Cardiac surgeons often shy away from repairing or replacing leaking mitral valves in elderly patients because of a historically high death rate and mediocre long-term survival. However, Mayo Clinic researchers found that the operation's death rate for patients over age 75 fell dramatically from 27 percent to 5 percent between 1980 and 1995.
"We want to dispel the message of gloom and doom that is given to older people," said Maurice Enriquez-Sarano, M.D., senior author of the study. "We may not make people live forever, but we can restore life expectancy in a similar manner in younger and older patients."
The mitral valve regulates blood flow from the heart's left atrium to left ventricle. A leaking valve causes blood to flow back from the lower to the upper chamber, which is called mitral regurgitation or MR. This abnormal flow can cause breathing problems, fatigue, irregular heartbeats and potentially fatal congestive heart failure.
Previous research indicates that the prevalence of MR increases with age. The number of Americans age 75 and older is expected to quadruple over the next 50 years, Sarano said.
The condition's degenerative form -- the more common one -- results from the valve becoming progressively thicker or a valve cord rupturing. Non-degenerative mitral regurgitation may result from several disorders, including a birth defect and rheumatic fever.
Surgeons can correct mitral regurgitation by repairing the valve or replacing it with an artificial valve. Sarano and colleagues investigated risks and benefits of the valve surgery for repair or replacement in older patients. "Mitral valve disease is a disease of the elderly, and you don't have to be a doctor to know the elderly are more likely to die than younger patients," said Sarano, professor of medicine and director of Mayo's Valvular Heart Disease Clinic in Rochester, Minn. "But we asked, 'Does surgery restore life expectancy in a similar way? Do the young and the old live the same percentage of what is expected for their age?'"
Researchers reviewed the records of 1,344 patients (mostly white) who had mitral regurgitation surgery at the Mayo Clinic between Jan. 1, 1980, and Dec. 31, 1995. They used 1995 as the cut-off for surgery to determine the long-term survival of patients.
They divided patients into three groups, based on their age at surgery: 75 and older (284 patients), 65–74 (504), and younger than 65 (556). The patients' average age was 65, 61 percent were male, and 64 percent had degenerative mitral regurgitation.
These patients were also compared to data on the age- and gender-matched U.S. white population in 1990 to determine their normal life expectancy.
At latest follow-up, the year 2000, 606 patients (45 percent) had died.
Not surprisingly, patients 75 and older were sicker -- and thus at a higher surgical risk -- than the other two age groups. They also suffered from more serious ailments, such as advanced symptoms of heart failure, atrial fibrillation, cardiovascular disease and other medical problems, Sarano said.
Some key findings from the study include:
- For all ages, death from mitral valve surgery dropped from 16 percent to 3 percent.
- For patients with degenerative mitral valve disease, five-year survival adjusted for life expectancy was 91 percent for the oldest group, 98 percent for the intermediate age group, and 97 percent for the youngest group.
- The feasibility of correcting a leaking mitral valve among elderly patients improved from 30 percent in 1980–1983 to 84 percent in 1992–1995.
- Mitral valve surgery was associated with restoration of life expectancy of elderly patients at almost the same percentage as that seen in patients younger than age 75.
Researchers said, however, that elderly patients in their study may not be representative of all MR elderly patients and "the benefits of surgery cannot be defined without a randomized clinical trial, which is not yet available."
Co-authors are Delphine Detaint, M.D.; Thoralf M. Sundt, M.D.; Vuyisile T. Nkomo, M.D.; Christopher G. Scott, M.S.; A. Jamil Tajik, M.D.; and Hartzell V. Schaff, M.D.
The Mayo Clinic funded the study. Detaint's participation was supported by a grant from the French Federation of Cardiology.
Statements and conclusions of study authors that are published in the American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect association policy or position. The American Heart Association makes no representation or warranty as to their accuracy or reliability.
NR06 – 1072 (Circ/Sarano)