Mitral valve prolapse and bacterial endocarditis: when is antibiotic prophylaxis necessary?

Mitral valve prolapse and Marfan syndrome

Marfan syndrome is a multisystemic genetic condition affecting connective tissue. It carries a reduced life expectancy, largely dependent on cardiovascular complications. More common cardiac manifestations such as aortic dissection and aortic valve incompetence have been widely documented in the literature. Mitral valve prolapse (MVP), however, has remained poorly documented. This article aims at exploring the existing literature on the pathophysiology and diagnosis of MVP in patients with Marfan syndrome, defining its current management and outlining the future developments surrounding it.

Mitral Valve Prolapse in Pregnancy

Mitral valve prolapse is a benign condition. Mitral regurgitation is only complicated in patients with severe mitral valve prolapse. Women with mitral valve prolapse in the absence of other cardiovascular disorders tolerate pregnancy well and do not develop remarkable cardiac complications. Nevertheless, serious complications of mitral valve prolapse, including arrhythmia, infective endocarditis and cerebral ischemic events, can be present in pregnancy. Debates remain with regard to the use of prophylactic antibiotics and β-blockers in the pregnant women with mitral valve prolapse. The prognosis of the pregnant patients might be closely related to the pathological and (or) functional changes of the mitral valve. Non-myxomatous mitral valve prolapse poses no or little obstetric risks in terms of pregnancy, labor and neonatal complications; whereas myxomatous mitral valve prolapse is a major etiology of valvular heart disease in women of childbearing age. In the pregnant patients with mitral valve prolapse progressing into major complications, surgical interventions are considered. Medicinal treatment of such patients with β-blockers should be a concern for the fetal safety.

Incidence and Predictors of Infective Endocarditis in Mitral Valve Prolapse: A Population-Based Study

OBJECTIVE

To determine the incidence and predictors of infective endocarditis (IE) in a population-based cohort of patients with mitral valve prolapse (MVP).

PATIENTS AND METHODS

We identified all adult Olmsted County residents with MVP diagnosed by echocardiography from January 1989 to December 1998 and cross-matched them with the Rochester Epidemiology Project-identified Olmsted County cases of IE from January 1, 1986, through December 31, 2006. We retrospectively analyzed and de novo confirmed each IE case using the modified Duke criteria.

RESULTS

There were 896 Olmsted County residents with echocardiographically diagnosed MVP (mean age, 53±21 years; 565 women [63%]). The mean follow-up period was 11±5 years. The 15-year cohort risk of IE after MVP diagnosis was 1.1%±0.4% (incidence, 86.6 cases per 100,000 person-years; 95% CI, 43.3-173.2 cases per 100,000 person-years); thus, the age- and sex-adjusted relative risk of IE in patients with MVP was 8.1 (95% CI, 3.6-18.0) in comparison to the general population of Olmsted County (P<.001). There were no IE cases in patients without previously diagnosed mitral regurgitation (MR). Conversely, IE incidence was higher in patients with MVP with moderate, moderate-severe, or severe MR (289.5 cases per 100,000 person-years; 95% CI, 108.7-771.2 cases per 100,000 person-years; P=.02 compared with trivial, mild, or mild-moderate MR) and in patients with a flail mitral leaflet (715.5 cases per 100,000 person-years; 95% CI, 178.9-2861.0 cases per 100,000 person-years; P=.02 compared with no flail mitral leaflet).

CONCLUSION

The population-based incidence of IE in adults with MVP is higher than those previously reported in case-control, tertiary care center studies. Patients with MVP and moderate, moderate-severe, or severe MR or a flail mitral leaflet are at a notable risk of developing IE in comparison with those without MR.

High occurrence of mitral valve prolapse in cardiac catheterization patients with pure isolated mitral regurgitation

The aetiological spectrum of angiographically verified pure isolated mitral regurgitation (MR) was studied in 48 consecutive adult patients (35 males). Severe MR was found in 35 patients (73%) and moderate MR in 13 patients (27%). Mitral valve prolapse (MVP) syndrome was found in 21 patients (44%). These were younger than the rest of the study population (55 +/- 13 vs. 62 +/- 6 years, p less than 0.05) and 15 (71%) of them were men. Endocarditis and chordal rupture occurred in 19% and 43% of the MVP patients. Sixteen patients (33%) had MR secondary to myocardial infarction while only three patients (6%) had MR of rheumatic aetiology. Bacterial endocarditis, hypertensive heart disease, hypertrophic obstructive cardiomyopathy and mitral annulus calcification were less frequently found. Mitral valve replacement was done in 20 (57%) of the patients with severe MR and MVP was the underlying disease in 15 (75%) of these patients. In conclusion, MVP is a frequent cause of pure isolated MR and of mitral valve replacement. In contrast to the preponderance of young females amongst MVP patients in population surveys, most of the MVP patients with MR in this study are middle-aged and elderly men.

Incidence of, risk factors for, clinical presentation, and 1-year outcomes of infective endocarditis in an urban HIV cohort

BACKGROUND

Previous studies described infective endocarditis (IE) in the era before highly active antiretroviral therapy (HAART); however, IE has not been well studied in the current HAART era. We evaluated the incidence of, risk factors for, clinical presentation, and 1-year outcomes of IE in HIV-infected patients.

METHODS

We evaluated all cases of IE diagnosed between 1990 and 2002 in patients followed at the Johns Hopkins Hospital outpatient HIV clinic. To identify factors associated with IE in the current era of HAART, a nested case-control analysis was employed for all initial episodes of IE occurring between 1996 and 2002. Logistic regression analyses were used to assess risk factors for IE and factors associated with 1-year mortality.

