SAN FRANCISCO – It’s been barely half a year since U.S. cardiologists and cardiac surgeons first became able to routinely offer operable, high-risk patients with aortic stenosis the option of transcatheter valve replacement, yet in the first few months the transcatheter approach quickly rivaled open surgery.
But for the time being in U.S. practice, transcatheter aortic valve replacement (TAVR) remains boxed into the high-risk niche, along with the subgroup of patients who are not suitable for open surgery, king of a pair of relatively small hills.
Mitchel L. Zoler/IMNG Medical Media
Dr. Friedrich-Wilhelm Mohr
And no matter how well TAVR performs in the current pair of trials that are comparing it with open surgical aortic valve replacement (SAVR) for intermediate-risk patients, it will remain relegated to niche status for years to come. That’s because roughly two-thirds of all operable patients with aortic stenosis who need valve replacement fall into the low-risk category, with a Society of Thoracic Surgeons (STS) risk score of less than 4%, which experts agree will remain SAVR’s exclusive territory for the foreseeable future.
The high-risk stratum of operable patients, which TAVR now dominates, constitutes about 10% of all patients who need a new aortic valve and can undergo open surgery, patients with an STS score greater than 8%. The intermediate-risk category – an STS score of 4%-8%, where TAVR now vies against open SAVR in two high-profile trials – makes up the final quarter of the operable-patient pie.
Within the high-risk and operable universe, TAVR’s rise has been meteoric, starting last October when the Food and Drug Administration gave Edwards, marketer of the SAPIEN valve system, approval for these patients. A small survey of operators from U.S. TAVR programs in March at the annual scientific session of the American College of Cardiology (ACC) revealed a uniform perception that by early 2013 a sizable majority of U.S. patients with severe aortic stenosis who are deemed operable and are at high surgical risk will wind up being treated by TAVR instead of SAVR. The cardiac surgeons who collaborate on TAVR seem to have fully conceded the advantages of TAVR for these patients.
"We generally go with TAVR. Most patients want it, and with the equivalence" in outcomes from the first PARTNER (Placement of Aortic Transcatheter Valves) cohort A (operable patients) trial (New Engl. J. Med. 2010:364:2187-98), "you usually go with the less invasive procedure," said Dr. Joseph E. Bavaria, professor of surgery and director of thoracic aortic surgery at the University of Pennsylvania in Philadelphia. The small number of high-risk patients who go to open surgery tend to be men, "because they do better with surgery, especially if their life expectancy is greater than 5-8 years," or patients with high stroke risk, Dr. Bavaria said in an interview at the annual meeting of the American College of Cardiology.
"Operable, high-risk patients get TAVR. I’m a surgeon saying that. I’ve already done the [PARTNER cohort A] trial, and I don’t want to do it again," said Dr. Michael Mack, a cardiothoracic surgeon at the Heart Hospital in Plano, Texas. "The results are the same [from TAVR and SAVR] at 30 days, 1 year, and 2 years, but boy do we beat up patients with open surgery. If it was my mom, she’d get TAVR," he said in an interview. "The tie goes to the less invasive treatment."
When high-risk, operable patients are seen by the heart team Dr. Mack works with, the only ones who go to SAVR are patients – generally men – who have a large aortic annulus and need a 29-mm-diameter valve, which is not available for the time being to U.S. TAVR patients; women with septal hypertrophy causing significant left ventricular outflow-tract obstruction; and the small percent of patients who opt for open surgery, usually because it’s the more established approach or because they fear a higher stroke risk from TAVR.
"The majority of high-risk, operable patients now go to TAVR; I think that’s pretty much true across the United States," said Dr. Jeffrey J. Popma, a cardiologist who does TAVR and is a professor of medicine at Harvard University in Boston.
Where TAVR stood in 2010 and 2011
How is TAVR performing? Performance can only be completely assessed months or years after the fact, so the impact that high-risk, operable U.S. patients received from TAVR’s use in routine practice in late 2012 and the first months of 2013 remains to be seen. The most recently treated patients now available for meaningful analysis in large numbers come from 2010 and 2011: new data reported at the ACC meeting from a U.S. program of continued TAVR access that began in late 2009 following the end of recruitment into the first PARTNER trial, and 1-year follow-up of nearly 14,000 patients who underwent TAVR in 2011 as part of routine practice in Germany and were entered into the country’s national TAVR registry.