By Richard N. Fogoros, MD 

 Medically reviewed by Anisha Shah, MD

In the 2007 Chicago Marathon, a runner collapsed and died, making national headlines. After performing an autopsy, the Chicago medical examiner announced that this man's sudden death definitively was not due to the oppressive heat and humidity that caused significant problems among many runners that day (and which eventually caused organizers to stop the race), but instead was due to "mitral valve prolapse" (MVP).

This verdict no doubt brought very great relief to the local officials responsible for going ahead with the race despite horrific weather conditions, and who (thanks to the autopsy conclusions) were now officially off the hook regarding this man's death.

Obviously, we can have no way of knowing the actual cause of this unfortunate runner's death. However, the Chicago medical examiner's confident pronouncement created at least some degree of panic among up to 75 million Americans who (by some estimates) might also have MVP. And for a few weeks, American cardiologists were flooded with worried phone calls.

 gradyreese / E+ / Getty Images

Mitral Valve Prolapse and Sudden Death

So, the question bears asking: Does MVP really cause sudden death?

The answer is that there does appear to be a slight increase in the risk of sudden death from ventricular tachycardia or ventricular fibrillation in people who have truly significant MVP but not in the large majority of people who have received the diagnosis of MVP. Most diagnosed with MVP have an extremely mild form of the condition, which carries no measurable risk.

Initial evidence that MVP may be associated with sudden death came mainly from autopsy series. In studies in which the heart has been carefully examined in people who have died suddenly, evidence of MVP can be found in a substantial minority. So naturally, MVP has been assumed to be the cause of these sudden deaths.

But two things are generally not mentioned in these studies. First, many sudden death victims have no identifiable cardiac abnormality at all. Second, when you are determined to find MVP, you will be able to find at least some evidence of it in a large proportion of the general population.

There is very little evidence that the vast majority of people diagnosed with MVP have any measurably increased risk of sudden death.

The Overdiagnosis of MVP

When you perform echocardiography in randomly selected people, depending on the diagnostic criteria used, MVP could be diagnosed in up to 20% to 35%.1 The amount of actual prolapse in the vast majority of these mitral valves is physiologically insignificant and poses no known threat.

Indeed, as the quality of echocardiographic equipment has improved over the years, it has become possible to detect ever smaller (often trivial and even non-existent) amounts of prolapse of the mitral valve. Most experts accept the fact that the condition "MVP" has become grossly over-diagnosed by cardiologists.2

The ability to detect some amount of MVP if you look for it hard enough can be very convenient for doctors (or for that matter, for race officials), because it can absolve them of having to look any further to explain symptoms or conditions that are difficult or inconvenient to diagnose or manage (dysautonomia being the most prominent of these). Hence, there is often a strong incentive to over-diagnose MVP.

Diagnosing MVP Appropriately

In 2008, recognizing that the diagnosis of MVP had grown inappropriately to epidemic proportions, the American College of Cardiology and American Heart Association published more stringent criteria for diagnosing MVP.3 Using these more appropriate criteria to make the diagnosis, there is indeed evidence of a somewhat increased risk of cardiac arrhythmias and sudden death, though that excess risk is still very small.

In fact, the main risk for these people is not sudden death, but the development of significant mitral regurgitation and subsequent heart failure. In these people the risk of sudden death is indeed elevated—but only to the same degree that it becomes elevated in anyone else who has severe mitral regurgitation, from any cause.

The prevalence of this kind of MVP (that is, actual, significant MVP) in the general population is only around 1-2% and not 35%. 4And even among this much smaller number of patients with MVP, fewer than 1 in 20 will ever develop significant mitral valve issues.

 Sources

Durst R, Gilon D. Imaging of Mitral Valve Prolapse: What Can We Learn from Imaging about the Mechanism of the Disease?. J Cardiovasc Dev Dis. 2015;2(3):165-175. doi:10.3390/jcdd2030165

Rajamannan NM. Myxomatous mitral valve disease bench to bedside: LDL-density-pressure regulates Lrp5. Expert Rev Cardiovasc Ther. 2014;12(3):383-92. doi:10.1586/14779072.2014.893191

Nishimura RA, Carabello BA, Faxon DP, et al. ACC/AHA 2008 guideline update on valvular heart disease: focused update on infective endocarditis: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines: endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation. 2008;118(8):887-96. doi:10.1161/CIRCULATIONAHA.108.190377

Delling FN, Vasan RS. Epidemiology and pathophysiology of mitral valve prolapse: new insights into disease progression, genetics, and molecular basis. Circulation. 2014;129(21):2158-70. doi:10.1161/CIRCULATIONAHA.113.006702

Additional Reading

• Bonow RO, Carabello BA, Chatterjee K, et al. 2008 Focused Update Incorporated Into The Acc/Aha 2006 Guidelines For The Management Of Patients With Valvular Heart Disease: A Report Of The American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Writing Committee to Revise the 1998 Guidelines for the Management of Patients With Valvular Heart Disease): endorsed by the Society of Cardiovascular Anesthesiologists, Society for Cardiovascular Angiography and Interventions, and Society of Thoracic Surgeons. Circulation 2008; 118:e523.

• Sriram CS, Syed FF, Ferguson ME, et al. Malignant Bileaflet Mitral Valve Prolapse Syndrome In Patients With Otherwise Idiopathic Out-Of-Hospital Cardiac Arrest. J Am Coll Cardiol 2013; 62:222.

By Richard N. Fogoros, MD
Richard N. Fogoros, MD, is a retired professor of medicine and board-certified in internal medicine, clinical cardiology, and clinical electrophysiology.