Minimally invasive mitral valve surgery appears to be superior to conventional sternotomy

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Patients who underwent minimally invasive mitral valve surgery had a shorter length of stay in the intensive care unit and fewer transfusions compared with those who underwent conventional sternotomy, according to a retrospective database analysis.

The procedures had similar rates of mortality, stroke and other complications and total hospital costs.

Lead researcher Emily A. Downs, MD, of the University of Virginia, and colleagues published their findings online in  The Annals of Thoracic Surgery on March 31.

“[Minimally invasive mitral valve surgery] should be the preferred approach for isolated mitral surgical procedure in appropriately selected patients at centers demonstrating excellence in minimally invasive outcomes,” they wrote.

The researchers examined 1,304 patients who underwent mitral operations and concomitant atrial fibrillation ablation from Jan. 1, 2011, through June 30, 2014. They were all part of the Virginia Cardiac Surgery Quality Initiative, which includes data from 18 hospitals and 14 cardiac surgery practices and captures more than 99 percent of open heart procedures in Virginia. Patients were excluded if they underwent nonablation concomitant procedures or emergent procedures.

Of the 1,304 patients, 32.6 percent underwent minimally invasive mitral valve surgery, while the remaining 67.4 percent had the surgery performed by conventional full sternotomy. Patients undergoing conventional sternotomy were significantly older (mean age of 64 versus 59), were more likely female (50.7 percent vs. 39 percent), had a significantly higher body mass index (26.9 kg/m 2 vs. 25.6 kg/m 2) and were significantly more likely to have hypertension, diabetes, end-stage renal disease, chronic lung disease and congestive heart failure.

The researchers then propensity matched the two groups according to age, comorbidities and preoperative laboratory values. Each group had 355 patients.

The rates of operative death (1.1 percent) and stroke (0.9 percent) were the same in each group. Patients undergoing minimally invasive mitral valve surgery had significantly fewer postoperative transfusions (11.6 percent vs. 28 percent) and significantly more mitral valve replacements (83.1 percent vs. 72.7 percent). They also spent significantly fewer days in the hospital (4 vs. 5) and in the intensive care unit (24 vs. 29.3).

Minimally invasive mitral valve surgery took significantly longer than conventional sternotomy, according to the researchers.

They noted a few limitations of the study, including that they had incomplete data on the mitral pathologic process and the cross-clamp/myocardial protection strategy used in each operation. The study also was subject to inherent selection bias because of its retrospective design. The researchers also mentioned that they did not capture all of the minimally invasive mitral valve surgery strategies and cannot draw conclusions about a specific technique.

“Our conclusions about the advantages of minimally invasive mitral surgical procedure reflect the average outcomes of our regional database and are encouraging in that centers with a variety of volumes and experience levels are included, but we cannot categorically state that every institution performing minimally invasive mitral surgical procedure will observe the same outcome and cost benefits,” they wrote.