RESULTS

IE incidence decreased from 20.5 to 6.6 per 1000 person-years (PY) between 1990 and 1995 and 1996 and 2002. The majority of IE cases were male (66%), African American (90%), and injection drug users (IDUs) (85%). In multivariate regression, an increased risk of IE occurred in IDUs (AOR, 8.71), those with CD4 counts <50 cells/mm, and those with HIV-1 RNA >100,000 copies/mL (AOR, 3.88). Common presenting symptoms included fever (62%), chills (31%), and shortness of breath (26%). The most common etiologic organism was Staphylococcus aureus (69%; of these 11 [28%] were methicillin resistant). Within 1 year, 16% had IE recurrence, and 52% died. Age over 40 years was associated with increased mortality.

CONCLUSIONS

IE rates have decreased in the current HAART era. IDUs and those with advanced immunosuppression are more likely to develop IE. In addition, there is significant morbidity and 1-year mortality in HIV-infected patients with IE, indicating the need for more aggressive follow-up, especially in those over 40 years of age. Future studies investigating the utility of IE prophylaxis in HIV patients with a history of IE may be warranted.

Dentistry and endocarditis

Bacterial endocarditis (BE), a rare heart infection caused by a bacteremia, has frequently been blamed on but rarely caused by dental procedures. Viridans group streptococci are found abundantly in the mouth and the gingival sulcus but have been surpassed by staphylococci as the leading cause of BE. Antibiotic prophylaxis has been recommended before dental procedures in patients at risk for BE, but it remains controversial because studies have failed to show that antibiotic prophylaxis is an effective preventive for BE or that dental procedures are an important cause of BE. The risks and costs of antibiotic prophylaxis, including antibiotic resistance, cross-reactions with other drugs, allergy, anaphylaxis, and even death, may exceed the benefits in preventing BE. The rationale for the use of antibiotic prophylaxis to prevent BE allegedly caused by dental procedure bacteremias must be seriously reexamined based on recent evidence, particularly the absolute risk rates for endocarditis after a given dental procedure.

The changing profile of bacterial endocarditis as seen at an australian provincial centre

BACKGROUND

The clinical profile of endocarditis has changed over the past four decades with studies showing trends towards increasing age, more nosocomial and prosthetic valve infection and increasing rates of Staphylococcus aureus infection. However, these studies have been biased by referral patterns.

METHODS

We reviewed data collected at three hospitals in the Barwon-South-West region in Victoria, Australia. All cases identified between 1994 and 1999 were reviewed according to the Duke criteria.

RESULTS

During this period, 58 patients were diagnosed as having endocarditis. The incidence rate during this time was 3.0 per 100 000 with a rise in the rate of admissions from 0.15 to 0.26 per 1000 from 1995 to 1999. Sixteen (28%) were nosocomial with the majority from line-related sepsis. No intravenous drug users were identified. Eighteen (31%) involved endovascular prosthetic material. S. aureus was the causative pathogen in 23 (40%), with 'viridans' streptococci contributing 12 (21%) and other organisms accounting for 12 (21%). Attributable mortality in this series was 17%.

CONCLUSIONS

We have seen a rise in the rate of endocarditis during this time. The proportions of endocarditis due to S. aureus and 'viridans' streptococci, as well as rates of nosocomial and prosthetic valve infection, are consistent with more recent series at referral hospitals and district hospitals, representing a change since studies performed in the 1960s and 1970s. Our findings confirm a trend towards a clinical profile seen at referral centres and reinforce the emerging importance of S. aureus, nosocomial bacteraemia and prosthetic valve endocarditis.

Severe mitral regurgitation due to mitral valve prolapse: risk factors for development, progression, and need for mitral valve surgery

Patients with mitral valve prolapse (MVP) may develop severe mitral regurgitation (MR) and require valve surgery. Preliminary data suggest that high body weight and blood pressure might add to the irreversible factors of older age and male gender in increasing risk of these complications. Fifty-four patients with severe MR due to MVP were compared with 117 control subjects with uncomplicated MVP to elucidate factors independently associated with severe MR: the need for valve surgery and the cumulative risk of requiring mitral valve surgery. Patients with severe MR were older (p<0.00005), more overweight (p = 0.002), had higher systolic (p = 0.0003) and diastolic (p = 0.007) blood pressures, and were more likely to have hypertension (p = 0.0001) and to be men (p<0.001). In both groups, men had higher blood pressure and relative body weight than women. In multivariate analysis, older age was most strongly associated with MR; higher body mass index, hypertension, and gender were independent predictors of severe MR in analyses that excluded age. Among the 54 patients with severe MR, the 32 (59%) who underwent mitral valve surgery during 11 years of follow-up were older, more overweight, and more likely to be hypertensive than those not requiring surgery. Among patients undergoing mitral valve surgery in 3 centers, mitral prolapse was the etiology in 25%, 67% of whom were men. Using these data and national statistics, we estimate that the gender-specific cumulative risk for requiring valvular surgery for severe MR in subjects with MVP is 0.8% in women and 2.6% in men before age 65, and 1.4% and 5.5% by age 75. Thus, subjects with MVP who are older, more overweight, and hypertensive are at greater risk for severe MR and valve surgery. Higher blood pressure and relative weight in men with MVP appear to contribute to the gender difference in risk for severe MR.

