AT THE AATS MITRAL CONCLAVE 2017
NEW YORK (FRONTLINE MEDICAL NEWS) – An analysis of a Society of Thoracic Surgeons database has identified a significant increase in volumes for isolated mitral valve surgery and leaflet prolapse this decade, with a shift toward minimally invasive approaches, according to a study of trends in mitral valve surgery in the United States presented here at the American Association for Thoracic Surgery Mitral Conclave 2017.
James Gammie, MD, of the University of Maryland School of Medicine, Baltimore, reported on the analysis of the STS Adult Cardiac Surgery Database in which more than 90% of the adult cardiac surgery centers in North America participate.
The retrospective review involved 115,360 isolated mitral valve (MV) operations performed from July 2011 to September 2016, with or without tricuspid valve repair, ablation for atrial fibrillation (AF) or atrial septal defect. After exclusions, the analyzed data set included 87,214 cases along with a subgroup of 36,948 patients who had leaflet prolapse.
“Degenerative disease remains the most common reason patients are referred for surgery,” Dr. Gammie said, noting that 60.7% of patients with an identified etiology had degenerative leaflet prolapse (etiology was unknown in 31% of the patients in the dataset).
“The operative approach has changed and continues to shift toward a less invasive approach,” Dr. Gammie said. Overall, 74.1% of operations involved sternotomy, but only 67.5% of those in the leaflet prolapse subgroup, with less invasive operations comprising 23% of all operations and 29.1% of those in the leaflet prolapse subgroup. From 2011 to 2016, total mitral surgical volume grew at a rate of 1.1% annually, but the volume for isolated MV operations grew 4.4% annually while leaflet prolapse procedures increased 7.6% annually, Dr. Gammie said.
Dr. Gammie described surgeons’ decision to perform ablation for preoperative AF during MV surgery a “coin toss.” One-third (34%) had AF, but only 51.2% of patients with AF in the total cohort and 54.4% of those in the leaflet prolapse subgroup got ablation. The overall MV repair rate was 65% for the total cohort but 83% for those with leaflet prolapse. For those who had MV replacement, the share of bioprosthetic devices increased steadily through the study period, from around 65% to 75.8%, Dr. Gammie said.
In the leaflet prolapse subgroup, 96.1% had annuloplasty and 29.2% had artificial chords implanted, with an average of two chords per operation. “There’s an increasing use of artificial ePTFE chords,” Dr. Gammie said. He noted the leaflet prolapse subgroup was composed of low-risk healthy patients. The mean ejection fraction (EF) for the cohort was 57%, and 47% of patients had EF of less than 60%. The overwhelming majority of patients (88%) had Class I indications for surgery with the remainder having Class IIa indications.
Dr. Gammie noted a few other emerging trends of MV surgery during the study period. “Patients with functional mitral regurgitation are rarely referred for operation: these patients made up fewer than 5% of patients undergoing mitral valve operations during the study period,” he said.;
With regard to outcomes, Dr. Gammie said, “There remain substantial differences between repair and replacement.” Replacement had almost twice the rate of reoperation for bleeding than repair (4.1% vs. 2.1%) and renal failure (3.4% vs. 1.4%).
“We observed that a substantial number of patients have an unsuccessful attempt at mitral valve repair before undergoing replacement – 16 % of the overall replacement group and 27% of patients having replacement for degenerative leaflet prolapse,” he said. “This does not appear to penalize patients in terms of outcome.”
The rate of permanent pacemaker was also significantly higher in the replacement cohort, 9.8% vs. 3.8% for repair operations, as was operative mortality, 3.7% vs. 1.1%. Said Dr. Gammie.
“This is something to think about as we move to less invasive approaches and overall operative mortality remains over threefold higher for replacement than repair.”
The leaflet prolapse subgroup showed similar disparities between replacement and repair groups. “The increased application of repair when feasible will be of value to improve outcomes, as will referral of patients earlier in the disease process ,” Dr. Gammie said.
During the discussion, Ralph Damiano Jr., MD, of Washington University School of Medicine, St. Louis, questioned the accuracy of the STS database in reporting patients with AF. “The problem with the STS database was that many patients coded who had a history of AF, when you go back to try to find any documentation, they don’t have it,” Dr. Damiano said.
“In our own STS database, about one-third of patients who were coded as having AF had no evidence of it, and that’s why in our institution they don’t get treated.” He added, “I’m not that surprised at the low repair rate when the average surgeon in the United States does five mitral repairs a year.”
Dr. Gammie disclosed that he is a consultant to Edwards Lifesciences and has an ownership interest in Harpoon Medical. Dr. Damiano disclosed that he is a speaker for LivaNova and a consultant to and a research grant recipient of Atricure.
