Transcatheter aortic valve implantation in intermediate risk patients

Transcatheter aortic valve implantation (TAVI) has had a major impact on both morbidity and mortality in high-risk and inoperable patients with severe aortic stenosis. Robust evidence has supported widespread adoption in this patient group but uncertainty exists as to whether TAVI may also achieve clinical equipoise with surgical aortic valve replacement (AVR)  in lower risk groups.  In the industry sponsored PARTNER 2 trial, patients deemed at intermediate surgical risk (generally with an STS score between 4 and 8) were randomized to either TAVI with the SAPIEN XT valve or conventional surgery (bioprosthetic valve of operative choice).  In a study powered for non-inferiority, a total of 2032 patients at 57 North American centers were recruited with a primary end-point of all cause mortality and disabling stroke measured at 24 months.  TAVI was found to be none-inferior to surgical AVR at 2 years with respective event rates of 19.3% and 21.1% (HR, 0.89; 95% CI, 0.73 to 1.09; P=0.25). The rates of stroke (6%) and death (17-18%) were very similar between groups. When analyzing only those patients whom underwent TAVI via transfemoral access (76% of the total population), there was a signal that TAVI resulted in a lower incidence of the primary end-point of death or stroke (P=0.05). The non-transfermoral (alternative) access cohort had similar outcomes to the surgical AVR group.  TAVI patients were found to have a lower incidence of major bleeding, kidney failure and new onset atrial fibrillation as well as having larger aortic valve areas.  In the surgical AVR group patients had less paravalvular leak and fewer vascular complications.  Interestingly, the rate of permanent pacemaker implantation was similar between the two groups at less than 10% (P=0.17)

Conclusions

In this landmark study, patients with intermediate surgical risk had similar, and in some instances, superior outcomes with TAVI as compared to conventional surgical AVR.  As with PCI before it, the rise of minimally invasive valve replacement appears inexorable and is likely to change the landscape of cardiac intervention over the coming years as both technology and operator experience improves.  In fact, these data reflect a TAVI technology that has already been supplanted in clinical practice by a next generation technology in most countries.

 

Leon MB, Smith CR, Mack MJ, Makkar RR, Svensson LG, Kodali SK, Thourani VH, Tuzcu EM, Miller DC, Herrmann HC, Doshi D, Cohen DJ, Pichard AD, Kapadia S, Dewey T, Babaliaros V, Szeto WY, Williams MR, Kereiakes D, Zajarias A, Greason KL, Whisenant BK, Hodson RW, Moses JW, Trento A, Brown DL, Fearon WF, Pibarot P, Hahn RT, Jaber WA, Anderson WN, Alu MC, Webb JG; PARTNER 2 Investigators. Transcatheter or Surgical Aortic-Valve Replacement in Intermediate-Risk Patients. N Engl J Med. 2016 374(17)1609-20

 

Summarized by  James McCabe, MD