Tratamiento quirúrgico en pacientes con insuficiencia mitral asintomática

Posted at — cardiocirugia — febrero 6th, 2010 — 22:42 under General,Temas de opinión

No time like the present: Study supports early mitral-valve repair in asymptomatic patients
February 1, 2010 | Reed Miller
Fort Lauderdale, FL – The authors of a large study of mitral-valve repair in asymptomatic patients argue in favor of early surgery, when the chances of procedural success are highest, instead of waiting for heart-failure symptoms to appear.
Current American College of Cardiology/American Heart Association (ACC/AHA) guidelines suggest that surgery is acceptable in mitral-regurgitation patients with no symptoms or changes in the left ventricle, if the chances of surgery success are at least 90%. However, the majority of patients in the US meeting these criteria do not have early surgery, lead author Dr A Marc Gillinov (Cleveland Clinic, OH) explained. “The problem with this strategy is that delay, in some patients, results in damage to the left ventricle.”
A study published in the Journal of the American College of Cardiology showed that only about half of all patients with mitral regurgitation underwent surgery, and three-quarters of those not operated on had at least one indication for surgery according to ACC/AHA guidelines.
“For asymptomatic patients with degenerative mitral-valve disease and severe mitral regurgitation, does delaying surgery until symptoms—even mild symptoms—occur cause adverse cardiac changes and jeopardize outcomes?” Gillinov and colleagues sought to answer this question with a 4586-patient study of mitral repair in asymptomatic patients. He presented results from the 13-year retrospective study here at the Society of Thoracic Surgeons (STS) 2010 Annual Meeting.
In the study, 30% of enrolled patients were NYHA class 1, meaning they were asymptomatic; 55% were class 2—mildly symptomatic; 13% were class 3; and 2% were class 4. The researchers performed a multivariable, propensity-matched analysis to assess the association of NYHA class with cardiac structure and function as well as postoperative outcomes. Class 2 patients were slightly older with higher right heart pressures, more atrial fibrillation, larger left atria, and reduced left ventricular function compared with class 1 patients. Class 3 and 4 patients were worse off than class 1 and 2 patients in all of these measures. However, Gillinov noted that the size of the left ventricle was fairly consistent and independent of NYHA class.
Overall hospital mortality was 0.37% but was particularly high in NYHA class 4 (5.1%). For NYHA classes 1 to 3, hospital mortality rates were 0.29%, 0.20%, and 0.67%, respectively (p for trend 0.004). Long-term survival progressively diminished with increasing NHYA class, but the matched analysis showed that these differences were primarily due to differences in left-ventricular function and the comorbidities that accompany increasing NYHA class.
There was no difference in average length of hospital stay between classes 1 and 2—six days—and the average length of stay for patients in classes 3 and 4 was about seven days.
Asymptomatic patients were simpler to operate on because they were less likely to have anterior bileaflet prolapse and less likely to have mitral calcification, Gillinov said. He suggested that there may have been a tendency for surgeons to wait until the valve degenerated enough to produce symptoms, which, unfortunately, reduced the chances the patient’s valve could be surgically repaired instead of completely replaced. Surgical repair was successful in 96% of class 1 patients, 93% of class 2, 86% of class 3, and 85% of class 4 (p<0.0001).
“What we can conclude from this [study] is that development of even mild symptoms has no survival impact but is associated with changes in cardiac structure and function that we think are likely deleterious,” Gillinov said at the STS conference. “Our inference is to continue to recommend and be aggressive about early surgery in asymptomatic patients with severe degenerative mitral-valve disease if we can provide a very high repair rate, greater than 90%, and a very low operative risk, well under 1%.”
“If you’re asymptomatic, regardless of age, within reason, we can make you live longer and better by fixing your valve,” he concluded.
Is it worth the risk?
Dr Robert Siegel (Cedars-Sinai Heart Institute) disagrees with the researchers’ conclusion that the class 1/asymptomatic patients were the best candidates for mitral-valve surgery, arguing that the data support not operating on the patient until or unless they have reached class 2.
He points out that, in the study, the hospital mortality was actually worse for patients in NYHA 1 vs than patients in NYHA class 2, 0.29% vs 0.20%. By not undergoing surgery while in class 1, patients avoid the risk of surgical mortality without adding any change in long-term survival. “I don’t want to die if I’m asymptomatic and don’t need surgery,” he said. “Patients in class 2, which is already an indication for surgery, did just as well—certainly not worse and maybe even better—than the class 1 patients. So why not wait until your patient has symptoms in class 2? You don’t lose anything.”
Also, because all of the patients were treated at the Cleveland Clinic, the hospital mortality rates in the study are probably much lower than they would be in the “real world”—as high as 2% for mitral repair and 5% for mitral-valve replacement, according to the STS database, Siegel said. In addition, in the study, the surgeons were able to repair the valve in almost all of the class 1 and 2 patients and in more than 80% of the class 3 and 4 patients, but STS data suggest only about half of the patients undergoing mitral-valve surgery end up with mitral-valve repair, and thus about 50% of patients have mitral-valve replacement. It is possible that many of these valves could be repaired at the top surgical centers specializing in mitral-valve repair, Siegel said.
He also pointed out that about 30% of repaired mitral valves will begin to leak within about 10 years, so delaying the repair in asymptomatic patients delays the emergence of a leak that much longer.
Study confirms guidelines
But by contrast, Dr David Bach (University of Michigan, Ann Arbor) also commenting on the study for heartwire, pointed out that the study doesn’t really “any surprising data, [because] the presence of symptoms is known to herald worse clinical outcomes after mitral-valve surgery.”
However, Bach said that the study’s finding that mitral-valve repair is less feasible among patients with more advanced mitral regurgitation is important. Insofar as repair is accepted as superior to valve replacement because it is more durable and/or does not require anticoagulation, “this might be another reason to consider earlier intervention for severe mitral regurgitation.

“Inasmuch as the presence of symptoms is an indication for intervention, neither current guidelines nor current practice support waiting for symptoms as a threshold for referral for mitral surgery for severe mitral regurgitation,” Bach said. “As such, these data do not support a dramatic shift in current indications for mitral-valve intervention as much as they underscore the risks associated with failure to adhere to current indications.
“However, caution should be taken in not pushing too far toward intervention on asymptomatic patients. There are no accepted indications for primary surgery—as opposed to a concomitant procedure during other cardiac surgery—for mitral regurgitation that is less than severe,” Bach warned. “In light of the quite subjective nature of determining mitral-regurgitation severity on any imaging modality, the clinician should be careful—while being aggressive with intervention and not waiting too long to refer patients for surgery—that mitral regurgitation truly is severe before considering intervention.”

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