only in 1965 were the midsystolic click and late systolic murmur identified as representing mitral regurgitation secondary to prolapse or herniation of the mitral valve leaflets into the left atrium during systole ( 3 ) . Subsequently, patients with these auscultatory findings were frequently recognized also to manifest a variety of cardiac symptoms, electrocardiographic abnormalities including cardiac arrhythmias, and disturbances of left ventricular contractile pattern, and to be susceptible to catastrophic events such as sudden death and bacterial endocarditis. Thus, only recently has mitral
prolapse been seen to be not as benign a condition as originally believed. Echocardiography has provided an atraumatic method to establish the diagnosis. With the greater use of cineangiography in management of patients having cardiac symptoms, the syndrome could be recognized in patients with the atypical pansystolic murmur or even total absence of auscultatory abnormalities (so-called "silent mitral prolapse") ( 4 ) . The use of echocardiography and cineangiography, however, also brought questions as to the sensitivity and specificity of the various manifestations observed during these examinations. This problem was soon compounded by the frequent finding of asymptomatic persons with evidence of mitral valve prolapse only by auscultation, or ultrasound, or cineangiography, but not by all three methods. Further, agreement has not been reached as to precisely which findings with any of these methods unequivocally identify the presence of mitral prolapse. Thus, with the lack of unequivocal diagnostic standards, the clinical significance of the syndrome remains unclear. That at least some patients are at increased risk to develop serious manifestations of cardiac disease is indisputable. Previous studies have documented the occurrence of subacute bacterial endocarditis and torn chordae tendineae. Mitral valve replacement has been needed because of severe mitral regurgitation, even without the aforementioned abnormalities. The complication of greatest concern is, however, sudden death presumably related to the presence of arrhythmias. In this regard a 13% occurrence of sudden death was reported in one 10-year longitudinal study of 40 symptomatic patients with mitral prolapse with obvious auscultatory findings and a high prevalence of electrocardiographic abnormalities ( 5 ) . Cardiac arrhythmias have long been recognized as commonly occurring in the syndrome, and supraventricular and ventricular tachyarrhythmias were among the earliest Editorials
Downloaded from https://annals.org by Tulane University user on 01/17/2019
525
features of this disorder to be described. A recent study has shown that arrhythmias occur more commonly in patients with mitral prolapse than in normal persons and that such arrhythmias may occur in a variable spectrum including bradyarrhythmias as well as tachyarrhythmias (6). The study reported in this issue confirms bradyarrhythmias in the syndrome and provides evidence that such rhythm disturbances may significantly impair hemodynamic function so as to result in syncope and, possibly, sudden death. In addition, the findings suggest that the bradycardia is consequent to an increase in vagal tone rather than to an intrinsic cardiac abnormality. Thus the severity of the arrhythmia may not be related to the severity of mitral prolapse. As with the complications previously described, the exact frequency with which severe symptomatic bradyarrhythmias occur remains uncertain. Nevertheless the physician must look for such potentially lethal rhythm disturbances in all patients with clinical evidence of the syndrome. Clearly the prevalence, clinical significance, and prognosis of the mitral valve prolapse syndrome are still not known with certainty. The major unanswered question is the frequency with which the various auscultatory, echographic, and cineangiographic abnormalities are associated with the known complications. This question remains an important one for study. Similarly, whereas the indications for mitral valve replacement in the presence of severe regurgitations and for pacemaker implants for symptomatic bradyarrhythmias are obvious, the roles for antiarrhythmic
526
therapy and antibiotic prophylaxis for bacterial endocarditis need to be clarified further. Significant complications associated with mitral prolapse will probably be found to occur mainly in those patients with definite abnormalities observable by all diagnostic methods including auscultation, echocardiography, and cineangiography. For the present, the progressively increasing list of major forms of cardiac dysfunction associated with the syndrome of mitral valve prolapse warrants the close evaluation of all patients with its clinical manifestations. (ANTHONY N. DEMARIA,
M.D.; Section of Cardiovascular Medicine, Department of Internal Medicine, School of Medicine, University of California, Davis; Davis, California) References 1. MARKIEWICZ W, STONER J, LONDON E, et al: Mitral valve pro-
lapse in one hundred presumably healthy young females. Circulation 53:464-473, 1976 2. GALLAVARDIN L: Pseudo-dedoublement du deuxieme bruit du coeur simulant le dedoublement mitral. Par bruit extracardiaque telesystolique surajoute. Lyon Med 121:409-422, 1913 3. CRILEY JM, LEWIS KB, HUMPHRIES JO, et al: Prolapse of the
mitral valve: clinical and cine-angiographic findings. Br Heart J 28:488-496, 1966 4. DEMARIA AN, KING JF, BOGREN HG, et al: The variable spec-
trum of echocardiographic manifestations of the mitral valve prolapse syndrome. Circulation 50:33-41, 1974 5. KOCH FH, HANCOCK EW: Ten year follow-up of forty patients with the mid-systolic click/late systolic murmur syndrome. Am J Cardiol 37:149, 1976 6. DEMARIA AN, AMSTERDAM EA, VISMARA LA, et al: Arrhyth-
October 2976 • Annals of Internal Medicine • Volume 85 • Number 4
Downloaded from https://annals.org by Tulane University user on 01/17/2019
mias in the mitral valve prolapse syndrome. Prevalence, and frequency. Ann Intern Med 84:656-660, 1976
nature