-Curative and preventive antibiotic therapy in infective endocarditis-

Durack's criteria, including echocardiographic manifestations, are the current standard for the diagnosis of infective endocarditis (IE). The most common microorganisms known to cause IE are streptococci and staphylococci, and therapeutic principles are based on an association of parenteral antibiotics, as far as possible bactericidal and prolonged. Treatment also includes the search for the source of infection and its eradication. IE with negative blood cultures requires special techniques to obtain the causal microorganisms. In about half of the cases, a nosocomial bacteriaemia results in IE in patients with a prosthetic valve. Surgery is mandatory in IE with complications and/or caused by particular microorganisms; surgery is essential in most patients with a prosthetic valve. Although the presence of specific links between some procedures and the occurrence of IE has not been clearly proven, a prevention policy is nevertheless justified, considering the morbidity and mortality. Prophylaxis is indicated in patients with the cardiac conditions at risk for IE. IE prophylaxis prevails over prophylactic antibiotics usually administered for surgery.

Valvular heart disease in pregnancy. A contemporary perspective

Valvular heart disease may have a significant impact on the course and outcome of pregnancy with implications for fetal as well as maternal health. Optimally, serious symptomatic valvular heart disease should be detected and treated before pregnancy. Whether a pregnant woman is known to have valvular heart disease or is diagnosed during pregnancy, it is imperative that she is managed by an experienced multidisciplinary team. Although medical therapy may alleviate symptoms of heart failure in some patients, definitive intervention either with percutaneous balloon valvuloplasty or with surgical valve replacement may be necessary.

Alcohol- and Caffeine-Induced Changes in Mitral Valve Echo Morphology and Auscultation in Healthy Females

Mitral valve prolapse (MVP) is a common cardiac valve abnormality that affects women more frequently than men. We have shown that mild dehydration induces echocardiographic signs of MVP in healthy females more frequently than in males. The present study investigated whether ethanol and caffeine, two commonly used substances, will induce changes in mitral leaflet morphology in normal subjects and whether these changes are gender dependent. Ten healthy volunteers were examined after ingesting 0.95 g/kg ethanol at breath ethanol values of 0.025% +/- 0.005%, 0.050% +/- 0.005%, and 0.075% (peak) +/- 0.005%, and at decreasing ethanol levels of 0.050% +/- 0.005% and 0.025% +/- 0.005%. Twelve healthy subjects were studied at 1.5, 3, and 4.5 hours after ingesting 5 mg/kg body weight of caffeine in a randomized, double-blind, crossover manner. A significant increase in mitral valve shape index (MVSI) on apical four-chamber view was documented in females following ethanol ingestion at all ethanol levels. These changes were accompanied by auscultatory findings characteristic of MVP. Decreased systemic vascular resistance, and afterload and increased heart rate, also occurred after ethanol ingestion. A significant increase in MVSI occurred on parasternal long axis in females at peak caffeine level; auscultatory findings characteristic of MVP also were documented. MVSI increased slightly on apical four-chamber view in males; however, no male subject developed auscultatory MVP. Body mass index was significantly lower in females (20.8 +/- 0.7 kg/m(2)) versus males (23.7 +/- 0.3 kg/m(2), P < 0.05). All subjects lost weight after caffeine intake; afterload and contractility also were increased. This study documents that ethanol and caffeine, at concentrations similar to those present in social intake, induced significant echo changes in mitral leaflet morphology and auscultation suggestive of MVP in healthy females. These results suggest that in addition to apparent hydration state, recent ethanol or caffeine intake should be taken into consideration before making the diagnosis of MVP.

A new causal model of dental diseases associated with endocarditis

Infective endocarditis (IE) is a serious disease that is associated with dental diseases and treatment. The objective of this study was to summarize the epidemiological information about IE and reevaluate previous causal models in light of this evidence. The world biomedical literature was searched from 1930 to 1996 for descriptive and analytic epidemiological studies of IE. Multiple searching strategies were performed on 9 databases, including MEDLINE, CATLINE, and WORLDCAT. Results show that: 1) the incidence of IE varies between 0.70 to 6.8 per 100,000 person-years: 2) the incidence of IE increases 20 fold with advancing age: 3) over 50% of all IE cases are not associated with either an obvious procedural or infectious event 3 months prior to developing symptoms; 4) about 8% of all IE cases are associated with periodontal or dental disease without a dental procedure: 5) the time from the diagnosis of heart valve deformities to the development of IE approaches 20 years: 6) the median time from identifiable procedures to the onset of IE symptoms is about 2 to 4 weeks: 7) the risk of IE after a dental procedure is probably in the range of 1 per 3,000 to 5,000 procedures: and 8) over 80% of all IE cases are acquired in the community, and the bacteria are part of the host's endogenous flora. The synthesis of these data demonstrates that IE is a disorder with the epidemiological picture of a chronic disease such as cancer, instead of an acute infectious disease, with a long latent period and possibly several definable intermediates or stages. A new causal model is proposed that includes early bacteremias that may "prime" the endothelial surface of the heart valves over many years, and a late bacteremia over days to weeks that allows adherence and colonization of the valve, resulting in the characteristic fulminant infection.

Clinical approach to infective endocarditis

The epidemiology of IE has evolved over the past 50 years. Mitral valve prolapse and degenerative valvular disease have replaced rheumatic heart disease as the most common predisposing conditions. The average age of patients with IE has increased, and nosocomially acquired cases are becoming more common. Although viridans streptococci are currently responsible for a smaller proportion of cases than previously, this group of bacteria remains the most common cause of prosthetic value and native valve endocarditis. Staphylococci are the most important cause in some community hospitals, in nosocomial IE, and in IVDUs. IE is a multisystem disease, and patients may present with diverse clinical features. In the absence of direct histopathologic and microbiologic examination of valvular vegetations, the diagnosis of IE depends on the detection of endocardial abnormalities and the isolation of a pathogen from blood. Blood culture remains the most important laboratory test and yields the causative microorganism in 95% of patients. Echocardiography has become an important tool for detecting endocardial lesions. The clinical features of IE in IVDUs are somewhat different than those in other populations. The microbiology is distinctive, and right-sided involvement with septic pulmonary emboli is the most common clinical scenario in this group.

