Surgical or Transcatheter Aortic-Valve Replacement in Intermediate-Risk Patients

Reviewed by Dr. Christopher B. Scoma
M.J. Reardon, et al. N Engl J Med. 2017 April; 376:1321-1331

SUMMARY
This multinational, randomized, non-inferiority clinical trial aimed to evaluate the safety of transcatheter aortic valve replacement (TAVR) as compared to surgical repair for the treatment of symptomatic, severe aortic stenosis in patients deemed to be at intermediate surgical risk (defined as 3-15% risk of 30-day surgical death). The study included 1660 patients (randomized across 87 centers) who were randomized to receive TAVR (n=864) or surgical aortic valve repair (n=796). The primary outcome was all-cause mortality or disabling stroke at 2 years. Secondary outcomes included major adverse cardiovascular and cerebrovascular events (MACCE), residual paravalvular aortic regurgitation, and atrial fibrillation. Exclusion criteria included recent myocardial infarction or stroke, left ventricular ejection fraction <20%, and presence of end-stage renal disease (GFR <20 mL/min).

Among patients who underwent TAVR, the incidence of all-cause mortality or disabling stroke was 12.6% at 2 years, as compared to 14.0% in those who underwent surgical repair (95% credible interval, -5.2 to 2.3%; posterior probability of noninferiority, >0.999). The incidence of MACCE in both groups was the same (18.6% in both groups at 2-years; 95% CI -4.2 to 4.2). TAVR was associated with lower incidence of atrial fibrillation (12.9% vs 43.4%, respectively; 95% CI -34.7 to -26.4), as well as lower incidence of post-operative acute kidney injury (1.7% vs 4.4%, respectively; 95% CI -4.4 to -1.0) compared to the surgical group. However, the TAVR group was shown to have a higher incidence of major procedure-related vascular complications (6.0% vs 1.1%, 95% CI 3.2 to 6.7) and residual aortic regurgitation at 1-year (5.3%, vs 0.6%, respectively; 95% CI 2.8 to 6.8) as compared to the surgical group.

COMMENTARY
The repair of severe aortic stenosis has classically been performed through surgical intervention. Transcatheter aortic valve repair initially emerged as a viable alternative for valvular repair in patients who were either not surgical candidates, or in patients who are deemed to be too high-risk to undergo surgery.1 It continues to seek to expand its role with the hope of helping patients to avoid major cardiac surgery where possible. This trial aims to re-assure clinicians that the TAVR procedure is no less safe than its open surgical procedure counterpart in select patient populations. This study suggests that, in patients who are considered intermediate risk for the surgical valve repair, the transcatheter approach is statistically non-inferior in its outcomes, specifically all-cause mortality and MACCE. The strengths of this study include the randomized multi-center approach with inclusion of >1,600 patients. One significant weakness of this study was the high withdrawal rate in the surgical group after randomization, which may have muddied the results (reported as intention-to-treat). Another weakness includes the relatively short follow-up (24 months), which may not have provided sufficient time to fully elucidate differences in long-term outcomes. Following the results of this cohort over the next few years will be important to better understand the long-term effects choosing the TAVR over surgical repair in patients with symptomatic, severe aortic stenosis.

REFERENCES
1. Smith CR, et al. Transcatheter versus Surgical Aortic-Valve Replacement in High-Risk Patients. N Engl J Med (2011). 364:2187-2198.

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