MGH study shows mitral valve prolapse not a stroke risk factor

June 30, 1999

Researchers from the Massachusetts General Hospital report that mitral valve prolapse, an abnormality of a heart valve, does not appear to be associated with an increased risk of stroke among young people. Earlier studies, many using outdated imaging techniques, had led to the belief that mitral valve prolapse was a significant risk factor for stroke.

The MGH report appears in the July 1 New England Journal of Medicine. It accompanies a report from the Framingham Heart Study that found mitral valve prolapse to be much less common in the general population than previously believed and less strongly associated with health problems. MGH researchers also were co-authors of the Framingham study, which used techniques developed at the MGH to diagnose mitral valve prolapse accurately.

"As many as 10 to 15 percent of the population have been told they have mitral valve prolapse, that they need to take antibiotics when having dental or other procedures, and that they are at increased risk for stroke, heart failure, heart rhythm abnormalities or other serious problems. Some may have to pay higher insurance premiums because of the diagnosis," says Robert Levine, MD, of the MGH Cardiac Ultrasound Laboratory. "We now know that this condition actually occurs in only about 2 percent of the population." Levine is the senior author of the MGH article and a co-author of the Framingham Study report.

Ferdinando Buonanno, MD, of the MGH Stroke Service, a co-author of the paper, adds, "The studies indicating that mitral valve prolapse was a risk factor for stroke were based on criteria that overdiagnosed the condition in both healthy patients and those who had experienced strokes. It now appears that even those with true mitral valve prolapse have no increased risk of stroke."

The mitral valve - one of four valves controlling the flow of blood through the heart - lies between the left atrium, which receives oxygenated blood from the lungs, and the left ventricle, which pumps blood out into the body. It is made of two flaps or leaflets that open to let blood pass through and close to prevent blood from moving backwards. In mitral valve prolapse, one or both of the leaflets do not close properly, bulging back and allowing blood to leak into the atrium, a process called regurgitation. Patients with serious mitral valve prolapse may develop endocarditis, an infection of the heart; stress on the heart muscle can lead to heart failure or irregular heart rhythm. In severe cases, patients may need to have their valves repaired or replaced.

The belief that mitral valve prolapse was common came from studies using some of the earliest forms of cardiac ultrasound or echocardiography. Based on the assumption that the mitral valve had a simple saucer-like shape with a central depression where the leaflets came together, researchers in the late 1970s believed that any image showing part of the valve bulging up in the middle reflected the backward motion of a prolapse.

That assumption was incorporated into a set of diagnostic criteria for mitral valve prolapse, which also included the presence of clicks and murmurs audible through a stethoscope. When researchers used those criteria to analyze the prevalence of mitral valve prolapse among the general population and among patients with cardiovascular conditions such as stroke, they diagnosed the condition in from 10 to 15 percent of apparently health individuals - with even higher rates among young women - leading to the belief that there was a hidden epidemic of a serious heart defect. In addition, a 1980 study of young people who had experienced strokes or related events diagnosed mitral valve prolapse in 40 percent of those studied, implying that the condition was a serious risk factor for stroke.

However, in the early 1980s a group of MGH researchers led by Levine began applying more advanced techniques of echocardiography to study the mitral valve and mitral valve prolapse. Observing that very few of those diagnosed with mitral valve prolapse actually had symptoms of illness or other signs of diseased valves, they theorized that poor understanding of the shape of the valve may have led to significant overdiagnosis of prolapse.

Using 3-dimensional ultrasound techniques pioneered at the MGH, they first published in 1987 evidence that, instead of being shaped like a saucer, the mitral valve actually is shaped like a saddle - or a Pringles potato chip - with a surface that curves in two opposing directions. Front-to-back ultrasound images show the central depression considered the normal valve's shape; however, images taken side-to-side would show an upward bulging in a normal valve, the appearance that the earlier criteria would have diagnosed as prolapse.

This observation, confirmed by subsequent studies at the MGH and elsewhere, has led to the development of more stringent diagnostic criteria for mitral valve prolapse. Armed with the new criteria, researchers are revisiting earlier studies of the condition, questioning beliefs about its prevalence and relation to a variety of diseases. Using new criteria, the Framingham Study analysis - conducted by Lisa Freed, MD, then a cardiology fellow at the MGH - found mitral valve prolapse in only 2.4 percent of a general population, with more serious prolapse observed in 1.3 percent of those studied. Rates of heart failure, atrial fibrillation (a serious heart-rhythm disturbance), stroke, fainting and chest pain were no more common among those with prolapse than those without the condition.