Greek physicians' and dentists' compliance with the British society for antimicrobial chemotherapy (BSAC) guidelines for preventing bacterial endocarditis

Two thousand questionnaires inquiring about applied prophylaxis for bacterial endocarditis were sent to practicing doctors in Greece. Two hundred and ninety-nine questionnaires were completed and returned (15% response rate) and were subsequently divided into two groups: Group A (163) consisting of responses from dentists, chest physicians and ear, nose and throat (ENT) specialists and group B (136) including responses from gastroenterologists, gynecologists, urologists and radiologists. The percentage of correct answers given in response by clinicians in Groups A and B to the main questions and in accordance with the 1992 guidelines of the British Society for Antimicrobial Chemotherapy (BSAC) were respectively: (a) 53% vs 35% asked patients their previous history pertaining to valve disease, rheumatic fever or prosthetic valve surgery; (b) 55% vs 33% administered prophylaxis to patients with relevant history prior to medical procedures; (c) 67% vs 0% of prescribing doctors administered the appropriate antibacterials; (d) 33% vs 31% initiated prophylaxis in proper timing prior to medical procedure; (e) 14% vs 13% administered antibiotics in correct time/route/duration of infusion where applicable, prior to medical procedure; (f) 7% of group A doctors administering recommended antibiotics, implemented prophylaxis with correct time/route/dosage while, although none of group B doctors administered recommended antibiotics, 7% implemented prophylaxis with correct time/route recommendations; (g) an overall 2% of doctors from both groups met the BSAC recommendations. In conclusion, it is imperative that the appropriate training of doctors in all subspecialties regarding prophylaxis of bacterial endocarditis and according to current recommendations be carried out.

Incidence of infective endocarditis in the Delaware Valley, 1988-1990

This population-based study aimed to determine the incidence of native, prosthetic, and bioprosthetic valve nosocomial infective endocarditis (IE), and IE associated with the use of injected drugs. Patients with IE during 27 months over the years 1988 to 1990, and residing in any of 6 counties in the Philadelphia metropolitan area were identified. An expert panel reviewed all patients to verify the diagnosis. Incidence rates were estimated after adjustment for failure to recruit and underreporting. Of 853 potential patients, 670 (79%) met the inclusion criteria. The overall incidence rate of IE was 11.6 cases/100,000 person-years (95% confidence interval [CI] 10.8 to 12.4). The rates for specific types of IE were: 4.45 (95% CI 3.97 to 4.94) for community-acquired native valve, 0.94 (95% CI 0.72 to 1.12) for prosthetic valve, 0.94 (95% CI 0.71 to 1.16) for nosocomial, and 5.34 (95% CI 4.80 to 5.87) for IE associated with use of injected drugs. Previous population studies found overall incidence rates of 1.7 to 4 cases/100,000 person-years, similar to our rate for community-acquired native valve IE. Type-specific rates have not been previously reported. The higher overall rate in this study is partly related to the high prevalence of injection drug use in our area.

Natural history of mitral valve prolapse

To assess the rate and predictors of complications in patients with mitral valve prolapse (MVP), 316 subjects (mean age 42 +/- 15 years) with echocardiographic MVP were followed prospectively for a mean of 102 months: 220 (70%) were women, 225 (71%) had clinically recognized MVP, and 91 (29%) were detected in family studies. During follow-up, 11 patients (0.4/100 subject-years) required mitral valve surgery, 6 died of cardiac causes (0.2/100 subject-years), 7 developed cerebral ischemia (0.3/100 subject-years), and 2 developed active infective endocarditis (0.1/100 subject-years). The overall rate of fatal and nonfatal complications (1/100 patient-years) was higher in men than in women (odds ratio [OR] 3.2, p < 0.003), in subjects aged > 45 than < or = 45 years (OR 3.4, p = 0.002), in clinically recognized patients than in affected family members (OR 3.8, p < 0.02), and in those with a holosystolic murmur (OR 26.9, p < 0.00005); the overall rate was lower in those with a midsystolic click (OR 0.3, p < 0.002). Echocardiographic left ventricular or atrial diameter > or = 6.0 or > or = 4.0 cm, respectively, was associated with a 16.7- and 15.1-fold higher likelihood, respectively, of subsequent complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise-induced mitral regurgitation is a predictor of morbid events in subjects with mitral valve prolapse

OBJECTIVES

This study attempted to determine whether a subset of patients with mitral valve prolapse and no mitral regurgitation at rest will develop mitral regurgitation during exercise and have a higher than anticipated risk of morbid cardiovascular events.

BACKGROUND

Mitral regurgitation in patients with mitral valve prolapse identifies a subset of patients at higher risk for morbid events. However, mitral regurgitation in patients with mitral valve prolapse may be intermittent and could go unrecognized. A provocative test to unmask mitral regurgitation in these patients would be useful.

METHODS

Ninety-four adult patients with mitral valve prolapse and no mitral regurgitation at rest were studied during supine bicycle ergometry using color flow Doppler echocardiography in the apical four-chamber and long-axis views. Patients were prospectively followed up for morbid events.

RESULTS

Thirty (32%) of 94 patients had exercise-induced mitral regurgitation. Prospective follow-up (mean 38 months) showed more morbid events in the group with than without mitral regurgitation and included, respectively, syncope (43% vs. 5%, p < 0.0001), congestive heart failure (17% vs. 0%, p < 0.005) and progressive mitral regurgitation requiring mitral valve replacement surgery (10% vs. 0%, p < 0.05). Cerebral embolic events, endocarditis or sudden death were rare and not different between groups.

