TAVR Appears as Effective as Surgical AVR for Combined Risk of Death or Disabling Stroke in Patients with Intermediate Risk Severe Aortic Stenosis

EBM Focus - Volume 11, Issue 20

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Reference - PARTNER 2 cohort A (N Engl J Med 2016 Apr 28;374(17):1609) (level 2 [mid-level] evidence)

  • Transcatheter aortic valve replacement (TAVR) is recommended for patients with aortic stenosis who meet the indication for AVR, but are not candidates for surgical AVR due to high risk of complications.
  • The PARTNER 2 trial found that TAVR is associated with a similar combined risk of death or disabling stroke compared to surgical AVR in intermediate risk patients with severe aortic stenosis, as well as reductions in major bleeding and new atrial fibrillation.
  • TAVR might be an alternative to surgical eligible patients with intermediate risk, but long term follow-up is needed to examine whether the benefits of TAVR persist.

The American College of Cardiology/American Heart Association recommends TAVR in patients with aortic stenosis who meet the indication for AVR, but are not candidates for surgical AVR due to high risk of complications (Circulation 2014 Jun 10;129(23):e521). In recent years, advancements in transcatheter valve systems and improved operator experience have led to increased use of TAVR in low and intermediate risk patients. However, only observational studies have examined this technique in low and intermediate risk patients thus far (Am Heart J 2012 Dec;164(6):910, Catheter Cardiovasc Interv 2015 Oct;86(4):738, Eur Heart J 2013 Jul;34(25):1894), warranting further investigations into its efficacy in this patient group. The Placement of Aortic Transcatheter Valves (PARTNER) 2 cohort A randomized noninferiority trial compared TAVR using a second-generation valve system to conventional surgical AVR in patients with severe aortic stenosis and an intermediate clinical risk (defined as 4%-8% risk of mortality within 30 days of surgery on Society of Thoracic Surgeons risk model).

Two-thousand thirty-two patients (mean age 82 years) were randomized to TAVR using the SAPIEN XT valve system vs. surgical AVR, and were followed for 2 years. Patients were assessed for TAVR access before randomization, with 76.3% suitable for transfemoral placement and 23.7% required transthoracic placement (transapical or transaortic access). The primary endpoint was a composite of all-cause mortality or disabling stroke (modified Rankin scale score ≥ 2 at 90 days after index event) at 2 years. Comparing TAVR vs. AVR, the primary outcome was observed in 19.3% vs. 21.1% (risk ratio 0.92, 95% CI 0.77-1.09, which met the noninferiority criteria of upper bound of 95% CI of the risk ratio< 1.2). In a subgroup analysis by potential TAVR access, the primary outcome was lower in patients suitable for transfemoral placement who had TAVR compared to AVR, but patients requiring transthoracic placement had (nonsignificant) higher rates of the primary outcome with TAVR compared to AVR. Other positive outcomes associated with TAVR included decreases in life-threatening or disabling bleeding, new atrial fibrillation, acute kidney injury, and hospital stay. However, TAVR was also associated with an increase in major vascular complications and nonsignificant increases in transient ischemic attack and aortic valve reintervention. No significant differences were found in all cause or cardiovascular mortality, any stroke, rehospitalization, myocardial infarction, new permanent pacemaker, endocarditis, or coronary obstruction.

This study indicates that TAVR may be associated with a similar risk of death and disabling stroke at 2 years compared to AVR in patients with intermediate-risk and severe aortic stenosis. This trial supports previous findings that major clinical outcomes with TAVR appear similar to AVR (J Am Coll Cardiol 2015 May 26;65(20):2184), and may turn out to actually reduce mortality and morbidity in patients in whom transfemoral approach can be used or in patients with high risk of major bleeding. Of interest, while the authors use the terminology “intermediate risk”, it should be noted that patients in this study were still considered in the highest risk quintile among patients considered for aortic stenosis surgery. Some additional limitations of the study include baseline differences in peripheral vascular disease and atrial fibrillation (both rates higher in the surgical AVR group), and a high number of withdrawals in both groups. Given the less invasive nature of the procedure, this study appears to expand the group of patients for whom TAVR may be preferred over surgical AVR. Additional follow up is needed, however, to see if TAVR is only providing a temporary solution, with a surgical AVR eventually needed, or whether the benefits persist on a long-term basis.

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