The current MGH study, conducted by Dan Gilon, MD, and colleagues, recreated the original 1980 study of stroke in young people. Analyzing cardiac ultrasound results for all patients under 45 treated for strokes or mini-strokes (transient ischemic attacks) at the MGH over a period of 10 years (1985 to 1995), the research team found the prevalence of mitral valve prolapse to be nearly identical to that seen in a control group without cardiovascular disease; prolapse was found in 1.9 percent of young stroke patients compared with 2.7 percent of controls, a statistically insignificant difference.

"There is no doubt that people with true mitral valve prolapse have some health risks, but stroke does not seem to be among them," adds Levine. "And if someone who had been diagnosed with prolapse several years ago asked me what to do, I would recommend they have it rechecked by an echocardiographer using the most up-to-date criteria, particularly if the diagnosis caused them to take antibiotics or otherwise affected their health care."

In addition to Gilon, who now is head of echocardiography at Hadassah University in Israel, Buonnano, and Levine, co-authors of the MGH study are Marcia Leavitt, Jane Marshall, RDCS, and Philip Kistler, MD, of the MGH and Marshall Joffe, MD, MPH, PhD, then at the Harvard School of Public Health. The study was supported by grants from the National Institutes of Health and the American Physicians Fellowship for Medicine in Israel.
-end-


Massachusetts General Hospital

Related Heart Failure Articles from Brightsurf:

Top Science Tip Sheet on heart failure, heart muscle cells, heart attack and atrial fibrillation results
Newly discovered pathway may have potential for treating heart failure - New research model helps predict heart muscle cells' impact on heart function after injury - New mass spectrometry approach generates libraries of glycans in human heart tissue - Understanding heart damage after heart attack and treatment may provide clues for prevention - Understanding atrial fibrillation's effects on heart cells may help find treatments - New research may lead to therapy for heart failure caused by ICI cancer medication

Machining the heart: New predictor for helping to beat chronic heart failure
Researchers from Kanazawa University have used machine learning to predict which classes of chronic heart failure patients are most likely to experience heart failure death, and which are most likely to develop an arrhythmic death or sudden cardiac death.

Heart attacks, heart failure, stroke: COVID-19's dangerous cardiovascular complications
A new guide from emergency medicine doctors details the potentially deadly cardiovascular complications COVID-19 can cause.

Autoimmunity-associated heart dilation tied to heart-failure risk in type 1 diabetes
In people with type 1 diabetes without known cardiovascular disease, the presence of autoantibodies against heart muscle proteins was associated with cardiac magnetic resonance (CMR) imaging evidence of increased volume of the left ventricle (the heart's main pumping chamber), increased muscle mass, and reduced pumping function (ejection fraction), features that are associated with higher risk of failure in the general population

Transcendental Meditation prevents abnormal enlargement of the heart, reduces chronic heart failure
A randomized controlled study recently published in the Hypertension issue of Ethnicity & Disease found the Transcendental Meditation (TM) technique helps prevent abnormal enlargement of the heart compared to health education (HE) controls.

Beta blocker use identified as hospitalization risk factor in 'stiff heart' heart failure
A new study links the use of beta-blockers to heart failure hospitalizations among those with the common 'stiff heart' heart failure subtype.

Type 2 diabetes may affect heart structure and increase complications and death among heart failure patients of Asian ethnicity
The combination of heart failure and Type 2 diabetes can lead to structural changes in the heart, poorer quality of life and increased risk of death, according to a multi-country study in Asia.

Preventive drug therapy may increase right-sided heart failure risk in patients who receive heart devices
Patients treated preemptively with drugs to reduce the risk of right-sided heart failure after heart device implantation may experience the opposite effect and develop heart failure and post-operative bleeding more often than patients not receiving the drugs.

How the enzyme lipoxygenase drives heart failure after heart attacks
Heart failure after a heart attack is a global epidemic leading to heart failure pathology.

Novel heart pump shows superior outcomes in advanced heart failure
Severely ill patients with advanced heart failure who received a novel heart pump -- the HeartMate 3 left ventricular assist device (LVAD) -- suffered significantly fewer strokes, pump-related blood clots and bleeding episodes after two years, compared with similar patients who received an older, more established pump, according to research presented at the American College of Cardiology's 68th Annual Scientific Session.

Read More: Heart Failure News and Heart Failure Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.