CONCLUSIONS

In patients with mitral valve prolapse without mitral regurgitation at rest, exercise provokes mitral regurgitation in 32% of patients and predicts a higher risk for morbid events.

Antibiotic prophylaxis in dermatologic surgery

Antibiotic prophylaxis is generally administered either to prevent wound infection or to hinder the development of endocarditis. Although the use of antibiotics in certain circumstances to prevent wound infection can be straightforward, there are other circumstances in which the decision to use antibiotics is much less clear. Endocarditis prophylaxis has traditionally been based on the American Heart Association's guidelines, which do not cover dermatologic surgery. This article discusses the rationale and controversies surrounding the use of antibiotic prophylaxis for prevention of both wound infection and endocarditis, reviews the few studies that pertain to dermatology, and provides recommendations for antibiotic prophylaxis on a case-by-case basis for those who perform dermatologic surgery.

Cost-effectiveness of infective endocarditis prophylaxis for mitral valve prolapse with or without a mitral regurgitant murmur

To assess the cost-effectiveness of prevention of infective endocarditis (IE) and to calculate cost-effectiveness of currently recommended regimens in patients with mitral valve prolapse (MVP), data on risk of death, complications, and health-care use, and cumulative incremental health-care costs due to the occurrence of IE were combined with data on the prevalence and manifestations of MVP, estimated years of life lost, and efficacy of antibiotic prophylaxis. Effectiveness and costs of standard endocarditis prophylaxis regimens were calculated per IE case prevented and years of life saved. Under the most likely scenario, oral amoxicillin prophylaxis for all MVP patients would prevent 32 cases of IE per million dental procedures at approximate costs of $119,000 per prevented case and $21,000 per year of life saved. Limiting prophylaxis to patients with mitral murmurs would prevent 80 cases of IE per million procedures at costs of about $19,000 per prevented case and $3,000 per year of life saved. Erythromycin prophylaxis was slightly less expensive than amoxicillin per benefit because of lower cost and lack of drug anaphylaxis, whereas intravenous ampicillin was 7 to 30 times more costly. Sensitivity analyses suggested that erythromycin prophylaxis might be cost-saving under some scenarios, whereas intravenous ampicillin use might cause net loss of life. Thus, prevention with oral antibiotics of the cumulative morbidity and incremental health care costs due to IE in MVP patients is reasonably cost-effective for MVP patients with mitral murmurs.

Clinical and health care cost consequences of infective endocarditis in mitral valve prolapse

Although mitral valve prolapse (MVP) predisposes to infective endocarditis (IE), both the clinical consequences of IE and the increment in health care costs it imposes on patients with MVP remain uncertain. Accordingly, 21 MVP patients with IE and 41 age- and sex-matched control subjects with initially uncomplicated MVP were followed (95% complete) a mean of 8 years. Outcomes included death, complications, health care use and cumulative incremental costs. More MVP patients with IE died (25 vs 5%, p < 0.05), underwent valve surgery (40 vs 8%, p < 0.01), had heart failure (50 vs 5%, p < 0.01) or embolization (53 vs 11%, p < 0.01), underwent cardiac catheterization (40 vs 13%), and saw their physicians > 2 times per year (88 vs 33%). The cumulative incremental cost of IE (1990 dollars) was $46,132 per case. Thus, IE in patients with MVP causes considerable cumulative morbidity and incremental health care costs.

Cost effectiveness of prophylaxis in dental practice to prevent infective endocarditis

BACKGROUND

Although antimicrobial prophylaxis for infective endocarditis (IE) is common practice for many dental procedures, there is little information on whether it represents value for money. A study was performed to evaluate the effectiveness of prophylaxis for all at risk patients in routine dental practice with published data from the United Kingdom.

METHODS

The risk of contracting infective endocarditis was calculated from published data to find (for high risk patients) both the annual number of deaths attributable to infective endocarditis and the number of high risk dental procedures performed without prophylaxis. Costs are estimated by examining the notes of 63 patients with proved IE during the decade 1980-90.

RESULTS

Such prophylaxis is highly cost effective before dental extractions, but its value for other invasive dental procedures is unproved. It was calculated that, for every 10,000 extractions in at risk patients, appropriate prophylaxis will prevent 5.7 deaths and a further 22.85 cases of non-fatal IE. This represents a saving in the costs of hospital care of 289,600 pounds for 10,000 extractions.

CONCLUSION

Prophylaxis to prevent IE in at risk patients undergoing dental extraction is highly cost effective. Net savings each year throughout the United Kingdom, that might be achieved by improving the existing proportion of such patients given antibiotics from its present level of about 50% would amount to 2.5 million pounds and would prevent over 50 deaths.

Development of valve dysfunction in adolescents and young adults with Down syndrome and no known congenital heart disease

We performed examinations and echocardiographic studies in 35 patients with Down syndrome (aged 20 +/- 4.2 years) with no known intracardiac disease. Sixteen patients (46%) had mitral valve prolapse; two of these also had tricuspid valve prolapse. Two had aortic regurgitation. Valve regurgitation was present in 4 (17%) of 23 patients more than 18 years of age but in none of the 12 patients 18 years of age or younger. We recommend screening of adolescent and young adult patients with Down syndrome for the development of valve dysfunction, especially before dental or surgical procedures.

