Patients with mitral regurgitation face a dilemma of whether to undergo corrective surgery early, when they might have no or few symptoms, or wait until their condition worsens. Current guidelines allow for watchful waiting until certain symptoms appear that would then "trigger" the decision to proceed with surgery. The authors argue that these guidelines are based on relatively weak class C evidence from clinical experience that is now 20 to 30 years old, and surgical methods, including mitral valve repair instead of valve replacement, have now made surgeries safer with good long-term outcomes, especially when performed at high-quality, high-volume centers. The results of this study from Mayo Clinic indicate that delaying surgery until clinical triggers appear leads to increased mortality and congestive heart failure. In an accompanying Editorial, Dr. Donald D. Glower suggests that guidelines should be modified so that early surgery is made a class I indication for severe mitral regurgitation with a high likelihood of repair, and that patients should seek care from experienced surgeons at high-volume centers.
About 2% of the U.S. population has mitral valve regurgitation, which left untreated, can remain mild or lead to arrhythmia or heart failure. Timing of surgery is a matter of controversy, with guidelines suggesting "watchful waiting" or medical treatment until heart failure or poor function becomes apparent. Now a report in The Journal of Thoracic and Cardiovascular Surgery, the official publication of the American Association for Thoracic Surgery (AATS), finds that allowing patients to reach these "surgical triggers" doubles the risk of postoperative mortality and heart failure compared to those who undergo early surgery.
"Our study indicates that early repair should be preferred to rescue surgery in patients with mitral regurgitation (MR)," explained lead author Maurice Enriquez-Sarano, MD, of the Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic (Rochester, MN). "Guideline triggers for MR surgery based on symptoms and complications are linked to excess postoperative mortality and morbidity versus early surgery. Early surgery in this era of low operative risk and high repair rates provides the best long-term outcomes after MR surgery."
MR is a condition caused by blood leaking backwards through the partially closed mitral valve that connects the two left-sided chambers of the heart. For many people, symptoms may be mild and progress slowly over decades. The sign found on examination is a heart murmur and the symptoms include difficulty breathing and severe fatigue and swollen feet or ankles (heart failure) as well as heart palpitations (atrial fibrillation), but can lead to progressive deterioration of functional capacity associated with excessive pressure in the lungs (pulmonary hypertension).
This study analyzed data from 1,512 patients who were seen at Mayo Clinic between 1990 and 2000 for surgical correction of MR. The average age was 64 years, 89% had mitral prolapse (a condition in which the leaflets and tendons supporting the mitral valve weaken, preventing the valve from closing tightly), and 88% had their valves repaired, rather than replaced.
Patients were divided into three groups according to surgical indication. The first group of 794 patients had Class I triggers, such as heart failure symptoms, an ejection fraction of <60%, or an end-systolic diameter of ≥ 40 mm. The second group of 195 patients had Class II triggers, which included complications such as atrial fibrillation or pulmonary hypertension. The third group of 523 patients had severe MR but no other surgical trigger, but underwent early surgery.
The investigators found that after adjusting for age, the mortality risk was approximately doubled in the Class I group and increased by 40% in the Class II group compared to those who underwent early surgery. The 15-year survival was 42% in the Class I group, 53% in the Class II group, and 70% in the early surgery group.
Patients may defer surgery because of anxiety about the procedure. Overall the operative mortality was 0.6% which was lower than the 2.5% predicted. The only group with operative mortality was the Class I indication group, which had a rate of 1.1% compared to no deaths in the Class II or early surgery groups. Hospital stay was also longer for those in the Class I (10.6 days) and Class II (10.5 days) groups compared to the early surgery (8.3 days) group.
During follow-up, 302 patients developed postoperative heart failure. After multivariate adjustment, an approximately 2.5 increased risk was found for heart failure in the Class I trigger group and a two-times increased risk was found in the Class II trigger group. Significant differences between groups were found for the combined end-point of death or heart failure: the rates were 37% in the early surgery group versus 65% in the Class I trigger group and 55% in the Class II group. "Early surgery for those with severe MR performed before clinical triggers develop provides the best operative outcome and lowest mortality/congestive heart failure," noted Dr. Enriquez-Sarano.
"Although this very carefully analyzed large series from a single institution is not definitive, the findings are indeed concerning that current clinical practice and guidelines are in fact putting larger numbers of patients at unnecessary risk of death and premature heart failure. If history continues to repeat itself, these data probably will be confirmed by other large centers and will eventually result in adjustment to the guidelines," commented Donald D. Glower, MD, of the Department of Surgery, Duke University Medical Center (Durham, NC) in an accompanying editorial.
Dr. Glower agrees that the early surgery approach should be reserved for higher-volume institutions and patients with a high likelihood of repair. He urges "physicians to be honest enough to look at themselves, and not just at the patients" when making decisions about when, where, or by whom patients with MR should undergo surgery.
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