Mild dehydration induces echocardiographic signs of mitral valve prolapse in healthy females with prior normal cardiac findings

This study was designed to investigate the hypothesis that mitral valve prolapse (MVP) can be induced after diuresis in women without the abnormality who have characteristic body habitus. Fifteen tall, slim, healthy female volunteers with a normal cardiac findings, echocardiogram, and history were investigated after mild diuresis with furosemide and after placebo. All subjects lost weight after furosemide and placebo administration; but mean weight loss was significantly greater after furosemide administration than after placebo administration. Echocardiography showed MVP in none of the 15 patients before treatment, in seven after administration of placebo, and in seven after administration of furosemide. Coaptation point prolapsed superior to the anulus in seven subjects with echocardiographically determined MVP. Left ventricular end-diastolic dimensions decreased significantly after placebo or furosemide administration in subjects in whom MVP developed compared with the measurement in those in whom MVP did not develop. Murmurs characteristic of MVP disappeared in all four rehydrated subjects and echocardiographic changes resolved in two of the five rehydrated subjects. Thus echocardiographically determined MVP can be induced by mild dehydration in women with phenotypic body habitus of MVP; changes may resolve with rehydration. Results suggest an explanation for variable physical examination findings in persons with MVP.

Genes, gender and geometry and the prolapsing mitral valve

Mitral Valve Prolapse (MVP) is usually a variant of normal occurring in about 4% of the population. Complications are relatively uncommon, but false associations due to ascertainment bias have had a potential for iatrogenic harm. Adverse outcomes which do occur in a subset of MVP subjects are considered here in relation to the contributions of genes, gender and geometry. There are definite associations between MVP and several dominantly inherited connective tissue abnormalities; it occurs in 85% of adults with Marfan syndrome. All these contribute to a very small proportion of the MVP population. A larger less easily characterised group with dominant inheritance and some features of a connective tissue disorder awaits DNA studies for identification. For most MVP subjects our data define significant family aggregation consistent with polygenic inheritance; the likelihood of a first degree relative having MVP is about two and a half times the population average. There is a higher prevalence in young women than in men-5% versus 3%; this has also been demonstrated for floppy mitral valve (MV) at autopsy. MVP complications of chordal rupture, severe mitral regurgitation and infective endocarditis are, however, two to three times more common in men, are age related and evident after the age of 50 years. Higher blood pressure in men may contribute to this in accordance with a response-to-injury hypothesis to explain progressive valve changes. Leaflet, annulus and left ventricular size differences and septal changes are geometric variants with a potential for increasing tension-related valve injury.(ABSTRACT TRUNCATED AT 250 WORDS)

The changing pattern of infective endocarditis in childhood

Forty-eight cases of infective endocarditis (IE) that occurred in 42 patients with congenital heart disease were reviewed from 1970 through 1990 and were compared with a 20-year review of 108 cases diagnosed between 1953 and 1972. The review demonstrates that the natural history of IE in children has changed over the last 2 decades, with half of the cases occurring after surgery for congenital heart disease. In the postoperative group, 46% of patients had undergone valve replacement and 7 of these (29%) had a right ventricular to pulmonary artery valved conduit as the site for IE, suggesting significant additional risk in this setting. Among patients with nonsurgically treated congenital heart disease and IE, mitral valve prolapse has emerged as an important underlying heart lesion occurring in 29% of patients. The bacterial spectrum has shifted, with a significant increase in the incidence of uncommon causative organisms. Mortality has continued to decline with survivorship of 90% in this series.

Influence of referral bias on the apparent clinical spectrum of infective endocarditis

PURPOSE

To assess the effect of referral bias on the clinical spectrum of infective endocarditis.

PATIENTS AND METHODS

We performed a retrospective study comparing a population-based cohort of incidence cases from Olmsted County, Minnesota, with a cohort of referred cases from the practice of the Mayo Clinic during the period from 1970 to 1987.

RESULTS

In the community cohort, age was an important risk factor for acquiring endocarditis (incidence rate ratio 8.8:1 for age 65 years or older versus age less than 65 years), but episodes in elderly patients were underrepresented in the referral practice. The proportion of cases due to Staphylococcus aureus was greater in the community than in the referral practice (p less than 0.02), while a trend toward overrepresentation of enterococcal endocarditis was seen in the referral population (p = 0.057). Symptom duration prior to diagnosis was significantly shorter in the community. Overall, measures of in-hospital morbidity and mortality were similar in the two populations, but advanced age was associated with adverse outcome in the community cohort.

CONCLUSION

The clinical spectrum of infective endocarditis may be distorted by referral. The increased risk of endocarditis in the elderly underscores the importance of adherence to recommendations for prophylaxis in this patient population.

The spectrum of mitral regurgitation in idiopathic mitral valve prolapse: a color Doppler study

To characterize the spectrum of mitral regurgitation in mitral valve prolapse, one hundred patients were studied by color Doppler flow mapping. The findings were correlated with the clinical presentation and with the possible complications. Mitral regurgitation was absent in 46 patients, mild in 26 patients, moderate in 18 patients and severe in 10 patients. The jet orientation was central in 15 patients, antero-medial in 13 patients and postero-lateral in 26 patients. The regurgitation was early systolic in 7 patients, late systolic in 20 patients and holosystolic in 27 patients. A good agreement was observed between the color flow patterns and the presence, timing and radiation of a murmur. Systolic clicks were not predictors of the presence or the severity of regurgitation. The grade of mitral regurgitation was positively correlated with, age, left heart enlargement and valvular redundancy. No sex difference was observed. The prevalence of serious arrhythmias or cerebral ischemic events was not significantly increased when a regurgitation was present.

Native valve infective endocarditis in the 1970s versus the 1980s: underlying cardiac lesions and infecting organisms

A retrospective review of the records of 135 patients with proven or suspected endocarditis, seen between January 1970 and December 1987, is presented. Among the findings: (1) Mitral valve prolapse (MVP) as an underlying lesion was more common in the 1980s group of patients (22%) than in the 1970s group (6%, p less than 0.01); (2) no significant difference was found in the occurrence of pathogens between the 1970s and the 1980s groups of patients; (3) in most patients (17 of 19) with MVP, the organisms isolated were Streptococci viridans; (4) most patients (15 of 17) with MVP had undergone a dental procedure without prior antibiotic treatment in the two months prior to admission. Prophylactic antibiotic treatment is suggested in patients with MVP undergoing dental procedure, especially in a subset of patients with flail or redundant valve leaflet as 16 of our MVP patients (out of 17) had this pathology on echocardiogram.

The reliability of the medical history in the identification of patients at risk for infective endocarditis

This study sought to assess the reliability of the cardiac history provided by patients. The results of the interviews and cardiologic evaluations found no significant correlation between those patients identified by their medical history as having a murmur, and those who were actually found to have a pathological condition warranting prophylactic therapy.

Exercise first-pass radionuclide assessment of left and right ventricular function and valvular regurgitation in symptomatic mitral valve prolapse

The changes in right ventricular (RV) and left ventricular (LV) function and in regurgitant fractions on first-pass exercise radionuclide angiography (RNA) were assessed in 29 consecutive patients with symptomatic mitral valve prolapse (MVP). The mean right ventricular ejection fraction (RVEF) was 35 +/- 8% at rest and 46 +/- 15% after exercise (p less than 0.001). The mean left ventricular ejection fraction (LVEF) was 62 +/- 11% at rest and 74 +/- 13% after exercise (p less than 0.001). Seven of 29 patients had an abnormal RV response and 6 had an abnormal LV response. Eight had abnormal wall motion after exercise. A total of 12/29 patients (41%) had one or more abnormalities. The mean left-sided regurgitant fraction before exercise was 27 +/- 17% in 21/29 patients (72%) and 31 +/- 21% after exercise (p = ns). An additional 5 patients (17%) developed left-sided regurgitation after exercise. These findings indicate that wall motion abnormalities and abnormal RVEF and LVEF responses to exercise occur in symptomatic MVP patients. In addition, 26/29 (89.6%) had left-sided regurgitation after exercise. Since the presence of a murmur did not correlate with the presence of mitral regurgitation by RNA, then symptomatic patients with MVP should have first-pass exercise RNA to assess the presence of regurgitation at rest and after exercise. Antibiotic prophylaxis is recommended in MVP patients with systolic murmurs or with regurgitation. Since patients without murmurs can have regurgitation, further study is necessary to determine the need for endocarditis prophylaxis in these patients.

Identification of high-risk and low-risk subgroups of patients with mitral-valve prolapse

Mitral-valve prolapse is a common cardiac valvular disorder with a wide range of severity and diverse clinical outcomes. The lack of a standard definition of mitral-valve prolapse may explain the variation in reported complication rates. To identify high-risk and low-risk subgroups, we retrospectively analyzed clinical and two-dimensional echocardiographic data from 456 patients with mitral-valve prolapse. Mitral-valve prolapse was defined on the basis of echocardiographic findings as systolic displacement into the left atrium of one or both leaflets beyond the plane of the mitral annulus in the parasternal long-axis view. Two groups of patients were compared: those with thickening of the mitral-valve leaflets and redundancy (designated the classic form; n = 319) and those without leaflet thickening (designated the nonclassic form; n = 137). The two groups were similar in age and sex ratio. Complications or a history of complications was more prevalent in the classic than the nonclassic form: infective endocarditis, 3.5 percent and 0 percent, respectively (P less than 0.02); moderate-to-severe mitral regurgitation, 12 percent and 0 percent (P less than 0.001); and the need for mitral-valve replacement, 6.6 percent and 0.7 percent (P less than 0.02). However, the frequency of stroke was similar in the two groups: 7.5 percent and 5.8 percent (P not significant). We conclude that in a selected population of patients with mitral-valve prolapse, those with the classic form (leaflet thickening and redundancy) are at higher risk than those without these features for the infectious and hemodynamic complications of mitral-valve prolapse, but not for stroke.

Mitral valve prolapse as a risk factor for infective endocarditis

The frequency of mitral valve prolapse was assessed in 48 patients with mitral valve endocarditis and in 96 controls matched for age and sex, attending a routine family screening clinic or having surgery of the limbs. The frequency of mitral valve prolapse in cases with endocarditis (9 of 48 patients) was more than three times that in controls (6 of 96) (odds ratio 3.5; 95% confidence interval [CI] 1.1-10.5). When patients with rheumatic heart disease, an established risk factor for infective endocarditis, were excluded from the study group, patients were nearly six times more likely to have infective endocarditis than were controls (odds radio 5.7; 95% CI 1.8-18.4). However, a higher risk of infective endocarditis was seen only in the subjects with mitral valve prolapse and a previously known systolic murmur (odds ratio 14.5; 95% CI 1.7-125). The results indicate that mitral valve prolapse constitutes a true risk factor for infective endocarditis only when associated with the presence of a precordial systolic murmur.

Comparison of auscultation with two-dimensional and Doppler echocardiography in patients with suspected mitral valve prolapse

Auscultation was compared to two-dimensional echocardiography (2D echo) and Doppler ultrasonography in 140 consecutive patients referred for evaluation for suspected mitral valve prolapse (MVP) to asses the precision of the two diagnostic methods. Ninety patients (64%) had midsystolic clicks, of which 42 (47%) had MVP by echocardiography; 6 patients (4%) had MVP by 2D echo but no click on examination. In 15 (17%) of the 90 patients, a click was heard only in the standing or squatting positions and 2D echo did not detect prolapse in the supine position in 10 (67%) of the 15. With auscultation as the reference standard for MVP, 2D echo has a sensitivity of 47% and a specificity of 89%. Of the 140 patients, 51 (36%) had systolic murmurs; Doppler detected mitral and/or tricuspid regurgitation in 26 (50%). In 23 (16%) patients, there was Doppler evidence of mitral or tricuspid regurgitation even though systolic murmurs were not heard. Auscultation shows a 53% sensitivity and 73% specificity for systolic murmurs, using Doppler ultrasonography as the reference standard. Of 48 patients with MVP by 2D echo, 15 (13%) had associated mitral regurgitation by Doppler. The results indicate that 2D echo and Doppler ultrasonography should be interpreted in concert with auscultation for the diagnosis of mitral valve prolapse and for therapeutic decision making.

The medicalization of normal variants: the case of mitral valve prolapse

Mild mitral valve prolapse, hypoglycemia, irritable colon, and premenstrual syndrome are examples of anatomico-physiologic phenomena that largely overlap with normal. Such "overlap syndromes" become labeled disease entities by the medical community through a process called medicalization. This report uses mitral valve prolapse (MVP) to exemplify the effects of medicalization on patients, physicians, and society. Ascertainment bias and insufficient controlled clinical studies have led to the description of a clinical entity replete with false associations (e.g., mitral valve prolapse syndrome) and overly pessimistic prognostication (e.g., risk of sudden death or endocarditis), leading to clinical overreaction, overtreatment, and unnecessary induction of disability. Though some physical complications may be prevented by recognizing severe MVP, there is substantial risk of iatrogenic harm by attributing complex symptoms and illness behavior to mild MVP, which is probably a normal variant. A three-dimensional analysis of illness experience is presented that may be of use in conceptualizing the clinical approach to overlap syndromes such as mild MVP. Conservative criteria for the diagnosis of significant MVP have been developed at the National Institutes of Health. Treatment of patients with mild MVP must emphasize that it is a normal variant without serious consequences. Because the risks of overmedicalization are so substantial, the impact of diagnostic labels on individual patients and society must be analyzed continually.

Reconsideration of echocardiographic standards for mitral valve prolapse: lack of association between leaflet displacement isolated to the apical four chamber view and independent echocardiographic evidence of abnormality

Mitral valve prolapse by current echocardiographic criteria can be diagnosed with surprising frequency in the general population, even when preselected normal subjects are examined. In most of these individuals, however, prolapse is present in the apical four chamber view and absent in roughly perpendicular long-axis views. Previous studies have shown that systolic annular nonplanarity can cause apparent prolapse in the four chamber view without actual leaflet displacement above the most superior points of the anulus, and there is evidence for such nonplanarity in vivo. It is then reasonable to ask whether superior leaflet displacement limited to the four chamber view has any pathologic significance or complications. The purpose of this study, therefore, was to address the following hypothesis: that patients with superior leaflet displacement confined to the four chamber view have no higher frequency of associated echocardiographic abnormalities than do patients without displacement in any view. Such abnormalities, which would provide independent evidence of mitral valve pathology or dysfunction, include leaflet thickening, left atrial enlargement and mitral regurgitation. Leaflet displacement was measured in the parasternal long-axis and apical four chamber views in 312 patients who were studied retrospectively and selected for the absence of forms of heart disease other than mitral valve prolapse. Leaflet thickness and left atrial size were measured and mitral regurgitation was graded. Patients with leaflet displacement limited to the four chamber view were no more likely to have associated abnormalities than were patients without displacement in any view (0 to 2% prevalence, p greater than 0.5). In contrast, patients with leaflet displacement in the long-axis view were significantly more likely to have associated abnormalities (12 to 24%, p less than 0.005), the frequency of which increased with the extent of leaflet displacement in that view (p less than 0.0001). These results suggest that displacement limited to the apical four chamber view is, in general, a normal geometric finding unassociated with echocardiographic evidence of pathologic significance.

Mitral Valve Prolapse in Young Patients

In brief: From 1% to 5% of young individuals are found to have, on clinical or echocardiographic examination, a prolapsing mitral valve. The majority of these patients are asymptomatic, and require from the physician an explanation of this defect and reassurance that the condition usually remains mild. Beta-blocking drugs are prescribed for patients with disabling chest pain, dizziness, or palpitation, or if potentially serious rhythm disorders develop. Physicians caring for these young patients must manage each case individually and must remain mindful that the natural course studies come from a perspective of only 25 years.

Underlying cardiac lesions in adults with infective endocarditis. The changing spectrum

The spectrum of recognized cardiac lesions underlying infective endocarditis has been changing as a result of the decline in incidence of rheumatic heart disease, the recognition of the entity of mitral valve prolapse, and the improvement in cardiac diagnostic techniques. Sixty-three cases of native valve endocarditis diagnosed in Memphis hospitals between 1980 and 1984 were reviewed. All diagnoses of underlying cardiac lesions were confirmed by two-dimensional echocardiography, cardiac catheterization, and/or histopathologic examination of valve tissues. Major categories of underlying lesions were as follows: mitral valve prolapse, 29 percent; no underlying disease, 27 percent; degenerative lesions of the aortic or mitral valve, 21 percent; congenital heart disease, 13 percent; rheumatic heart disease, 6 percent. Thus, mitral valve prolapse and, in the elderly, degenerative lesions have displaced rheumatic and congenital heart diseases as the major conditions underlying endocarditis. Redundancy of the mitral valve leaflets was noted in 17 of 18 patients in whom endocarditis was superimposed upon mitral valve prolapse. The risk of infective endocarditis appears to be substantially increased in the subset of patients with mitral valve prolapse who exhibit valvular redundancy.